Advance Transportation Management Technologies (Abridged)

Advanced Transportation Management Technologies
Chapter 1. Introduction Chapter 2. Freeway Management Systems 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 2.11 Ramp Control Freeway Mainline Control Dynamic Roadway Control Priority Control for HOV Transportation Management During Reconstruction Detection Traffic Surveillance Dynamic Message Signs (DMS) Highway Advisory Radio (HAR) Communications In-Vehicle Navigation Systems 2-4 2-16 2-22 2-26 2-33 2-37 2-61 2-69 2-75 2-77 2-114 28 pages Chapter 3. Traffic Signal Control Systems 32 pages Chapter 4. Incident Management 19 pages Chapter 5. Electronic Toll Collection System 23 pages Chapter 6. Transits Management Systems 31 pages Chapter 7. Regional Multimodal Travel Information Center 8 pages Chapter 8. Integration of Systems 55 pages Chapter 9. Funding 9.1 9.2 9.3 9.4 9.5 ISETA NEXTEA Private Funding Potential Innovative Financing Case Studies of Financing Projects 9-4 9-10 9-38 9-40 9-49 20 pages 119 pages

FHWA/OTA © April 1997

Introduction

CHAPTER 1

Introduction

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Introduction

1.1 OFFICE OF TECHNOLOGY APPLICATIONS
The mission of the Office of Technology Applications (OTA) of the Federal Highway Administration (FHWA) is to ensure the timely identification and assessment of innovative research results, technology, and products, and the application of those that are determined to be of potential benefit to the highway community. The OTA works in all areas of highway technology, including asphalt and concrete pavements, structures, geotechnology, hydraulics, traffic operations and management, safety, and motor carriers. This office also includes activities related to the implementation of approximately 100 products from the Strategic Research Program (SHRP). Technologies and products identified through the OTA’s assessment are developed, implemented, and promoted with State and local agencies, private industry, universities, and others in the national and international highway communities. The OTA works closely with the FHWA program and field office staffs. In addition, the OTA is expanding its alliances with the State and local agencies, private industry, universities, and others to broaden the network through which technology can reach its users. The organizational structure of OTA consists of the director of the Office of Technology Applications, who serves as the principle advisor to the Associate Administrator for Safety and System Applications and by extension, to the Federal Highway Administrator on all technology assessment and deployment, Local Technical Assistance Program, and SHRP implementation matters pertinent to the FHWA’s objectives and programs. The director also participates fully in relevant FHWA policy determinations and directs all activities of the Office of Technology Applications. The OTA’s program, for the most part, is divided into four types of projects: application projects, demonstration projects, special projects, and test and evaluation projects. Technical activities are assigned to one of the categories depending on the stage that the technology is in and, if the technology is already developed, what technology transfer or marketing approach would be most useful in reaching a technology’s intended users. The OTA’s organizational structure reflects the broad range of activities represented in the other FHWA offices. It consists of three divisions and the SHRP Implementation staff:

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Engineering Applications Division administers a program that includes technical areas such as asphalt and concrete pavements; bridge design, construction, management, and protection; geotechnology; and hydraulics. Safety and Advanced Transportation Division administers a program that includes technical areas such as safety, highway design, traffic operations and control, and motor carriers. Technology Management Division crosses all technical areas in its technology assessment role and works with the office of International Programs in its technology transfer contacts. It provides fiscal, management, and publication support to the OTA, and similar assistance to program offices in relation to the applications program. The division also administers the Local Technical Assistance Program for the FHWA.

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Strategic Highway Research Program Implementation Staff serves as the liaison when the SHRP technology is identified for transfer to its users.

As mentioned, the four categories of OTA program activities are demonstration projects, application projects, test and evaluation projects, and special projects.

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Demonstration Projects - Efforts to nationally promote a proven material, process, method, equipment item, or other feature that FHWA has targeted for adoption by the highway community. Application Projects -Individual efforts to assess, refine, or disseminate an emerging technology. Such efforts may include contracts, regional or national seminars or workshops, specifications, notebooks or pamphlets, instructional/how-to guides, open houses, and focused clearinghouses that are not part of demonstration or test and evaluation projects. Test and Evaluation Projects - Efforts to evaluate innovative or emerging technologies that have been identified as having a great potential for use nationwide. Special Projects - Evaluation efforts of industry and the FHWA, in conjunction with interested States, to evaluate a material, process, method, or other feature. An effort begins with a technology sharing meeting, progresses through a work plan and several control experiments (or operational tests) to a closeout evaluation. These special projects can lead to a demonstration, test and evaluation, or a combination of the two types of projects.

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The OTA staff consists of approximately 45 persons, of whom about 36 are professionals and paraprofessional. The Advanced Transportation Technologies Team, which will manage this demonstration project, consists of a Team Leader, three highway engineers, three on-site engineering consultants, and one engineering technician.

Demonstration Project No. 105, Advanced Transportation Management Technologies
Technical assistance in the form of a demonstration project, Demonstration Project No. 105 (DP 105), will provide an opportunity for policy and decision makers from transportation agencies including State and local Departments of Transportation (DOTs), Departments of Public Works (DPWs), and Metropolitan Planning Organizations (MPOs) to become aware of the state-of-the-practice technologies available to assist them in corridor management. DP 105 will make top State and local highway managers, planning policy makers, and administrators aware of the significant role of these corridor management technologies in controlling congestion and improving mobility and safety. This demonstration project will be an effective method of providing a timely transfer of technology. In addition, there is a need for providing adequate technical assistance to operate and maintain these systems. DP 105 will focus on proven corridor management systems and will use information on existing and emerging technologies in the development of the educational and training material.

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Public/private partnerships have been formed between the Federal government and private industry to identify, acquire, and display the available technologies in terms of hardware and software used with existing and emerging technologies. The objectives of this demonstration project are: 1. To provide technology transfer on state-of-the-practice corridor management techniques/technologies to improve mobility and safety; 2. To develop an executive summary for top management, administrators, and planning policy makers to make them aware of the significant role of these corridor management systems in improving mobility and safety; and 3. To provide hands-on demonstrations on the state-of-the-practice hardware and software in corridor traffic management systems. Through the use of a workshop and hands-on simulation, DP 105 will present a comprehensive examination of the various components of a transportation-management system. These components, listed below, include management and control strategies of both freeways and related surface streets as an integrated system. DP 105 will show how a corridor fits into the larger regional picture. It will demonstrate the complexity of the interconnection among the various components and sections (including freeways and surface streets) of the region. A change or modification to one component or any one section of the system will affect traffic operations in another. DP 105 will demonstrate the ability to handle and coordinate freeway and arterial networks representing an entire region subject to traffic-management control. DP 105 will focus on the highway element of transportation-management systems consisting of rubber-tired vehicles only. This will include travel associated with the private automobile and other vehicle classifications, such as trucks and buses, on both freeways and surface streets. DP 105 encompasses the state-of-the practice techniques/technologies in corridor or regional management. It includes the development of interactive instruction for presentations to State and local DOTs, DPWs, and MPOs. Participants will be provided with the opportunity to observe and participate in discussions and operation of the corridor-management techniques/technologies as they relate to rubber-tired vehicles only. These technologies must be marketed and in service in the United States. The technology has to be proven and be currently available off-the-shelf. This demonstration project, DP 105, will utilize information available on existing transportationmanagement technologies and systems in use for the development of outreach and educational material for presentations. DP 105 is one of five Federal Highway Administration Technology Transfer demonstration projects that have toured or are touring the nation and are related to each other. Discussion of the other four follows.

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Other Related Demonstration Projects •
Traffic-Control Equipment and Software (DP 93). This was a two- to two-and-one-half day workshop on and hands-on demonstration of recently developed electronic traffic control equipment and software used at intersections. The project includes controller detectors, communications, preemption, test equipment, conflict monitors, closed-loop/distributed systems, centralized control systems, hybrid control systems, and other peripherals found in National Electrical Manufacturer’s Association (NEMA) and Type 170 cabinets. Twenty-five manufacturers and vendors provided technology to be displayed in a 48-foot tractor/semitrailer. The presentations emphasized the benefits of adopting and implementing more reliable and powerful traffic-control systems to reduce urban congestion. The project began a nationwide tour in January 1993 and concluded in July 1996. It has been presented to managers, traffic engineers, and traffic-signal technicians from city, county, and State transportation agencies from 49 States, Puerto Rico, and the District of Columbia. These jurisdictions control the majority of the nation’s signalized intersections, many of which are expected to be improved because of the information presented in this demonstration project. The presentation was given to representatives from equipment manufacturers that supply about 85 percent of the traffic-control technology in the United States. Initial response from participants has been overwhelmingly positive. • Incident-management Workshop (DP 86). This is a two-day workshop that demonstrates the concepts of incident management. It reaches people from many different disciplines and agencies, such as police, fire, State and local highway, towing, and media, who respond to incidents on freeways and surface streets. DP 114 will not deal with any of these components of incident management. Advanced Motor Carrier Operations Technologies (DP 111). The goal of DP 111 is to demonstrate new technologies and programs that enhance motor carrier safety and productivity. The project will focus on three themes: administrative technology applications, in-vehicle technology applications, and roadside technology applications. The mechanism for this demonstration will be a mobile exhibit housed in an expandable trailer. Equipment obtained on loan from vendors will be displayed in a hands-on format and kiosks containing product, service, and program information will be provided in the trailer. Short presentations and workshops will be presented to address the technological and institutional barriers that hinder the implementation and use of new technologies. The primary target audiences of DP 111 are the enforcement community, the trucking industry, and truck drivers. The demonstration will be taken to truck shows, national and regional conferences and symposiums, and to sites in States across the country where safety and weight enforcement agency personnel can be reached. Integrated Information Transportation system (ITIS) (DP 113). ITIS is a demonstration project designed to showcase the benefits of combining highway, transit, and intermodal-related information systems into a single information system architecture. This is a two- to three-day workshop and hands-on demonstration of the various methods and technologies that an agency can utilize in building an ITIS. The process implies at least three kinds of integration; institutional, process or information flow, and technological. It will assist management in determining at what point they

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are in the integration process and what needs to be further accomplished. The methods will include business process reengineering, total quality management, and adoption of standards. The tools and technologies to be discussed/demonstrated include data warehousing, client/server architecture, and Intranet. This represents a management vision of a new framework for doing business.

1.2 BACKGROUND
Congestion on the Nation’s urban freeways and arterials has significantly worsened during the past few years. Delay due to traffic congestion is projected to increase fivefold from 1984 to 2005. As congestion on urban freeways and arterials is increased, an increase in accident potential, undesired long delays, adverse pollutants, increased operating costs, and adverse sociological effects results. Numerous transportation-management systems have been developed and implemented in lieu of significant new roadway construction. These systems are used as remedial measures for freeway and arterial congestion and improving traffic operations in corridors. A “corridor,” as used in this context, comprises, in addition to the freeway and its ramps, freeway frontage roads, arterial streets, and cross streets that are links between the freeway ramps and the arterials. Freeway corridors comprise the key components of an overall regional multimodal transportation system. Corridor traffic management consists of monitoring and controlling the actual conditions on the corridor system in a manner that will maximize the use of the existing roadway system. Strategies used to manage corridors include ramp metering and control, freeway-to-freeway metering and control, priority control, incident management, freeway surveillance, driver information, electronic toll collection, and work zone traffic management. Since 1990, there has been a strong emphasis on the development of enhanced and advanced technologies to bring greater efficiency to our transportation systems. This is part of the initiative for Intelligent Transportation Systems (ITS) mandated by Congress as part of the Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA). The goal is to create efficiencies within the transportation infrastructure that will mitigate congestion and improve safety and, at the same time, reduce the need to build more lanes of highway. ITS has been developed and advanced traffic management and control efforts will continue to escalate so as to provide remedial measures for traffic congestion and options for improving traffic operations. ITS includes a wide variety of current and evolving technologies that, when effectively integrated and deployed, offer a number of benefits including more efficient use of energy resources and significant improvement in safety, mobility, accessibility, and productivity. In the past, ITS technologies were represented and structured around a set of user services. There were 29 user services, listed below, defined for the ITS program. The purpose of defining user services was to relate ITS strategies and technologies to specific user needs. User services represented a customer orientation rather than a facility or technology orientation. These user services follow:

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Travel and Transportation Management • • • • • • En-route driver information Travel services information Traffic control Route guidance Incident management Emissions testing and mitigation

Travel Demand Management • • • Pretrip travel information Ride matching and reservation Demand management and operations

Public Transportation Management

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En-route transit information Public transportation management Personalized public transportation Public travel security

Emergency Management

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Emergency notification and personal security Emergency vehicle management

Advanced Vehicle Control and Safety Systems

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Longitudinal collision avoidance Lateral collision avoidance Intersection collision avoidance Vision enhancement for crash avoidance Safety readiness Precrash restraint deployment

Introduction

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Automated highway systems

Electronic Payment Services Commercial Vehicle Operations

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Commercial vehicle electronic clearance Automated roadside safety inspection Commercial vehicle administrative processes On-board safety monitoring Freight mobility Hazardous material incident response

A wide variety of ITS technologies has been developed and tested. Most have exhibited the potential for significant benefits, yet few have been deployed extensively to date. The desire to accelerate deployment of these technologies prompted the U.S. Department of Transportation (USDOT) to establish, on January 10, 1996, a national goal: “To build an intelligent transportation infrastructure across the United States within a decade, to save time and lives and improve the quality of life for Americans.” The intelligent transportation infrastructure can pertain to the following components: • • • Metropolitan Areas (Operation Timesaver Focus) Commercial Vehicle Operations Rural Areas

Infrastructure components are essential to each area and by nature, infrastructure underpins all areas. However, the rest of this document concentrates on the metropolitan component of the infrastructure. It is in these metropolitan applications that the elements of the intelligent transportation infrastructure, as defined below, will be referenced. The creation of the national intelligent transportation infrastructure has reclassified the ITS technologies into elements that are both stand-alone and components of a larger ITS platform. Each element of the infrastructure can be deployed on its own merits. If deployed as an integrated system, however, the performance of these technologies would be enhanced. A freeway-management center would be able to talk to and share information with a traffic-control center. This information would help that center manage its system better without necessarily giving up authority and control. Up-todate (real-time) information passed on to transit systems, multiple management and control centers, emergency vehicles, etc., will enhance operations of those recipients. Through the intelligent transportation infrastructure and vision of the USDOT, successful traffic- and transportation-management programs will be deployed throughout the country. Such efforts will
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create the platform needed for these intelligent transportation technologies to effectively monitor, manage, control, and operate traffic on the Nation’s freeways and surface streets. As this platform is being implemented across the nation, there will be an increasing need to fully understand, evaluate, and optimize traffic flow patterns and to maximize the roadway throughput. There will be an enormous need for dynamically modifying signal timing and patterns in response to changing traffic demands and real-time traffic data. Equally important will be the need for integrated freeway-surface street systems with various control and management strategies.

1.2.1 METROPOLITAN INTELLIGENT TRANSPORTATION INFRASTRUCTURE
The nine elements that make up the metropolitan intelligent transportation infrastructure follow:

Freeway-Management Systems
Real-time information about traffic flow and roadway conditions is key to managing the roadway network in a proactive manner. Methods for monitoring freeway conditions include inductive-loop detectors, video cameras (with and without signal processing capability), and microwave radar and ultrasonic monitors. These sensors provide occupancy, presence, count, and in some cases, speed and queue length data. Other sources of information on the freeway include the traditional inputs from police and maintenance personnel as well as increasing numbers of cellular phone reports from drivers. Information collected by the freeway-management systems can also be used by the other intelligent transportation infrastructure elements. Relevant information can be made available to support incident management and congestion mitigation activities on the freeway and to allow coordination of these actions with adjacent traffic-signal control systems. With video coverage of incidents on the freeway, the incident-management team can determine the severity and type of incidents that have occurred and can direct the appropriate resources to the scene. This permits both faster response and better utilization of the incident/emergency response resources, through a tailored response. The freeway-management system(s) include(s) a Freeway Management Center (or multiple centers when responsibility for the freeway system is shared by more than one jurisdiction) and information links to the Regional Multimodal Traveler Information Center and other transportation-management and control systems in the metropolitan area. These capabilities can provide, or be enhanced to provide, for the coordination of emergency response and incident management, and to support the management of special-event situations. Examples of integrated/cooperative management include regular analysis and updating of control and incident response strategies and coordination with other local traffic-management systems in the area for handling special events. Deployment objectives: • • Provide critical information to travelers through infrastructure-based dissemination methods, such as variable message signs and highway advisory radio. Monitor traffic and other environmental conditions on the freeway system.

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Identify recurring and nonrecurring flow impedimentso that short-term and long-term actions can be taken to alleviate congestion. Implement various control and management strategies (such as ramp metering and/or lane control, traffic diversion). Use probe vehicles as an additional sensor for collecting real-time traffic information.

Traffic-Signal Control Systems
Signaling systems that react to changing traffic conditions are an important element in improving transportation system efficiency. To be effective, advanced signal-control systems require an accurate current picture of the traffic flow and status on the roadway network. This information consists of real-time inputs from traffic sensors (inductive loops, video cameras, etc.), status and incident reports from police and cellular call-ins, etc. Historical demand information, such as time-of-day specific data would, at a minimum, permit the establishment of separate time-of-day signal-control strategies. Advanced signal systems automate the use of real-time traffic flow information to change the signal timing to efficiently accommodate traffic demands on all streets. State-of-the-art traffic signal-control systems are capable of dynamically modifying signal timings in response to changing traffic demand. They coordinate operation between adjacent signals to maximize the roadway (network) throughput. Coordination of adjacent signals allows the traffic manager to establish timing that moves vehicles through selected portions of the traffic network with less delay. At a minimum, these coordinated signal-control systems can provide for the selection of several timeof-day or special signal-timing patterns that can optimize operations along major arterial routes and over traffic networks. When part of an integrated intelligent transportation infrastructure, traffic-signal control can give priority to transit or emergency vehicles. These “open-architecture” hardware/ software systems are designed to be upgraded in capability, enabling relatively inexpensive installation of improved products. This open-architecture approach also supports the potential extension and integration of capabilities, such as coordinated operation with adjacent freeway and arterial systems. The National Transportation Communications for ITS Protocol (NTCIP) is being developed to support interoperability and interconnectivity of traffic control and ITS devices and support capabilities such as variable message sign control, camera control, vehicle classification, and general purpose data collection and device control. The various signal systems in a region should be capable of electronically sharing traffic flow information with the signal systems of adjoining jurisdictions in order to provide metropolitan-wide signal coordination. This information sharing supports coordination of traffic-signal systems along major corridors, and results in smooth traffic flows across jurisdictional boundaries. Deployment objectives: • • Deploy signaling systems that react quickly to changing traffic conditions. Collect and process real-time traffic information to provide up-to-date status of the transportation system.

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Install automated tools that take all traffic data into account and provide the traffic manager with a clearer picture of the status of the transportation system. Deploy modular systems that facilitate future upgrades and allow addition of new capabilities as they become available.

Transit-Management Systems
On-time performance is a critical factor in the public’s decision to choose transit as a mode of travel. Transit fleet management includes hardware/software components on buses and in dispatching centers, radio communications systems, and operations and maintenance facilities and personnel. Depending upon the specific needs of the jurisdiction’s fleet-management system, additional capabilities could be considered such as automatic vehicle location, advanced voice and data communications, automatic passenger counting, driver information (voice and visual), vehicle diagnostics, geographic information system databases for schedule management and emergency response, as well as computer-aided dispatching. These systems reduce cost by improving efficiency, while also providing better information to travelers. Advanced fleet-management systems, which include Automated Vehicle Location Systems, provide reliable bus position information to the dispatcher. With computer assistance, the dispatcher can compare the vehicle’s actual location with schedule information to track schedule adherence and, when necessary, take corrective actions to either get the vehicle back on schedule or to dispatch additional resources to cover the route. This function could be performed manually by the dispatcher or automatically, depending upon the level of automation. In addition, any pertinent schedule information would be disseminated in near-real-time to the traveler, either via kiosks or at home or the office. This information can be used by travelers in conjunction with information from other sources, and allows trip planning to include mode selection. The system can be enhanced to provide a display of information on routes and schedules for transit passengers on the vehicle. Other enhancements include in-vehicle sensors to monitor information such as passenger loading, fare collection, vehicle diagnostics, etc., to support efficient management of the transit system. In the event of an emergency, the dispatcher can notify the police or other support services of the situation and direct the responding authorities to the exact location of the incident. Information links from transit management to and from freeway- and signal-control functions can be valuable, as when a transit vehicle may require priority at signalized intersections to better meet route schedules. Deployment objectives: • • • • •
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Provide real-time, accurate transit information to travelers. Monitor the locations of transit equipment so as to provide more timely information on arrival times. Optimize travel times for transit vehicles. Support flexible routing of transit vehicles. Support automated maintenance monitoring of transit vehicles.

Introduction

Incident-Management Programs
Rapid and effective response to incidents is a key factor in saving lives and reducing travel delay. Many metropolitan areas have programs for quickly identifying and responding to incidents that occur on freeways and major arterials. The objectives are to rapidly respond to incidents with the proper personnel and equipment, to aid crash victims, and to facilitate the rapid clearance of the incident from the roadway. Timely execution of these activities saves lives while minimizing the buildup of queues and reducing the delays and frustrations of the traveling public. In this manner, the involved public agencies and individuals can satisfactorily meet their requirements and responsibilities. To accomplish incident management, real-time input from the freeway and arterial surveillance systems and the agencies responsible for managing them is critical. The various jurisdictions and agencies responsible for operations and enforcement in the metropolitan area work together to develop policies and operating agreements that define specific responsibilities for all aspects of incident management, including detection, verification, response, clearance, scene management, traffic control, and information dissemination. These multi-jurisdictional operating agreements ensure routine cooperation, coordination, and communications among all agencies, including law enforcement, fire, ambulance, highway traffic control and maintenance, environmental (as well as HAZMAT response teams) and other public agencies, as well as private towing services. Improved surveillance, augmented by rapid and accurate reporting of incidents, allows the rapid dispatch of appropriate equipment and personnel to the incident scene. Availability of accurate and timely incident information to the traveling public will further help reduce delays for drivers and transit riders. Use of a common regional digital map system by the various traffic and incident-management organizations will allow the incident-management team to better locate the reported incident, and will facilitate coordination among the several agencies involved in the incident response. Deployment objectives: • • • • Coordinate incident management across regional boundaries to ensure efficient and sufficient response. Use traffic-management capabilities to improve response times. Use on-board moving map route guidance equipment to assist incident response vehicles (e.g., ambulances and tow trucks). Reduce traveler delays due to incidents.

Electronic Toll-Collection Systems
Electronic toll collection reduces delays at toll plazas and operating costs of toll agencies. Electronic toll-collection systems are in operation within or around a number of metropolitan areas (and on segments of rural interstate systems) for automated toll collections. The systems include hardware and software for roadside and in-vehicle use, including payment cards or tags, and a communications system between the vehicle and the roadside. Toll payment is processed as the vehicle passes the toll station at a safety speed, thereby decreasing delays and improving system productivity.

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The system may include any combination of debit, credit, or stored value toll tag capability. Electronic toll-collection systems can be installed in various configurations, including mainline barrier plazas and systems where tolls are based on entry and exit points. Specific functional components of the system will include automatic vehicle identification, automatic determination of toll amount for differing classes of vehicles, automated enforcement of toll violations, and flexibility in financial arrangements (e.g., prepaid debit tag, payment cards). Deployment objectives: • • • • Reduce delays at toll-collection plazas. Reduce costs incurred by toll operating agency. Use common toll readers and tags to promote interoperability and reduce cost to the traveling public. Reduce handling and processing of money.

Electronic Fare Payment Systems
Electronic fare payment is both convenient for the traveler, who no longer has to fumble for exact change, and a cost savings for public agencies as they reduce manual handling and processing of money. Electronic fare payment systems will be in operations for collection of transit fares, parking lot fees, etc. The systems will include hardware and software for roadside, in-vehicle, and in-station use, and passenger/driver payment cards, which might include financial and card accounting systems. Electronic fare collection eliminates the need for travelers to carry exact fare (change) amounts and facilitates the subsequent implementation of a single fare payment medium for all public transportation services. These systems can include debit, credit, and/or stored value cards. Manual cash payment will continue to be supported. Eventually, travelers will be able to use standard financial institution credit cards to pay fares, much as they use a credit card at the gas pump today. Where appropriate, the system would facilitate private-company participation in programs where the employer subsidizes employee work-related travel on the transit system by directly depositing funds in employees’ transit accounts. Deployment objectives: • • Provide a single medium for paying travel-related fares and parking fees. Reduce the necessity for travelers and public agencies to handle money.

Regional Multimodal Traveler Information Centers
Providing timely travel information enables the public to make informed transportation choices. Metropolitan areas generally consist of multiple local jurisdictions and State level organizations, each responsible for providing some level of traffic surveillance, management, and control within their own jurisdictions. There is a need for an integrated source of roadway and transit information to provide
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Introduction

a comprehensive and integrated view of the roadway and transit conditions throughout the metropolitan area or region. Some users such as travelers, traffic managers and transit operators, and privatesector transportation-intensive businesses may use this information directly. Additionally, the private sector may elect to repackage this data and provide it as part of a marketable value-added service. The information repositories may be either centralized (i.e., housed and managed in one facility) or distributed (i.e., housed and managed in separate facilities) systems that directly receive roadway and transit information from the various roadway-surveillance systems and other information sources, either public or private. The intelligent transportation infrastructure will be capable of combining the data from the various sources; this allows packaging of the data in a variety of formats and providing the information to the users through different distribution channels, such as telephone voice and data services, radio and TV broadcasts, kiosks, computer-based (e.g., Internet) services, etc. Various options exist for either public or private-sector distribution of transportation information. Traveler information may be provided both directly to the public and to public or private-sector Information Service Providers (ISPs) that will supplement it with additional information, features, and services, and market the enhanced service products. Traveler information will be pulled from the various intelligent transportation infrastructure elements into a comprehensive regional information system, thereby facilitating the timely distribution of critical travel-related information to the traveler and transportation-related commercial users. Deployment objectives: • • • • Promote regional coordination in collecting, processing, and presenting traveler information. Collect and maintain comprehensive transportation data. Format/package this data in such a way that it will be meaningful to the traveler. Provide travel information to the public via a range of communication devices (broadcast radio, cellular telephone, the Internet, cable TV) for presentation on a range of devices (home/office computers, television, kiosks, radio).

Emergency Response Systems
Efficient management and use of emergency equipment is an important contributor to a safe transportation system. By equipping emergency response vehicles with automated vehicle location capabilities, these vehicles allowing dispatchers to know the locations of various pieces of equipment. Also, this location information can be used to get emergency vehicles to their destinations more quickly. Assignments of response vehicles to cover reported incidents can be based on vehicle location when, for instance, they are not at their station and the routing of these vehicles to the incident scene can be accomplished more effectively based upon accurate knowledge of current vehicle location and traffic condition. Use of a common regional digital map system by emergency services personnel will facilitate the coordination among the several agencies involved in the incident response and will improve their ability to respond to an incident. Emergency management services will also support automated MAYDAY capabilities, a concern in rural areas where accidents may be undiscovered for lengthy periods of time.
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Deployment objectives: • • • Use traffic-management capabilities to improve response times. Use on-board moving map route guidance equipment to assist emergency vehicle operators. Improve response to HAZMAT incidents by providing emergency personnel with timely, accurate information.

Rail-Highway Grade Crossing Systems
Railroad Grade Crossings are a special form of roadway intersection. The fact that one of the roads is a railroad with trains that travel at high speeds and can take up to a mile or more to stop poses special challenges. As a result, automated systems that allow the deployment of safety systems to adequately warn drivers of crossing hazards are now becoming available. The railroad grade crossing component eventually may support real-time information on train position and estimated time of arrival at Highway-Rail Intersections (HRI), real-time roadway traffic conditions at HRIs, proactive train control by train control centers, and interactive coordination between roadway Traffic Management Centers (TMCs) and train control centers. The railroad grade crossing component is expected to interface with planned and existing rail automation and safety systems including: • Advanced Train Control System (ATCS), which interacts with the Central Dispatch System; the OnBoard Locomotive System; the On-Board Work Vehicle System; and the Field System. These subsystems are interconnected by a Data Communications System. Vehicle Proximity Alerting System (VPAS), being tested as a potential communication system between trains and special classes of vehicles (e.g., school buses, large trucks, hazardous materials haulers, and emergency vehicles). Remote monitoring systems that will warn local rail dispatchers and/or TMCs of equipment failures at HRIs.

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Deployment objectives: • • • Improve and automate warnings at highway rail crossings. Provide travelers with advanced warning of crossing closures. Coordinate rail movements with the traffic-signal control system.

These systems identify recurring and nonrecurring congestion by collecting and monitoring real-time traffic information at a transportation management center. When appropriate, the TMC implements appropriate control and management strategies such as ramp metering, lane control, and priorityaccess control. The TMC provides critical traffic information to travelers via dynamic message signs, in-vehicle systems, highway advisory radio, or area-wide traffic information broadcasts. (The benefits of these systems can be found in Appendix A).

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Introduction

1.3 METROPOLITAN AREA INTELLIGENT TRANSPORTATION INFRASTRUCTURE MODEL DEPLOYMENT INITIATIVE
The objective of the Model Deployment Initiative (MDI) is to demonstrate four metropolitan area deployments of intelligent transportation system infrastructure that feature integrated, regional, multimodal, inter-jurisdictional transportation-management systems and traveler information services. The model deployment sites will also provide a setting for conducting rigorous evaluation of an integrated, metropolitan area ITS deployment. In addition to introducing the public to the benefits of ITS products and services, these four sites will serve as “showcases” for local decision makers across the United States and will support tours and seminars on the benefits of ITS infrastructure investments by both the public and private sectors. A more detailed description of each site’s model deployment project follows.

New York, New Jersey, Connecticut
The New York, New Jersey, Connecticut region’s model deployment initiative will showcase the intelligent transportation infrastructure to millions of commuters and travelers. No other region in the Nation can compare with the transportation volumes, modes, and complexities of this region. The implementation of the model deployment in the region will create a seamless, intermodal, multimodal, inter-jurisdictional intelligent transportation system that will dramatically raise the level of multimodalism in the region’s travel and greatly increase travelers’ access to real-time transportation information. SmartRoutes Systems will manage the traveler information component of the region’s model deployment, and will develop fee-paying clients for customized traveler information services. TRANSCOM, a coalition of 14 transportation and public safety agencies New York-New JerseyConnecticut metropolitan area, will be the lead organization. TRANSCOM was created in 1986 to provide a cooperative coordinated approach to regional transportation management. Other partners in the Model Deployment project include Lockheed Martin Federal Systems; PB Farradyne; JHK & Associates; Walcoff & Associates; Sam Schwartz Company; SmartRoute Systems; Navigation Technologies; MetroCommute Options Group; Metro Vision of North America; Shadow Broadcasting Services; CALSPAN.

Phoenix, Arizona
The Phoenix, AZ, AZTech Model Deployment features an integrated transportation-management system that coordinates the freeway and traffic-signal systems across jurisdictional boundaries. Etak and Metro Networks will manage the traveler information component of AZTech, and will promote business development of fee-paying clients. The Phoenix AZTech Model Deployment will integrate the Trailmaster Freeway-Management System, seven local area city Traffic-Signal Operations Centers along identified priority (SMART) corridors, city of Phoenix Public Transit Department management and dispatching system, Maricopa County Emergency Management System, Sky Harbor International Airport management/information system, and electronic fare systems associated with the Phoenix Public Transit Department and Sky Harbor International Airport for a truly regional, multimodal transportation-management system. The partners include the Arizona Department of Transportation; Maricopa County; Pima County; the cities of Phoenix, Tucson, Chandler, Glendale, Mesa, Scottsdale, and Tempe; Regional Public Transit
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Authority; Phoenix Transit Department; Maricopa Association of Governments; Pima Association of Governments; Arizona State University, Sky Harbor International Airport; TRW Transportation Systems; Scientific Atlanta, Inc.; and the Etak Team (Metro Networks, CUE Paging Corp., Differential Corrections Inc., SEIKO Communications Inc., SkyTel, Hewlett Packard, Fastline, Clarion, Delco Electronics, Volvo, IT Network, Delco Electronics, and AT&T.).

San Antonio, Texas
The objective of San Antonio’s model deployment initiative is to provide and integrate additional Antonio technologies into the existing TransGuide infrastructure. Intelligent transit management and emergency management systems will be integrated with TransGuide’s advanced traffic-management system. Intelligent transportation infrastructure components such as coordinated traffic-signal control, highway-rail intersection monitoring, and multimodal traveler information will also be incorporated. From the moment a visitor arrives in San Antonio, every possible activity will demonstrate the importance of ITS. For example, the airport baggage pickup will have information kiosks; taxi cabs and rental cars will be equipped with in-vehicle route guidance; bus stops next to major hotels will provide real-time information to riders; real-time traffic information will be available through the Internet and via UHF channel 54. The model deployment will expand the existing advanced traffic management system by developing and deploying 300,000 intelligent vehicle registration tags with embedded transponders and 83 Automatic Vehicle Identification (AVI) readers so that these vehicles may be used as traffic probes. The readers will provide accurate real-time travel speeds on freeway and major arterials throughout the metropolitan area. To protect individual privacy, the transponders will not be connected to the vehicle identification numbers or the drivers of vehicles. The partners in the project include the Texas Department of Transportation, VIA Metropolitan Transit Authority, city of San Antonio Department of Public Works, city of San Antonio Police Department, City of San Antonio Fire Department, Brooke Army Medical Center, Alpine Electronics Research of America, Zexel USA, ScientificAtlanta, Amtech Systems Corporation, and Southwest Research Institute.

Seattle TimeSaver
The Seattle TimeSaver Model Deployment will provide intermodal transportation management and integrated, real-time highway and transit information services for the entire Seattle metropolitan area. The Seattle TimeSaver Model Deployment project will implement and integrate seven features of the intelligent transportation infrastructure, including traveler information, transit management, electronic payment, traffic management and signal control, freeway management, and incident management. Multimodal congestion and transit information will be gathered and disseminated to all jurisdictions. Agencies will be able to independently control their respective systems, but will now have system-wide information available for their transportation-management decision making. The project will add realtime transit arrival information at Metro Transit stations, incorporate traveler information into Washington Information Network kiosks, a cable TV channel, and real-time traffic and transit information and video for TV-quality, Internet based traveler information for the public and for output to Information service providers using personal digital assistants, two-way pagers, in-vehicle navigation devices, and interactive TV. Etak and Metro Networks will manage the traveler information component of the seattle model deployment, and will promote business development of fee-paying clients.

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Introduction

The partners in the project include the Washington State Department of Transportation; Amerigon, Inc.; Arenel International, Inc.; Battelle Pacific Northwest Laboratories; Boeing Company; city of Bellevue Transportation Department; David Evans and Associates, Inc.; Etak Inc.; Fastline; IBI Group; Infrastructure Consulting Corporation; King County Department of Transportation; Metro Traffic Control, Inc.; Microsoft, Inc.; Overlake Transportation Management Association; Pacific Rim Resources, Inc., PB/Farradyne Inc., Rockwell International Corporation, Seiko Communications Systems, Inc.; TCI Telephony Services, Inc.; Puget Sound Regional Council; TRAC-UW; Transportation Division Seattle Engineering Department; US WEST Communications; University of Washington; Washington State Department of Information Services; Washington State Department of Transportation; Willows Corridor Transportation Partnership; and XYPOINT Corporation. (Case Studies of ITS deployments in major metropolitan U.S. areas can be found in Appendix B).

1.4 OBJECTIVES OF WORKSHOP
The objectives of this workshop are: • • • To provide technology transfer on state-of-the-practice transportation-management techniques/ technologies to improve mobility and safety; To make top management, administrators, and planning policy-makers aware of the significant role of these transportation-management systems in improving mobility and safety; and To provide hands-on training on the state-of-the-practice hardware and software in transportation-management systems.

1.5 PURPOSE OF THE REFERENCE MATERIAL
The purpose of the Participant Reference Material is to provide a comprehensive document for participants to be used as a reference in meeting the objectives of the workshop. It contains descriptions of the intelligent transportation infrastructure elements as well as the techniques/strategies and technologies of each component. It also includes the various emerging technologies.

1.6 ORGANIZATION OF THE REFERENCE MATERIAL
This reference material is generally organized around the intelligent transportation infrastructure elements. Each chapter is designed to reflect an element, addressing the various control and management components that make up the element. Each element component is further broken down into techniques/strategies and technologies that make up the component. For each component and/ or element, sources and Internet Web page addresses are provided for further discussion on the topic. Chapter 2 provides a complete description of the Freeway Management Systems element.

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Control components, including ramp control (e.g., ramp metering, ramp closure), mainline control (e.g., mainline metering, freeway-to-freeway metering), dynamic roadway control (e.g., lane control, dynamic speed control), and priority control (e.g., priority access control, HOV facilities) are discussed. Components on traffic management and vehicle monitoring and detection, including transportation management during reconstruction, surveillance, and detection, dynamic message signs and traveler information systems, vehicle user devices, and communications, are discussed. Chapter 3 provides a complete description of the Traffic-Signal Control Systems element. Components on traffic-signal control (e.g., isolated intersections, interconnected signals, central control, special control) and integrated freeway-surface street signal control (e.g., corridor control, areawide integrated strategy, diversion strategy) are discussed. In addition, the various technologies and systems used for signal control (e.g., closed-loop systems, real-time traffic adaptive signal control, SCOOT, traffic controllers) are presented. Chapter 4 provides a complete description of the Incident-Management Programs element. Components and techniques/strategies on management of incidents (e.g., detection, verification, response and clearance, driver information) are discussed. In addition, the various technologies (e.g., media, patrol, courtesy vehicles, aerial surveillance, CCTV, electronic sensors, DMS, HAR, commercial radio) used for the detection and verification of incidents are presented. Chapter 5 provides a complete description of the Electronic Toll-Collection Systems element. Components and technologies on electronic toll collection (e.g., optical/infrared, inductive loop, radio frequency, surface acoustical wave) are presented and discussed. Chapter 6 provides a complete description of the Transit-Management Systems element. Components and techniques/strategies on management of transit systems (e.g., automatic vehicle location, global positioning systems, on-board displays) are discussed. In addition, the various technologies (e.g., GPS satellite, differential GPS, dead reckoning) used for locating and tracking transit vehicles are presented. Chapter 7 provides a complete description of the Regional Multimodal Traveler Information Center element. Components and techniques/strategies for regional multimodal traveler information centers (e.g., single control center, multiple integrated control centers) are discussed. In addition, the various technologies (e.g., support systems, data management, dissemination of traveler information) are presented. Chapter 8 describes integration of systems, including the integration of the elements of the metropolitan intelligent transportation infrastructure. Chapter 9 describes funding resources including ISTEA, NEXTEA, and innovative financing strategies.

Return to Table of Contents
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Freeway-Management Systems

CHAPTER 2

FreewayManagement Systems

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Freeway-Management Systems

Freeway-management systems consist of strategies/system components and technologies combined to monitor, control, and manage freeway traffic more effectively. Strategies/system components and technologies in use include: ramp control (e.g., ramp metering, ramp closure); freeway mainline metering; freeway-to-freeway metering; reversible roadway control (e.g., lane control, variable speed control); priority control for high-occupancy vehicles (HOV) (e.g., priority access control, HOV facilities); transportation management during reconstruction; surveillance and detection (e.g., vehicle detectors, call boxes, CB monitoring, weather and environmental detection, overheight vehicle detection, automatic truck warning system, closed circuit television (CCTV); driver information systems (e.g., changeable message signs (CMS), lane-use control signals, highway advisory radio, call boxes and commercial telephone, in-vehicle systems); communications (e.g., media types, data and voice, video). Freeway management includes a Freeway Management Center (or multiple centers where responsibility for the freeway system is shared by more than one operating entity in a metropolitan area) and links to other ITS components in the metropolitan area. From these centers, personnel electronically monitor traffic conditions; activate response strategies; and initiate coordination with intraagency and interagency resources, including emergency response and incident-management providers. Closed-circuit television and an array of sensors (e.g., inductive loops, magnetometers, microwave radar, ultrasonic, infrared, video image processing, automatic vehicle identification, and passive acoustic devices) may be used to electronically monitor freeway conditions in real-time. Other sources of information concerning real-time freeway conditions include communications received from police and maintenance personnel, as well as cellular telephone reports called in from drivers. Traffic condition data are analyzed to identify the cause of a flow impediment and to formulate an appropriate response in real-time. Traffic control devices, such as ramp meters or lane control devices, may be proactively appplied to provide a better balance between freeway travel demand and capacity during congested conditions. Information may be provided to travelers through roadside traveler information devices such as dynamic message signs and highway advisory radio. Emergency response and incident-management providers may be notified to respond to nonrecurring incident events. Automatic Vehicle Identification (AVI) readers may be used to acquire probe vehicle data. SOURCES: • • • • • Traffic Control Systems Handbook, February 1996, Publication No. FHWA-95-032, Prepared for FHWA by Dunn Engineering Associates. Freeway Management Handbook, available spring 1997 FHWA Publication. Inform Evaluation, Vol. 1:Technical Report, 1991, Publication No. FHWA-RD-91-075. Inform Evaluation, Vol. 2: Executive Report, 1991, Publication No. FHWA-RD-91-076. Assessment of Advanced Technologies for Relieving Urban Traffic Congestion, December 1991, NCHRP Report 340.

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2.1 RAMP CONTROL
Entrance ramp control is the most widely used method of freeway traffic control. Its main objective is to limit the number of vehicles entering the freeway so that demand does not exceed capacity. The techniques/strategies for ramp control include ramp metering and ramp closure.

2.1.1 TECHNIQUES/ STRATEGIES
Ramp Metering
Ramp metering is a method of regulating or restricting traffic flow (limits the rate at which traffic can enter the freeway) in such a manner that capacity on the freeway, downstream of the on-ramp, is not exceeded. The calculation of metering rates depends on the metering purpose: congestion reduction or merging operation safety. a. Congestion reduction - If the metering system intends to reduce congestion, demand must be kept less than capacity. Metering rate is based on the relationship between upstream demand, downstream capacity, and the volume of traffic desiring to enter the freeway at a particular ramp. b. Safety - In many cases, ramp metering provides a smoother ramp merging operation. The primary merging safety problem involves rear-end and lane-change collisions caused by platoons of vehicles on the ramp competing for gaps in the freeway traffic stream. Metering breaks up these platoons and facilitates single-vehicle entry. The primary concerns of ramp metering are:
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Development of queues that back up onto the surface streets. Potential diversion of freeway trips to adjacent surface streets. Potential for increased violations of the ramp signal. To the public, ramp meters are often seen as a restraint on a roadway normally associated with a high degree of freedom—a new form of control where before there was none Even though a 2-to 5-minute wait at the ramp is more than compensated for by improved travel time on the freeway, motorists may only notice the waiting time on the ramp. A perceived advantage to longer distance communters at the expense of shorter distance travelers. Close-in residents, for example, may be deprived of immediate access to the freeway, while long-distance commuters can enter beyond the metered zone and receive all the benefits of ramp metering without ramp delays.

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Modes of Ramp Control There are two basic Modes of Ramp Control: restrictive and nonrestrictive metering.

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a. Restrictive Metering - By in this mode, the metering rate may be used to measurably reduce the average demand in order to prevent main roadway congestion or to alleviate the extent of existing congestion. The two constraints placed upon restrictive metering are: 1. The minimum metering rate that may be practically implemented while still retaining reasonable driver compliance (approximately 200 to 250 vehicles per hour); and 2. Available ramp queue storage space. b. Non-restrictive Metering - By this mode, the metering rate is increased to clear that portion of the queue extending beyond available ramp storage. In general, those ramps with adequate storage and one or more viable alternate routes will operate restrictively much more frequently than those with inadequate storage and poor alternate routes. Entrance Ramp Control There are three categories of entrance ramp control: pretimed, local actuated or traffic responsive, and system control. a. Pretimed - The simplest form of control, whereby the metering rates are fixed and change only in accordance with a preset time-of-day/day-of-week schedule (characterized by time-clock rather than traffic-responsive operation). This type of ramp metering is always recommended as a backup in the event of a communications, central computer, or other critical equipment failure. b. Local Actuated or Traffic Responsive - Ramp metering directly influenced by mainline traffic conditions. As occupancy levels on the mainline change, the metering rates on the ramp are changed accordingly. c. System Control - Ramp metering of a system of entrance ramps based on total freeway real-time traffic conditions. There is an interconnection of ramps that permits the conditions at one location to influence the metering at the other locations. Ramp Metering Strategies There are four basic strategies for ramp metering. These are clock time metering, demand/capacity metering, speed control metering, and gap acceptance merge-control metering. a. Clock Time Metering - A count down clock is assigned to each associated on-ramp and the signal is set to green each time the clock returns to zero. b. Demand/Capacity Metering - An evaluation of excess capacity immediately downstream of the metered on-ramp is performed at given intervals, based on counts from surveillance detectors on the freeway mainline.

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c. Speed Control Metering - The procedure for this form of ramp metering is similar to that of the demand/capacity strategy. A metering rate is established based on speed evaluations mode at a freeway link detector station. d. Gap Acceptance Merge-Control Metering - Ramp vehicles are released by the control signal so as to merge smoothly in gaps, expressed in units of time and detected in the outside freeway lane. SOURCES: • • • • • • • Ramp Metering Status in North America, 1995 Update, June 1995, Report No. DOT-T-95-17, Prepared by Gary Piotrowicz of FHWA and James Robinson of VDOT. Ramp Metering Design Guidelines, August 1995, Caltrans. Ramp Metering Policy Procedures, January 1995, Caltra. Route 85 Ramp Metering Plan, February 1995, Caltrans. Route 85 Ramp Meter Operation, Stage III, April 1995, Caltrans. Ramp Metering on Route 50 in Sacramento: First Year of Operation, Fall 1984, Caltrans. Evaluation of the Two-Capacity Phenomenon as a Basis for Ramp Metering, December 1990, Prepared by San Diego State University for Caltrans.

Ramp Closure
The most restrictive form of ramp control is ramp closure. This involves closing the ramp to traffic on a permanent or a short-term basis. Ramp closure has been used successfully in numerous cities in the United States and Japan (e.g., Houston, Los Angeles, San Antonio, Fort Worth). This is appropriate where:
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Ramps have inadequate storage. Freeway traffic is operating at capacity on a section before the entrance ramp. Ramp does not allow traffic to merge into the freeway traffic stream without considerable hazard or disruption. Ramp introduces serious weaving problems.

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2.1.2 TECHNOLOGIES
Ramp Metering
Hardware The following hardware technologies are used for the various categories of ramp metering.
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a. Left and Right Side Signals The most visible part of the ramp meter system is the ramp signal, usually pedestal mounted on both sides of the ramp. It consists of a three-section upper signal head and a two-section lower signal head. b. Signs There are two general types of signs used in ramp metering: warning signs and regulatory signs. 1. Warning Signs - The three main types of warning signs are: • “Signal Ahead” Warning Sign. Recommended when the ramp meter signal or queue is not within the field of view of oncoming traffic. This type of sign is installed near the entrance to the metered ramp facing each lane of traffic entering the ramp. “Meter On” Warning Sign. This is an internally illuminated sign mounted on a vertical post. When illuminated, it alerts drivers that a ramp entry to the freeway is ahead. The “Meter On” sign may be used instead of the “signal ahead.” “Prepare to Stop” Warning Sign. Recommended on high-speed ramps or freeway connectors where the approach speeds exceed 45 mph.

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2. Regulatory Signs - Several types of regulatory signs are available, including: • • • • “Stop Here On Red” Sign. This sign is located (mounted) below the signal indication and includes an arrow pointing down and to the right. “One Vehicle Per Green” Sign. This sign is located (mounted) approximately 50 ft.upstream of the stop bar. “Merge Left” Sign. This sign is usually installed at the point where a two-lane ramp begins to taper to a single lane. This sign is required whether a meter is present or not. “Right Lane Buses and Car Pools Only” Sign. These signs are installed at regular intervals in advance of the ramp meter if HOV bypass lanes are used on two-lane ramps. This is to indicate that the right lane is for HOV only.

c. Demand, Output, Merge, and/or Queue Detectors on the Ramp 1. Demand Detector - This type of detector is located just upstream of the stop bar on the entrance ramp. The signal will remain red until a vehicle is detected by the demand detector. 2. Output Detector - This detector is located just downstream of the stop bar on the entrance ramp. This detector is used to assure single vehicle passage. 3. Merge Detector - This detector is located in the merge area of the of the ramp and the freeway. This detector is used to detect vehicles attempting to merge into the freeway (detects presence of vehicles in the merge area).
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Advanced Transportation Management Technologies

4. Queue Detector - This detector is located on the ramp, well in advance of the ramp metering signal, near the frontage road. It is used to detect vehicles’ presence for extended periods of time (an indication of long queues on the ramp). It is used at locations where ramp backups may impact surface street operation. d. Upstream, Downstream, and Bottleneck Freeway Mainline Detectors In traffic-responsive metering, upstream demand and downstream capacity, as well as real-time measurements at the bottleneck, are necessary to determine metering rates. Traffic variables including volumes, occupancies and speeds are measured using upstream, downstream and bottleneck mainline detectors and are used to determine the relationship between the demand and capacity at different positions before and after the on-ramp. e. Local and Master Controllers With Interconnect and Cabinet With Amplifiers The controller cabinet is the roadside enclosure that houses the ramp meter equipment including the controller (e.g., Model 170 or 179 controller). The most common types of cabinets used in rampmetering operations are the California Type 334 cabinet and the New York Type 330 cabinet. The equipment housed in the cabinet includes: 1. Model 170 or 179 Controller. This controls traffic flow on the metered ramp. 2. Input File, Model 222 Detector Amplifiers, Model 242 and Model 252 Isolators. The input file is an electronic unit housing the input-detector (“loop”) amplifiers and AC and DC isolators. 3. Power Distribution Assembly (PDA)/Output File, Model 200 Load Switches. This is an electronic unit housing the load switches. 4. Auxiliary Output Device. The auxiliary output file is an electronic unit housing optional Model 200 Load Switches for the extra signal heads required on a three-lane metered ramp. 5. Terminal Boards. These provide the interconnection for the controller modem to the Traffic Operations Center. f. Central Processor at Control Center With Data Communication Interface

The equipment used in the Traffic Operations Center to monitor and control ramp meters includes: 1. Freeway Operations Status Display (FOSD). This usually consists of a large screen display system that is visible to all operators of the freeway system. It is usually color-coded where the different colors are used to indicate traffic speeds in real-time. 2. Central Processor. The centrol processor monitors overall freeway conditions and is used to execute the ramp metering program. 3. Communications Computer. This controls the modem links between the Traffic Operations Center and the metered ramps.
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Freeway-Management Systems

4. Computer Workstations. Computer workstations are used to control the ramp metering central processor. They are used to input data or modify parameters of the ramp-metering program. Software The following software technologies are used for the various categories of ramp metering: a. Automatic Rate Selection Method. Most traffic-responsive metering systems determine metering rate with this method. Metering rates are selected based on predetermined thresholds and rate tables. b. Control Emulation Method. This model, developed in Minnesota, emulates real-time selection metering using simulated freeway traffic. c. Predictive Algorithm Method. This method, based on statistical pattern recognition, anticipates bottlenecks one or two minutes prior to their occurrence. Time-series intervention analysis is used for implementation of the predictive algorithm method. d. Off-Line Simulation Modeling. Traffic simulation modeling is sometimes used by Traffic Operations Centers, off-line, to determine optimal metering rates based on simulations of different metering algorithms and their impacts on mainline and surface street operations. Such models include FREQ, INTRAS, FRESIM, CORFLO, FRED, etc. FRED (Freeway Ramp Evaluation Database) is used in the INFORM system.

Ramp Closure
Available hardware technologies used for ramp closure include: • • • • • Manually Placed Barriers (e.g., cross bucks, barrels, cones). Automated Barriers (e.g., gates similar to those used at rail-highway grade crossings). Warning Devices. Dynamic Massage Signs. Signals.

2.1.3 CASE STUDIES
A listing of Freeway Management Systems that include ramp-metering operations installed around the country can be found in Appendix A 1,2,3

Portland, Oregon
The first ramp meters in the Pacific Northwest were installed along a 10-kilometer section of I-5 in Portland in January 1981. The meters are operated by the Oregon Department of Transportation.
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Advanced Transportation Management Technologies

I-5 is the major north/south link, and is an important commuter route through the metropolitan area. This initial system consisted of 16 metered ramps between downtown Portland and the Washington State line. Nine of the meters operated in the northbound direction during the evening peak and seven controlled southbound entrances during the morning peak. The meters operate in a fixed time mode. There are currently 58 ramp meters, operating on five different freeways. Prior to metering, it was common along this section of I-5 for platoons of vehicles to merge onto the freeway and aggravate the already congested traffic. The northbound evening peak hour average speed was 26 kph. Fourteen months after installation, the average speed for the same time period was 66 kph. Travel time was reduced from 23 minutes (highly variable) to about 9 minutes. Premetered conditions in the southbound morning peak were much less severe hence the improvements were smaller. Average speeds increased from 64 to 69 kph resulting in only slight reductions in southbound travel times. Other results evaluated for the evening peak period include fuel savings and a before-and-after accident study. It was estimated that fuel consumption, including the additional consumption caused by ramp delay, was reduced by 2,040 liters of gasoline per weekday. There was also a reduction in rear-end and sideswipe accidents. Overall, there was a 43 percent reduction in peak period traffic accidents.

Minneapolis/St. Paul, Minnesota
The Twin Cities Metropolitan Area Freeway-Management System is composed of several systems and subsystems that have been implemented over a 25-year period by the Minnesota Department of Transportation (MNDOT). The first two fixed time meters were installed in 1970 on southbound I-35 east, north of downtown St. Paul. In November 1971, these were upgraded to operate on a local traffic-responsive basis and 4 additional meters were activated. This 8-kilometer section of I-35 east has been evaluated periodically since the meters were installed. The most recent study shows that after 14 years of operation, average peak hour speeds increase from 60 to 69 kph, or 16 percent faster than before metering. At the same time, peak period volumes increased 25 percent due to increased demand, the average number of peak period accidents decreased 24 percent, and the peak period accident rate decreased 38 percent. In 1974, a freeway-management project was activated on a 27-kilometer section of I-35 west from downtown Minneapolis to the southern suburbs. In addition to 39 ramp meters, the system included 16 closed-circuit television cameras, 5 variable message signs, a 2-kilometer zone of highway advisory radio (HAR), 380 vehicle detectors, and a computer control monitor located at the MNDOT Traffic-Management Center in Minneapolis. This project also included extensive “freeway flyer” (express bus) service, and eleven ramp meter bypass ramps for HOVs. An evaluation of this project after 10 years of operation shows that average peak period freeway speeds increased from 55 to 74 kph or 35 percent. During the same 10-year span, peak period volumes increased 32 percent, the average number of peak period accidents declined 27 percent, and the peak period accident rate declined 38 percent. More than one million dollars a year in road-user benefits are attributed to reduced accidents and congestion. This system also has positive environmental impacts. Peak period air pollutant emissions, which include carbon monoxide, hydrocarbons, and nitrogen oxides, were reduced by just under 2 million kilograms per year.
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More than 300 additional ramp meters were implemented from 1988 to 1995, and there are currently 368 meters in operation. Further projects are now in the design and construction phases. During the next five years, the plans are to complete the ramp metering system that will cover the entire Twin Cities freeway network. The success of the Twin Cities system has shown that the staged implementation of a comprehensive freeway-management system on a segment-by-segment, freeway-by-freeway basis, over a long period of time, is an effective way of implementing an area-wide program.

Seattle, Washington
In September 1981, the Washington State Department of Transportation (WSDOT) implemented metering on I-5 north of the Seattle Central Business District. Initially the system, named FLOW (not an acronym), included 17 southbound ramps that were metered during the morning peak, and 5 northbound ramps that were metered during the evening peak. Currently, the ramp metering system includes 54 meters on I-5, I-90, and SR 520. These meters are all operated by centralized computer control. Future expansion plans include additional ramp meters on SR-520 east of Lake Washington, all of I-405, and I-5 south of Seattle. One evaluation of the initial 22-meter system showed that between 1981 and 1987, mainline volumes during the peak traffic periods increased 86 percent northbound and 62 percent southbound. Before the installation of metering, the travel time on a specific 11-kilometer course was measured at 22 minutes. In 1987, the travel time for the same course was measured at 11.5 minutes. During the same six-year period, the accident rate decreased by 39 percent. A somewhat unique application of metering was implemented in Seattle an SR-520 in 1986. While diversion caused by metering is often controversial, one of the objectives of metering. SR-520 was to reduce commuter diversion through a residential neighborhood. The meters were installed on the two eastbound ramps on SR-520 between I-5 and Lake Washington. One of these ramps, the Lake Washington Boulevard on-ramp, is the last entry onto SR-520 before the Evergreen Point Floating Bridge. Because there were no bottlenecks downstream of this ramp, traffic would normally flow freely onto the bridge and beyond. Motorists, especially commuters from downtown Seattle, were using residential streets to reach the Lake Washington Boulevard on-ramp to avoid congestion on SR620. This on-ramp, however, was a major contributor to congestion on SR-520 because of the high entering volumes. By metering the ramp, it was anticipated that traffic diverting through the adjacent neighborhood from downtown would be discouraged by the delay caused by the meter. Motorists would instead use the Montlake Boulevard on-ramp which was also metered at the same time. An HOV bypass lane was also installed at the Montlake Boulevard on-ramp. Two other objectives of this project were to improve flow on SR-520 and to encourage increased transit use and carpooling. After four months of operation, an evaluation of this two-ramp meter “system” indicated a 6.5percent increase in mainline peak period volume, a 43-percent decrease in the volume on the Lake Washington Boulevard on-ramp, an 18-percent increase the volume on the Montlake Boulevard onramp, and a 44-percent increase in HOVs using the Montlake Boulevard on-ramp. Another indication of the effectiveness of the combination of the HOV bypass and the improved SR-520 flow is a decrease of 3 minutes in METRO (King County Department of Metropolitan Services) transit travel times for buses traveling from downtown to the east, and a 4-minute decrease for buses traveling
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Advanced Transportation Management Technologies

from University District to the east. The reliability of the bus travel times also improved and METRO adjusted the schedules for these routes accordingly. In 1993, the WSDOT implemented weekend ramp metering for the first time. Three ramps north of Seattle on southbound I-5 have been metered several hours due to heavy weekend volumes. Because of this success, in March of 1995, weekend metering was expanded to include four additional southbound ramps. In April of 1995, WSDOT began operating seven southbound I-5 meters during the evening commute. This is WSDOT’s first metering implementation in both directions of a corridor during the same peak period. The motivation behind this operational change is that the traditional reverse commute direction has become increasingly congested. Prior to this, metering along this section had operated southbound (inbound toward Seattle) during the morning commute and northbound (outbound) during the evening commute.

Denver, Colorado
The Colorado Department of Transportation activated a pilot project to demonstrate the effectiveness of ramp metering on a section of northbound I-25 in March 1981. The initial system consisted of five local traffic-responsive metered ramps operated during the morning peak on a 4.7 kilometer section of I-25 south of the city. Periodic evaluations revealed significant benefits. An 18-month study showed that average peak period driving speed increased 57-percent and average travel times decreased 37-pecent. In addition, incidence of rear-end and sideswipe accidents declined 5 percent due to the elimination of stop-and-go conditions. The success of the pilot project led to expansion of the system. In 1984 a central computer was installed and a system coordination plan that permits central monitoring and control of all meters. Since 1984, additional ramp meters have been added and today there are 28. In late 1988 and early 1989, a comprehensive evaluation of the original metered section was conducted. A number of changes occurred between 1981 and 1989, the most significant of which was the completion of a new freeway, C-470, which permitted more direct access to I-25 from the southwest area and generated higher demand for I-25. Volumes during the two-hour morning peak period increased from 6,200 vph in 1981 to 7,350 vph in 1989 (on three lanes). Speeds measured in late 1988 decreased from the original evaluation, but remained higher than the speeds before metering was implemented; 69 kph before, 85 kph after in 1981, and 80 kph in late 1988. The frequency of accidents during the morning peak period did not increase between the original evaluation and 1989, as a result, the accident rate decreased significantly because of the increased volumes. Rearend and sideswipe accidents decreased by 50 percent during metered periods. An interesting unplanned “evaluation” of the system occurred in the spring of 1987. To accommodate daylight savings time, all of the individual ramp controllers were adjusted one hour ahead. Unfortunately, the central computer clock was overlooked. The central computer overrode the local controllers and metering began an hour late. Traffic was the worst it had been in years. This oversight did have a bright side for the Colorado Department of Transportation: since the incident, the media have been even more supportive of ramp metering.

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In 1988, the Colorado Department of Transportation conducted a study to evaluate different levels of ramp metering control. The study compared ramp meters operating in local traffic-responsive mode versus meters operating under centralized computer control. The results showed that if local trafficresponsive metering could maintain freeway speeds of more than 90 kph, centralized control had little or no additional benefit. However, if local traffic-responsive metering was unable to maintain speeds near the posted speed limit of 90 kph, centralized control was very effective. Data showed speeds increased 35.5-percent, from 50 to 68 kph, and vehicle hours of travel were reduced by 13.1-percent. This evaluation shows the importance of implementing operating strategies that correspond to the needs of the freeway network.

Detroit, Michigan
Ramp metering is an important aspect of the Michigan Department of Transportation’s (MDOTs) Surveillance Control and Driver Information (SCANDI) System in Detroit. The SCANDI metering operation began in November 1982 with six ramps on the eastbound Ford Freeway (I-94). Nineteen more ramps were added on I-94 in January 1984 and three more in November 1985. An evaluation performed by Michigan State University for MDOT determined that ramp metering increased speeds on I-94 by about 8-percent. At the same time, the typical peak hour volume on the three eastbound lanes increased to 6,400 vehicles per hour from an average of 5,600 vph before metering. In addition, the total number of accidents was reduced nearly 50-percent and injury accidents were down 71-percent. The evaluation done by Michigan State also showed that significant additional benefits could be achieved by metering the three freeway-to-freeway connectors on this section of I-94.

Austin, Texas
In the late 1970s, in Austin, the Texas Department of Transportation implemented traffic-responsive meters at three ramps along a 4.2-kilometer segment of northbound I-35 for operation during the morning peak period. This section of freeway had two bottleneck locations that were reducing the quality of travel. One was a reduction from three to two lanes and the other was a high-volume entrance ramp just downstream of a lane drop. Metering resulted in an increased vehicle throughput of 7.9-percent and an increase in average peak period mainline speeds of 60-percent through the section. The meters were removed after the reconstruction of I-35 eliminated the lane drop in this section. This situation shows the versatility of ramp metering in that it can also be used effectively as a temporary solution. Austin is in the preliminary design stages and is expected to begin ramp metering again in about three years.

Long Island, New York
At the other end of the spectrum from Austin’s implementation is the INFORM (Information For Motorists) project on Long Island. The INFORM project covers a 34-kilometer-long by 8-kilometerwide corridor, at the center of which is the Long Island Expressway (LIE). Also included in the system is an east-west parkway, an east-west arterial and several crossing arterials and parkways, a total of 207 kilometers of roadways. System elements include 70 metered ramps on the LIE and the Northern State/Grand Central Parkway.

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In 1989 after two months of operation, an analysis of the initial metered segment was conducted. In the peak period, the study showed a 20-percent decrease in mainline travel time (from 26 to 21 minutes) and a 16-percent increase in average speed; from 47 to 56 kph. Motorists entering at metered ramps also experienced an overall travel time reduction of 13.1-percent and an increase in average speed from 37 to 45 kph. The maintenance of efforts (MOE) tests for this project include vehicle emissions. For this initial segment, the analysis indicates there was a 6.7-percent reduction in fuel consumption, 17.4-percent reduction in carbon monoxide emissions, 13.1-percent reduction in hydrocarbons, and 2.4-percent increase in nitrous oxide emissions. The latter is associated with the higher speeds. Initial observations of the effect of metering the INFORM project’s four-lane parkway indicates the benefits may be even greater than those achieved on wider freeways. Intuitively this makes sense because the impact of an unrestricted merge on only two lanes (in one direction) can be severe. A more extensive evaluation of the INFORM project was completed in 1991. Data from this study showed much more conservative results. It is believed that this study is more representative of the true traffic conditions. The main reason for this is related to the “queuing off” (shutdown of the meter due to excessive queuing) of the ramp meters. The original study did not include areas where metering was usually shut off due to heavy ramp volumes, while this study accounted for all ramps. This evaluation showed that while throughput had only increased about 2-percent, the average mainline speeds had increased from 64 to 71 kph, or about 9-percent. However, at two separate bottleneck locations, data showed increases of 53 to 84 and 53 to 89 kph, or gains of about 36 and 40percent, respectively. This evaluation also included calculation of a “congestion index.” This index is the proportion of detector zones for which speeds were less than 48 kph (30 mph). While no benefit was shown in the evening peak period, the morning peak period showed an improvement of 25percent in the congestion index. The accident frequency also showed encouraging improvement with a 15-percent reduction compared to the control section.

San Diego, California
In San Diego, ramp metering was initiated in 1968. That system, installed and operated by the California Department of Transportation, now includes 134 metered ramps on 110 plus kilometers of freeway. No detailed evaluations of metering have been conducted on the San Diego system since the early installations, but sustained volumes of 2,200 vph to 2,400 vph and occasionally even higher, are common on San Diego’s metered freeways. A noteworthy aspect of the program is the metering of eight freeway-to-freeway connector ramps. Metering freeway-to-freeway connectors requires careful attention to storage space, advanced warning, and sight distance. If conditions allow, freeway connector metering can be just as safe and effective as other ramp meters.

2.1.4 SUMMARY OF ENTRANCE RAMP METERING BENEFITS
Metering entrance ramps significantly improves mainline traffic flow. The preceding case study evaluations, as well as others, show metering consistently increases travel speeds and improves travel time reliability, both of which are measures of reduced stop-and-go, erratic flow. It should be emphasized that these benefits occurred even though in most instances mainline volumes had significantly increased. Metering helps smooth out peak demands that would otherwise cause the mainline flow
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to breakdown. A strong case can be made from the data reported that metering actually increases the throughput of a freeway. The data from Minneapolis, San Diego, Seattle, Detroit, and Denver shows mainline volumes well in excess of 2,100 vph per lane on metered sections, and sustained volumes in the range of 5-percent to 6-percent greater than on premetered conditions. Improved traffic flow, particularly the reduction of stop-and-go conditions, also reduces certain vehicle emissions. This has been shown in both the INFORM project and in the Twin Cities Freeway-Management System. The other direct benefit, but one that has not been fully quantified, is the reduction in accidents attributed to metering. The case studies presented in this report consistently show a reduction in accident rates of 24- to 50-percent. However, the benefits derived from accident reduction goes well beyond the direct costs related to medical expenses and vehicle damage. To illustrate, assume an accident blocks one lane of three at the beginning of the peak period an a freeway with a two-hour peak demand of 6,000 vph. Studies show an accident blocking one of three lanes reduces capacity by 50-percent. A 20-minute blockage would cause 2,100 vehicle-hours of delay, a queue more than 3 kilometers long, and take two-and-one-half hours to return to normal assuming there were no secondary accidents or incidents. Clearly the safety aspects of metering are a major benefit. Ramp meters, or flow signals as they are called in Houston, have been used to improve traffic flow for years. Cities like Seattle, Minneapolis, and Portland all have similar systems that have reported measurable improvements in traffic flow. In Portland, studies showed that flow signals increased average freeway speeds by 40 kph in just 14 months. In Seattle, freeway travel time went from 22 minutes to slightly more than 11 minutes after flow signals were installed. In Minneapolis, freeway travelers experienced a 38-percent reduction in the peak-period accident rate after flow signals were installed.

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2.2 FREEWAY MAINLINE CONTROL
Freeway mainline control is the regulation, warning, and guidance of freeway traffic in order to: achieve more uniform and stable traffic flow as demand for the facility approaches capacity; reduce the potential for rear-end collisions if congestion develops; facilitate incident management and recovery from congestion; divert freeway traffic to alternate routes to utilize corridor capacity; and change the directional capacity of the freeway by use of reversible lanes.

2.2.1 TECHNIQUES/STRATEGIES
Mainline Metering
Mainline metering is primarily used at locations approaching major traffic bottlenecks such as approaches to bridges or tunnels, and for regulating the number of toll booths that are open at any given time. By regulating the number of toll booths that are open at any given time, the traffic demand entering the freeway system via the mainline is controlled according to available freeway demand and capacity downstream. Another application of mainline metering is metering of the HOV lane. Certain locations in California meter the on-ramp HOV lanes at the same locations as the other lanes. In Seattle, WA, there is one metered HOV lane (northbound on-ramp to the I-5 express lanes) that operates in conjunction with the Metro bus tunnel on-ramp. Mainline metering has also been implemented on the east end of the San Francisco-Oakland Bay Bridge, where signals are placed over each of the 14 nonpriority westbound lanes at a point downstream of the toll booths, releasing vehicles to merge into five lanes on the bridge. Where congestion on the freeway cannot be prevented by entrance ramp control, mainline metering is installed on the mainline approach to the entrance ramp. Jacobson and Landsman suggest that mainline meters be installed on freeways approaching bottleneck locations where analysis indicates that improved traffic operations will result. They also suggest guidelines for mainline metering systems, including: • • • • Whenever possible, install meters at locations on roadways that are level or have a slight downgrade, so heavy vehicles can easily accelerate. Install meters where the sight distance is adequate for drivers approaching the mainline meter to see the queue in time to safely stop. Provide an HOV lane that allows HOVs to bypass the mainline meter traffic queue. The HOV lane should extend from the mainline meter upstream to the rear of the worst anticipated traffic queue. Installation of mainline metering in Washington State would require an extensive marketing and publicity campaign.

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SOURCES: • Case Studies of Freeway-to-Freeway Ramp and Mainline Metering in the U.S., and Suggested Policies for Washington State, January 1994, by Eldon L. Jacobson and Jackie Landsman, TRB paper.

Case Studies a. San Francisco The mainline metering facility on westbound I-80 at the San Francisco-Oakland Bay bridge is a unique system in that the meters are located just downstream of a 22-bay toll plaza. Westbound traffic approaching the San Francisco-Oakland Bay bridge passes through the toll plaza and is then metered so that the 22 lanes of traffic can be narrowed to four as efficiently as possible. HOT lanes are also provided that allow HOBS to bypass the traffic queues. Wait time at the meters can reach 30 minutes. However, with the meters off, queuing occurs on the bridge rather than at the meters, and the delays exceed those that occur when the meters are on. Public opinion of this metering has been quite good, considering the long delays. The mainline metering is operated during peak traffic periods, which vary, depending on traffic volumes. The meters are also operated outside peak periods whenever the traffic volume reached a preselected level or when an incident on the bridge blocks the traffic lanes. b. Hampton Roads Tunnel This tunnel, located in southeastern Virginia, provides the only connection between Hampton and Norfolk. Before mainline metering began in August of 1983, delays of up to two hours were not uncommon. The congestion in the tunnel caused cars to overheat and Carbon Monoxide (CO) levels to increase. The metering operation was commenced whenever traffic speeds in the tunnel dropped below 25 kph. As a result of metering, CO levels were reduced requiring less ventilation, and fewer vehicles overheated keeping lanes open and moving. The metering was an operational success. However, due to motorist complaints and a lack of political support, these meters have been removed. c. Baltimore Harbor Tunnel The Baltimore Harbor Tunnel was a test site used in the mid-1970s to study restricted flow on traffic facilities. The project involved implementing mainline metering 1,200 feet upstream of the tunnel portal. Metering was activated when flows became congested; this usually occurred at speeds between 32 and 40 kph. Results of the analysis showed increased speeds in the tunnel and capacity increases of about 10 percent per lane. Again, similar to the Hampton Roads situation, mainline metering was discontinued as a result of political pressure. Summary of Mainline Metering Often new and different traffic engineering techniques like mainline metering take time to catch on. This relates to taking the “let somebody else make the mistake first” position. However, to study the effects of mainline metering, agencies can look at unregulated conditions that exist. Two examples of
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unregulated mainline metering include, toll booths and incidents. Mainline toll booths act similar to meters in that there is a reduction in capacity because every vehicle must come to a stop. As seen in Chicago, after exiting the toll booths the freeway returns to freeflow conditions. Lane blocking incidents are also artificial reductions in capacity. Again, after passing the scene of the incident, traffic usually returns to free-flow conditions. It shouId be noted that even though the end results are similar to mainline metering, unregulated metering creates larger and unnecessary queuing. This is because these situations are not being managed in an organized manner, as would be the case with metering. Freeway bottlenecks can occur for a number of reasons. Commonly, they occur at geometrically constrained locations where tunnels and bridges exist. At these situations, mainline metering is a viable traffic management tool that has been proven to increase throughout and improve flow conditions. However, mainline metering is the most restrictive form of ramp metering. For this reason it suffers from a lack of political and public support, making mainline metering difficult to implement (Gary Piotrowicz and James Robinson, 1995).

Freeway-to-Freeway Metering
Freeway-to-freeway ramp metering consists of installing signals, on the side of the roadway or overhead, on the ramps found at freeway-to-freeway interchanges. When freeway-to-freeway connectors remain uncontrolled, large traffic volumes have access to the freeway. These volumes are much higher than those found at typical freeway on-ramps. The majority of the installations are found in California and Minnesota. In California, it was found that commuters are willing to wait in a queue for the meter in exchange for improvements in their trip farther downstream. Due to the public’s increased frustration with traffic congestion, freeway-tofreeway metering was shown to have a high level of acceptance for traffic management. According to the Caltrans Ramp Meter Design Guidelines, the installation of ramp meters on connector ramps (freeway-to-freeway connectors) shall be limited to those facilities that meet or exceed the following geometric design criteria: • • • Standard lane and shoulder widths. Tail-light sight distance, measured from 1,070-mm eye height to 600-mm object height, is provided for a design speed of 80 km/h minimum. All lane-drop transitions should be accomplished with a taper of 50:1 minimum.

Jacobson and Landsman suggest that meters be installed meters on freeway-to-freeway ramps where system performance and efficiency will be improved They also suggest the following guidelines for freeway-to-freeway ramp metering systems: • Consider and implement freeway-to-freeway ramp meters at locations where recurring congestion is a problem or where route diversion should be encouraged.

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•

Route diversion should only be considered where suitable alternative routes exist, to avoid diverting drivers through residential neighborhoods. Freeway-to-freeway ramp meters should be installed to improve the mainline flow and on-ramp merge, or to help multiple ramps merge into one ramp. If the intent of the meters is route diversion, then trailblazers or appropriate signing should be considered to educate drivers on preferred alternative routes. Avoid metering vehicles twice within a short distance. Avoid metering single-lane, freeway-to-freeway ramps that feed traffic into an add lane. Do not install meters on any freeway-to-freeway ramp unless analysis ensures that the main line flow will be improved, so that people using the freeway-to-freeway ramp are rewarded for waiting in line at a meter. Install meters on freeway-to-freeway ramps where more than one ramp merges before feeding onto the mainline, and congestion on the ramps occurs regularly. If traffic queues that impede mainline traffic develop on the upstream mainline because of a freeway-to-freeway ramp meter, then the metering rate should be increased to minimize the queues on the upstream mainline, or additional storage capacity should be provided. Freeway-to-freeway ramp meters should be monitored and be controllable by the appropriate traffic management center. Whenever possible, install meters at locations on roadways that are level or have a slight downgrade. Also, install meters where the sight distance is adequate.

• • •

•

• •

Case Studies a. Los Angeles In Los Angeles, only a few interchanges have freeway-to-freeway ramps that are metered. The first was at the interchange of I-5 and I-110. Additional freeway-to-freeway ramp meters have been set up with the completion of the new Century freeway. In 1992, a two-lane ramp meter was installed on the connector of southbound I-5 to help manage the heavy traffic flow onto southbound I-110. The meter is turned on during the morning peak period. b. Minneapolis Minneapolis has the largest number of freeway-to-freeway ramp meters in the U.S. Its two earliest installations were activated in 1971 at the interchange of Trunk Highway 36 and I-35E. Since then, 25 more freeway-to-freeway ramp meters have been activated throughout the Minneapolis/St. Paul metropolitan area. In 1974, ramp control was initiated from eastbound I-94, a six-lane freeway, to southbound Trunk Highway, a four-lane freeway to reduce the heavy congestion that was occurring downstream of this location and to improve the flow of the corridor in general. Before implementation, the two-lane ramp had carried 1,080 vph during the PM peak hour. After the meters had been turned on and both lanes had been metered, the volumes on the ramp dropped to 690 vph during the PM peak hour. MnDOT estimates that over two-thirds of the reduction are due to route diversion.
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Typical delays on the ramp are over 1 minute, but they can react up to 8 minutes with one-quarter mile queues. Four ramps were metered on the four-lane I-35W in 1975 as part of the Urban Corridors Demonstration Program in Minneapolis. The volumes on these ramps were reduced by approximately 20 to 25 percent after metering. Metering at this location is considered to be partly responsible for the 38 percent increase in speeds on northbound I-35W. c. San Diego San Diego began using freeway-to-freeway ramp metering in 1971 when it first installed a meter at the interchange of SR 15 and SR 94. Since then, three more installations have been added, two of which feed SR 94 and the third I-8. The justification for these meters was to better manage the queuing and delay that was occurring at these interchanges and to better manage the freeway system in general. The most recent direct connector metering installation in San Diego was in 1985 and was at the interchange of SR 67 and I-8. This three-lane meter was installed to relieve congestion on I-8 just downstream of the interchange. Before metering, this section of I-8 was frequently congested with long queues that extended upstream from the interchange. Since the meters were turned on, the flow downstream on I-8 has averaged 2,500 vehicles per hour per lane and speeds have averaged 60 mph. In 1978, a meter was installed at westbound SR 94 to southbound SR 94 to relieve some of the congestion and queuing through the SR 94 interchange. In addition, a meter was added to the cross street feeding the southbound SR 125 on-ramp, which merges with the westbound SR 94 direct connector just before their confluence with southbound SR 125. Both meters are operated by an automated, traffic-responsive system on the basis of mainline volumes, so the meters are typically on only during peak periods. The direct connector also features a peak-period inside HOV lane in addition to the two regular lanes. All three lanes, including the HOV lane, are metered. When the meter on the direct connector was first activated, the ramp carried approximately 1,900 vph during the peak hour, with an average wait of I minute and a maximum wait of about 3 minutes. Today the volume on the three-lane ramp is approximately 2,900 vph and a maximum wait during the peak period can exceed 10 minutes. In spite of the high ramp delays, there have been very few complaints, and responses to the metering have continued to be positive (Eldon L. Jacobson and Jackie Landsman, 1994). Summary of Freeway-to-Freeway Metering (Connector Metering) Connector metering offers an additional opportunity for agencies to manage the flow of traffic on a freeway system. It also improves equity amongst motorists along the corridor by metering vehicles that may have entered the freeway on a un-metered entrance ramp. San Diego operates most of its connector meters during the morning peak, metering vehicles that predominately come from outlying areas. In rnany instances meters are installed to improve mainline operations and better manage queuingand delay that occurs at freeway-to-freeway interchanges. However, as shown in Los Angeles, connector metering has other uses. The success stories described above all occurred while in
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many instances long queues and delays occurred on the connectors. However, motorists have become tolerant because they experience mainline freeways that operate at high levels of performance (Gary Piotrowicz and James Robinson, 1995). SOURCES:
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Case Studies of Freeway-to-Freeway Ramp and Mainline Metering in the U.S., and Suggested policies for Washington State, by Eldon L. Jacobson and Jackie Landsman, TRB paper, January 1994. Ramp Metering Status in North America, 1995 Update, June 1995, by Gary Piotrowicz and James Robinson, US Department of Transportation, Publication No. DOT-T-95-17.

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2.3 DYNAMIC ROADWAY CONTROL
Messages reflecting closed lanes, reduced speed limits, and required lane changes are displayed for selected lanes of freeways on overhead mounted dynamic signals and signs. Lane-use control and variable speed control require signage over lanes of the freeway coupled with devices to detect speeds and volumes resulting in congestion. The detectors identify changes in traffic patterns that signal the beginning of congestion or incidents, thus prompting appropriate messages and lane and speed selection by the management center,.

2.3.1 TECHNIQUES/STRATEGIES
Lane Control
Reversible lane control is used to change the directional capacity of a freeway in order to accommodate peak directional traffic demands. These are used where the peak period traffic volumes show a significant directional imbalance (e.g., 70 percent to 30 percent).

Variable Speed Control
Variable speed control is used to reduce the speed of traffic on a freeway to a level that corresponds to a maximum volume. As the peak flow demand increases, speed control can help improve the stability and uniformity of flow and reduce the occurrence of rear-end collisions. Also, lower speed limits could be used during hazardous driving conditions such as fog, rain, or snow.

2.3.2 TECHNOLOGIES
The following technologies are used for lane control and variable speed control: These are overhead signals using indicators to permit or prohibit the use of special lanes on a freeway. Lane-use control signals are most commonly used for reversible-lane control. Other applications include: keep traffic out of a freeway lane to facilitate the merging of traffic from a ramp or other freeways; on a freeway near its terminus, to indicate a lane that ends; to indicate a temporary closure of a freeway lane due to an incident. The technology includes: fiber optic or light-emitting diode (LED); sign case with display elements (a downward green arrow, amber X, flashing amber X, and red X); power switch; photo sensor control to control light output levels. This technique has been used on two of Dallas’ busiest corridors to temporarily reassign traffic flow in specific lanes, thus doubling the number of lanes in the peak direction. The five-lane roadways dedicate four lanes per peak direction, and the fifth lane for the opposing traffic. These lanes are equipped with overhead dynamic message signs (DMSs) placed every 1,000 feet, alerting the motorist of the shift in lane direction by displaying an amber X in the lane about to change and a red X once the shift is complete. These installations have increased capacity by 33 percent for the peak direction. Types of DMSs used for this application include: fiber optic, LED, bulb matrix, blankout.

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The Manual on Uniform Traffic Control Devices (MUTCD) describes the use of the lane control signals as follows. • • • • Downward green arrow - Used to indicate an open lane is open and that a driver is permitted to drive in the lane over which the arrow is located. Amber X - Used to prepare the driver to vacate the lane (similar to the use of amber indications at intersection traffic signals). Flashing amber X - Indicates that a lane may be used for a left turn (applicable to arterial streets only). Red X - Used to indicate that the lane over which it is displayed is closed to that direction of traffic, and that a driver shall not drive in that lane.

In a study performed by the Texas Transportation Institute on lane-use control signals at various sites in Texas, the results support the use of both the green arrow and the red X for these purposes. Nearly all subjects participating in the studies correctly interpreted the green arrow, and more than 80 percent correctly interpreted the red X. The studies also showed that the red X is perceived as requiring a reaction by motorists (to exit the lane) within 0.10 mile after it is displayed. However, the amber X was found to elicit widely varying responses depending on the context in which it was used. When displayed in conjunction with green arrows, motorist interpretations of the amber X were more consistent with its intended meaning of an impending lane closure and the need to vacate the lane. When presented in conjunction with a red X, motorists appeared less likely to associate an amber X with an impending lane closure. They instead interpreted the amber X to indicate congestion or other hazard in the lane downstream for which they would need to slow down and be careful. They further recommend that the amber X be replaced by an amber diagonal arrow to provide a more consistent interpretation of the action desired from the motorist.

Variable Speed Limit Signs
These signs are of the same type as lane-use control (e.g., blankout signs the type used as pedestrian walk/don’t walk, dynamic message signs).

Gates
Hydraulically or electrically controlled lifting gates (barriers) present a physical barrier in the road and are used to control access to lanes on the freeway during recurring and nonrecurring congestion.

Dynamic Message Signs Movable Lane Barriers
These are physical barriers installed, temporarily, by a transfer vehicle to separate lanes of a freeway. More discussion of these systems is found in Section 2.4.

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Regulatory Signs with Beacons
Case Study TransGuide - From the TransGuide ITS Design Report (transguidewwwserver.datasys.swri.edu:80/ articles/designreport.html )

Lane Control Signal (LCS)
The LCSs are the most numerous mechanisms for communicating with drivers. They provide limited, simple communications in the form of one signal for each lane of the freeway. The signal displayed for each lane can be a RED X, a GREEN DOWN ARROW, a YELLOW X, a YELLOW DOWN ARROW, a YELLOW SLANT ARROW pointing right, or a YELLOW SLANT ARROW pointing left. The RED X indicates that the lane is closed. The GREEN DOWN ARROW indicates that the lane is open. A YELLOW X indicates that the lane will be closed at some point downstream. A YELLOW DOWN ARROW indicates that the lane is open, but that there may be a hazard on an adjacent shoulder. A YELLOW SLANT ARROW pointing left or right indicates that the lane will be closed downstream and that the traffic should move into the lanes indicated by the arrow to find clear lanes or to exit from the freeway. If a lane is blocked, the scenario implemented should have two RED Xs in that lane upstream of the incident. Before the two RED Xs, one YELLOW SLANT ARROW should be displayed. The contents of the LCS display are controlled by the TransGuide operators, either directly or through the initiation of scenarios. The LCS will normally display a GREEN DOWN ARROW for all lanes that are not blocked. The other signals are displayed based on specific scenarios initiated by the operators. In general, blocked lanes will have a RED X displayed by at least two LCSs in the lane upstream of the blockage. The use of a RED X on two LCSs ensures that the motorist will see a RED X in the lane even if one LCS fails. Upstream of a RED X, at least one signal in a blocked lane will normally contain a YELLOW ARROW advising motorists to begin moving out of the blocked lane. Hazards on the shoulders will normally cause a YELLOW DOWN ARROW to be displayed upstream from the hazard. Each scenario is evaluated to determine the best configuration of VMS messages and LCS signals. The LCSs are composed of halogen bulbs, fiber optic bundles, color filters and lenses. Table 19 shows some of the characteristics of the specified LCS. Two halogen bulbs provide the illumination for each color and color filters are used to produce the appropriate colored light. Fiber optic bundles carry the light to the face of the LCS, and lenses direct the light toward the drivers. The lighted dots are surrounded by a flat black faceplate to provide sufficient contrast so the segments can be clearly distinguished at 1/4 mile. Each of the indicators is illuminated by bundles coming from two bulbs, so the indicators can still be seen even if one of the bulbs is burned out. The LCSs are required to provide automatic dimming for night operation and to ensure that dimming does not turn off a bulb if the other bulb providing that color is burned out. There are several mechanisms to ensure that the LCSs are capable of operating continuously, reliably, and affordably. An LCS can be polled by the system and instructed to report the status of each lamp. Most LCSs can be visually checked using the camera system. The LCSs are required to automatically report failed bulbs. The specifications require easy service access to LCSs, and TransGuide specifica-

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tions place specific environmental compatibility requirements on signals. Finally, the specifications also specify long life requirements for the bulbs. These measures should help ensure that the LCSs operate continuously, reliably, and affordably for many years. SOURCES: • Driver Interpretations of Existing and Potential Lane Control Signal Symbols for Freeway Traffic Management, 1993, TexasTransportation Institute, Research Report 1298-1.

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2.4 PRIORITY CONTROL FOR HOV
Priority control provides preferential treatment for buses, carpools and other High-Occupancy (priority) Vehicles (HOV) that use the freeway. It is designed to relieve traffic congestion on freeways by encouraging better utilization of vehicles. This is accomplished through the following techniques/ strategies.

2.4.1 TECHNIQUES/STRATEGIES
Priority Access Control
Priority access control is used in conjunction with entrance ramp metering and gives priority to HOV traffic by providing bypass lanes on the ramps or exclusive ramps. The HOVs avoid any delay associated with ramp queues and enter the freeway with no disruption. This priority access can be in the form of bypass lanes or a preferential metering rate. The priority lanes are usually restricted to buses or HOVs. The Freeway Management Handbook gives some design specs for these lanes: bypass lanes should be 12-feet wide with full ramp shoulders where possible, and should extend 300 feet beyond the metering signal to permit HOVs to merge with normal ramp traffic. The ramp bypass traffic should merge first with regular ramp traffic and then with freeway traffic. Regulatory signs with “Right Left Lane Buses and Carpools Only” are erected to indicate the use of these lanes. In addition, pavement marking on these lanes bearing “CAR POOL ONLY” or “BUS ONLY” with diamond symbols are usually used, separating them from the mixed-use lane by solid white pavement markings of 8 inches wide or more. SOURCES: • • Evaluation of Preferential Lanes for HOVs at Metered Ramps, November 1982, Report No. FHWA-RD-82/121, Prepared by Caltrans. Effect of HOV Bypass Lane Location on Violation Rates, October 1990, Prepared by San Diego State University for Caltrans.

HOV Facilities
a. Separated facilities - Separate roadways specifically constructed for the use of HOV providing for separation between HOV traffic and the other traffic. Usually these facilities are constructed in the median of an existing freeway with a concrete barrier. HOV can operate safely at high speeds, and the existing freeway efficiency is not reduced. Ingress/egress ramps are used when the HOV facility is physically separated from mixed-use traffic. b. Reserved Freeway Lanes - Reserved HOV freeway lanes have been used in two configurations: concurrent flow; and contraflow. Concurrent flow lanes are designated in the same direction as the peak flow on the same side of the median. This lane may be provided by adding a lane or by preempting an existing lane. Contraflow lanes are on the opposite side of the median where the

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HOV traffic moves against the peak flow of traffic. The use of contraflow lanes is restricted to freeways with an imbalance in directional peak flow. Guidelines for signing and pavement markings for HOV treatments can be found in the MUTCD. c. Bus-Only Facilities - These are either separate right-of-way facilities (e.g., Easy busway Pittsburgh, PA) or bus lanes along streets within existing right-of-way (e.g., Spring Street, Los Angeles, CA and Bellevue,WA). SOURCES:
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Operational Design Guidelines for High Occupancy Vehicle lanes on Arterial Roadways, November 1994, Publication No. DOT-T-95-14. An assessment of High Occupancy Vehicle (HOV) Facilities in North America, Executive Report, August 1992, Publication No. DOT-T-94-17. High Occupancy Vehicle (HOV) Guidelines for Planning, Design, and Operations, Final Report, June 1991, Publication No. DOT-T-91-17. HOV Systems in a New Light, National Conference on High Occupancy Vehicle Systems, June 1994, Transportation Research Circular 442.

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2.4.2 TECHNOLOGIES
The following technologies are used for priority access control and HOV facilities:

Separate Right-of-Way.
This is a roadway or lane developed in a separate and distinct right-of-way and designated for the exclusive use of HOVs.

Buffer and/or Concrete Barriers. Semaphore Barrier Gates.
Semaphore barrier gates (like rail-highway grade crossing gates) come down and lock (nonbreakaway) to close HOV lane to excess traffic . They are closed at the entrance when the lanes are open in the opposing direction. Caltrans uses these gates in combination with pop-up delineators on Interstate 15. The software at the traffic management center (TMC) prevents operation the devices in an improper sequence, such as the lowering a barrier gate without the corresponding pneumatic pop-up delineators in place. The system monitors the status of all closure device sensors and prevents operation of closure devices unless the system status is known and proper.

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Closed Circuit Television. Dynamic Message Signs. Paint Striping of Buffer for Delineation (Concurrent Flow Lane). Bypass Lanes at Ramps (Concurrent Flow Lane). Plastic Posts (Pop-Up) or Movable Concrete Barriers for Delineation (Contraflow Lane).
These systems consist of a barrier transfer vehicle and movable concrete barriers providing temporary physical separation between opposing flows. These barriers consist of 3-foot concrete segments joined together by pins. These barriers are installed using a transfer vehicle, and are usually transfered in the morning and afternoon peak periods to facilitate the peak traffic in each direction. Pop-up delineator systems are operated pneumatically to raise or lower the delineators. The systems are used with detectors (most commonly used are loop detectors) to gather vehicle speeds and volumes both on the lanes and in advance of the entrance to detect gaps in the trafffic.

2.4.3 CASE STUDIES
The San Diego Association of Governments (SANDAG) has begun a three-year demonstration project that allows 500 single-occupant vehicles to use the HOV lanes on I-15 for a monthly fee. The I-15 ExpressPass Program is initially charging $50 per month to single-occupant vehicles that use the reversible lanes with the revenues going towards improving bus and carpool services in the area. This fee will vary and will be used to assess how pricing can be used to manage traffic and to test the value commuters place on time saving while driving. With demand far exceeding supply, the cost has since (start of project was November 1996) increased to $70 per month. Transponders will replace stickers in July 1997 and later electronic toll collection will be implemented where users will pay by trip and not per month. With the success of the I-15 ExpressPass, Houston is gearing towards a similar project. In this project, HOV2 vehicles will be able to use the HOV lane during the peak periods, currently restricted to HOV3 (The Urban Transportation Monitor, March 14, 1997) The Massachusetts Highway Department has created HOV lanes on I-93, the Southeast Expressway in Boston, using the Quickchange Movable Barrier technology. It provides five inbound lanes of traffic during the morning peak period and three outbound lanes. The process is reversed for the evening peak period. The use of this technology does not require the HOV lanes to be dedicated, thus allowing the lanes to be returned to general purpose traffic after the peak traffic subsides. The 10 km HOV lane has provided 10 to 15 minute travel time savings for three-plus car poolers, vanpoolers and public transit (Traffic Technology International, August/September 1996). Now, with the aid of reversible-lane technology, roadways in two of Dallas’ busiest corridors temporarily reassign traffic flow on specific lanes, effectively doubling the number of lanes in the peak direction during morning and evening rush. In those periods, the five-lane roadways dedicate four

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lanes to the peak direction-reserving one for left turns-and the fifth to the opposite direction. At other times, the roadways devote the usual two lanes to each direction, and the middle lane to left turns. Each shift takes approximately 10 minutes. Managed from remote locations at the traffic operation center, “smart” 24-by-30-foot overhead electronic signs, placed an average of every 1,000 feet, alert motorists to the gradual switch of lane direction by displaying an amber “X” in a lane about to change direction and a red “X” once the shift is complete. Each smart sign mechanism is internally programmed with timing sequences; all report to a control center, where computers monitor and synchronize activity and alarms signal any problems. In addition to the smart signs, regular information signs on the parkways and guide markings on the pavement provide clear instructions to motorists. With a capital expense of $1.2 million, Dallas increased the rush-hour capacity of two older thoroughfares by 33 percent for the peak direction. The city’s reversible-lane program also decreases congestion, pollution, and travel times, as it allows motorists to choose alternative routes during the ongoing reconstruction of the major freeway, scheduled for completion in the year 2000. Minimizing delays and inconvenience to commuters and businesses, the efficient and cost-effective system has enhanced access to downtown Dallas.

Katy Freeway (I-10 West) - Houston, Texas
The Katy Freeway HOV lane is located on I-10 West in Houston, Texas. The location of this facility,, which serves as the major travel corridor on the west side of the city. The 13-mile HOV lane was opened in stages between 1 984 and 1990. It is a one-lane, barrier separated, reversible HOV lane located in the freeway median. Three park-and-ride lots and three park-and-pool lots are located in the corridor. Access and egress is provided by both slip ramps and direct access ramps. The Katy Freeway HOV lane is one of four operational HOV lanes in the Houston area and is part of a planned 96-mile HOV network. The HOV lane is open in the inbound direction from 4:00 a.m. to 1:00 p.m. It is then closed from 1:00-2:00 p.m. to reverse the flow of HOV traffic. The lane reopens at 2:00 p.m. and operates in the outbound direction until 10:00 p.m. The vehicle occupancy requirement on the facility has changed a number of times over the life of the project. Only buses and authorized vanpools were allowed to use the facility when it opened in 1984. Due to low utilization, it was opened to authorized carpools with four or more persons in April 1985. The occupancy requirement was lowered to 3+ in December 1985, and in August 1986 it was changed to 2+ and the authorization requirement was dropped. The 2 + occupancy requirement remained in effect until the fall of 1988. In response to the high volumes occurring in the morning peak hour, and the corresponding decline in travel speeds and travel time reliability, a 3+ vehicle occupancy requirement from 6:45-8:15 a.m. was reinstated in October 1988. The 3+ hours were slightly revised to 6:45-8:00 a.m. in May 1990, and in the fall of 1991, the 3+ requirement was applied to the afternoon peak hour from 5:00-6:00 p.m. The vehicle volumes grew steadily after the lane was opened to 2+ carpools, reaching a high of almost 1,500 peak-hour vehicles in 1986. The vehicle and person volumes dropped initially after implementation of the 3+ occupancy requirement, but have been increasing since that time. 2 As of
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December 1991, approximately 840 vehicles and 4,000 persons were using the HOV lane during the morning peak hour. In the peak period (6:00-9:30 a.m.) approximately 2,350 vehicles and 8,760 persons were using the lane.

I-394 - Minneapolis, Minnesota
The I-394 freeway and HOV lanes are located on the western side of he Minneapolis-St. Paul metropolitan area. The facility extends 11 miles from downtown Minneapolis to the city of Wayzata. I-394, which represents the final segment of the interstate system to be completed in the area, was constructed on the alignment of an existing arterial, US 12. Completed in the fall of 1992, the final freeway and HOV design includes two general-purpose traffic lanes in each direction and two different HOV treatments. East of Highway 100, a three-mile, two-lane, barrier-separated, reversible HOV facility is located in the median of the freeway. Those HOV lanes provide direct access into the downtown parking garages built as part of the overall project. West of Highway 100, eight miles of concurrent flow HOV lanes are in operation. An interim HOV lane was used during construction of the I-394 facility. The interim facility was marketed as the “Sane Lane,” and was implemented to help manage traffic during construction and to introduce the HOV concept in the area. The interim HOV lane was approximately three miles long, and was located in the median of US 12. Opened in November 1985, the interim HOV lane operated in the inbound direction during the morning peak period (6:00-9:00 a.m.) and in the outbound direction in the afternoon (2:00-7:00 p.m.). The operating hours changed slightly during the interim period in response to construction needs. A 2 + vehicle occupancy requirement has been in effect over the life of the project, and buses, vanpools, and carpools are allowed to use the facility. The interim HOV lane was in operation for approximately five years. During this time, an average of some 500 vehicles carrying 1,400 persons used the facility during the morning peak hour (2). In the fall of 1992, approximately 1, 100 vehicles carrying 3,580 persons were using the peak-direction concurrent flow HOV lane west of Highway 100 during the morning peak hour.

Route 55 - Orange County, California
Route 55 (the Newport-Costa Mesa Freeway) serves as a heavily-traveled link between the residential areas in eastern Orange and Riverside Counties and the employment centers in central Orange County. Eleven miles of HOV lanes-or commuter lanes as they are called locally-were opened on Route 55 in 1985. The Route 55 HOV facility consists of a pair of concurrent flow commuter lanes (one in each direction), and is open to buses, vanpools, and carpools on a 24-hour basis. A 2 + vehicle occupancy requirement is in effect on the Route 55 HOV lanes. The vehicle volumes have been relatively consistent over the eight-year period, averaging between 1,100 and 1,500 vehicles during the morning peak hour in the peak direction. However, morning peak-hour vehicle volumes as high as 1,600 have been recorded on the Route 55 HOV lane. The corresponding person movements have also remained relatively constant over this period, averaging between 2,300 and 3,200 persons during the morning peak hour in the peak direction. Since very little bus service is provided in the Route 55 corridor, the vehicle volumes and person movements for the HOV lanes primarily reflect carpools.

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I-279 - Pittsburgh, Pennsylvania
The project is a four-mile, two-lane, reversible, barrier-separated HOV facility located in the median of I-279. Two short one-lane segments are located at the southern end of the facility, providing access to Three Rivers Stadium via I-579 and the downtown area via I-279. The freeway and HOV lanes were first opened in August of 1989. The HOV lanes were open to buses, vanpools, and 3+ carpools during the first three years of operation. In August 1992, a demonstration project was implemented in which the vehicle occupancy requirement on the HOV facility was lowered to two or more persons per vehicle. The I-279 HOV lanes operate in the inbound direction from 5:00 a.m. to noon. From noon to 2:00 p.m. the lanes are closed to reverse the flow of HOV traffic. From 2:00-8:00 p.m. the lanes operate in the outbound direction with the HOV restrictions. Finally, from 8:00 p.m. to 3:00 a.m. the lanes operate in the outbound direction with no vehicle occupancy restrictions. This is done in part to accommodate traffic leaving events at Three Rivers Stadium. With the 3+ occupancy requirement, the morning peak-hour vehicle volumes had increased from approximately 164 vehicles in November 1989 to 345 vehicles in November 1991. The corresponding peak-hour person volumes had increased from some 1,100 persons to 2,200 persons. After the vehicle occupancy requirement was lowered to 2+ for a demonstration project in August 1992, the morning peak-hour volume increased to 868 vehicles and the corresponding person movement rose to 2,600.

I-5 North - Seattle, Washington
The concurrent flow HOV lanes are located to the north of both downtown Seattle and the University of Washington. The southbound HOV lane is 7.7 miles in length and the northbound HOV lane is 6.2 miles in length. The I-5 North HOV lanes were opened in 1983 and are operated on a 24-hour basis. From 1 983 until July 1991, a 3+ vehicle occupancy requirement was in effect. On July 29, 1991, the occupancy requirement was lowered to two or more persons per vehicle as part of a demonstration project. An average of about 280 vehicles used the facility during the morning peak hour in the first few weeks following the opening of the facility. That volume had grown to 410 vehicles after the first three months of operation and 460 vehicles after the first 20 months (7, 8). Between 1985 and August 1991, an average of 460 to 550 vehicles used the HOV lane during the morning peak hour in the peak travel direction (2, 9). After initiation of the demonstration project lowering the vehicle occupancy requirement to 2+, the morning peak-hour, peak-direction volumes averaged between 1,200 and 1,400 vehicles. Between 1985 and 1991, an average of 3,710 persons used the facility during the morning peak hour in the peak travel direction. Approximately 70 percent, or 2,605 persons, rode buses on the HOV lane, while 30 percent, or 1,105 persons, were in 3+ carpools. After the vehicle occupancy requirement was changed to 2+, the person volumes increased to an average of 5,644 during the morning peak hour in the peak travel direction. Bus ridership remained relatively constant with the reduced occupancy requirement, but the number of persons carried in carpools increased to 3,039-approximately 54 percent of the total morning peak-hour, peak-direction person volume on the facility.
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Shirley Highway (I-395) - Washington, D.C./Northern Virginia
The opening of the initial five miles of bus-only lanes on the Shirley Highway (I-395) in 1969 represented the first use of an HOV facility on a freeway in the United States. The project, which was opened in several stages between 1969 and 1975, is now approximately 11 miles in length. The two-lane, reversible HOV facility is located in the median of the freeway and is separated from the general-purpose traffic lanes by concrete barriers. Park-and-ride lots and direct access ramps are provided at strategic points along the corridor. A number of changes have been made in the occupancy requirements and operating hours for the Shirley Highway HOV lanes. Only buses were allowed to use the facility during the first four years of operation. In December 1973, the HOV lanes were opened to vanpools and carpools with four or more persons. In January 1989, a 3+ carpool definition was implemented for the facility. Until 1985, the lanes operated in the inbound direction from 11:00 p.m. to 11:00 a.m. and in the outbound direction from 1:00-8:00 p.m. The lanes were closed for maintenance and reversing the flow of HOV traffic during other hours. As a result of a Congressionally-mandated demonstration project in the spring of 1985, the operating hours of the HOV lanes were changed to 6:00-9:00 a.m. in the inbound direction and 3:30-6:00 p.m. in the outbound direction. The lanes are open to general-purpose traffic during the remainder of the day, except when they are closed to reverse the flow of traffic. Bus service levels and service orientation were changed in 1983 with the opening of the Metrorail Yellow Line, resulting in a slight decline in vehicle and person volumes on the HOV lanes. Approximately 39 peak-hour buses, carrying some 1,920 persons, used the HOV lanes during the first year of the project. By 1974, that number had increased to 279 buses and 11,340 passengers. As of 1991, the morning peak-hour volume for buses, vanpools, and carpools was approximately 2,773 vehicles, carrying some 18,406 persons.

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2.5 TRANSPORTATION MANAGEMENT DURING RECONSTRUCTION
To ensure the safety of motorists and construction staff and the optimal operation of the transportation systems, it is imperative to develop a comprehensive traffic management plan for construction and maintenance work. The traffic-control plan must address key issues such as design strategies, contractual requirements, transportation policies, enforcement policies, public relations, and trafficcontrol strategies. Design strategies include such measures as temporary or permanent frontage roads, narrowed lanes, and paved shoulders to provide adequate capacity during the construction period. Contractual requirements may include restriction of work hours, methods of construction and procurement, and incentive/disincentive clauses. Transportation policy issues that may be need to be addressed include: improvement to alternate routes, aggressive ride-share programs coupled with improvements to parkand-ride facilities and mass transit, and subsidized toll or transit passes. Proper enforcement of the applicable laws within the construction zone could have significant effects on the safety and operation of the transportation facility. Dissemination of the information regarding the project scope, schedule, alternative routes and modes, and addressing the public’s concerns through various media (i.e., television and radio spots or news, newspaper ads and articles, the Internet, and telephone services) are keys to successful management of traffic during reconstruction projects. Many of the traffic-management strategies discussed earlier in this and other chapters of this document (i.e., incident management, traveler information systems, and corridor management) can effectively be applied to facilities under construction. Ramp metering, ramp closures, mainline metering, HOV facilities, traffic signals and interconnect, traffic surveillance, variable lane controls, and variable speed limit are just some of the strategies that could impact the traffic operations in a construction zone.

2.5.1 TECHNOLOGIES
A variety of traffic-control devices has traditionally been employed in construction and work zones. The technology may vary from a static construction sign to a trailer-mounted Changeable Message Sign (CMS) to portable Highway Advisory Radio (HAR). The guideline for the design and application of the traffic control devices in a work zone is found in Part VI of the Manual on Uniform Traffic Control Devices. There are many different traffic-control devices used in construction zones and many books and manuals are dedicated to this topic. The following is not meant to be a comprehensive catalog of the available technologies, but representative of the types of devices available and their applications.

Signs.
Temporary traffic-control zone signs, convey both general and specific message. Regulatory signs categorized as regulatory, warning, and guide signs, inform users of traffic laws and regulations and impose legal obligations on all drivers. Warning signs notify drivers of general and specific conditions on or adjacent to a roadway. Guide signs are designed to provide drivers simple instructions and/or information about the roadway and/or route.

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Portable Changeable Message Signs (PCMS).
PCMSs are similar to dynamic message signs both in terms of functionality, as well as technology. PCMSs allow the managing agency the flexibility to display any of various messages that best suit the needs of the agency. PCMSs have a wide variety of applications in temporary traffic-control zones, including roadway or ramp closures, accident or emergency incident management, width-restriction information, advisories on road-work scheduling, traffic management and diversion, warning of adverse conditions (operationally and environmentally), and operation control. The technologies of the message panels for the PCMS is the same as that of the DMS. However, the requirement of the control system is modified to allow field adjustment of the message, and additional requirements for the power source and mounting must be included. Unlike the DMSs, which are often controlled from Operations Centers, the PCMS messages are changed in the field. Therefore PCMSs require some method of message input and viewing capabilities. Additionally, PCMSs require portable primary and back-up power sources. The primary source could be a diesel engine or solar panels. The back-up source is often a battery system or a diesel engine. The sign is either mounted on a trailer pulled by a separate vehicle or mounted on a truck.

Arrow Displays.
Arrow displays may be used in the arrow or chevron modes for stationary or moving lane closures. The display is rectangular in shape with a nonreflective black finish. The color of the limit-emitting elements is yellow and can be produced by similar technologies, as described under the DMS section.

Channelizing Devices.
The function of channelizing devices is to warn and alert drivers of conditions created by work activities in or near the traveled way, to protect workers in the temporary traffic-control zone, and to guide motorists and pedestrians safely. They should provide for a gradual shift of traffic from one lane to another or onto a bypass or detour, and/or accommodate a reduction in traveled way. They may also be used to separate mixes of traffic (i.e., single-occupancy vehicles, HOV, trucks, pedestrians, bicycles) or opposing traffic. Channelizing devices include but are not limited to cones, tubular markers, vertical panels, drums, barricades, temporary raised islands, and barriers.

Pavement Markings.
Similar to channelizing devices, pavement markings are a part of a system of devices used to manage the traffic in construction zones. They must be complemented by other devices to effectively guide the motorist through a construction zone. Pavement markings may be categorized as striping, Raised Pavement Markers (RPM), and delineators.

Portable Barriers.
Portable barriers are designed to prevent vehicles from penetrating work areas while minimizing vehicle-occupant injuries. The portable barriers have been in use for many years and have proven to be an effective method of separating travel way from the work area. They may also be used for channelization purposes. Because of their portability, these barriers can easily be moved by time of

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day or in case of an incident to accommodate for additional lanes and capacity in the peak direction. Portable barriers may be constructed of concrete, metal, polymerized fiber (filled with water or sand), or any material that can physically prevent vehicular penetration.

Temporary Traffic Signals.
Temporary traffic signals can be used for special applications in temporary and long-term work areas. Regardless of their temporary nature, they must meet and maintain the standards set forth in the MUTCD. The design and functionality of these signals is not much different from those of the permanent signals except for the use of such techniques as alternate power sources and portable loops or video detection.

Portable Highway Advisory Radio (HAR).
Portable HARs effectively provide construction and traffic-related information to the motorist in advance of or within a construction zone. The technology remains the same as the permanent HAR systems except for the alternate power source and mobility requirements. There are trailer and vanmounted HAR systems in use today. This technology could be very beneficial since it could serve a large audience.

2.5.2 CASE STUDIES
Smart Work Zone technology uses cameras to monitor work areas in the Minneapolis-St. Paul area and relays the information to the local traffic center, which in turn uses DMSs to alert motorists about work-area caution zones. A survey by MnDOT revealed that the public is getting the message. Most of those polled said the warning signs were accurate, useful, and gave them the information they needed. In addition, MnDOT posts the work-zone information on the Internet (ITS World, Jan/Feb 1997). SOURCES: • • • • • Manual on Uniform Traffic Control Devices (MUTCD), September 1993, Publication No. FHWAHI-94-027. Special Report 212 - Transportation Management for Major Highway Reconstruction, 1996, Transportation Research Board. Proceedings of the Symposium on Work Zone Traffic Control, June 1991, Publication No. FHWATS-91-003, Hugh W. McGee, Lynne F. McGee, Nancy L. Geisler . Corridor Transportation Management for Highway Reconstruction, May 1986, Publication No. DOT-I-86-35, William T. Steffen, Sonia Weinstock, Mary Ellen Sullivan. Corridor Traffic Management for Major Highway Reconstruction - A Compilation of Case Studies, September 1986, Publication No. HPN-23/R11-86(300).

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2.6 DETECTION
Electronic freeway detection systems provide real-time traffic information on volumes, speed, and occupancy of each lane of the freeway. Congestion is identified through algorithms that use data from constantly monitoring detectors. With accurate information, traffic management agencies can implement control strategies, detect and manage traffic during incident conditions, and activate motorist information systems that will improve the quality of operations in the traffic network.

2.6.1 INSTALLING DETECTION SYSTEMS
A communication system linking the central control room with detector systems, video cameras (CCTV equipment, video imaging, etc.), and changeable-message-sign controllers is essential to the optimal operation of detection and control systems. The Freeway Management Handbook (DTFH61-95-C00128) discusses the process for planning, designing, and installing detection, as well as video surveillance systems. This process a system engineering approach that is an iterative process whereby operational problems are identified, system concepts and objectives are established, potential solutions are developed and evaluated, new solutions are identified, and system objectives are redefined. This approach can be used for: planning and implementing a new system where no current transportation management system exists; modifying an existing system to add new transportation management functions; or upgrading the technology in an existing traffic management system to current standards. This process is followed in this section, Detection, to illustrate how it can be used for planning a system. It can also be used for other strategies/technologies throughout this document. The following steps make up this process.

Problem Identification
The first step in the process is to identify the problems to be addressed by the detection system. Issues to be addressed in the problem identification stage are: • • • Identifying and locating operational problems; Determining functions to be performed by the detection system; and Inventorying existing detection capabilities.

a. Identify and Locate Operational Problems. This process involves identifying those freeways that would most benefit from the use of detection systems: those with significant amounts of congestion. These areas may be ones where significant increases in traffic demand are expected, where significant amounts of maintenance or construction activities occur, where there is increased delay, where there are slower and inconsistent travel speeds, and where there is a high frequency of traffic incidents. b. Determine Functions of Detection System. A detection system may serve several objectives, including: • Detection of incidents that impact traffic operations
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• • •

Monitoring traffic operation and supporting the implementation of control strategies (e.g., lane control, ramp metering, etc.); Monitoring environmental and pavement conditions; and Monitoring traffic during construction and/or special events.

c. Importance and Types of Data. The importance and type of data to be collected must be identified for selection of the appropriate detection system. Both real-time and historical data may be needed for traffic management, to monitor current traffic operations as well as to establish a record of past traffic conditions. The types of data to be collected may include the following. • • • • • • • Speed Volume Occupancy Vehicle travel times Bus location Queue length Pavement condition

In addition, the accuracy and cost of the detection system must be balanced. The accuracy of the data may be more important for some systems (e.g., incident detection). The accuracy of the data as well as the traffic parameter range and collection interval are presented in Table 2.6.1 d. Inventory Existing Detection Capabilities. The existing detection resources and communications system must be identified and evaluated to determine their suitability for continued use. It is important to determine if these systems meet existing needs and if they can accommodate changes in system requirements. It is also very important to evaluate the communications system for the various detection technologies and to identify the communications requirements.

Identification of Partners
Another important step in the implementation of a successful detection system is to identify the partners that are to be involved. These partners come from three areas: intra-agency; interagency, and other. a. Intra-agency. The intra-agency partners may be representatives from the following areas: management; planning; design; operations; and maintenance. This team of individuals is identified from the start of the planning stage and is crucial in the decision-making process. It is essential to have commitment from top management as well as support staff to assure so that resources are allocated to these systems and to assure system success.
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b. Interagency. The interagency partners may be State, city, and/or county representatives, to ensure that proper coordination is maintained between jurisdictions. This coordination will help in identifying problems and minimizing the effects of certain activities and events on overall traffic operations. It is therefore important to exchange real-time information between these jurisdictions on a continual basis, and to maintain a database for use by such entities as law enforcement, emergency, media, wreckers, and other information services, as well as commercial vehicle operators and the general public. (Appendix C presents an interagency agreement for a Regional Transportation Management System in Harris County, Texas). c. Additional Resources. Other groups of resources to be considered for identifying and evaluating the various detection technologies include: manufacturers and suppliers, the users, the researchers, consultants and other interested groups. Information gathered from these groups will help in the identification and determination of the state-of-the art as well as the state-of-the-practice, and will help in bridging the gap between the two.

Establish Goals and Objectives
Establishment of the goals and objectives of a system, requires identification of what the system is to accomplish. Goals are used to define the system’s long-range functions. Objectives define the level of performance to be expected in the future. The detection system provides support for other elements of a transportation management system (e.g., incident management, traveler information, ramp control, etc.). The goals and objectives of the detection system, therefore, relate to the goals and objectives of the elements supported by it. For example, the goals of an incident management system may be to reduce the impact of incidents on traffic operations. The objectives of the system may be to detect an incident in less than two minutes and reduce the incident clearance time by five minutes. The detection system can, therefore, be evaluated by determining the system’s ability to meet these established objectives.

Establish Performance Criteria
There is a wide range of traffic detectors from which to choose, and with advancements in technology, the alternatives are becoming even greater. It is therefore important to develop performance criteria to help in the selection process. The performance criteria should be related to the ability of the system to meet the established goals and objectives. Criteria that may be used to measure the performance of a detection system include: reliability of the system (e.g., percent of time the system is producing desirable results, amount of maintenance required); accuracy of the data (e.g., percent of false alarms, difference between measured data and actual data); timeliness of the data (e.g., time between detection and actual occurrence). These criteria can be used to establish parameters to evaluate detection systems.

Define Functional Requirements
The next step in the decision-making process involves defining all of the functions necessary to achieve the established system objectives. The functions should be defined independent of the available technologies. These functional requirements of the detection system should be dependent

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upon the element that it will support (e.g., elements that use such data as speed, volume, occupancy, travel time, queue length, headway, etc.).

Define System Architecture
After defining the functional requirements of a detection system, the next step is to define the system architecture. This is the framework within which the system carries out the functions required to support the established objectives. Information concerning the development of system architecture for transportation management systems has been prepared through the national architecture development effort for ITS. The system architecture for the detection system should be based on this national development and defined to meet local issues and concerns.

Identify and Screen Technologies
Once the functional requirements and architecture of the detection system have been defined, the next step is to identify those technologies that meet the defined requirements. The steps in identifying and choosing the appropriate technologies include the following. a. Identification of Alternative Technologies. There are a number of technologies available for collecting traffic data. The characteristics, applications, and requirements for various detection technologies are discussed in the following section. Available detection systems and their capabilities are constantly changing due to technological advancements and system improvements. It is therefore important to identify the state-of-the-art in detection systems. It is also important to continually interface with the following groups and individuals during the identification process: manufacturers, users, consultants, researchers, other interested individuals. Numerous sourcesof information (see below) are available for assistance in identifying available and evolving detection technologies. In addition, the Internet has a wealth of information on various manufacturers of detection systems, as well as sites for information on detection technologies. (see below) b. Evaluation of Alternative Technologies. When evaluating detection technologies, the following factors should be considered for each detector: location of detector (i.e., embedded in pavement or nonintrusive); installation, operation, and maintenance requirements; reliability; expected life; life-cycle costs; type of communication medium available; requirements for future expansion. After the initial screening, which will look at these factors, the detailed evaluation should include the following: estimating costs and benefits of each alternative; comparative analysis; and selecting the system offering the most potential. Numerous extensive and comprehensive studies have been performed to test and evaluate detection technologies. The two most recent are the Hughes Aircraft study ( ) and the Minnesota Guidestar study ( ). In the Hughes Aircraft study, off-the-shelf, state-of-the-art detectors obtained from various manufacturers were field tested and evaluated. The detector technologies are shown in Table 2.6.1 and the site locations, test period and the amount of data collected are shown in Table 2.6.2. Table 2.6.3 provides a qualitative assessment of the detector technologies tested under various traffic parameters.
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Table 2.6.1
Symbol U-1 U-2 U-3 M-1 M-2 M-4 M-5 M-6 IR-1 IR-2 IR-3 IR-4 VIP-1 VIP-2 VIP-3 VIP-4 VIP-5 A-1 MA-1 L-1 T-1 Technology Ultrasonic Doppler Ultrasonic Presence Ultrasonic Presence Microwave Radar Motion Medium Beamwidth Microwave Radar Doppler Medium Beamwidth Microwave Radar Doppler Narrow Beamwidth Microwave Radar Doppler Wide Beamwidth Microwave Radar Presence Narrow Beamwidth Active IR Laser Radar Passive IR Presence Passive IR Pulse Output Imaging IR Video Image Processor Video Image Processor Video Image Processor Video Image Processor Video Image Processor Passive Acoustic Array Magnetometer Microloops Tube-Type Counter Manufacturer Sumitomo Sumitomo Microwave Sensors Microwave Sensors Microwave Sensors Whelen Whelen Electronic Integrated Systems

Model SDU-200 (RDU-101) SDU-300 TC-30C TC-20 TC-26 TDN-30 TDW-10

RTMS-X1 780D1000(Autosence 1) 842 833 Cat Eye Autoscope 2003 Traffic Analysis System Marksman C-CATS 810 IDET-100 2000 SmartSonic TSS-1 Self-Powered Vehicle Detector 701 Delta 1

Schwartz Electro-Optics Eltec Eltec Grumman Econolite Computer Recognition Systems Golden River Traffic Sumitomo EVA AT&T Midian Electronics 3M Timemark

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Table 2.6.2
Data Collected (MB) 200

Location

Test Period and weather Winter 1993; Cold, snow, sleet, fog Winter 1993; Cold, snow, sleet, fog Summer 1993; Hot, humid, heavy rain, lightning Summer 1993; Hot, humid, heavy rain, lightning Autumn 1993; Warm, rain

Runs

Traffic-Flow Direction Departing (am) and Approaching (pm) Approaching

Minneapolis Freeway I-394 at Penn Ave. Minneapolis Surface Street Olson Hwy, at Lyndale Ave. Orlando Freeway I-4 at SR 436 Orlando Surface Street SR 436 at I-4 Phoenix Freeway I-10 at 13th Street Tucson Surface Street Oracle Rd. at Auto Mall Dr. Phoenix Freeway I-10 at 13th Street

15

7

32 Approaching

28

670 Departing

21

200

Approaching 32 868 Departing

Autumn 1994; Warm Summer 1994; Hot, low humidity, some rain

34

2892

31

1060

Approaching

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Table 2.6.3 LowVolume Count x x x HighVolume Count x x x LowVolume Speed x HighBest in Volume Inclement Speed Weather x x x -

Technology Ultrasonic Microwave Doppler Microwave True Presence Passive Infrared Active Infrared Visible VIP Infrared VIP Acoustic Array SPVD Magnetometer Inductive Loop

x x

x x x

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In the Minnesota Guidestar study, nonintrusive detection technologies were field tested and evaluated. In the initial equipment field test, the nonintrusive detectors shown in Table 2.6.4 were tested at Interstate 394 and Penn Avenue in Minneapolis. In the extended field test, the detectors shown in Table 2.6.5 were tested and evaluated at the same site as the initial field test. The extended field test evaluated detector technologies under a variety of environmental and traffic conditions. Appendix D provides a summary of the findings with Figures.

Table 2.6.4 Devices Evaluated in the Initial Field Tests

Technology Passive Infrared Passive Magnetic Radar Doppler Microwave Doppler Microwave Doppler Microwave Doppler Microwave Passive Acoustic Pulse Ultrasonic Video

Vendor Eltec Instruments Safetran Traffic Systems Electronic Integrated Systems Microwave Sensors PEEK Traffic Whelen Engineering Whelen Engineering International Road Dynamics Microwave Sensors Rockwell International

Device Model 842 Sensor 232E IVHS Sensor RTMS TC 26B PODD TDW 10 TDN 30 SmartSonic TC 30C TraffiCam

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Freeway-Management Systems

Table 2.6.5 Devices Evaluated in the Extended Field Tests

Technology Passive Infrared Passive Infrared Active Infrared Passive Magnetic Radar Doppler Microwave Doppler Microwave Passive Acoustic Pulse Ultrasonic Pulse Ultrasonic Video Video Video Video

Vendor Eltec Instruments ASIM Engineering, Ltd. Schwartz Electro-Optics Safetran Traffic Systems Electronic Integrated Systems PEEK Traffic Whelen Engineering International Road Dynamics Microwave Sensors Novax Rockwell International Image Sensing Systems ELIOP Trafico S.A. Peek Transyt

Device Model 833 Sensor 2-IR-224 Autosense I 2-232E Sensor RTMS PODD TDN 30 2-SmartSonic TC 30C Lane King TraffiCam Autoscope 2004 EVA 2000 S Video-Trak 900

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c. Selection of Appropriate Technology. The conclusion that the best system is the one with the greatest benefit:cost ratio is not always correct. For example, a simple, low-cost system with fewer benefits may have the same benefit-cost ratio as a more sophisticated, affordable system with more benefits. Therefore, the analysis should include allowable expenditure for the system and the net benefits of each alternative.

Plan Development
After the system’s detection technologies have been selected, the next step is to develop a plan for implementation. The purpose of the Implementation Plan is to ensure that the system is designed, built, operated, and maintained to accomplish its purpose in the most efficient manner possible. The Implementation Plan is required when either a traffic control system or an expansion of an existing system is Federally funded. The Implementation Plan documents the results of the previous steps and identifies how the system will be implemented in the field. The Implementation Plan should also assess the phasing, procurement, and funding options for implementing the system. For further discussion on the contents of the Implementation Plan, see Appendix E. The operations and maintenance requirements of the planned systems must be in balance with the availability of proper personnel, equipment, and budget resources to operate and maintain the systems. More information of operations and maintenance of systems is provided in Appendix F.

Identify Funding Sources
Funding sources should be identified during development of the Implementation Plan. Funding for detection systems may come from both the Federal and State sources. On the Federal level, funding is available through ISTEA. Under ISTEA, Federal aid is available to assist with capital and operating expenses for transportation management programs. By including projects in the Transportation Improvement Program (TIP), a spending plan required by the Federal government, agencies can receive ISTEA funds. ISTEA permits startup and operating costs from the following sources: Surface Transportation Program (STP); National Highway System (NHS); and Congestion Mitigation and Air Quality Program (CMAQ). ISTEA funds are generally used for system deployment and to provide startup assistance. Public/private partnership is another approach that many agencies are using to increase the source of funding for transportation management systems. Further discussion and details of funding opportunities for transportation management systems at the local, State, and Federal levels is found in Chapter 9.

Implementation and Deployment
The implementation process includes the activities involved in installing the components of the detection system to meet established goals and objectives. Issues to be considered in the implementation of detector systems include: phasing of installation or construction; training of operators and maintenance personnel; and system deployment approaches. The procurement strategies include: solesource; engineer/contractor; two-step approach; system management; design-build. Appendix E discusses these strategies.

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Evaluation
Once a detection system has been installed, it is important to evaluate its effectiveness in meeting the objectives. Numerous methods of evaluating the effectiveness of detection systems and other transportation management systems are used by practitioners. The most common method is the beforeand-after method. By this method, the performance of the transportation management system is measured before the system is implemented and compared with measures of the same performance criteria after implementation. Appendix G provides other evaluation procedures for selected ITS strategies.

2.6.2 TECHNIQUES/STRATEGIES
Vehicle Detectors
Vehicle detection systems identify unforeseen reductions in freeway capacity and allow initiation of appropriate procedures to restore the freeway to full capacity. The inductive-loop detectors are the most extensively used today.

Call Boxes
Call boxes are often installed along freeways to provide motorists a means of calling for assistance. They are also used for incident detection, to inform the operating agency of the incident and its nature. Call boxes have become multitasking—not only for motorist aid but also for the acquisition and transmission of traffic data and weather and environmental data. Other capabilities include: full duplex voice capability; transmission and receipt of digital data; and detection and processing of real-time traffic information.

CB Monitoring
Drivers of CB radio-equipped vehicles report observed incidents to a central control center via channel 9, which was designed as an official emergency channel by the Federal Communications Commission (FCC) in 1970.

Weather and Environmental Detection
These systems consist of: surface sensors, which monitor pavement temperature and surface conditions including presence of ice, frost, water, and snow; atmospheric-condition sensors, which monitor air temperature, dew point, relative humidity, precipitation, wind direction, and wind speed; remote processing units, which collect and transmit the surface and atmospheric data from the sensors to a central processing unit; and central processing unit, which processes all the data for graphic presentation and trasmits the data to remote terminals. During the last 20 years, a number of State highway agencies have installed ice-detection and weather-information systems. Evaluations have included the performance of the system equipment as well as its usefulness, effects on highway safety, and cost-saving aspects. To encourage and assist State Highway agencies in evaluating their systems, the FHWA initiated Test and Evaluation Project No. 11, Ice Detection and Highway Weather Information Systems, in 1988. The project was originally identified as Special Experimental Project No. 13, but
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the name was changed in 1990. Eight cooperating agencies agreed to evaluate their use of these systems during the winters of 1989 and 1990. All participants used the SCAN system and SCANCAST service from Surface Systems, Inc. Appendix H provides a summary of this effort.

Overheight Vehicle Detection
These detectors detect the presence of overheight vehicles to prevent damage to the vehicles and highway structures. The detection and warning systems use infrared light, with a transmitter of the light on one side of the highway and a receiver on the other side. When an overheight vehicle is detected, the driver is warned of an approaching structure by means of a system of alarm bells and flashing lights. These systems are used on overpasses, approaches to tunnels, approaches to parking garages, etc. The detectors are used in conjunction with warning message devices including blankout signs, static signs with flashers, and audible warning devices.

Automatic Truck Warning System
Truck rollover on freeway interchange ramps is a serious safety problem. Large trucks overturn or rollover on curved ramps as the truck’s driver attempts is trying to negotiate the curve. Severe traffic disruption often results from these rollovers and the severity can be multiplied by the type of cargo the truck is hauling. In concept, a truck warning system must perform three primary functions: collection of data about the vehicle and highway, determination of rollover risk, and operation of a device to warn the truck’s driver of the risk with sufficient time to take corrective action. It is possible to design a warning system that is entirely infrastructure-based or entirely vehicle-based. In addition, it is conceivable to design an integrated system that uses both infrastructure information and data derived from on-vehicle measurements.

2.6.3 CASE STUDIES
The following are deployments and/or operational tests that apply state-of-the-practice and advanced technologies in automatic truck warning systems:

DC Beltway Demonstration Project
This demonstration project, installed at three locations on the Washington, DC, Beltway, includes the state-of-the-practice for an infrastructure-only automatic truck warning system. Piezoelectric, inductive loops and optical sensors measure the weight, speed, and height of passing vehicles as they approach the freeway ramp, and based on that data, trucks are identified and classified. If the estimated lateral acceleration is higher than the preset rollover threshold for the identified class and type of vehicle, warning lights on a roadside sign are activated until the vehicle passes the sign.

NHTSA Cooperative Agreement
A vehicle-based rollover system is in development under this cooperative agreement whereby the roll behavior of a tractor-trailer combination is measured by sensing the forces on the fifth-wheel coupler between tractor and trailer. The measured forces are then used with a computerized model of the vehicle suspension to estimate how closely the vehicle approaches rollover. The estimated risk is to
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be displayed on an in-cab display, allowing the driver to learn how the vehicle behaves and avoid high-risk driving. This development is for training purposes only. SOURCES: • • • • Feasibility of an Automatic Truck Warning System, September 1993, Publication No. FHWA-RD93-039. An Automatic Warning System to Prevent Truck Rollover on Curved Ramps, Public Roads, Spring 1994, Vol. 57, No. 4, by Hugh W. McGee and Rodney R. Strickland. Invehicle Safety Advisory and Warning System (IVSAWS), Vol. II: Final report, March 1996, Publication No. FHWA-RD-94-190, Prepared for FHWA by Hughes Aircraft Company. Heavy Vehicle Intelligent Dynamic Enhancement Systems, NHTSA Cooperative Agreement, Publication No. DTNH22-95-H-07002.

2.6.4 TECHNOLOGIES
Vehicle/User Devices
Technologies for vehicle/user devices are described below. a. In-Road Detection/Warning Systems In-road detection/warning systems use sensors deployed in or alongside the roadway just before a hazardous off-ramp. These sensors detect trucks and measure characteristics of the vehicles. Based on those measurements and the known lateral acceleration demand of the upcoming off-ramp, a roadside CPU estimates the risk of rollover for that vehicle. If that estimated risk exceeds a threshold set by the responsible local agency, the central processing unit (CPU) activates flashing lights or another warning device to alert the truck’s driver to the rollover hazard. Various sensors (e.g., piezoelectric, inductive loop, optical, video imaging) are used to measure the weight, speed, and height of trucks as they approach freeway off-ramps. Based on this data, trucks are identified and classified by a local controller (CPU) and separated on the basis of height (i.e., greater or less than 11 feet high) into box and tanker. Speed is measured at two points, allowing longitudinal acceleration to be estimated, and speed during the turn on the off-ramp, is projected with estimation lateral acceleration in the turn. If the lateral acceleration, that is estimated, is higher than a preset rollover threshold for the type and class of truck identified, warning signs and/or signals (e.g., sign with or without some type of beacon) on the roadside are activated until the truck passes. Overheight detectors (see above) are used to determine if a truck’s height is above a threshold height. The weight of the truck is usually obtained using commercial Weigh-In-Motion (WIM) systems. These systems use a combination of inductive-loop and piezo sensors. A controller is needed to accept all of the electrical inputs from the detection devices, process the information, and send signals to activate the warning devices. This controller is usually customized (i.e., no controller exists
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off-the-shelf to accept all of the inputs from all detectors and process all information) to accept and process the information. Warning devices usually consist of two types: a static sign with yellow beacons that flash when activated, and a static sign in combination with a dynamic message sign (DMS) (e.g., blankout sign) that displayS a message such as “Trucks Reduce Speed” when activated. b. In-Vehicle Detection/Warning Systems The in-vehicle detection/warning system measures the actual roll behavior of a truck under lateral acceleration and alerts the driver through an in-cab signal of the rollover danger. The system consists of equipment installed both in the vehicle and at roadside. The components of the systems follow. 1. Roadside Transponder - Transmits information on ramp characteristics such as ramp superelevation, etc. 2. Roadside Antenna - Relays the information from the roadside transponder to the truck 3. Roadside Detectors - Detects trucks and their speed, weight, and activates the transponder when the vehicle approaches the ramp. 4. In-Vehicle Electronic Reader - Receiving and reads ramp information sent by the antenna. 5. In-Vehicle Computer - Processes all driver-input (e.g., vehicle, cargo, load type, vehicle height), and roadside data, and activates an in-vehicle warning device if the rollover threshold has been exceeded. There are many technologies available for collecting traffic data. They range from the most used, inductive loop, to the newest and most promising technology, video image processing. radius,

Vehicle Detection
The following are available technologies used for vehicle detection. a. Inductive Loop The inductive-loop detectors are the most extensively utilized today. They provide data on volume, speed, and density (occupancy). The technology consists of a loop wire of one or more turns embedded in the pavement and connected to an electronic amplifier (located in the controller cabinet). This detector identifies the presence or passage of a vehicle. Inductive loop systems can provide data on volume, speed, occupancy, presence, headway, and classification. Advantages: • • •
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Flexible design. Wide range of applications. Provides basic traffic parameters.

Freeway-Management Systems

Disadvantages: • • • • Installation requires pavement modifications. Installation and maintenance require lane closures. Detectors subject to of traffic stresses. Subjection to damage and dislocation by road traffic or roadway equipment such as sweepers and snow plows.

b. Magnetometer This small, cylinder-shaped detector is placed in a drilled hole in the road for limited use in real-time surveillance. Limited applications include use under bridge decks, when damage to the reinforcing steel becomes a concern, and in roadways where deteriorating pavement dictates minimal saw cut. Advantages: • • • Easier to install than loops. Can be used in situations where loops are not feasible (e.g., bridge decks). Less susceptible to traffic stresses than loops.

Disadvantages: • • • • Installation requires pavement modifications. Installation and maintenance require lane closures. Small detection zone. Typically used to provide count and occupancy only.

c. Radar/Microwave This detector is non-pavement intrusive and is commonly used to monitor vehicle speeds for law enforcement and traffic management applications. Some advanced radar/microwave detectors can also be used as presence detectors. Because they use electromagnetic energy, radar/microwave sensors are typically unaffected by weather conditions, especially when measurements are made from a short distance. They can also be used for both day and night operations. One problem with radar/microwave detectors is that they tend to lock onto the strongest return signal, which is often produced by the largest vehicle in the traffic stream (a large truck). Smaller vehicles may not be detected by some units. Therefore, the vehicle mix of the traffic stream may affect the accuracy of the data supplied by this type of technology. Radar/microwave systems can provide volume, speed, occupancy, and presence detection.

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Advantages: • • Generally insensitive to weather conditions. Provides day and night operation.

Disadvantages: • • • Requires FCC license for operation and maintenance. May lock on to the strongest signal (e.g., large truck). Susceptible to interference from other devices operating at the same frequency.

d. Ultrasonic These detectors (e.g., smartsonic) are passive acoustic sensors and automated-signal and information-processing systems that listen (no energy is radiated by the system) for the noise generated by stationary or moving vehicles in a detection zone on the roadway. Only those vehicle sounds from within a specific detection zone are retained. Sounds from locations outside the detection zone (such as an adjacent lane) are severely attenuated and are ignored. The detection process for vehicle sound energy is analogous to the way the metal in vehicles is detected as those vehicles pass over a loop. It is an overhead-mounted system with limited side mount. Ultrasonic detection fully emulates loop-output signals, and thus requiring no modification to existing system hardware or software. Ultrasonic systems can provide volume, speed, occupancy, presence, and classification data. Advantages: • • • Completely passive Generally insensitive to weather conditions Provides day and night operation

Disadvantages: • • Relatively new technology for traffic surveillance Environmental conditions such as winds, heavy snowfall, and rain may inhibit the propagation of sound waves.

e. Infrared There are two types of infrared detectors: active and passive. Active infrared detectors focus a narrow beam of energy onto an infrared-sensitive cell, and vehicles are detected when they pass through the beam, interrupting the signal. These detectors can be used either as presence or pulse detectors. Detector performance can be affected by weather conditions (fog, rain, snow) causing inconsistent beam patterns. Passive infrared detectors do not transmit energy, but measure the amount of energy emitted by objects in their field of view.
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Infrared detection systems can provide volume, speed, occupancy, presence, and classification data. Active infrared detectors depend on the reflection of transmitted laser beams. Advantages: • • • • Active detector emits narrow beam for accurate determination of vehicle position. Provides day and night operation. Provides most basic traffic parameters. Passive detectors can be used for strategic loop replacement

Disadvantages: • • • • f. Operation affected by precipitation such as rain or fog. Difficulty in maintaining alignment on vibrating structures. Susceptible to sudden changes in background radiation due to rain or clouds. Some surfaces such as windshields and black metal and plastic car bodies are poor reflectors. Video Image Processing

With video image processing, cameras provide images that are used by a video processor to emulate traffic data. It is possible to define multiple detection locations within the camera viewing area. These “pseudo-detectors” are not fixed, but may be moved by the operator if desired. The type of signal processing algorithm used by the image processor dictates the type of data obtainable by the system. These systems can provide volume, occupancy, and presence detection. In more advanced systems, individual vehicles are tracked as they pass through the field of view, allowing identification of speed, vehicle classifications and travel times in the detection zone. Most processing algorithms have been optimized counter shadows, illumination changes, and reflections. Advantages: • • • Location or addition of detector zones can easily be done on the PC. Provides basic traffic parameters. Provides wide-area detection.

Disadvantages: • • Inclement weather, shadows, and poor lighting can affect performance. May require significant processing power and a wide communication bandwidth.
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Table 2.6.6 provides a list of detector technologies with their functional capabilities and cost. Table 2.6.7 provides estimated operating and maintenance costs for various detection technologies. Table 2.6.8 Summarizes the detector technologies discussed and the applications for which they are best suited.

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Table 2.6.6 Characteristics of Traffic Detectors
Applications Cost

Detector Life Moderate Moderate Current Low

Count

Lane Coverage Classificaper Presence Speed Occupancy tion Sensor Bandwidth Reliability Technology Installation Detector (each)

Inductive loop X X Low Long High Current X X Size of loop Moderate ($1000)

X

Low ($500-800)

Magnetometer X Current (1) X Single lane High

X

Moderate ($1000)

Low-Moderate ($500-1,500)

Microwave radar (2) (2) Multiple X (2) Long High

X

Moderate

Long

Low ($500) Low ($500)

Low-Moderate ($700-3,000) Moderate-High ($1,000-8,000)

Infrared X (2) X X

X

Single (active); Multiple (passive) LowModerate Single Low Moderate High

Developing

Ultrasonic X (2) X X

X

Developing

Low ($500)

Low-Moderate ($600-1,500)

Acoustic X (2) Multiple X X

X

LowModerate

N/A

N/A

Developing Developing

Low ($500) Low ($500)

Moderate ($1,500)

Video Image Processing X X Multiple X X

X

Moderate- Moderate Moderate High

Very High ($10,000-25,000)

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Table 2.6.7 Estimated Operating and Maintenance Costs for Detection Systems

Description Base Unit $0 $200 - $300 $200 - $300 Costs include contract maintenance/ replacement of loops. Costs assume four lanes per station, with two loops per lane. Costs also assume loop failure rates of 4% to 6% per year. Costs include routine maintenance of detectors. Costs assume four lanes per station, with one detector per lane. Costs include routine maintenance and calibration of detectors. Costs assume one video detector per station.

Estimated Annual Estimated Annual Estimated Annual Combined O&M Operations Maintenance Cost/Unit Cost/Unit Cost/Unit Cost Assumptions

Inductive Loop

Per station

Radar, Ultrasonic, Infrared $200 - $300 $0 $500 $500

Per station

$0 $200 - $300

Video Image Per station Processing

Table 2.6.8 Traffic Detector Applications Infrared Magnetometer Acoustic Active X X X X X X X X X X X X X X X X X X X X X X X X X Inductive Loop X X X X X X Microwave/ Radar Passive Ultrasonic Video Image Processing

Monitoring Application

Incident Detection

Traffic Conditions

Special Event

Implement Control Strategies

Vehicle Classification

Ramp Metering

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2.6.5 CASE STUDIES
TransGuide - From the TransGuide ITS Design Report (transguidewwwserver.datasys.swri.edu:80/ articles/designreport.html )

Loop Detectors
Loop detectors were chosen as the method of detecting incidents based on several factors. One significant factor is the climate in San Antonio, which is relatively amenable to buried detection technology. There are essentially no extended periods of time when the ground freezes. There is also very little snow and therefore no salt is used on the roadways. An additional factor is that loops were already included in some of the existing freeways when they were constructed. Finally, loop detection technology is a well understood and mature detection technology. While other detection technologies may be applied in the future, the initial sections of the TransGuide ITS are being implemented using loop detectors. Other detection technologies available include radar detection, visual or video detection, and audio based detection. Each of these technologies is being used in experimental or operational systems. However, none is as mature as the loop detector and none was demonstrably better or cheaper than loop detector technology when the TransGuide system was specified. While loop detectors may be susceptible to reliability problems in some locations, they are well suited to the San Antonio climate. Radar detectors are being experimented with in other cities; however, they do not offer specific information on separate vehicles. Radar detectors also require overhead installation, which may increase installation and maintenance costs. Video detection methods are beginning to be available, but they are relatively expensive and may suffer from some accuracy problems in specific vehicle or environmental conditions. Audio detection methods are also being developed, but they don’t offer specific information on every vehicle and lack a performance history. Loop detectors are buried in pairs approximately every ½ mile along the main lanes of the freeway, although freeway geometry causes this spacing to be less in some sections. Isolated loop detectors are also buried at strategically located positions, such as on and off ramps. The single loop detectors can determine the count of vehicles passing over the detectors (volume) and the percentage of time a vehicle is over the sensor (occupancy). In addition to volume and occupancy, pairs of loop detectors can be used to determine the average speed of vehicles passing over the loops. The loop detectors consist of six foot by six foot loops buried one inch under the roadway. The loops are constructed using one 14-American Wire Gage (AWG) conductor. Loop pairs are installed 12 feet apart and are made up of differing numbers of turns to minimize crosstalk. Changes in a loop’s inductance are detected to sense the presence of a vehicle. The loop detector signals are analyzed by LCUs similar to those used in traffic signals. The LCUs use the loop detector signals to determine volume and occupancy and (for dual loop configurations) speed. The LCUs also continually check the loops for long stretches of continuous presence or complete lack of presence, which may indicate loop detector problems. Problems are reported to the mainframe computer at the TOC and can result in reconfiguration of the loops.
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CAPITAL
The Cellular Applied to ITS Tracking and Location (CAPITAL) ITS Operational Test is based on partnerships between the FHWA and several public and private participants. It is a project that was designed to determine if cellular telephone technologies provide an accurate and cost-effective means of wide area traffic detection and surveillance. In addition it will determine if vehicle location information from cellular phone-equipped probe vehicles can be effectively integrated into real-time traffic control system for regional traffic management, traveler information or other purposes. The two basic components of the system are a vehicle locating component and a communication link to pass the information to a traffic control and management center. The CAPITAL system allows any vehicle equipped with a cellular phone to be a potential probe, with infrastructure modifications required only at the cellular tower sites. Unlike the tag-based approach which yields probe data only on those road segments instrumented, CAPITAL can provide probe vehicle speeds every few seconds on any road segment in the cellular coverage area on which mobile phone users are traveling. The traffic information component is performed by the Traffic Information Center. Within the center, MIST software processes probe vehicle speed data and cellular call activity statistics. Data fusion techniques synthesize real-time estimates of traffic conditions from raw speed data and historical speed profiles. An important finding from the system test is that cellular phone usage on a given link accelerates as traffic volumes approach and exceed link capacity—indications of presence of incidents. A high concentration of Emergency 911 calls was another indication of an incident. The data distribution component provided the capability to broadcast traffic to designated users. Traffic information was displayed graphically at several traffic control centers and other selected locations for invehicle use. Land-line and cellular telephones were used to deliver traffic information to users (Robert Larsen, August/September 1996)

2.6.6 EVOLVING TECHNOLOGIES
Smart Call Box
A Field Operation Test that will use California’s extensive call box system and increase its functionality by adding an interface to traffic management devices. The project will test the feasibility of using the Smart Call Boxes to collect traffic census data; obtain traffic counts, flows and speeds for incident detection; report information from roadside weather information systems; control changeable message signs; and control roadside closed-circuit television cameras.

Vehicle Probes
The vehicle itself has become an important surveillance tool for monitoring conditions on the roadway. Vehicles, acting as moving sensors (probes), can provide speed and delay on links traversed. This information can be transmitted to a central computer system where information can be combined or fused with other information for more accurate representation of the actual travel conditions. Technologies that utilize vehicles as probes include:

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Automatic Vehicle Identification (AVI)
These systems permit individual vehicles to be uniquely identified as they pass through a detection area. A roadside communication unit broadcasts an interrogation signal from its antenna. When an AVI equipped vehicle comes within range of the antenna, a transponder (tag) in the vehicle returns that vehicle’s identification number to the antenna. This information is then transmitted to a central computer where it is processed.

Automatic Vehicle Locating (AVL)
This system enables the approximate location of a vehicle to be determined and tracked. There are numerous techniques and technologies that are used for locating a vehicle including Global Positioning Systems (GPS), radio frequency triangulation, proximity beacons, and cellular telephone systems. For the most part, the position of the vehicle is compared to a map database using map matching techniques.

Cellular Telephone Probe
A vehicle’s location can be determined from signals resulting from cellular phone usage within a vehicle, using RF receivers and triangulation techniques. Using this technology in conjunction with map matching algorithms, vehicles can be tracked. This will allow vehicle speeds, as well as travel times to be measured. SOURCES: • • • CAPITAL: Using Cellular Phones As Traffic Probes, August/September 1996, by Robert Larsen, Traffic Technology International. Detection Technology for IVHS, Volume I:Final Report, December 1996, US Department of Transportation, Federal Highway Administration, Publication No. FHWA-RD-95-100. Field Test of Monitoring of Urban Vehicle Operations Using Non-Intrusive Technologies, Volume 4: Task Two Report, Initial Field Test Results, May 1996, US Department of Transportation, Federal Highway Administration. Field Test of Monitoring of Urban Vehicle Operations Using Non-Intrusive Technologies, Volume 5: Task Three Report, Extended Field Tests, December 1996, US Department of Transportation, Federal Highway Administration. Traffic Detector Handbook, 1990, ITE.

•

•

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2.7 TRAFFIC SURVEILLANCE
Traffic surveillance is the core of any effective advanced traffic-management system. It helps in accumulating accurate and reliable traffic information; identifying and verifying recurring and nonrecurring congestion; identifying severity of problem areas; continual monitoring of traffic over a network; and evaluating the effects of traffic operational improvements. The Freeway Management Handbook discusses the process of planning, designing, and installing traffic-surveillance systems. The following steps make up this process:
l

Problem Identification. Identification of Partners. Establish Goals and Objectives. Define Functional Requirements. Establish Performance Criteria. Define System Architecture. Identify and Screen Technologies. Plan Development. Identify Funding Sources. Implementation and Deployment. Evaluation.

l

l

l

l

l

l

l

l

l

l

Section 2.6 Detection, provides further discussion of this process and the steps. SOURCES: • Urban Freeway Surveillance and Control: The State of the Art, November 1972.

2.7.1 TECHNIQUES/STRATEGIES
Closed Circuit Television (CCTV)
CCTV provides a means of visually confirming detected congestion and monitoring freeway operation. This is performed by operators in a central control room who monitor traffic conditions using cameras installed at selected locations on the freeway. CCTV is used in freeway management for various applications including:

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a. Incident management. Once an incident has been detected, CCTV is used to verify and confirm the incident, obtain more information as to location and nature (severity) of the incident, and assist in the response to the incident. b. Monitoring of Traffic. Traffic on the freeway mainline, HOV lanes and their operation, ramp metering operation, operation of changeable message signs and driver response my be monitored. c. Monitoring of Corridors. CCTV is used to monitor parallel surface streets and signalized intersections along with ramps and metering to verify traffic and capacity for route diversion. d. Safety and Enforcement. Monitoring for safety and law enforcement is possible at vital traffic areas such as rail-highway grade crossings intersections, and to detec electronic toll collection violators, truck weigh-station violators, etc.

2.7.2 TECHNOLOGIES
The following technologies are used for freeway video surveillance:
l

CCTV Cameras, Lenses, and Environmental Enclosures. CCTV Cameras with Video Image Detectors (VIDS). Compressed Video. Video Image Processing.

l

l

l

CCTV Cameras
The modern video cameras uses a chip rather than a tube, to pick up the video image. The use of these chips as image pick-up devices has brought about advancements in camera compactness, durability, and performance. This type of camera is described as a Charged Coupled Device chip camera with a solid-state imager. Types of tube cameras: a. Standard Vision Cameras, designed to work in even, constantly full light. b. Ultricon and Newvicon Cameras, designed to work in lower light levels and require an auto iris lens. c. Silicon Intensified Target Cameras, designed to work in extremely low-light conditions Types of Charged Coupled Device Cameras: a. Complementary Metal Oxide Semiconductor Cameras, designed to work in well-lit areas. They have high sensitivity to Infrared (IR) light and low sensitivity in low lighting conditions.
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Advantages: • • • Good horizontal resolution. Low cost. High sensitivity to IR provides the camera with the ability to work with IR lighting enhancements.

Disadvantages:

• •

High sensitivity of chip to IR makes this a weak choice for use in the bright sun. Low sensitivity to low-light conditions makes it a poor choice for nighttime applications. When the available light drops below an acceptable level, a grid-like set of white lines may appear in the center of the picture.

b. Interline Transfer Cameras, designed to work in areas with wider light variations. They are highly sensitive to IR light and have good response in low lighting conditions. Advantages:

• • • •

Good horizontal resolution. With IR enhancement lighting or white-light enhancement lighting, this camera works well in lower light applications. High IR lighting response gives the camera the ability to work with IR lighting enhancements. Much-improved resistance to vertical transfer smear.

Disadvantages:

• •

Even though this camera has better lower light sensitivity than other cameras, it requires enhancement lighting and wider aperture lenses. Because of the camera’s sensitivity to IR light, an IR cut filter may be required with outdoor applications.

c. Frame Transfer Cameras, like the interline transfer cameras are designed to work in areas with wider light variations. They have good sensitivity to IR light and have a fairly good response in low lighting conditions. Advantages:

• •

Good horizontal resolution. Good low-light sensitivity.

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•

Good sensitivity to IR light gives the camera the ability to work with IR lighting enhancements.

Disadvantages:

• • •

These cameras are considerably more expensive. Only a few manufacturers produce this camera, making availability low. The camera imager is very sensitive to bright light sources, which can cause bright vertical lines (called vertical transfer smear) in the image.

Chip cameras (charged coupled device) have numerous advantages over the tube cameras for traffic-management applications. Major advantages follow:
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Tube cameras have a problem with burned or retained image when left viewing a static illumination source. When this happens, there is an actual desensitizing of the target area (the photosensitive material where the light is focused) in direct proportion to the light focused on it. As a result, an image of the area that was being monitored remains after the lens is capped or the camera is relocated. When this occurs, the camera must be replaced. The electronic design and solid-state material of chip cameras prevents them from burning or retaining images. For this reason, chip cameras far outlast tube cameras. Tube cameras are large, bulky, and emit a lot of heat. The large size of the camera is attributed to the fact that the camera requires large tubes, it requires a lot of circuitry for high voltage to power the tube, and many board-mounted pieces to run the camera. A lot of heat is produced by the camera tube filament and by the large amount of normal circuitry needed to run the camera. Chip cameras, by contrast, are low-voltage units (i.e., the lack of tubes cuts down the amount of electronic circuitry needed and voltage required). Chip cameras are smaller, lighter, and more versatile, and can be installed where ventilation is not accessible, due to their generation of less heat. Tube cameras have blooming problems (i.e., exaggeration of a bright area or spot within a video image, such as that caused by a headlight or street lamp). When a tube camera produces an image, a beam of electrons is produced in the tube by an electron gun and is propelled at great rates toward the front target of the tube. As the cathode of the electron gun in the tube wears out, the electron stream used to discharge the target weakens, thus hampering the tube’s ability to fully recover the bright areas of a scene, which causes the blooming effect. Chip cameras do not bloom, since they do not have electron guns or target areas. The basic design of the tube camera limits the range of imaging enhancements that may be builtin. Tube cameras are capable only of producing a linear videosignal, whereas chip ameras are able to produce a digital video signal directly from the chip. This allows chip cameras to produce such enhancements as built-in zoom, freeze actions, electronic shutter, and digital video motion detection. Peripheral equipment must be used to achieve such enhancements with tube cameras. Chip cameras generally produce better image quality than tube cameras. Even though the tube camera has more horizontal lines of resolution than the chip camera, it has a limited gray shade

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response and therefore produces images that appear soft to the human eye. Chip cameras have a very high density or contrast output. The newest camera technology on the market is the Digital Signal Processing (DSP) camera. These cameras are discussed in Chapter 8, Evolving Technologies. The use of color versus black-and-white cameras is an important consideration. Black-and-white cameras generally provide higher horizontal resolution than color cameras. Resolution is a measurement of the number of television/monitor lines produced by the camera. It is expressed as lines per picture height, or number of lines horizontally. Black-and-white cameras provide 580 horizontal TV lines, while the maximum number of TV lines produced by color cameras is 460. In addition, blackand-white cameras have better low-light performance than color cameras, which makes them better cameras in locations where there is a lack of highway lighting. Black-and-white cameras are most often used in tunnels where there is not much light. In daytime operations, color cameras perform as well as black-and-white cameras. Color cameras provide important information that is often needed to describe vehicles and to identify license plates for law enforcement. In addition, as technology advances, color cameras are preferred for traffic surveillance, because their images are more pleasing and most people relate to color images.

CCTV Camera Lenses
The CCTV camera lens is used to project the scene on the camera imager for reproduction as a video signal by the camera. A wide variety of lenses of different sizes with different features and characteristics can be used, depending on the application and environment in which the camera is used. The basic parameters affecting the viewing capabilities of a camera are: a. Focal Length. The focal length of a lens provides the distance from the lens to the imager. As the focal length increases, the image size also increases and magnification occurs. For freeway traffic management, it is necessary to use a zoom lens with wide focal-length range, to provide both a wide angle of view to view all lanes of traffic in both directions at close range and a telephoto view to zoom on an incident up to a half-mile away. b. F-Stop. F-stop is a measurement of the amount of light that can reach the sensing device through the lens, a function of the focal length divided by the aperture. The higher the F-stop, the less light transmitted through the lens. As a lens is zoomed for viewing distance or the lens aperture is decreased, the F-stop increases. Freeway traffic management applications require that video images be produced in low-light conditions; therefore the lens should have a low Fstop. c. Angle of View. Angle of view is a measure of the camera’s field of view, typically measured in degrees. When a zoom lens is used, the angle of view decreases as the scene width shrinks. Angle of view is a function of the camera imager size, the lens format size, and the focal length range. Once the required angle of view is determined, decision can be made regarding imager size, lens size, and zoom lens focal lengths.

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CCTV Environmental Enclosures
The main purpose of camera enclosures is to protect the camera and from severe weather conditions (e.g., cold, humidity, rain, snow), road moisture, chemicals used on the pavement during snow and ice (e.g., salt), pollution, dirt, dust, etc. The sealed and pressurized camera housing is most often used in traffic-surveillance operations where the camera is mounted high on a pole outside. The Cohu housing, for example, pressurized with 5 psi of dry nitrogen, has desiccant bags and a humidity indicator installed within the enclosure and is made from aluminum tubing. Most camera enclosure units come with a sunshield and waterproof seal to protect the camera and lens assembly from moisture and the heater/defroster system (Appendix I provides a planner for Traffic Management Video System).

2.7.3 CASE STUDIES
TransGuide - From the TransGuide ITS Design Report (transguidewwwserver.datasys.swri.edu:80/ articles/designreport.html)

Cameras
The selection of the camera, the lens, and the spacing between the cameras involved several interrelated factors. A very powerful lens system could meet the video requirements with much wider camera spacing than a less powerful lens system. The more expensive cameras provide remote capabilities that allow the operators to make better use of more powerful lens systems. There are tradeoffs between the initial expense of the cameras and the initial expense of the additional communications system equipment required for less expensive cameras, as well as tradeoffs between higher installation and maintenance and cameras with higher initial costs. Cameras investigated included one-chip low resolution cameras, one-chip high resolution cameras, three-chip high resolution cameras, and digital cameras. The three-chip color cameras selected provide the good color and resolution needed. The highest resolution digital color cameras did not make a noticeable difference in the useable quality of the picture compared to the associated increase in costs. They also lose some effectiveness when digital magnification is used. The lower resolution and less expensive cameras provide noticeably less useful video to the operator. The camera technology selected was the three-chip, ½-inch, high-resolution color Charged Coupled Device (CCD) Frame Interline Transfer (FIT) camera. Most of the controls on the camera are controllable via an RS-232 interface, a standard serial digital interface used to communicate between devices. The user can control the gain and iris, as well as less frequently used characteristics, including various pedestal levels, shutter speeds, black and white balancing, and the detail level of the video camera (DTL). The one major characteristic for which remote control was not specified is the filter. A 5600K filter was manually selected on each camera as it was installed. The specifications required that the camera use at least 772 pixels horizontally and 492 pixels vertically to provide National Television System Committee (NTSC) video with a minimum of 650 lines of horizontal resolution. The specifications required a wide range of gain settings (-3, 0, 3, 6, 9, 15, and 18 dB) to allow the camera to work well in many lighting conditions, including near dark. The FIT three-chip set eliminates many of the streaking effects seen in the Interline Transfer (IT) chips used in some other cameras. The camera selected meets these specifications and is capable of providing high resolution,

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color video signals of good quality in most traffic control and emergency response situations. It provides 750 lines of horizontal resolution with a 60 dB signal-to-noise ratio.

Lenses
The selection of the lens system for TransGuide was an integral part of the video equipment selection process. Camera spacing versus lens magnification was one of the primary tradeoffs analyzed in the selection of a lens system. The camera/lens configurations were required to provide clear video of incidents at the resulting ranges of 1/4 mile, 3/8 mile, and ½ mile. The number of cameras required at each spacing was also considered. The results of the investigation led to a choice of 1-mile (nominal) spacing for the cameras. The availability of a lens stack and camera consisting primarily of off-the-shelf components, which could provide useable video at ½ mile, was a prime determining factor in the selection of that spacing. Once the camera spacing was determined, the selection of the lens system necessary to meet the TransGuide requirements at that spacing could be made. The lenses specified for the TransGuide video system are made up of several components, including a standard 2/3-inch lens capable of being remotely zoomed from 9.5 to 15. An adapter, required to allow the 2/3-inch lens to interface with the ½-inch camera lens mount, provides an effective magnification of approximately 1.48. A teleconverter with a magnification of 1.5 and an additional extender lens with a magnification of 2.0 are also specified as part of the lens system. The specifications require that the extender be capable of being remotely added to or taken out of the lens configuration. Overall, the specified lens system is capable of providing a magnification of between 21 and 33.3 without the extender and between 42 and 66.6 with the extender in place.

2.7.4 EMERGING TECHNOLOGIES
Digital Video Cameras
From its inception, video has been recorded and transmitted as analog electrical signals. While analog video transmitters and receivers can be built inexpensively, analog video is very expensive to transmit and to store. Further, today’s powerful digital computers cannot process analog signals, so analog information cannot be easily sorted, searched or edited. The transition of video from the analog to the digital domain changes everything. Digital video can be stored and distributed more cheaply than analog video, and digital video can be stored on randomly accessible media such as magnetic disk drives (hard discs) and optical disc media (CDS). Once stored on a randomly accessible media, video becomes an interactive media, allowing video to be used in various applications. Digital video also dramatically increases transmission efficiency, which means that communications networks, from the public telephone system to coaxial cable television systems to telecommunications satellites, will be able to carry from six to ten times more channels of video programming than was possible before, dramatically increasing consumer choice. The ability to transmit video over the public
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switched telephone network will also allow video conferencing, accelerating the work-at-home movement that is changing the way we are all employed (ccube.dvptechdoc.com/ftrstry/dvd.html). The major benefit of Digital Signal Processing (DSP) cameras is the minimization of analog circuitry which is susceptible to adding noise to the video parameters with temperature. DSP camera technology eliminates discrete components, thus, potentially improving reliability. The component reduction further facilitates smaller, lighter-weight cameras that consume less power. Firmware within the DSP replaces discrete components and facilitates application of advanced video processing algorithms. With processing speeds of DSP increasing, many more advanced signal processing functions will eventually be accomplished in the camera’s DSP Some advantages of DSP cameras include: it . stabilizes image from wind gusts and mounting pole vibrations; it facilitates frame-to-frame integration to improve sensitivity; potential improves image quality by reducing analog components which are subject to drift.

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2.8 DYNAMIC MESSAGE SIGNS (DMS)
Dynamic message signs are traffic-control devices used for traffic warning, regulation, routing, and management. They are designed to affect the behavior of motorists, thus improving the traffic flow, by providing real-time highway-related information. DMSs are the backbone of the traveler information system, improving roadway operations and safety. They display messages informing the motorist of recurring problems, nonrecurring problems, severe environmental and weather conditions, special events, highway priority and HOV lanes, operational characteristics such as toll facilities, exclusive lanes, routing and diverting of traffic, weigh stations, etc. DMSs consist of three types of real-time signs: advisory, guide, and advance. Advisory DMSs display real-time information on freeway status and advise motorists as to the best course of action. They are used for incident management and special events. These signs are located at freeways, at entrance ramps to the freeway, and on arterial streets approaching the freeway. Guide DMSs may be used to indicate alternate routes during incident management. Although static trailblazer signs are commonly used to divert motorists to alternate routes, DMSs are becoming more and more popular and have been used to display dynamic trailblazers with changeable arrows for guidance. Advance DMSs are used to alert or the motorist to upcoming advisory DMSs. In most cases, this advance sign is static. However, dynamic advance signs have been used to display a simple message alerting the motorist of more information up ahead. This combination of dynamic signs has been very effective in incident management. SOURCES: • • Guidelines on the Use of Changeable Message Signs, May 1991, Publication No. FHWA-TS-91002. Guidelines on the Selection and Design of Messages for Changeable Message Signs, 1992, by Texas Transportation Institute, Research Report 1232-10.

2.8.1 TECHNOLOGIES
Rotating Drum
Rotating drum signs are the oldest type of changeable message sign. They are the most reliable and most efficient when a limited message is to be displayed. The rotating drum is a mechanical device with a three-sided rotor, to display messages, and uses raised sheet metal or spray-masked letters on a painted aluminum, wood, or translucent plastic background. Advantages: • Low power usage - the sign only draws power when changing the state of the rotor.
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• • • •

Material used is high-intensity scotchlite (same as static signs) and is highly visible in bright conditions. Low maintenance - long mean-time to-failure rate. Any color may be incorporated into the message. Exact shapes of symbols and letter types can be displayed.

Disadvantages: • • • In the process of rotating drum, unwanted messages may be visible for a short period of time. Requires external lighting during low visibility periods and at night. Limited number of messages that can be displayed (normally four drums with three messages per drum).

Reflective Disk Matrix
Reflective-disk matrix signs consist of standard reflective-disk elements coated with florescent saturn yellow tape on the set side and the reset side of the disk element flat back. This type of sign reflects light from some external source such as the sun, headlights, or bottom-mounted lighting. The signs use power only when the disks are rotated or flipped. The reflective-disk elements are electromagnetic and operate on short DC pulses from a microprocessor controller. Advantages: • • • Low power usage - power is used only when the disks are rotated or flipped. In direct sunlight, reflectivity is more visible than illuminated signs. The disk elements are large, giving the message contents a large fill area.

Disadvantages: • • • • Poor legibility when the sun is behind the sign, due to poor legend contrast. Sun and external lighting can cast shadows, covering portions of the legend. Non-glare lexan, used in front of the sign, reduces the life of the lexan requiring changing every year to maintain visibility. Reflective disks need to be changed every four years due to fading of the fluorescent yellow tape.

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Neon
Neon signs use neon tubing to form legend characters. The display area size, however, limits the number of messages that can be displayed. The neon tubing maybe stacked for each message, or each message may be separate on the sign face. Advantages: • • • Enlarged surface displayed area accommodates more messages. Two neon tubes per message provide redundancy. Red neon fairs is visible under all types of weather conditions.

Disadvantages: • • • Large number of messages requires numerous layers of tubing. Green neon is less visible for freeway applications. Neon signs do not incorporate light dimming and each application must be customized.

Bulb Matrix (Incandescent)
Bulb matrix signs are made up of incandescent light bulbs used to form characters or graphics. The bulbs are electronically turned on and held on during the period of display. Advantages: • • • Very effective in capturing motorist attention. Excellent visibility under all lighting conditions, except in direct sunlight. Low capital cost.

Disadvantages: • • • • Very high power consumption. High cost of maintenance - bulbs change about once every year. Mean time between failures is high due to high voltage internally and the electronics required to control the sign. In direct sunlight, the bulbs have a tendency to washout.

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Light-Emitting Diode (Clustered)
Light-Emitting Diode (LED) signs are made up of clusters and are steady-state devices that provide enough intensity when voltage is applied. Available colors are red, green, yellow, and orange. Advantages: • • • • • Lower power usage - the LEDs require on the order of 20 MA and are multiplexed to lower the overall power. High reliability - rated at 100,000 hours of continuous operation (12 years). Effective in capturing motorist attention. Writing speed is much faster than electromechanical methods. No mechanical parts that can wear and fail.

Disadvantages: The intensity of LEDs is reduced at high temperatures - ventilation is necessary. Different colors, such as green or amber, may degrade in direct sunlight. Since LEDs are low voltage, high current is required to power up the sign.

Fiber-Optic Matrix (Fixed-Grid)
Fiber-optic signs use a light radiated from an internal source (halogen lamp) and directed to the sign’s viewing face through a bundle of fibers. On the sign face, the points of light (pixels) are arranged in a matrix array. Each point of light that appears on the matrix screen comes from the end of an individual light guide. Advantages: • • • • Message changing is almost instantaneous. High contrast and luminance levels result in long distance legibility and high clarity. Color filters can create almost any color. Messages can either be symbols or words.

Disadvantages: • The message is displayed only when the internal light source is activated.

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Fiber Optic Matrix With Shutters
These fiber-optic signs use electro-mechanical shutters and fiber-optic bundles to form changeable pixels. A light source is covered and uncovered by the shutters illuminating the pixels. The viewing face is similar to the bulb matrix sign with the lighted elements being fiber-optic rather than incandescent bulbs. Advantages: • • • Low power use - a light source is not used for every pixel but for multiple pixels (two 50 W halogen lamps for each set of three characters or 105 pixels). Light source through the fiber bundles make day and night visibility very good. A magnetic memory in each shutter retains the shutterposition indefinitely without control power.

Disadvantages: • • • • Light sources only have an average life of 8,000 hours, making maintenance high. The electronic controls of the shutters, light sources, and backup light sources are complex, making maintenance high. The 5x7 matrix array of fibers restricts the presentation of exact symbols and lower case letters. The cone of vision produced by the focused fibers restricts viewing.

Liquid Crystal Display Blankout Signs
Blankout signs display messages only when the sign is illuminated. The messages are fixed and can be displayed, in entirety or a portion, when illuminated. They are normally neon-type, but can also be of fluorescent lamps behind a cut-out legend, or fiber optics on a fixed grid. Advantages: • • • Exact shapes of symbols may be displayed. Message changing is instantaneous. Any color combination may be employed.

Disadvantages: • Very limited in the number of messages and applications.

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Hybrid-Fiber-Optic/Reflective Disk
These signs use the standard reflective disks for daytime viewing and fiber-optic pixels for night-time viewing. The fiber-optic pixel is located behind the disk, radiating light through small holes. A fiberoptic light source is used for every three disk modules and is controlled by a photocell and the sign microprocessor controller. The light source is illuminated at all times but visible only when the disk is in the yellow position - “on.” Advantages: • • • • Disks may be used to display messages in the event of a power failure. In direct sunlight, the reflectivity of the disks is better than that of other illuminated types. During night-time operation, illumination of the disks is not required since messages are being formed by fiber pixels. Utilizes strengths of both fiber-optic and reflective disk technologies.

Disadvantages: • • Reflective disks must be changed every four years due to fading of the fluorescent yellow tape. The life of the light source (bulb) is only 8,000 hours.

Hybrid - Light Emitting Diode/Reflective Disk
These signs are the latest in sign technology. Like the fiber-optic/reflective disk technology, the disks are used for daytime viewing and they open up to allow LEDs to be visible to viewers. The LEDs inside the disks are a cluster of up to five high-power amber LEDs. The LEDs are controlled separately from the disks, and either may be activated in the event of the other’s failure. Advantages: • • • • • Disks may to display messages in the event of a power failure. In direct sunlight, the reflectivity of the disks is better than that of other illuminated types. Utilizes the strengths of both LED and reflective disk technologies. Requires power only to change disks and LEDs, which use only 20 MA per element. Long life of both disk elements and LEDs.

2.8.2 CASE STUDIES
Most Freeway Management Systems have DMSs; a discussion can be found in Appendix B.

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2.9 HIGHWAY ADVISORY RADIO (HAR)
The HAR is intended to provide more specific traffic information at key locations more immediately than is possible through traditional commercially broadcast traffic reports. HAR uses either live messages, preselected taped messages, or synthesized messages, based on information from the Traveler Information Database (TID). It is expected that area HAR systems will ultimately employ an automated Voice Response System (VRS), a microcomputer-based system that uses TID information as its basis for operation. The VRS then develops digitized audio messages for dissemination.

2.9.1 TECHNIQUES/STRATEGIES
There are two types of HAR systems: Vertical “Whip” Antenna Systems and Induction Cable Antenna Systems.

Vertical Antenna Systems
Vertical Antenna Systems use individual antennas or a series of antennas electronically connected together to transmit information. The signal radiates from the antenna in all directions, providing a circular area of transmission. Vertical antenna systems are small, easy to install, and can be placed within several hundred feet of the roadway. They are also less costly to purchase and install than induction cable systems. However, they are subject to damage by weather, accidents, and vandalism. They often require special equipment to ensure that the signal is stable, reliable, and easily tuneable. Also, because the information is broadcast in a circular zone of coverage, the signal may interfere with other coverage zones on the same or adjacent roadways.

Induction Cable Antenna Systems
Induction Cable Antenna Systems use a cable installed either under the pavement or adjacent to the roadway. This type of antenna design produces a strong but highly localized signal within a short lateral distance (100 to 150 feet) of the cable. The signal is strong enough to provide full coverage of a multi-lane facility without causing interference to other HAR systems. Also with this system, messages can be individualized by direction of travel. Information is received by the motorists within range of the cable. As a result, interference to other radio systems in the area is minimized. Since the cable must extend the full length of the desired coverage area, induction cable systems are more costly to purchase, install, and maintain. Furthermore, they are not easy to install, especially in builtup areas or on existing facilities, and once installed, they cannot be transported from one location to another. SOURCES: • • Highway Advisory Radio User’s Guide, Publication No. FHWA-RD-80-166. Highway Advisory Radio Systems Design Guidelines, Publication No. FHWA-RD-80-167.

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2.9.2 TECHNOLOGIES
HAR rely upon any of the following technologies for transmission.

FCC-Licensed 10-Watt Transmission
FCC-licensed 10-watt transmission allows a broadcast radius of approximately 3 miles. Any frequency between 530 KHz and 1710 KHz can be used for transmission. However, the FCC has opened up the former dedicated traveler information/HAR frequencies (530 KHz and 1,610 KHz) to commercial broadcasting. Therefore, the potential for interference from commercial broadcasters has increased. Transmission by this means is omnidirectional. Consequently, several adjoining 10watt transmission zones may encounter interference problems due to radio frequency interference of adjacent transmitters.

Low-Power Transmission (Not Requiring FCC Licensing)
Low-Power Transmission uses 0.1-watt transmitters (not requiring FCC licensing) interconnected and synchronized to form a zone. The zonal configuration allows relatively linear broadcast zones with 1,800-foot spacings between transmitters. The technology has been tested as part of the Santa Monica Smart Corridor project. An operational test bed is being set up in downtown Los Angeles to evaluate its performance in a high-density urban zone. Based on the most recent test results, low-power zonal transmission offers less interference and a stronger signal than a more conventional 10-watt transmitter. Transmitters can be adjusted to avoid overlap between zones.

Institutional Arrangement With One or More Public Radio Stations
By this arrangement, a station’s regular programming may be preempted for traffic information. One drawback is that it will be broadcasted region-wide, while the information may only involve one or two locations.

Leaky Coax
Leaky Coax technology uses direct buried coaxial cable to provide linear coverage. However, this technology has not yet been utilized and direct burial cable poses a number of maintenance problems, particularly involving construction projects in the vicinity of the cable.

FM Side Carrier Allocation (SCA)
Side Carrier Allocation (SCA) utilizes the “sideband,” or space between radio station frequencies, for digital voice broadcasting. Specially equipped radios can tune in the sideband to receive the clear digital signal.

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2.9.3 CASE STUDIES
Numerous Freeway Management Systems have HAR; a discussion can be found in Appendix B.

2.10 COMMUNICATIONS
A freeway management and control system is comprised of many different elements: field components such as signal controllers, ramp meters, field masters, and changeable message signs; surveillance hardware such as detectors and TV cameras; central equipment such as computers, peripherals, and TV monitors; and the human element-operators and maintainers. Each of these components must exchange information with the others. Further, communication system is required to transfer information between the field equipment and the control center. This information may be in the form of video pictures, voice messages, or control and surveillance data (low-speed data). SOURCES: • Communications Handbook for Traffic Control Systems, 1993, FHWA Publication No. -93-052, U. S. Department of Transportation, Washington, DC, by Robert L. Gordon, R. A. Reiss, W. M. Dunn, and D. R. Morehead. Internetworking with TCP/IP Volume I Principles, Protocols, and Architecture, 3rd Edition, 1994, , Douglas E. Comer. Multiple Access Communications, Foundations for Emerging Technologies, 1993, Norman Abramson, Institute of Electrical and Electronics Engineers. National Transportation Communications for ITS Protocol—Overview, 1995, National Electrical Manufacturers Association. National Transportation Communications for ITS Protocol—Simple Transportation Management Framework, 1995, National Electrical Manufacturers Association. National Transportation Communications for ITS Protocol—Class B Profile, 1995, National Electrical Manufacturers Association. Intelligent Vehicle Highway Systems Mobile Communications Guidelines, September 1993, by Mitre Corp. 1993 Wireless Communications Symposium, technical Papers, 1993, Hewlett Packard. Proceedings of the Second Federal Wireless User’s Forum Workshop, September 1993, US Department of Commerce. IVHS and Vehicle Communications Compendium of Papers Presented at the 1991 SAE Future transportation technology meeting, Portland Oregon, August 1991, SAE.

• • • • • • • • •

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2.10.1 TECHNIQUES/STRATEGIES
Transmission
a. Data and Voice Transmission- Data and voice transmission technology is virtually all digital and largely based on the T-Carrier system and the Synchronous Optical NETwork (SONET) standards in both public and private networks. This generally allows a second manufacturer’s equipment to be added to a given site without reconfiguring the hardware. b. Video Transmission - Full motion video requires 6 MHZ of bandwidth per camera, as compared to a bandwidth requirement of only 0.005 MHZ for low-speed (1200 baud) data channel. Video is an analog source, while data communications and the T-Carrier and SONET standards are digital. Video transmission is best done over wide-band technologies utilizing dedicated microwave frequencies, coaxial cable, and optical media (fiber optics). Developments include fiberoptic video multiplexers (providing up to 36 video images over a single fiber) and fiber-optic transmission equipment which permit analog video and digital camera control data to be transmitted over the same fiber. An alternative is to use digital data/voice media along with the means to compress the analog signal into a digital format. A CODer-EnCoder (CODEC) unit can digitize the video image and compress the bandwidth such that real-time images may be transmitted over the telephone lines or other data communications media (e.g., radio, satellite) and back to an analog format for viewing on a television monitor. A reasonable degree of full motion (10 to 30 frames per second) and resolution is maintained, even when there is significant motion in the video image or the camera is being panned or tilted. The best video quality is associated with the highest transmission rates (typically 384 kilobytes per second or higher). When it is infeasible to install cable or lease cost for fiber is prohibitive, compressed video offers an attractive alternative. Early attempts at transmitting video over voice grade lines (slow scan) were unacceptable for most freeway management applications because the refresh rate was typically 60 seconds (a snapshot). With compressed video techniques, refresh rates of eight to ten frames per second are possible. Although the image appears slightly jerky, it is more than adequate for monitoring freeway operation. The system requires a compression and decompression computer for each camera/monitor link and off-the-shelf software. The communications medium is a leased Integrated Service Digital Network line, typically $50 to $75 per month. Lease cost and installation charges to continue to decrease due to strong consumer demand from PC users.

Architecture
The architecture of a communications network defines what kind of equipment will be used in the system. It does not necessarily define the medium; the same architecture can often be operated over different media, and different media are frequently used in the same system. In some cases, however, the selection of a particular architecture requires a specific medium or, at the very least, allows or precludes classes of media.

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In general, architectural approaches to communications systems fall into two camps. The first camp accommodates systems that require reliable real-time transmission of messages. The second camp does not. The need to accommodate real-time communications therefore becomes the single most important decision in the selection of a communications architecture. a. Real Time The term real time is often defined as messages being passed within a specified amount of time. To most traffic engineers, this time frame is usually one second. Other branches of the computer industry, however, have very different standards. In industrial control systems, for example, real-time operation often requires response to a stimulus within 100 microseconds. Some process-control systems boast of response times as short as 6 microseconds. The use of the term real time to describe a desired response horizon is therefore not very specific. A much more rigorous definition of real time is that the system must respond to external stimuli in a definable and predictable way; that is, deterministically. In a traffic system, for example, the very long one-second event horizon is satisfactory, but the system must predictably provide that response horizon every time. In any system that processes stochastic messages, this predictability is very hard to guarantee. The Internet provides a good example. Internet communications are entirely stochastic. The demand on the network for passing messages depends entirely on the behavior of a host of independent users. So demand on the network is a random variable that can be characterized by a bell curve of some sort. No matter how much communications capacity is provided, there will be some occasions where it is not enough and the required horizon is violated. b. Deterministic Architecture In systems requiring mandatory real-time communications, a different approach is usually adopted to ensure real-time performance. In these systems, the communications paths are divided, either physically or logically, into private channels with predetermined performance characteristics. If, for example, a proposed system is required to send a command message to each of 1,000 traffice signals exactly once each second, the private-channel approach will be used. In such a system, traffic signals are grouped into communications subgroups. Each subgroup has its own physical path back to a hub site. Communications on that physical path are subdivided in a very deterministic way. If there are eight traffic signals on that path, the time available on that path will be divided into eight time slices. Each time slice is a predetermined size, and each traffic signal receives exactly that size portion of the physical path no matter what. Thus, each devices has a fixed and predictable communications rate. For example, typical traffic signal systems employing private-channel architectures allow eight controllers sharing a single physical channel that has a capacity of 1,200 bits per second (bps). The effective communications rate to each device is therefore 150 bps. The physical paths are brought back to a hub, and combined onto a trunk line. The trunk line is divided in exactly the same way as the physical path to the traffic signals. On the trunk line, therefore, we may have 64 or 128 traffic signals communicating, each on its predetermined time slice. The overall performance of the trunk line has to be fast enough to accommodate all the fixed private

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channels. This process of devoting time-slices to each of a large number of private channels is called time-division multiplexing. The private-channel scheme was developed by the telephone industry. When a caller places a call, a private channel is established between the caller and another party. That channel may traverse a huge variety of distribution lines, trunk lines, and switching equipment, but the size and capacity of that channel is predetermined. Virtually all technologies developed within the telephone industry use time-division multiplexing, including the T-Carrier standards for twisted-pair wire and the SONET standards for fiber-optic cable. The advantage of a private-channel architecture is that it is deterministic, and can therefore accommodate systems that require real-time communications. The specific time horizon of the real-time messages is not important, architecturally. Once a deterministic system is chosen, then the time horizon is strictly a matter of the performance of the network. Faster communications channels can move more messages, and can therefore either be divided into more private channels or can deliver a higher message frequency to fewer channels. The disadvantage of the private-channel scheme is that it does no efficiently use communications capacity. Each remote device must deterministically be allotted its own time slice, whether or not a message is being communicatedl. During the many intervals when a device is communicating nothing useful, the sub-channel devoted to that device is wasted. The corollary is that a device that is transmitting many communications must meter those messages out over many time slices. Private-channel systems cannot flexibly accommodate occasional high demand from individual devices. Deterministic architecture using private channels is analogous to the circuit switching architectures described in many communications textbooks. c. Stochastic Architecture For systems that do not require real-time communications, a different approach may be taken. The shared-channel approach allows many devices to share the same communications channel. In the previous example, eight intersections each received a private channel of 150 bps. In a sharedchannel system, all eight intersections use a single channel of 1,200 bps. Messages are routed to the proper controller by including its address in the message. This approach is known as a multi-drop communications channel, because the physical channel has multiple drops to individual field devices. Many times, the shared channels will be returned to hubs and be multiplexed onto private-channel trunk lines to make a hybrid system. In other cases, the hub computers combine the data from many devices, and then share a high-capacity channel back to the central computer for a multi-tiered shared-channel architecture. By the shared-channel approach, messages that have the appropriate addressing can traverse quite complicated networks to get from origin to destination. This is the approach taken in most computer networks and inter-networks, including the Internet. The advantage of the shared-channel approach is that it can be very efficient. Because each controller has access to the full capacity of the channel, each controller can send high-demand bursts of communications at high speed, though, of course, doing so will inhibit communications to other
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devices on the same channel. Demand on the channel increases when more than one device needs to send large messages at the same time. The time required to get the messages through becomes longer in this case. The channel capacity must be designed, therefore, to provide acceptable time horizons under expected peak communications demand. Another advantage is that once the decision has been made to avoid mandatory real-time communications, media with reduced reliability become available. For example, a system that requires real-time communications for sending control commands may not be able to tolerate the indeterminacy of a shared-channel communications scheme. Such indeterminacy may also be caused by limited communications reliability. Many wireless communications media provide no better than 99.9 or 99.99 percent reliability, which translates to many minutes of downtime a month. This reliability has nothing to do with the equipment; it only describes loss of communications caused by external events, such as bad weather or outside radio frequency interference. Systems that cannot tolerate indeterminacy will need determinacy in the media as well as determinacy in the architecture. A disadvantage of shared-channel schemes is that they are more difficult to design. In determinant systems, the communications demand generated by each device is fixed. The capacity required to accommodate that fixed demand is provided to every field device at all levels of the system. The system therefore behaves in a way that can be determined beforehand. In stochastic systems, communications demand is a random variable that must be characterized before the appropriate capacity can be designed and provided. The reliability of the system is a function of the probability that the capacity will be great enough for any given demand peak. Fortunately, most traffic engineers should implicitly understand this approach: it is exactly the same way roadway capacity is characterized. Because messages in nondeterministic systems must move in a shared environment, each message must sufficiently describe itself to the communication system to get to the other end without mishap. The protocols required to accomplish this are discussed later, but this requirement suggests that all data in shared-channel architectures be divided into messages, or packets. These systems are therefore often described in communications textbooks as packet-switched networks. Not all sharedchannel architectures use packet switching in the rigorous sense, but the concept is an important one. A designer seeking very detailed technical information on how to design stochastic communications systems will find the needed information within the packet-switching subject area. d. The Line is Not So Clear Having established a sharp line between the two architectural approaches to communications systems, that line must be rendered again with much less clarity. Both camps (those that accommodate real-time transmission and those that don’t) have been migrating towards one another for some years, and elements of each will be found in most modern systems. In stochastic systems, we assume that the messages are generated by a large number of independent sources, which makes the total communications demand a random variable that is close to being normally distributed. This demand pattern creates a very symmetrical bell curve centered on average demand. In most traffic-management systems, the demand distribution is not the result of a large number of independent processes. In traffic-signal systems, for example, the local controllers send and receive very similar messages defined from a very limited set of possibilities. Peak demand is
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much easier to control and predict, such that it is not completely indeterminate. If a system can impose sufficient discipline on the peakiness of the communication demand, the peak capacity can be characterized and designed for. Consequently, even a stochastic system can provide determinant real-time communications when carefully designed. This possibility allows shared-channel communications architectures to be coupled with centralized control systems normally used with privatechannel determinant communications systems. For example, the Siemens UTC, which is the parent system of one of the implementations of the highly centralized SCOOT system, employs sharedchannel multi-dropped communications between the communications processors and the local intersection controllers. Likewise, many systems that do not require real-time communications use determinant communications architectures. Traditionally, the telephone industry has driven advances in communications technology. Consequently, equipment for private-channel communications systems is readily available, and has been for many years. The use of such an approach is a practical response to the marketplace, even though it may not be architecturally pure. With recent advances in communications for computer networks, and with much greater interest from the telephone industry in stochastic networks (at least for major trunking), practical reliance on private-channel equipment and standards is no longer necessary. Finally, it is quite possible and common to implement one system architecture via a medium designed for the other architecture. For example, many fiber-optics systems use SONET, which has a privatechannel architecture, to move shared-channel communications. Many computer networks use a Tcarrier standard to carry a stochastic communications protocol. Again, this is a response to the availability of equipment designed by and for the telephone industry. This mixture of approaches is also associated with the tendency of stochastic systems to depend on software standards and deterministic systems to be rooted in hardware standards. In stochastic shared-channel architectures, discipline is maintained by a software communications protocol, such as the TCP/IP suite used by the Internet. These protocols may be communicated over telephone lines, which are the ultimate in private-channel communications media. But this is an architectural anomaly. Any stochastic system using TCP/IP would much rather use a physical medium that is oriented towards shared channels, such as Ethernet 10-Base-T, which also runs on twisted-pair wire (at least for a limited distance). A detailed example will summarize these principles. A single physical communication path on a trunk line may carry 10 T1 channels. Each T1 channel can carry 24 telephone conversations at one time. So the physical trunk line that carries 10 T1s can accommodate 240 simultaneous conversations. If each of these conversations is actually an Internet user dialed into the system, then the performance of each of these users will be a guaranteed 56,000 bps, using the latest modems. This privatechannel scheme provides a deterministic 56,000 bps to each user. A single Ethernet network can provide computer network access for 240 users. When all the users are demanding the network, the performance might be quite poor, much less than the 56,000 bps throughput that the privatechannel scheme would guarantee. Even thought the overall capacity is about the same, the shared Ethernet channel would be more clogged because of the extra time required to sort out collisions and deal with the chaos of randomly generated messages. Most of the time, however, only a few users would be generating high demand, and those users would get much greater throughput than 56,000 bps. A single user accessing the trunk line over the dial-up connection is limited to 56,000
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bps, even if the other 239 channels are not being used. A single user on the Ethernet network gets 10 million bps. e. Reliability and Redundancy Many communications systems enhance reliability by providing redundant elements. The most common redundancy scheme for communications is the self-healing ring, which is defined for fiber-optics systems that employ the SONET standards. In a self-healing ring, signals are transmitted simultaneously clockwise and counterclockwise around a ring of hubs. Each hub is therefore connected to the other hubs in two ways. If the cable is broken between two hubs, then all the hubs are still accessible from one or the other direction of the ring. The equipment in a SONET system is designed to automatically switch between directions to correct faults. Some systems design self-healing rings along a linear path by squeezing the ring together until it forms a line. This does not provide protection as well as a true ring, because a physical interruption of the cable will likely affect both sides of the “ring” and still isolate some of the hubs. However, it still allows the system to recover from equipment failures. This approach is used in the San Antonio TransGuide system, adding protection as the two sides of the ring travel down opposite frontage roads of the freeways that are part of the system. Ring topology is commonly associated with SONETs, but the concept may be applied anywhere. For example, the new Las Vegas Area Computer Traffic System uses a broadband microwave communications network. Half the band is transmitted clockwise, and the other half is transmitted counterclockwise. When interference disturbs a link, all hubs are still accessible, though the time to switch from one side to the other may be longer than would be typical in a SONET. Redundancy helps improve reliability, but it does not reduce maintenance requirements. Actually, ring topology and other redundancy schemes increases maintenance requirements, because the equipment is more complicated, and in some cases, duplicated (which means that more equipment must be maintained). Redundancy increases overall maintenance requirements, but reduces the urgency of maintenance. When a link is damaged on a SONET, the system continues to function, so operation of the system does not depend on immediate repairs. The repairs must still be made quickly, because the system no longer has redundancy. In many agencies, maintenance budgets are down to crisis levels, meaning that only those repairs that are critical to system functionality will be performed. In such circumstances, ring redundancy may be a problem rather than a solution, because the redundant elements will not be repaired as they fail. Once the redundant elements have failed, the system no longer benefits from the enhanced reliability. But the agency has still borne the increased cost of redundancy, both in initial cost and in overall maintenance requirements. In such cases, agencies would be better served spending the money on systems that are easier to maintain and resist damage more effectively. An example illustrates the point. Some systems being designed achieve redundancy by connecting local devices to two communications hubs using fiber optic cable. If a local device is destroyed (as the result, for example, of a traffic accident) then the other devices on the path will still be functional. Thus, an agency might use a fiber system, knowing that the agency’s inability to perform quick repairs on the fiber is offset by the redundancy scheme’s reduction of the urgency of repair. If that
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agency suffers from crisis-level maintenance cutbacks, however, then the minimum repair necessary to make the system functional may be all that is performed. Continuing the example, if a backhoe dips into the cable between two devices, the repair may be deferred indefinitely, because the system is still operational. In such a case, the agency would have been better off with a simple twisted-pair copper system that can be more easily repaired with typically available technicians. The savings can be directed towards deeper trenches and larger conduit, which will make damage less likely and repairs easier. Another principle that emerges from this example is that the technology of the communications should not outstrip the ability of the maintaining agency. Returning to the example, a technician performing the emergency replacement of a knocked-down traffic controller will attempt a repair of the twisted-pair copper wire. The wire itself will also be more robust and resistant to damage. If the medium is fiber-optic cable, then the fiber may be damaged some distance away from the place where it comes out of the ground, and a broken fiber at the connector will require a specialized repair. Consequently, the technician performing the emergency controller replacement will most likely not even attempt a repair, and will defer it to a more specialized repair crew at a later time. System reliability therefore suffers.

Guidelines and Standards
a. Deterministic Architecture Private-channel architectures were initially developed by the telephone industry. Consequently, a host of standards are available for defining multiplexed digital communications. All these standards can be characterized in a single continuum known as the electrical digital hierarchy, which is represented in Table 2.10.1 below.

Table 2.10.1. The Electrical Digital Hierarchy.
DESCRIPTION OC48 OC36 OC24 OC18 OC12 OC9 OC3 OC1 DS3 DS2 DS1C DS1(T1) DS0 DS0A DS0B
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TOTAL DATA TRANSFER RATE 2.48832 Gb/s 1.86624 Gb/s 1.24406 Gb/s 933.12 Mb/s 622.08 Mb/s 466.56 Mb/s 155.53 Mb/s 51.84 Mb/s 44.736 Mb/s 6.312 Mb/s 3.152 Mb/s 1.544 Mb/s 64 kb/s 64 kb/s 64 kb/s

COMPOSITION 48 DS3 (1344 DS0) 36 DS3 24 DS3 18 DS3 12 DS3 9 DS3 3 DS3 1 DS3 (plus SONET overhead) 28 DS1 4 DS1 2 DS1 24 DS0 Basic Unit—One Digital Voice Channel 2.4, 4.8, 9.6, 19.2, or 56 kb/s filling a single DS0 20-2.4, 10-4.8, or 5-9.6 kb/s subchannels on a single DS0

Freeway-Management Systems

The hierarchy is divided generally into three sections. One of these standards covering standard serial communications, sets guidelines for communications at the slowest speeds. These standards are defined by several agencies, including the Electronics Industries Association (for physical media) and the Consultative Committee for International Telephone and Telegraph (CCITT, for communications layers above the physical media). Communications at this level range in speed from 110 bps to 115,000 bps, but multiplexing equipment is only available to combine the speeds shown for DS0A and DS0B. Any discussion of serial communications standards also requires a discussion of modem standards. Most modems designed for use on dial-up telephone lines have a standard serial interface. On the telephone line side of the modem, the standards for how the digital signal is modulated into an audio signal vary widely. At the slowest (and oldest) end of the spectrum, the standards are defined by the telephone companies, and designate how signals will be modulated so that two modems from different manufacturers can interoperate. These standards include the Bell 103 standard for 300-bps communications, and the Bell 212 standard, which increased the speed to 1,200 bps. The later standards include V.22bis (for 2,400 bps), V.32 (for 9,600 bps), V.32bis (for 14,400 bps, or slower if need be), and V.34 (for 28,800 bps and faster, with fallback to slower speeds when necessary). In addition to modulation standards, other standards are usually applied to improve robustness and throughput. These include V.42, which is for error correction, including the Microcom Networking Protocol (MNP) classes 1 through 4, and V.42bis (MNP 5), which is a data compression standard used in conjunction with V.42. All the “V” standards are defined by the CCITT. The middle level of the electrical digital hierarchy covers high-capacity communications over copperwire links. These are commonly known as the T1 or T-Carrier standards, but are more specifically known as the Digital Signal Types. “T1” is also used to describe DS1, or Digital Signal Type 1. The T1 standards grew out of the telephone industry, and are currently defined by the American National Standards Institute (ANSI). The basic unit of T1 is a digital voice channel, which is defined nominally to be 64 kilobits/second, and is known as DS0 sixty-four kilobits/second is the digital capacity required to carry the human voice with reasonable fidelity for telephone applications. A DS0 can be further subdivided, but any signal larger than DS0, all the way up through SONET speeds, must first be broken down into DS0 channels, sent across as many channels are required, and reassembled on the other end. Higher standards are multiplexed combinations of multiple DS0 channels. If the basic unit of transmission is a DS0 voice channel, then the basic unit of trunking, or multiplexing, is the DS1, which is commonly known as T1. A DS1 multiplexes 24 voice channels. The highest level in the T1 standard is DS3, which combines 28 DS1s, or 672 voice channels. A designer using T1 has much equipment to choose from. For example, a number of manufacturers provide Ethernet bridging equipment that runs over T1. The full Ethernet speed of 10 Mbits/second cannot be obtained, but the equipment handles the task of dividing the Ethernet signals into 24 DS0s, and then recombining them on the other end. Similar equipment is available for moving video images across multiple voice channels. So, even though T1 is a private-channel standard, shared-channel communications schemes will often employ it at some level.

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A T1 is also available as an unchannelized path. The Ethernet bridging equipment mentioned in the previous paragraph uses unchannelized T1, which means that the equipment is designed to use the full bandwidth of the T1 as if it was a combination of many DS0s. At the highest level, the electrical digital hierarchy defines standards for fiber-optic systems. The ANSI T1 standard body set guidelines for SONET to carry multiple T1 combinations across linked selfhealing rings. Outside North America, the same standards are called Synchronous Digital Hierarchy by the CCITT. The basic unit of SONET is the optical carrier. The smallest unit is the OC-1, which carries (in addition to the SONET overhead) a DS-3. SONETs are defined up to OC-192, but equipment is commonly available only for OC-3, OC-12, OC-24, and OC-48. OC-48 carries 48 DS3’s, which is equal to 32,256 voice channels, on a single pair of fibers. SONET includes a definition of self-healing rings, as discussed in the previous section. b. Nondeterministic Architectures Standards for nondeterministic, or stochastic, architectures must include the control protocols necessary to resolve conflicts within the system. The protocols must also have the capability to route messages through the network, because messages for different destinations will share the same communications path. For systems that can impose a lot of discipline on the variety of messages, the protocol can be quite simple. The greater the need for variety, the greater demand on the protocol to manage the transmission of messages. The need to manage the transmission of messages through a shared-channel network means that communications standards must include software as well as hardware requirements. The software requirements will be discussed in the next section on protocols. The hardware standards for shared-channel communications are mostly generated by the computer networking industry. For low-speed communications, these standards are the same as those used in private-channel architectures. For example, many traffic-signal systems use 1,200-bps modems conforming to the Bell 212 modulation standard. This standard allows these modems to be multidropped along a common pair of copper-twisted pairs. For high-speed twisted-pair networks, Ethernet is the protocol of choice. Ethernet defines a basic communication rate of 10 Mbits/second, and requires synchronization on both ends. This data rate and synchronization limits the time delay for a message to 44 microseconds. The physical range for Ethernet is therefore sharply limited, and the standard is therefore used mostly for local-area networks. Ethernet is a multi-dropped environment, where all devices hear all messages. Ethernet has recently been extended to 100 Mbits/second. When network segments that use the same software protocols need to be joined together over a long distance, a bridge is employed. A bridge packages data from one subnetwork and sends it over a fixed path, such as a telephone line, to a corresponding bridge attached to another network. The bridge makes all the members of one network look like local members of the other network, and vice versa.
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When several networks that use different software protocols are joined together, a router manages the mapping of messages from one network to the other. The router looks more deeply into the message than does the bridge, and repackages the message to send it on to the destination or the next router. When routers are used to build links over fixed paths, they are called bridge-routers, or brouters. The Ethernet standard (IEEE 802.3) is controlled by the Institute of Electrical and Electronics Engineers, but the standard was originally defined by a consortium of Intel, DEC, and Xerox. For networks of high-performance computers that are linked with fiber-optic cable, the Fiber Distribution Data Interface (FDDI) is becoming an accepted standard. FDDI provides a token-ring approach protocol running at 100 Mbits/second. In a token ring environment, a token is passed from computer to computer in the network. While the computer holds the token, it may transmit packets of data to other computers. The token is passed in turn around the network repeatedly. The token-ring approach is deterministic in that discipline on the channel is absolute, and all possible collisions are precluded. FDDI is defined only for optical networks, and specifies the 1,300-nm wavelength of light. FDDI networks can be repeated to cover up to 200 km. c. Polled and Non-Polled Protocols Multi-dropping creates the possibility of two devices attempting to use the channel at the same time. This potential conflict requires some discipline in how devices can access the channel. The simplest scheme precludes remote devices from transmitting a message unless they are individually commanded to do so by a master device. This approach is known as a polled protocol. The master device sends out a poll request message to a specific field device. That device then sends a response. Other devices will hear the transaction (or at least the master’s side of the transaction), but will keep silent. The polled protocol can be characterized by the phrase speak only when spoken to. When modems prepare a communications channel for communications, they first send out a tone called a carrier. The modem will then vary the pitch or frequency of that tone to distinguish between binary ones and zeros (called marks and spaces). Once the message is complete, the modem will stop sending the carrier tone, leaving the channel silent. 1. CSMA. Non-polled protocols are also known as multiple-access protocols, because they permit various devices on the channel to initiate communications protocol. The simplest of the non-polled protocols is known as Carrier-Sensed Multiple Access, or CSMA. With CSMA, a modem will first listen for a carrier tone on the channel. Hearing none, it will establish a carrier. The problem comes when two devices try to establish a carrier at the same time. The messages from both devices will be on top of each other, and both will be garbled. The receiver will not receive the message, and will send no acknowledgment back to the sender. In most CSMA protocols, the modems will wait a short period of time and, hearing no ac knowledgment, attempt the communication again. The CSMA approach can be described by the phrase speak when the channel is clear. The problem with CSMA is that when a large number of devices is trying to access the chan nel at the same time, the performance of the channel can spiral out of control. With a con stant delay before resending a message, two devices can compete for the channel repeatedly
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until one gets ahead of the other. The more crowded the channel, the more likely these collisions occur, and the greater the backlog of sent-but-unacknowledged messages, which means that the devices will try harder to access the channel, and so on until the channel is hopelessly jammed. CSMA systems, therefore, work best in situations where some external discipline might be imposed on the communications. For example, many traffic-signal systems temporarily remove an intersection from the system if three successive status messages are missed. In a non-polled environment, such a rule will allow the system to back out of jammed state, although only by reducing the operational performance of the system. These problems are avoided by placing strict limits on the loading of the channel. These limits usually restrict the average loading to about 10 percent of the channel, assuming independent message generation by all users. When message generation can be more carefully controlled, greater loading is possible. Some of the schemes for recovering from collision are very clever and effective. Well-disci plined CSMA systems employing these schemes can achieve channel loading as high as 85 percent without jamming. CSMA is most commonly used in high-performance networks where the ratio of individualuser need is small compared to the total capacity. For example, Ethernet uses CSMA. Ethernet subject to jamming (called Ethernet meltdown) and depends on the software protocols above the Ethernet to resolve high-conflict rates. 2. ALOHA. To minimize the problem of jamming for networks where users access the channel at random times, devices can wait a random period of time before attempting to resend unacknowledged message packets. The random delay injects a little air into the jam, and allows it to sort itself out much more efficiently. These random delays also decrease the efficiency of the channel to levels much lower than well-disciplined CSMA systems. ALOHA systems were developed primarily for satellite communications, but are also employed in many data radio systems. 3. Deterministic Multiple Access Systems. Some systems impose absolute discipline on the channel to prevent any possible collision. As previously mentioned, the token-ring approach is one such system. Others include Frequency Division Multiple Access (DMA), which gives each user its own frequency, and Coded Division Multiple Access, in which the signaling characteristics of each packet are uniquely coded such that other packets become invisible to the equipment. Spreadspectrum radio uses CDMA. d. Software Protocols Most of the previous discussion centers on the specific protocols of the communications medium. All these standards are applied at the bottom layer of a communications system. The bottom layer is the physical layer, the part that directly manages the signaling on the medium in question. Once the signals are translated into bits and bytes, they are processed by computer programs within the communications software of the device. Each message is encapsulated within a series of wrappers, each of which defines some aspect of the packet of data. These wrappers are called layers, and conform to a communications model developed by the International Standards Organization (ISO).

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The ISO seven-layer model has been called the Open Systems Interconnect (OSI) model. The ISO-OSI model is shown below:
Layer
Application

Description
The program that desires the communication resides here. For example, the Internet uses the Simple Mail Transfer Protocol to send e-mail and the File Transfer Protocol. Another example is the Internet’s Hypertext Transfer Protocol, used on the World Wide Web. Used for providing services needed by many applications that may share a network, such as conversion of graphical images into bit-streams or text compression. Not used much in actual systems-most of the functionality originally modeled for this layer has ended up in the application layer. This layer was specifically designed to handle remote terminal access services. Not used much in public systems. The Transport Layer ensures end-to-end reliability. Protocols within this layer break outgoing messages into packets, and add ordering and error-correction information to each packet. For incoming messages, the transport protocol reassembles the packets into continuous data streams. The transport layer makes sure that packets are received intact and assembled in the proper order, which is called guaranteed delivery and sequential ordering, respectively. This layer is the boundary between logical addresses and physical addresses. For incoming messages, this protocol determines if the message belongs on this computer. For outgoing messages, this protocol wraps a routing header onto the message to send it to the next routing device or to the destination, if it is directly connected. The Internet Protocol is a network layer protocol. The interface between the upper software layers and the hardware. The data link protocol defines the boundaries of message packets to the physical hardware, and includes a simple acknowledgment and error detection scheme to confirm successful communications to the hardware. The physical layer defines the signaling and timing characteristics of the medium over which messages will be transmitted. All modem protocols, for example, and all the protocols of the Electrical Digital Hierarchy reside within the physical layer.

Presentation

Session Transport

Network

Data Link

Physical

A central principle of the multi-layer model is that each layer need not know anything about the other layers. The application layer does not need to know anything about which protocol is used in the transport layer. Consequently, a profile of protocols can be defined, selecting the specific protocol for each layer as appropriate for the system in question. An example shows how this system works. In the Internet, a user of the World Wide Web will use a specific profile for downloading a Web page. At the application layer, the protocol will be the Hypertext Transfer Protocol (HTTP). The presentation and session layers are not used by the Internet. The transport layer protocol will be the Transmission Communications Protocol, or TCP which con, verts outgoing data streams into packets, or datagrams, and adds to each packet the information needed to guarantee delivery and reassemble the packets in the proper order, which the TCP module on the other end will do. The TCP module cares not that the application protocol is HTTP Thus, the . TCP module in the origin computer talks to the TCP module in the destination computer.

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Carrying the example further, the TCP datagram is then passed to the network layer, in which resides the Internet Protocol (IP). The IP will add routing information, including the destination logical address. The IP will then consult its routing tables, and determine which computer the datagram needs to go to next, and will add that address to the datagram. Again, the IP knows nothing about the information added or needed by the TCP or the HTTP The IP module transmits information to the IP module on the next ma. chine in the network. Thus, end-to-end matters are handled by the TCP module, and machine-to-machine matters are handled by the IP module. Finally, the IP-massaged datagram is passed to the data link layer for interfacing with the hardware. For dial-up users on the Internet, this layer is probably controlled by the Point-to-Point Protocol (PPP). The PPP establishes a channel over which two modems may communicate, and ensures error-free transmission to the modem. The PPP module in one computer talks to the PPP module in the next computer on the network, and is again ignorant of all protocol packaging above it. The suite of protocols used by the Internet is known as TCP/IP but includes many more specific protocols , than just the two most popular ones listed in the name. This discussion of multi-layer protocols is critical to understanding the National Transportation Communications for ITS Protocol (NTCIP) discussed in a later section. e. Video Communications The data transmission requirements for full-motion video are so extensive that they deserve a separate discussion. The addition of video surveillance to a system design fundamentally changes the requirements of the system. For data only, the major decision concerns selecting deterministic digital communications or nondeterministic (stochastic) digital communications. When video is added, the major decision affecting cost is whether or not to use analog video transmission or digital video transmission. 1. Analog Video. Full-motion video, in analog form, requires 6 MHZ of bandwidth, of which 4.5 MHZ is required by the color-burst, or picture, and the remainder for audio. Analog video is a continuous scan of electrons moving horizontally in rows down the screen. In North America, video signaling is defined by the National Television Standards Committee (NTSC). NTSC video is defined as 525 lines of vertical resolution, or scan rows, and all rows are scanned 30 times per second. In many systems, including most consumer television systems, the signal strength and display equipment is not good enough to clearly transmit and display all 525 lines, and most consumers are more accustomed to seeing about half that. The standard is defined to allow this degradation without loss of synchronization. Television stations broadcast television using amplitude modulation, or AM. Television can also be transmitted using frequency modulation, or FM. Although broadcast television uses only AM, video surveillance systems have other options. In private microwave systems, video can be broadcast either by AM or FM signals. Two bands (12 GHz and 18 GHz) are reserved for AM wideband transmission. Wideband refers to the transmis-

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sion of many video images, each of which has its own frequency, using a single transmitter. Many other frequencies are available for FM video transmission. FM television may be transmitted over fiber optics very effectively. In fact, in most systems this proves to be a much cheaper alternative than digital video. Multiple FM video signals can be modulated onto a single fiber, routinely allowing as many as 32 video channels per fiber. Specialized equipment can transmit as many as 100 video channels using FM multiplexing. Many systems are now using equipment that transmits analog video over twisted-pair copper wire for distances of up to several miles, with repeaters. Video is also commonly transmitted over coaxial cable, though this application seems less popular than it once was. In any medium, however, the signals themselves are governed by the NTSC description. The advantages of analog video transmission are it provides extremely high-quality video cheaply and efficiently over wireless and fixed media. For example, a fiber system moving video images needs a modulator for each image, an FM multiplexor, the fiber, a de-multiplexor, and a demodulator between the camera and the control-room display switcher. Each of these items is routinely available, and is commonly used for video surveillance in other industries and for transmission by cable television companies. Another advantage is that is allows graceful failure. If the communications link is degraded, the picture will be degraded in like amount. A significant amount of reserve signal quality is available in analog video. For example, video at the camera meets commercial broadcast standards, and has a signal-to-base noise ratio of about 58-60 dB. The decibal scale is logarithmic: each change of 3 dB signifies a doubling or halving of signal strength). Most cable television systems operate at about 40 dB signal/noise, which is about 1.5 percent of the signal strength of true broadcast quality. Yet most viewers would consider the resulting image to be good. Usable video can be obtained with signal-to-noise ratios of as little as 28 dB. The disadvantage of analog video is that it does not usually permit sharing a channel with other digital communications. Generally, a fiber that is devoted to analog video cannot be used for digital communications, and vice-versa. This limitation may not be total, however. Equipment is now available for using different wavelengths of light on the fiber. One wavelength is reserved for data, and the other for video. This technique is known as wave-division multiplexing. 2. Digital Video. If each horizontal scan line is divided into 700 picture elements, or pixels, then each scanned screen image contains 367,000 pixels. If each pixel defines a level of red, green, and blue (the additive primary colors used in constructing a color video image), and if each color can be defined at 256 levels, then each pixel needs three bytes to describe it. The size, in bytes, of a single frame of broadcast-quality video is therefore a little more than a megabyte. If 30 frames are transmitted per second, then the data stream is going by at 265 Mb/second. In practice, an analog video image can be stream-digitized at less than broadcast quality at much lower rates. Typically, full-motion video is expected to consume 100 Mb/second. Even at this rate, the bandwidth requirements of digital video are vast compared to data requirements for most systems.

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The computer industry, driven by developments in video teleconferencing over telephone lines, has been working on strategies to reduce these requirements to more acceptable levels. These strategies fall into three categories: image compression, data compression, and reduced framing rates. Image compression reduces the resolution of the image, both in terms of sharpness and color. For example, a digital video image that is 263 lines by 350 pixels and monochrome can be transmitted in about 23 Mb/second. This is the same quality as most black-and-white television. If the monochrome image size if further reduced to 128 by 170, as with many teleconferencing systems, the requirements are further reduced to about 5 Mb/second. Full-range monochrome can be reasonably represented with 256 shades of gray, or a single byte per pixel. We can also transmit color images with a single byte per pixel, but the quality of the color will be noticeably reduced. Still, for many applications, the degraded signal serves the purpose. This is about the minimum image quality that is usable in traffic surveillance systems. The second strategy is to compress the data as a stream. Most video images contain large areas of single colors that can be summarized. If some image quality can be lost, these compression algorithms represent similar colors as the same color. Another technique for data compression is to transmit only those pixels that changed from the previous screen. Combined, these techniques can reduce the image to as little as 5 percent of its original size, depending on the complexity and stability of the image. This alone reduces the original full-motion video signal to five megabits/ second. The image in the previous example, which required 5 Mb/second without data compression, can therefore be transmitted in as little as 384 kb/second, which is one-quarter of a T1 circuit. The final strategy is to reduce the number of frames per second. In past years, a similar technique was known as slow-scan television. But slow-scan was an analog process that usually displayed a slowly moving scan line across the image. In modern systems, a frame is displayed instantly (or within the NTSC 30th of a second), and then frozen on the screen until it can be completely updated. Systems usually use a slower frame rate as a last resort when other compression methods don’t work. Framing rate can be adjusted on the fly, making it a good technique for stochastic packet-switch networks, where network performance is not predictable. Generally, framing rates down to 15 frames/second are not noticeable, except when the camera is panning quickly. Framing rates as slow as 8 to 10 times per second are still usable for traffic surveillance. For video teleconferencing, framing rates as slow as four or five times a second are typical, and such a rate reduces the image- and data-compressed example above to 56 kb per second, obtainable over telephone lines. The standards for digital video compression are in continuous development by the Motion Picture Expert Group, a working group of the International Standards Organization. Compressed images conforming to their standards are called by their acronym, MPEG. Most digital traffic surveillance systems, however, have been installed using proprietary compression schemes, which usually exceed the performance of the public standards. The advantage to digital video is that it shares the same communications path with data. If trunkline services are leased, for example, this advantage is crucial. Excellent video can be ob2-92

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tained from compression to T1 or dual-T1 data rates, and these lines can be leased from telephone companies routinely. The disadvantage is the cost. In systems where the agency is building its own infrastructure, a digital video systems can represent a huge investment compared to an analog system over the same media. The example from the analog video section showed that the video link could be established with four routine and relatively inexpensive pieces of equipment. Actually, in an analog system, each video signal requires a modulator and demodulator, and all the video signals in a group can share the multiplexors. In a digital system, each video image must first be digitized and compressed, using uses a coder-decoder, or codec. The resulting signal is then piped into the digital and SONET transmission equipment, which at each hub consists at least of a communications service unit (CSU), a data service unit (DSU), a T1 modem, and an OC frame. The cost and complexity of this equipment is significantly greater than analog equipment.

Selection Techniques
Communications systems are complicated. But an understanding of their architecture and technologies can have a huge impact on the cost of a system. About two-thirds of the construction budget for most modern traffic-management systems is spent on communications. The first step is to determine the requirements. Two questions are critical: 1. Will the system transmit video images? 2. Does the system require mandatory real-time control communications? If the system will transmit video images, then several more questions must be answered: 1a. Will the video be transmitted over leased service? 1b. What image quality is required? 1c. What is the maintenance capability of the agency? If leased service is a must, then digital video is probably the only option. If not, then the higher the image-quality requirements, the more cost-effective analog becomes. Limited maintenance capabilities also suggest the simpler analog equipment. If the system does not require mandatory real-time communications (see the discussion on system architecture in Chapter 3, the reliability of the media can be reduced significantly and wireless media can be considered. Also, systems that don’t require real-time control can take advantage of the greater flexibility and interoperability offered by nondeterministic shared-channel networks that use packet-switching techniques. These systems are readily available for all communications media. If the system does require mandatory real-time communications, then the selection is not so easy. A shared-channel system is still possible, though the system will have to impose the necessary discipline on the communications messages to ensure deterministic performance. Generally, systems requiring

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real-time control will lean toward the deterministic private-channel or circuit-switched systems (Appendix J presents an analysis for selecting a communication medium for a Traffic Signal Control System).

The National Transportation Communications for ITS Protocol (NTCIP)
The NTCIP is an ongoing project resulting from a collaboration of the user community and the National Electrical Manufacturer’s Association (NEMA). The general trend in systems towards more open architecture has driven the NTCIP’s efforts to resolve the problem of non-interchangeability within systems. During the course of the work, however, the NTCIP framers realized the need to expand the scope to cover different kinds of devices that must coexist on and share communications networks, and they expanded the scope of the NTCIP to include most communications links between the control center and roadside systems components of ITS. The NTCIP seeks to provide two fundamental capabilities: interchangeability and interoperability. Interoperability refers to the ability for dissimilar devices to share a single communications channel. Interchangeability has been defined as the ability to replace a device from one manufacturer with a similar device from another manufacturer without damaging the operation of the system. a. Interoperability Interoperability requires that messages to all devices be defined according to the same rules. In effect, they must use the same protocols at each layer of the ISO-OSI model. As such, all messages must have recognizable wrappings to allow consistent traversal of the communications network. 1. Protocol Profiles - A key concern of the NTCIP to accommodate the different kinds of system architectures that are available in the industry. The initial efforts defined communications for distributed systems between master controllers and local signal controllers. These messages must be able to be polled at a reasonable frequency on existing low-speed networks. The focus of the initial work was therefore on efficiency. But this approach did not accommodate the needs of higher-level communications (e.g. between central and master), nor did it provide a reasonable facility for passing messages along complex networks. The work was therefore divided into two parts: a higher class that would provide logical addressing and a lower class that would only provide physical addressing. Software would be required to unwrap the more complete higher protocol to pass it along a lower network. In a distributed system, this boundary would be handled by a communications hub computer or master controller. In a centralized system, the boundary software would reside in the central computer (at least, theoretically). So the idea of different grades of protocol profiles grew from the need to support diverse system architectures. Since those early discussions, the number of profiles has grown to address different needs within systems. These profiles are: Class B, for communications over twisted-pair copper wire at low speeds. Includes physical addressing only, and can only communicate between a single master device and multi-dropped slave devices. Class A, for communications over higher-performance networks. Provides logical addressing and routing, and can therefore traverse complex networks. It does not provide transmission control,
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such as guaranteed delivery and sequential ordering, beyond packetizing. The overhead required for logical addressing and routing renders it unsuitable for low-speed networks, unless a slow polling frequency can be tolerated. Class C, for communications requiring transmission control. In addition to the Class A features, Class C messages also include sequential ordering and guaranteed delivery. Class C also provides a file- transfer service. Class E, currently being conceptualized to cover communications between control centers. At present, the likely result is two profiles. The more efficient profile will provide conventional services and defined message content. The more advanced protocol might use an object-oriented approach, where message content can be defined as part of the message, allowing modifications to the system without changing the software at all control centers. Only the Class B protocol has been codified into a standard at present. In the discussion of layered protocols, we defined a profile as a definition of the component protocols across all layers. The protocol definitions for the first three classes are as follows:

Table 2.10.3. Protocol Definitions.
Layer
Application

Class A

Class B

Class C
SNMP STMP File Transfer Protocol (FTP, part of TCP/IP)

Small Network Management SNMP Protocol (SNMP, part of TCP/IP) STMP Simple Transportation Management Protocol (STMP, defined in NTCIP)

Presentation Session Transport Network Data Link

Not Used Not Used User Datagram Protocol (UDP, part of TCP/IP) Internet Protocol (IP) Asynchronous High-speed Data Link Control (HDLC, an industry standard) EIA-232, for serial communications Bell 202, for 1200-bit/ second modems

Not Used Not Used Not Used Not Allowed HDLC

Not Used Not Used Transmission Control Protocol (the TCP in TCP/IP) IP HDLC

Physical

EIA-232

EIA-232

Bell 202

Bell 202

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b. Interchangeability Interchangeability allows similar devices from different makers to be interchanged on the network without damaging the operation. Interchangeability is more difficult to achieve than interoperability, because the functionality of the system is bound up in the concept. Interchangeability requires the common definition of message content. Once the messages are defined, they can be transmitted using any appropriate profile of protocols. Consequently, the NTCIP is a definition of protocol profiles, which defines architectural issues, and message object, which defines functionality. To provide a flexible way to keep up with messages, and to avoid standing in the way of new innovations, the NTCIP employs an object-oriented message structure. Each message is defined by its content, and the devices then interpret what must be done with that object. The objects are defined in a hierarchy, which provides good organization and consistency. For example, all the signal phase timings are part of the phase branch of the tree. The phase branch is part of the actuated signal controller tree, and so on. Objects are defined for each type of device that will communicate using NTCIP Ultimately, the list of . devices will encompass all roadside systems. Initially, the NTCIP Steering Committee is committed to developing objects for the following devices: Actuated Signal Controllers • • • • • Dynamic Message Signs Environmental Sensors Camera Controllers (not video images) Hub Computers Ramp Meters

The first two of these are now complete, and work is underway on the remaining devices. Within systems, NTCIP can be implemented in a variety of ways. The most critical application resides in the link from the field device to a hub computer or central computer. In these links, messages share the most expensive part of the communications infrastructure, and also the most vulnerable. To assist the user with applications of the NTCIP the Steering Committee is preparing a series of , tutorials, known as the NTCIP Guides. These will be published by the Steering Committee about the time the first NTCIP-compliant devices will be ready. User agencies will need a means of testing devices for compliance, and also tools for troubleshooting NTCIP networks. The FHWA is currently preparing public-domain software, known as the NTCIP Exerciser, to provide these services for users. The software will be available without restriction, both in source and compiled versions for useon desktop computers. The Exerciser will allow testing agencies
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to send and receive messages from devices that claim to be NTCIP-compliant. The content and semantics of a message will be interpreted by the Exerciser. The Exerciser will also provide a macro-programming capability that will allow users to develop test suites customized for the device in question. c. Standards Development The NTCIP represents a joint effort of users and manufacturers. Currently, the NTCIP Steering Committee consists of six representatives each from the Institute of Transportation Engineers (ITE), the American Association of State Highway and Transportation Officials (AASHTO), and NEMA, plus ex officio members from the Federal Highway Administration. The process for standards preparation and approval meets the requirements for each of the constituent organizations, and is therefore quite complicated. In general, however, the Steering Committee, upon recognizing a problem that needs to be solved, establishes a working group to gather interested parties and create a draft. The process is guided by the Steering Committee, who recommends the resulting draft standard for experimental implementation. When ready, the final draft standard will be formally reviewed through the three organizations, and accepted as a joint standard. Many working groups are working on various aspects of the protocols. Some groups are quite simple and relatively informal. They may consist of manufacturer’s representatives and a few interested users. Working groups can be quite elaborate. For example, the largest working group of the NTCIP Steering Committee is the Transit Communications for ITS Protocol, or TCIP committee. The TCIP , includes dozens of representatives of users groups, system designers, and manufacturers. The NTCIP development effort is an open process that encourage active participation from all interested parties. More information about the NTCIP and the development process can be obtained from the official NTCIP Home Page on the Internet’s World-Wide Web. The address is http:// www.fhwatml.com/ntcip/.

The Transit Communications Interface Protocol (TCIP)
The Transit Communications Interface Protocol (TCIP) is a family of standards now under development that will focus on data interfaces. TCIP will enable electronic data exchange among transit agency departments, traffic and transportation management entities and Information Service Providers. The TCIP was initiated in November, 1996. Funded by the U.S. Department of Transportation’s Joint Program Office for Intelligent Transportation Systems, and developed by the Institute for Transportation Engineers (ITE), the TCIP effort is a one-year standards development effort designed to provide the interface structures that will allow disparate transit components and organizations to exchange data. As specified in the Project Plan: The project will define the information and information transfer requirements among public transportation vehicles, the Transit Management Center, other transit facilities, and other ITS centers; develop physical and data link requirements; develop required message sets; and establish liaison and coordinate between ITE and other Standard Development Organizations (SDOs) on the development of related standards. It will provide the leadership to coordinate, develop, and deploy a comprehensive set of transit communication interface protocols (TCIP) that allows effective and efficient

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exchange of data used for ITS user services and transit operations, maintenance, customer information, planning and management functions. The scope provides for interfaces among transit applications to communicate data among transit departments, other operating entities such as emergency response services and regional traffic management centers. The results of this effort will be to a set of provisional standards for TCIP . The ambitious schedule will be coordinated with the TCIP Technical Working Group (TWG) to ensure industry review at every stage (Paula Okunieff, et al, February 24, 1997).

2.10.2 TECHNOLOGIES
The following technologies are used for communication of freeway systems.

Twisted-Pair Cable
Twisted-pair cable is individually insulated copper wires twisted into pairs, and combined into a shielded cable. Agency-owned twisted-pair cable is widely used for the low-speed transmission of traffic control data (e.g., between hubs and field elements), with the network configured with between 8 and 16 field drops on each two-pair (4-wire) channel. The exact number of drops depends on the amount of data to be transferred between central hub and the field locations, and the rate of transfer. Video transmission is possible on twisted-pair cable but requires repeaters every 3,000 feet to 3.6 miles, depending on the wire gauge. Typical data rates are 1,200 bps. Voice can be carried on a single pair. Bandwidths range from 300 Hz to 3,000 Hz. Installation of twisted-pair cable can be accomplished by: underground in conduit; underground by direct burial; aerial utilizing existing or new utility poles. The method used will have a significant impact on cost. Advantages: • • • • Represents a low cost form of transmission. Easy to splice. No specific interface equipment required. Electrical characteristics are favorable to basic analog transmission.

Disadvantages: • • Data cable splicing is not recommended. There is a bandwidth limitation in that twisted pair cable tends to attenuate high-frequency electrical signals, thereby limiting the ability to transmit digital information at high rates.

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•

Bandwidth limitation prevents transmission of live television images, though recent developments permit transmission of slow-scan television. (Prototype equipment is available for transmission of full-motion television over twisted-pair copper wire). No protection from Electromechanical Interference or Radio Frequency Interference (EMI/RFI) when using twisted-pair cabling facilities for video. Low security.

• •

Coaxial Cable
Coaxial cable consists of a center conductor surrounded by a dielectric material (insulator) and enclosed within a grounded conductive outer shield. The center conductor is typically copper-clad aluminum; the dielectric may be a solid (foamed polyethylene) or gas; and the outer conductive shield is typically aluminum and may be braided metal fabric, a corrugated semi-rigid metal, or a rigid metal tube. There is also an outer jacket consisting of low-density, high-molecular-weight polyethylene. This construction significantly reduces the effect of external radiated or induced noise, particularly at higher frequencies. Very large bandwidths (5MHz to 550MHz) may be transmitted over coax. This bandwidth can be divided to handle more than 40 channels on one cable, with additional capacity to handle multiplexed data channels. Coax is especially flexible, supporting a wide range of data rates can be supported in coax (from 1200bps to 10Mbps). The cable can also support shared use in integrated systems. Advantages: • • • • Because of its physical structure, coaxial cable is more immune to electromagnetic interferences and has a much higher bandwidth than twisted-pair cable. Minimal signal losses. Low signal leakage. Higher bandwidth allows for transmission of video signals (cable television using coaxial cable can transmit as many as 75 independent video signals) and for the transmission of digital data at very high rates. Bandwidth of coaxial cable permits theoretical transmission rates as high as 700 million bps. A single high-speed channel can serve an entire system (many channels of information can be multiplexed onto a single space). This is an advantage in urban areas where cable sizes are limited by available conduit space.

• •

Disadvantages: • • Dedicated systems need repeaters spaced at 1-km increments. Splice connections are susceptible to noise and transient problems.

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• • • •

Coaxial cable can not be spliced together by manual strip and twist method. Inherent nature of cable and the importance of conductor alignment make the coaxial cable much more difficult to splice. Lower communication reliability than fiber optic. Higher maintenance and adjustment effort required compared to fiber optic. Low security.

Leased Telephone
The most common type of leased telephone company (Telco) channel is the 3002 conditioned analog channel, which transmits voice-grade data (300 Hz to 3,000 Hz) and can be used as a twisted-pair channel with multiple controllers operating on a TDM channel. Typical available leased circuits include voice-grade/data grade analog (1,200 bps), digital (56 kbps), T-carrier and SONET. Data rates achievable with 3002 are typically limited to 1,200 bps. Voice frequency FSK modems are required and can be configured for either full- or half-duplex operation. Leased telephone lines are frequently used for traffic surveillance and control system applications. These applications include interconnection between a central computer and field equipment such as traffic-signal controllers, DMSs, freeway ramp meters, traffic counting equipment, etc. Advantages: • • • • • • • The network is already in place. Reliable communications solution in that there is a grid redundancy element due to the general coverage of the carrier’s network. No responsibility on the lessee to maintain the required infrastructure. That responsibility lies with the telephone company. Capital costs are very low, involving connection from access points to cabinets and central facility. Appropriate where a high volume of voice or data communication is required between separate facilities. Can be used for temporary applications. Used where other forms of communication technologies are not cost-effective.

Disadvantages: • • • High lease costs, always tied to general service rate increases. Less control of the communication network; requirements and limitations on leased channel may impede use. No flexibility in the design of the communication network; constrained by telephone company cable network.

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•

Not a cost-effective communication medium for distant communications requiring multiple central offices.

Leased Cable Television (CATV)
Because CATV (cable television networks) are usually implemented on coaxial cable, the characteristics of CATV channels are very similar to those of dedicated coaxial cable systems. Two major differences: 1) the available bandwidth on CATV, which is a function of the network loading and the franchise agreements, may be limited; and 2) not all CATV systems are designed for bidirectional communications. A potential problem with CATV is that the existing area of coverage and the network layout may not coincide with the traffic signal density. Advantages: • • • • • • A single 6-MHz channel is adequate for data transmission. The network is already in place. Design efforts and initial installation costs are very low. Franchise agreement may provide for government use of CATV cable and bandwidth at reduced rates or free, reducing recurring costs. Second separate coax institutional network (I-net) may exist for the express purpose of providing bidirectional services to commercial subscribers. I-nets generally provide good levels of service to subscribers.

Disadvantages: • • • • • • • • Most CATV networks designed and installed with emphasis on downstream transmission of video signals to cable subscribers. Video channels take up most available bandwidth. Bandwidth available to traffic control may be very narrow, ranging from a single 6-MHz channel to four or five channels. Single 6-MHz channel does not support full-motion video transmission in addition to data communications. Frequencies of available channels are often most susceptible to noise and interference. Quality of video signal required for CATV considerably less than required for data transmission. CATV subscribers sometimes concentrated in residential areas. Service to Central Business district and industrial areas sparse or nonexistent.

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• •

Area of coverage and network layout may not coincide with traffic-signal and other equipment locations. Traffic-control system may have to compete with other public I-net users for more desirable channels.

Fiber Optics
Fiber optic technology consists of a nonmetallic conductor that guides light rays. The glass fibers are coated with a cladding of glass or plastic having a refractive index different from the glass in the fibers. The difference in refractive indices causes light waves striking the cladding layer below the critical angle of incidence to be reflected back into the core section. In this way, light rays are propagated to the other end of the fiber with low intensity loss. The use of fiber optics requires a dedicated, owned communications network. This requires right-of way and conduit throughout the network. Right-of-way is usually the limiting factor for private companies, but not for the State. The cost of installing and maintaining conduit, however, can be significant. The information-carrying capacity, or bandwidth, of fiber is related to the spreading or dispersion of the light pulses. Pulse dispersion is a function of both pulse width (data rate) and distance. The capacity of fiber-optic systems is expressed in Mbps-km — the product of the data rate and the repeater spacing. Capacities of up to 500,000 Mbps-km (4Gbps at 117 km) have been achieved. The maximum repeater spacing in fiber-optic networks is a function of both the bandwidth of the transmitted signal and the signal attenuation. One of the most common, easiest methods for providing multiple channels is to simply install a multiple-fiber cable, and use a separate fiber for each channel. Because fibers are so small (more than 200 bare fibers can be placed side by side in the space of an inch) a cable of 12 or even 50 fibers is smaller than a single twisted-pair copper cable. In addition, due to the high cost of sophisticated multiplexing electronics, installing multiple fibers can be more cost-effective. Fiber is immune to electrical interference. Since the signal is optical in nature and there is no metallic medium, fiber-optic transmissions are not affected by cross talk, ground loops, or ingress. Fiber is essentially a point-to-point technology — in order to serve multiple drops on a fiber circuit, it is necessary to use a drop and insert modem. One application is trunking where several low-speed channels are multiplexed into a high-speed data channel and transmitted over a single fiber from a central point to a remote distribution point. At the remote location, the multiplexed signals are demultiplexed into low-speed channels and then transmitted over twisted-pair cable to the field drops (controllers). Similarly, the responses from the controllers are gathered at the remote distribution location, multiplexed together, and transmitted back over another fiber to the control center, where they are demultiplexed and read by the computer. Fiber-optic cable may be installed in conduit, direct burial, or aerial applications. Advantages: • Large capacity.

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• • • • • •

The capability of expansion is practically unlimited, as fiber bandwidth is very large. Immunity to electromagnetic and radio-frequency interference. High integrity for data transmission. Emits no radiation. epresents a highly secure means of communication, because it is difficult to tap a fiber tube without detection of the resulting signal loss. A small, flexible (small bending size and radius), and lightweight cable. Safety in hazardous environments.

Disadvantages: • Designing a fiber-optic network requires substantial engineering effort, due to complexity of networks, light distribution characteristics and mediums, and other factors.

Microwave
Microwave is an air-path medium; it does not require a physical connection between the transmitter and receiver. Signals are radiated from an antenna, propagating through the atmosphere along a line-ofsight path. Frequencies used must be unique in that area and direction to prevent interference from other microwave transmissions. Because of this constraint, microwave frequencies are licensed by the FCC. It is, therefore, very difficult to obtain microwave frequency allocations in crowded urban areas. When frequencies are available, they are usually in the higher frequency bands (18 and 23 GHz), which have reduced transmission distances. Configurations for microwave communications are typically point to point or point to multipoint, depending on the requirements of the network. The point-to-point network is one where the transmitter propagates the microwave signal to a receiver located some distance away (0.5 miles to 40 miles, depending on the frequency utilized). The point-to-multipoint system requires one transmitter propagating the microwave signal to receivers at multiple sites in the field. The utilization of microwave communications falls into two major categories. The first is an analog microwave system in which the method of modulation is typically FM. This type of system is utilized for the transmission of video images (CCTV) which provides a full-motion image. The second is a digital microwave system in which the method of modulation is typically TDM/TDMA (Time Division Multiplexing/Time Division Multiple Access). This is an all-digital system which is used for data and voice. Video may be transmitted through use of digital video compression techniques. Frequencies are in the range above 1 GHz (1,000 MHZ). Microwave frequencies are attenuated by the atmosphere, with attenuation increasing with frequency. Rain and fog can be detrimental to microwave transmissions. The southern California region’s mild climate makes it ideal for microwave, while climates of the Pacific Northwest, the East Coast, and Midwest are considered more difficult in the design of a microwave communications link.

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Since microwave is an air-path medium, it is regulated by FCC and the available bandwidth is a function of how much bandwidth has been allocated in the area and how much is still available. Maximum data rate is a function of the available bandwidth — 10 Mbps data stream can be transmitted over a channel only 7 MHz wide. Microwave can be used like fiber in trunking applications for data. In one application, signals along an arterial, located 10 to 15 miles from the control center are interconnected into three full-duplex data channels via twisted-pair cable. These data are multiplexed together and transmitted to the control center over a microwave link. In another application, microwave is used for video transmissions across a large body of water. Advantages: • • • • Useful as a point-to-point trunk. Can transmit data and a limited number of full-motion video channels. Can control groups of traffic-control devices. Can use both analog and digital transmission.

Disadvantages: • • • • • • • Requires line-of-sight path. In most cases, requires FCC license. Limited channel availability. May offer little choice of operating frequency its very difficult to obtain microwave frequency allocations in crowded urban areas. Possible interference due to rain, snow, and atmospheric conditions. May require antenna tower. Available bandwidth usually limited; this is a function of how much has been allocated in the area.

Satellite
Satellite is similar to microwave technology in that both use some of the same frequencies for transmission through the atmosphere. With satellite, however, instead of utilizing a line-of-sight transmission path, the signal is directed to a satellite transponder. Very Small Aperture Terminal (VSAT) satellite systems use 14 GHz and the downlink (i.e., transmissions from the satellite to the earth) use 12 GHz. The satellites themselves are in a geosynchronous orbit above the Earth’s equator, thereby appearing stationary in the sky and providing 24-hour-a-day coverage. In addition to the satellite links, a central hub element and earth stations are also required to provide a VSAT-based communications network. The “hub” may be located at a traffic management center, and
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serves as the focal point for communications between the remote sites and the control center. The “earth station” is the communications component of a remote site. The earth station consists of an antenna, an RF transceiver mounted on the antenna, and a digital interface unit. For video applications, the digital interface unit is connected to the camera’s central receiver (for pan, tilt, zoom) and a codec unit. In general, the VSAT medium is ideal for long-distance communication links (e.g., communications between the Caltrans District 12 Traffic Operations Center and Sacramento) since the cost of leasing VSAT channels is independent of distance. In general, VSAT becomes cost-effective relative to leased lines at a transmission distance somewhere in the range of about 300 miles. Since VSAT lease costs are a function of the percentage of time that the inroute/outroute link is actually utilized, this technology may also have cost-effective applications in a localized communications network where transmissions are required only on an as-needed basis, such as for CCTV that is only used as needed for incident verification. Another potential use of VSAT is for communications where a dedicated cable network and/or leased telephone circuits are not readily available, or where a surveillance camera needs to be mobile. For example, VSAT may be used in conjunction with the maintenance and protection of traffic during roadway construction, and during major incidents in areas where CCTV is not available, but real-time video surveillance would be a great asset. Advantages: • • • • • • • • Cost of circuits is independent of their length. Cost-effective for long-haul communication links. Downlink signals can be received over a wide area. Cost-effective for point-to-multipoint distribution applications. Uplink signals can originate from a wide area. Flexibility for temporary or mobile applications. Provides option to links that cannot be achieved by earth-based communications media. The high-altitude satellites avoid various earth-level interferences.

Disadvantages: • • • Not proven cost-effective for local communications. Limited number of service providers. Channel-leasing costs subject to increases.

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•

Most transportation agencies have no need for the frequent long-distance transmission capabilities of satellite technology.

Optical Infrared
An air-path medium, infrared signals are transmitted from an infrared LED or laser diode (LD)S through the atmosphere along an unobstructed line-of-sight path to the destination. The mode of transmission is similar to the microwave but at a much higher frequency — higher than 300 GHz. Because of its narrow beamwidth and low-power infrared, transmission is not regulated by the FCC. The bandwidth, as with fiber optics, and the maximum data rate of infrared links is dependent on distance. At short distances (less than 1 mile), an infrared link can support full-motion video. At distances up to 10 miles, infrared links can support a 9.6 kbps serial data channel. Infrared is essentially point-to-point transmission, like microwave. One application might be where many channels of data are multiplexed into a single highspeed channel for transmission to a distribution site. Another application might be the transmission of CCTV video signals from the cameras to the control center. Advantages: • • • Like microwave, it is a point-to-point transmission. Higher frequencies than the microwave (higher than 300 GHz). Transmission not regulated by FCC.

Disadvantages: • • Requires line-of-sight path. Severe weather conditions such as fog, smog, or smoke (but not rain) can cause degradation of the infrared transmission.

Radio
Radio technology transmits radio frequency electromagnetic energy — not contained within a waveguide (air-path) through space. Radio frequencies can range from the hundreds of kHz to 1 GHz, and are regulated by FCC. The most likely bands in traffic control are the 928/952 MHz bands, the 450/512 MHz bands, and the cellular radio bands. These frequencies are reserved for point-to-multipoint, master-to-remote, duplex data communications. The total bandwidth (number of channels) is dependent on the number of users and how many channels are already allocated. Advantages: • • • Can provide voice communications to highway maintenance vehicles. Can propagate into built-up areas and buildings. Can support 9,600 baud data rate.

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•

Can prove cost-effective depending on application.

Disadvantages: • • • • • • • Terrain may limit range. Limited channel availability in urban areas. Because of the narrow channel width, radio channels are not usually multiplexed. Requires antenna at each controller site. Turnaround time excessive for some applications. Service reliability may limit use in some applications. Regulated by FCC.

Cellular Radio
A cellular radio is technique for frequency reuse in a large radio communications system. Cellular radio is based on the concept of “cells” which are 2 to 20 miles across. The center of each cell is a control radio that handles the network management functions, including the assignment of frequency subchannels. A radio requests a frequency over a control channel and one is assigned by the cellular control system. Frequencies are in the 825 to 890 MHz band. Instead of allocating a channel for a single user over an entire area, a large group of frequencies is divided into cells. This allows nonadjacent cells within the system to use the same frequency channel without interference, i.e., frequency reuse. One application might be a communication between a portable remote terminal and the central computer. Another application might be dial-up connection between the central microcomputer and the on-street master in a distributed system. Advantages: • • • • • • • Allows frequencies to be re-used without interference. Frequency reuse tremendously multiplies the number of channels available. May prove cost-effective for infrequent communications. Eliminates need to connect to a telephone company service. Effective for controlling portable DMSs. May prove effective for temporary installations. Network covers approximately 93 percent of the U.S. population.

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Disadvantages:
l

Radio transmission of data at low power levels is susceptible to noise. Airtime cost excessive for continuous communication service. Actual data throughput reduced due to protocol overhead. Remote areas may not have service.

l

l

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Spread-Spectrum Radio
In spread-spectrum radio transmission, the signal occupies a bandwidth in excess of the minimum necessary to send the information. The band spread is accomplished by means of a code thta is independent of the data, and a synchronized reception with the code at the receiver is used for subsequent data recovery. With spread-spectrum radio, the entire band (i.e., 902 to 928 MHz, as designated by FCC) is available for use by all users. This is accomplished by “spreading” the signal over the entire 26-MHz spectrum (in the 902 to 928 MHz band) and requires that the receiver “lockon” to the transmitted signal, which adds to the efficient use of the available spectrum. Due to the spreading of the signal over a wide frequency range, electromagnetic noise (interference typically generated at a very narrow band width) has less effect on the signal integrity. This system is designed to replace the physical medium links in most closed-loop systems — consisting of half-duplex, 1,200 baud, TDM/FSK communications. Advantages: • • • • • • • • • • Flexible installation. Does not require cable installation and maintenance. Does not require FCC channel, use approval in the 902 to 928 MHZ band. Works extremely well in a high-noise environment. Currently in use for many industrial process control applications. Uses low transmitter power. Can be used in a mixed system of wired or radio interconnected controllers. No land-line interconnect required. Relatively low equipment cost. Potential for broad range of traffic control-system applications.

Disadvantages: •
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• • • •

Power restrictions limit the transmitter output to approximately 10 miles. Higher bandwidth than radio fixed-frequency transceivers. Requires external antenna and cable. Unprotected channel space.

2.10.3 CASE STUDIES
TransGuide - From the TransGuide ITS Design Report (transguidewwwserver.datasys.swri.edu:80/ articles/designreport.html )

Communications System
The communications system ties all of the other pieces of equipment in the system together. One of the basic attributes of a traffic information system is its geographically dispersed nature. The sensors used for detection, verification and characterization of incidents must be distributed throughout the road system, and the information produced by the traffic management center must be distributed to the drivers on the roads to be useful. There must be a system for collecting the raw data used to generate traffic information and for disseminating that information to the drivers. Several architectures were considered as the basis of the TransGuide system. Some of the architectures consist of a single physical medium. Others contain a variety of media. Selection of the architecture, the physical media and the mechanism for switching the control and video was based on the fact that those attributes are interrelated.

Communications System Architecture
Several different types of communications system architectures are used in traffic control systems, and several were investigated as part of the specification task for the TransGuide system. Primary considerations included the system maintainability (including the availability of network management capabilities), equipment requirements, environmental requirements, reliability, and supportability. Factors investigated included the overall architectures, the level of performance, and the impact of funding mechanisms. Traffic control systems frequently contain several types of communications media; one to handle the data and control functions, one to handle the video signals, and another to handle future ITS applications. These systems typically contain a T1 network, a multimode fiber optic cable, and a single mode fiber optic cable. The T1 network is used for voice and data transmission, the multimode fiber optic cable is used for transmitting a modulated version of the analog video signal, and the single mode fiber optic cable is intended for future ITS requirements. The use of three separate systems significantly increases the problems associated with managing the networks. There are no off-the-shelf network management systems available to manage three disparate networks. In fact, separate off-the-shelf network management systems capable of managing all three types of networks independently were not readily available while TxDOT was specifying the
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TransGuide system. The complexity of maintaining more than one type of network, and the additional cabling and connecting required for separate networks, exacerbates the management problem. One communications system considered for distributing video signals included modulation and demodulation equipment for each camera, one on each end of the fiber optic cable. In this configuration, providing the video signal to any of the displays would require a large analog video switch capable of switching any one of the cameras (eventually up to 1500) to each of the displays in a non-blocking fashion. The system requirement to be able to view any camera on any of the CRTs (simultaneously, if desired) places this architecture at a severe disadvantage. A communications system in which each camera is hardwired to a specific CRT does not require a large analog switching capability. However, it does not meet the system requirements. Another communications system choice was to use frequency division multiplexing of the video signals onto a common set of cables. Initially, a single cable could handle all of the cameras, but eventually three to ten cables would be required, depending on the number of channels multiplexed onto each cable. This communications system would operate much like a cable television system, minimizing the overall amount of cable installed. It would also primarily use off-the-shelf components. However, some parts of the system would probably not be available off-the-shelf. The system would also require either separate data and voice networks or would require custom equipment to transmit voice and data signals over the cable. The communications system eventually selected includes the use of dual single mode fiber optic cables from fiber hubs located strategically throughout the system. The cables are separately routed. An automatic fail-over mechanism switches to the back-up cable in the event of a failure of the primary cable or drive laser. There are several significant advantages to this communications architecture. The digital fiber optic system is compatible with the use of Synchronous Optical Network (SONET), a telephone industry communications standard. The use of the same single mode fiber optic cable used by telephone companies and the use of SONET indicate that long-term support will be available. The selection of communications equipment used by telephone companies also means that there are off-the-shelf network management systems available to control the network, which means reduced maintenance costs and increased system reliability. The selection of the same fiber optic cable, interfaces, and protocols used by telephone companies also means that equipment is standard and available off-the-shelf as well. The availability of environmentally hardened field equipment for this communications architecture also allowed system designers to minimize development of special equipment and operational maintenance costs while maximizing the reliability of the system. One of the driving factors in the selection of the OC3 based communications system was the availability of environmentally hardened (primarily high temperature) equipment to perform the functions required in the fiber hubs. The fiber hubs must be located near the cameras themselves and are therefore geographically distributed. The use of equipment that is not environmentally hardened in non-environmentally controlled fiber hub cabinets is incongruent with the reliability and availability goals of the TransGuide system. If the communications system components required for the fiber hubs were not available in temperature hardened versions, the fiber hubs distributed throughout the city would have to be environmentally controlled, significantly increasing both the initial cost of the system and ongoing operation and maintenance costs.
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Diversity can be provided in fiber optic systems by two different physical connection architectures. One architecture is defined as a ring, and redundancy in a ring is based on multiple routes between nodes. A second architecture is defined as a star, and redundancy in a star is based on route diversity. The selection of the best communications architecture for the TransGuide system was based on the unique attributes of the TransGuide communications system. In the ring architecture, each node is connected to two other nodes to form a logical ring. Each node can communicate in either direction around the ring. Therefore, a ring configuration does not allow a single failure (such as a cut conduit) in any one place to isolate any node on the ring from any other node. Most telephone company systems are built using the ring architecture. A system based on the ring architecture requires communications equipment at each node capable of handling all communications through that node. Each node in a telephone company communications system generally communicates in a statistically distributed manner to each of the other nodes in the system. Random node-to-node communications are not a requirement of the TransGuide communications system. Each TransGuide node communicates only with the TOC node. In a ring architecture, all communications from each node would need to be capable of reaching the TOC node in either direction. Each node would require the ability to transmit all of the communications from most of the other nodes in the ring. To implement such a ring architecture in the TransGuide system, multiple rings would have had to be configured using OC24 or OC48 equipment in the fiber hubs. Neither OC24 nor OC48 equipment is available in environmentally hardened versions. The Irvine’s Field Operational Test uses Asynchronous Transfer Mode (ATM) communications technology to carry out the real-time bi-directional exchange of data and video. The Field operational Test will integrate the Caltrans TMC and Irvine’s Arterial Response Plan system module using MIST via an Ethernet connection over a fiber optic link. The infrastructure includes 28 type 2070 ATCs, additional OPAC loops and five arterial DMSs at strategic locations. The 2070s contain traffic control firmware which exchanges real-time data with the OPAC algorithm through the Data Exchange Module. The key ATM attribute is its capability to support multimedia and integrate such services along with data over a signal-type transmission method (Karna et al, August/September 1996)

CHART
A hybrid approach of both building and leasing telecommunication facilities was taken by the State of Maryland and their CHART system. They did an analysis of the communications needs and an assessment of the build vs lease tradeoff. The study took in some 600 miles of highway with over 1000 field devices, including 200 CCTV cameras, loops and radar detectors within the CHART system as well as telecommunication needs to link five local district operations centers, highway maintenance facilities, other district offices and park and ride facilities. With the size of this communication network, the distribution of data was a major issue. They analyzed eight different network configurations taking into consideration also the existing infrastructure which is 100 miles of fiber optic backbone in the Baltimore-Washington metropolitan area. With the amount of video footage they had to supply to various broadcasts, they have implemented compressed video transmission at 384 kilobits over T-1 phone lines throughout the state of Maryland. The Maryland study revealed that it would be more cost-effective to use wireless communications to link certain field devices than it was to trench with wire. They have Cellular Digital Packet Data network in
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place across Maryland (through Bell Atlantic) and can provide a cost-effective method of sending data (Ian Nuttall, August/September 1996). Some other conclusions drawn from the Maryland study included (Transport Technology Publishing, October 1996): • Where the density of roadway devices, detectors, cameras, etc., is low, there is no way to economically justify building a network to serve these areas. It was considerable cheaper to use wireless communications to get data from devices to the network nodes than laying cable to the devices in many cases. The telecomm industry has changed and is continuing to change rapidly and new technology, already operational in some locations, will greatly reduce the cost of the leased network over the next several years. It was, therefore, recommended that a 3 year lease be chosen vs anticipated 10 or 20 year lease the industry was willing to provide.

•

2.10.4 EVOLVING TECHNOLOGIES
Video Through Telephone
Telephone provides the most cost effective means of video transmission. There are two main categories for telephone circuits: Dial-up and Leased. Dial-up uses the same lines as those used for everyday voice communication in making a call or sending a fax. One is charged only when using it. Dial-up is mostly used when it is not necessary to view a camera for long periods of time. It is very cost effective when used for short periods of time in viewing an area or sending a video to the traffic control center. Leased telephone lines are used when it is necessary to use video surveillance for long continuous viewing of an area.

SlowScan Trough Telephone Lines
This technology uses dial-up phone lines to transmit video using scanning techniques. The video is scanned or painted onto the monitor like a snap shot and pictures are refreshed every 25 to 40 seconds. This technology is very efficient and cost effective in traffic management where real-time video is not needed and only snap shots of traffic conditions are required and updated, at approximately one-half to one minute. One application where this technology is used is to view and confirm messages on changeable message signs. Speed of image transmission is depended on the resolution required. For higher resolution images, such as reading a license plate, the speed of transmission is slower than low resolution images.

SlowScan Trough Cellular Phone
This technology uses cellular phones to transmit slow-scan video. One application where this technology is used is where temporary cameras are needed to gather images or other information that are isolated from the network. Since the use of cellular phones is increasing at an alarming rate, this technology can be used in the future to gather surveillance information from just about anywhere.

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Digital Compressed Video
Where it is infeasible to install cable or lease cost for fiber is prohibitive, compressed video offers an attractive alternative. Transmission of full motion video images is 30 frames per second. Past compressed video techniques, refreshed rates of eight to ten frames per second.. This resulted in the image appearing slightly jerky. However, with new technology, it is now possible to compress the video so that it fits onto the telephone line at full motion. The picture delivered is almost real-time, but to the naked eye and for the purposes of traffic management and surveillance it is sufficient. For instance, to represent one frame of a video in the 0s and 1s of computer language, it takes over a megabyte of memory. Since there are 30 frames in the standard second of video, one would need 33 MB of memory transfer or storage for one second of video. Compression methods can reduce this data at nearly a 200:1 ratio — creating a much more manageable and cost-effective data stream. The process of video compression uses a process that shrinks images so that they occupy less storage space and can be transmitted faster and easier. The bits that define blank spaces and other redundant data are removed and are replaced with a smaller algorithm that represents the removed bits. Digital compression technology will be the key to multimedia and other emerging video communications. Products and services affected by compression include multimedia personal computers, video conferencing, interactive video training and games, high-definition television (HDTV), digital broadcasting services and many others.

Laser
This technology is similar to the fiber optic technology where the signal transmitted is converted from an electrical signal to a light wave signal. However, unlike fiber, the transmission is wireless, through space. There is no FCC licensing involved, no right-of-way fees, no cable installation needed, is not susceptible to EMI or RFI interference and has a very high bandwidth. The disadvantage of the laser technology is that it has a very short operating distance, approximately one mile, needs a straight line of site for the laser transmission, and the video quality is affected by rain, fog, and snow. SOURCES: • • • ATM Networks in ITS, August/September 1996, by Kamal Karna, Jack Bailey, and Jim Arnold, COMtrans. Getting to the Bottom Line on Telecommunication Costs, August/September 1996, by Ian Nuttall, COMtrans. An Overview: Transit Communications Interface Protocols (TCIP), February 24, 1997, by Paula Okunieff, Tom Buffkin, Xudong Jia, Karen Levine, Eva Lerner-Lam, and Isaac Takyi, (www.tcip.org/ paper1.html).

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2.11 IN-VEHICLE NAVIGATION SYSTEMS
2.11.1 TECHNOLOGIES
In-vehicle navigation systems combine advanced Global Positioning System (GPS) technology for precise navigation, detailed digital moving maps able to track a vehicle’s progress in near real-time, and a yellow pages directory of instantly acceptable travel information about restaurants, hotels, entertainment, and shopping (Wilsterman, 1994). The GPS receiver integrated into these systems provides the position of the vehicle on the road in real-time mode, and display that position on a map in a high-resolution color Liquid Crystal Display (LCD) screen. The map, as well as the travel information, is recorded on a CD-ROM disk drive. Wilsterman (1994) describes the operation of these devices as follows: The driver of the vehicle selects his/her route in real-time while driving. This can be done by entering the destination’s name or address, for instance, home or office. The GPS navigation system receives positioning signals from the NavStar network of 24 satellites to pinpoint the vehicle’s geographic location, including latitude, longitude, and altitude, and places it on the in-vehicle display map within 100 yards of the car’s actual position. The GPS receiver can be set to automatically update the vehicle’s position every second, continuously displaying the vehicle’s movement in real-time. This makes it easy for the driver to choose a route, evaluate alternatives, and change course in response to road and traffic conditions. These systems have a built-in zoom function that, just like a video camera, zooms in on a location or pans back, allowing the motorist to reference multiple viewing levels or stages. The zoom illustrates details of individual streets and neighborhoods on its lowest level, to an eagle’s-eye view of entire cities, regions, and highway networks on its highest level. Accessed by a wireless remote, the digital maps are easy to read with clear text and rich graphics that not only identify but also distinguish between interstate highways, State roads, local streets, alleys, parks, landmarks, airports, and natural boundaries. EtakGuide, a product compatible with Sony’s navigation technology, uses audio and video prompts, icons, and colorful screen menus to help novices use the system. Krakiwsky (1996) categorized the navigation systems into five types: autonomous, advisory, fleet management, inventory and portable. The first three types are classified according to their communications capabilities. Autonomous systems have no communications; advisory systems normally have one-way communications — receipt of traffic information, for example; and fleet management systems have two-way communications between the base station and each vehicle. Inventory and portable classes reflect the specialized use and important portability characteristics of some newer navigation systems. The inventory category includes systems related to time- and coordinate-tagging of road-related information for road inventory and other surveillance purposes. The portable category covers products that are the natural extension of portable data assistants (PDAs) — palmtop and laptop computers, for example — into personal navigation assistants (PNAs). The boundaries between these categories have become more blurred as products evolve.

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The three major technologies for determining a vehicle’s position are: the global positioning system (GPS), dead reckoning and map matching. With selective availability (SA) turned on, accuracy is about 30 meters but can degrade further to about 100 meters. SA is the deliberate degradation of GPS satellite signals by the DOD to withhold real-time capability from undesirable users. Differential GPS (DGPS), a technique used to improve accuracy, offers precision to within one to ten meters, but corrections for the effects of SA must be sent to the vehicle to get this improved accuracy. Using GPS requires a direct line of sight from the receiver to the satellite, so it must be used in conjunction with other positioning methods if vehicles will be traveling in urban canyons (streets surrounded by tall buildings) or tree-covered areas. GPS is a universal, low-cost technology — a few to several hundred dollars -- that is revolutionizing navigation. Dead reckoning can supplement or replace GPS and uses a selection of speedometers and odometers, a compass, and a gyroscope to determine the direction and distance traveled by a vehicle. The system must be initialized using the coordinates of a known starting point. The sensors’ accuracy is fairly high for short periods of time, but they require corrections by GPS or map matching over longer periods to avoid error accumulation, which can reach a few hundred meters during extended travel. Dead reckoning devices can double the cost of a system and make it difficult to move the equipment from one vehicle to another. Map matching is used to augment the less-than-perfect positioning provided by satellites or dead reckoning. It assumes that the vehicle is on a road contained in its digital map database. When a positioning system provides coordinates that do not exactly match those of a link, a road segment in the digital road map, the map matching algorithm finds the nearest link, and snaps the vehicle onto it. Changes in the vehicle’s direction and distance traveled are tracked, and the pattern of travel is compared with the road network in the map database to pinpoint vehicle location. Navigation and tracking systems, with the exception of autonomous systems, rely on one- or two-way voice and data communication. Several types of communications technologies can be employed, including: conventional radio, cellular systems, trunking, satellites, beacons and signposts, radio data systems (RDS) and paging. Communications devices are the fastest-changing component of tracking and navigation systems. They affect the cost more than almost any other system components. The choice of communications depends on the intended application and user requirements such as reporting rate, throughput capacity, geographic coverage, and cost. The most commonly used communications system in automatic vehicle location (AVL) designs throughout the world is conventional radio . Equipment may be portable or mobile, the type often dash-mounted in vehicles such as taxis. This system is intended to operate in defined geographical regions; users share a common radio frequency channel and compete for air time. Cellular’s wide acceptance (19 million–plus U.S. users) and national coverage (approximately 90% of the U.S. population and 60% of its geographic regions) have led to significant interest in the AVL marketplace for cellular communications as a means to transmit data over the air. Cellular phones are relatively inexpensive, and airtime costs are decreasing with more competition. Some satellite-based systems complement existing terrestrial-based systems — cellular and special mobile radio, for example — to fill in uncovered areas.
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Beacons and signposts communication devices transmit and receive information by microwaves, infrared light waves, or short distance radio frequencies. They are part of the fixed infrastructure and are typically situated at intersections to exchange information with passing vehicles. This type of system requires a heavy investment in infrastructure. According to Kelly Tisdell and Edward J. Krakiwsky (1997), more than 400 land navigation, tracking, and positioning systems are on the market today. These systems make up: route planning and optimization, fleet tracking, route guidance and MAYDAY.

Route Planning and Optimization
One of the most popular route-planning and optimization products on the market is Roadshow (Roadshow International, McLean, Virginia). The system uses an algorithm to calculate the least-cost route and allow users to consider variables such as traffic bottlenecks, one-way streets, and rush-hour traffic delays. These variables are specified by the user during calibration based on past experience and current knowledge of the route and are adjusted as needed to respond to changes. A Windows-based personal computer displays customer data and a map showing the best route and allows users to modify that route. Roadshow is fundamentally a stand-alone route-planning system — meaning a PC workstation is dedicated to the task of route management and dispatching — but communications capabilities are an option so dispatchers can track and reroute a fleet of vehicles in real time.

Route Guidance
Navmate a popular route-guidance system, integrates a GPS receiver, navigable electronic map databases, a directional sensor, and a control processor. The driver inputs a destination — an address or point of interest — and the system offers turn-by-turn directions with audio and visual cues. If traffic is stalled by construction or an accident, the driver can abort the current route. The system will then calculate an alternative route that avoids the problem. If a driver makes a wrong turn, the system calls attention to the error and asks if the driver would like to calculate a new route based on the vehicle’s current position. Zexel has licensed Navmate to General Motors, Rockwell International, and Siemens Automotive. Rockwell’s PathMaster, a licensed version of Navmate, is now the most widely available route guidance system in the United States. A more recently released product, CARIN (car information and navigation) also integrates a GPS receiver, wheel sensors, an electronic compass, and navigable electronic maps. It incorporates many of the same functions as Navmate, including both audio and visual instructions, but CARIN adds cellular communications, which provides some additional benefits. Traffic and weather information will soon be available via cellular phone for integration into travel plans, and an SOS feature will be able to relay coordinates to authorities in case of an emergency. When the vehicle is stationary, the onboard monitor can also be used as a television. The system is currently available in the United States as an option on BMW 5 and 7 Series models.

Mobile Navigation Assistant System
ADVANCE involves the use of a Mobile Navigation Assistant (MNA) system, a next-generation in-vehicle guidance system, developed by Motorola. Each vehicle is equipped with GPS capability, to
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determine vehicle location; an RF communications system, to receive real-time traffic information and transmit vehicle location information; and a voice/graphics-based route guidance system. Route guidance is calculated by an in-vehicle computer. It receives information from the Traffic Information Center (TIC) through a radio frequency data modem. Because each vehicle is also acting as a probe, transmits traffic information (e.g., travel time data) from the vehicle to the TIC. The system receives information and sends data independent of the driver. The Mobile Navigation Assistant contains the following: • A 5.7-inch color (LCD) that provides the driver interface—with a touch screen and fixed buttons that allow the user to enter destination data, request specific functions, and access feature menus. A driver enters a destination by address, street intersections, or by choosing a point of interest resident in the on-board memory. Sensors including wheel speed, compass and differential global positioning satellite. A trunk-mounted computer that controls all vehicle systems. Single CD-ROM disk drive for mass data storage.

• • •

The MNA provides visual route guidance directions on the LCD display, and audio instructions through a speaker. Some of the early findings of ADVANCE were: • • • • The density of probes need not be high for a probe-based system to be effective. The travel time reports provided by the probes were generally very accurate. Drivers can safely use in-vehicle systems while driving in traffic. The gap between potential and actual system performance must be closed before the confidence of prospective ATIS users can be won sufficiently to encourage them to buy the system and act consistently on ATIS guidance.

Radio Broadcast Data System
A system known as Radio Broadcast Data System (RBDS) in the United States and as Radio Data System (RDS) in Europe is a way of sending information directly to wireless receivers. One of the initial uses for this technology is to broadcast accurate real-time traffic information directly to vehicles or smart information kiosks. Another use for RBDS is to broadcast differential correction information for use by global positioning system receivers. Currently, traffic information is widely available through commercial broadcast radio; however, it does not always reach the traveler at a time or location where the information is useful. By using RBDS technology, timely traffic information is delivered directly to an instrumented vehicle or kiosk. Thus, relevant traffic information is always available to the traveler.

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The Phoenix Deployment Test Through the Phoenix Deployment Test, real-time traffic information is gathered from the Arizona Department of Transportation, city of Tempe, Metro Networks, and Skyview Traffic Watch, Inc. Crusader Software (PC NT 3.51) developed by Daltek AB is used to encode the traffic information. Differential Corrections, Inc. broadcasts the encoded information from KSLX FM 100.7 radio station. Volvo systems (Dynaguide in-vehicle and PC-based units) overlay the traffic information onto Maricopa County Department of Transportation maps of the metropolitan Phoenix area. Retki software, developed by Liikkuva (running on notebook PCs), overlays the traffic information onto maps of the metropolitan Phoenix area. Since 1994, General Motors has been offering the Duidestar in-vehicle units developed by Rockwell International and Zexel in its new Oldsmobiles, and will also offer the OnStar GPS-based guidance system from Delco/Hughes Electronics as an option on most of its 1997 Cadillacs at a cost of approximately $1000 per unit. Numerous rent-a-car companies are also offering in-vehicle navigation units. Hertz and Avis are both offering the NeverLost system developed by Rockwell International and Zexel. National is offering the Siemens GPS-based units. As discussed in the Regional Multimodal Traveler Information Systems section (Chapter 8), in-vehicle devices were used in the Atlanta Traveler Information Showcase for route guidance using real-time traffic information. In addition, The Hertz Rent-a-Car Corporation equipped 20 of its rental cars with the in-vehicle devices. Oldsmobile outfitted 30 vehicles of the fleet it provided to the Atlanta Committee for the Olympic Games with the devices. BMW provided the Showcase with five vehicles. The in-vehicle device were also placed in some private company fleets and Federal Highway Administration automobiles. Currently, Acura, BMW, Oldsmobile, and Toyota offer navigation systems as optional equipment on some of their models. Sony, Rockwell, Clarion, Kenwood, and Amerigon systems can be installed in most older vehicles dating back to 1988. Hertz offers NeverLost (usually for an extra $6 per day) on mid- and full-size rental cars as well as some Ford Explorers. The same system is available from Rockwell as the Pathmaster at car audio retailers. The Oldsmobile, BMW, and Toyota systems force the driver to scroll through a list of selections to choose the destination. Acura’s system allows the driver to type a destination directly on the touch screen. BMW stores its navigation software on CDS in the vehicle’s trunk. Acura and Oldsmobile use easily removable hard drives. Two carmakers have combined cellular phone and GPS technology without on-board navigational software to create a different kind of system. Cadillac’s OnStar and Ford’s RESCU systems can pinpoint the vehicle’s location within a few hundred feet and offer help when the motorist needs it. If, for example, a vehicle is in a collision severe enough to deploy the airbags, OnStar transmits a signal via satellite to a control center in Farmington Hills, Michigan, giving the location of the vehicle. An operator at the center will place a cellular call to the motorist of the vehicle to confirm the airbag deployment. If the motorist does not respond, the operator calls 911 in the area of the vehicle’s location to dispatch police and an ambulance. Besides summoning help if the airbags deploy, OnStar can remotely unlock the doors if the driver of a vehicle has locked the keys inside; can call the control center toll-free and the operator of the control center can sound the horn and flash the lights of a vehicle that the motorist cannot find; notifies the
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control center if it detects that a vehicle has been stolen and the center then gives the location of the vehicle to the police. The Ford RESCU’s control center is in Dallas. The features of the RESCU system are similar to the OnStar with additional features: an icon appears, on the overhead console, for an ambulance and one for a tow truck. If the motorist pushes the icon button, the vehicle’s location, and speed are sent to the center and the center will get appropriate help after verifying the call. RESCU, unlike OnStar, cannot remotely unlock a vehicle, flash lights to help motorist find the vehicle (Herb Shuldiner, March/ April 1997). RoadTrac in Roswell, Georgia introduced Ceres, a location-based vehicle security and monitoring product. Ceres uses GPS, cellular technology and a monitoring center to provide a variety of emergency and assistance responses to criminally threatening situations, accidents and breakdowns, medical emergencies, vehicle theft and mistakenly locked doors. In addition, it includes a remote key ring panic button which sends an alarm to the monitoring center and activates alarms on the car itself. It also offers a CD-ROM which allows the vehicle to be tracked on a personal computer (Inside ITS, January 13, 1997). SOURCES: • • • The Art of In-Vehicle Navigation, November 28, 1994, by Goug Wilsterman Intelligent Highway Systems, a Supplement to Engineering News Record http://www.azfms.com/About/rbds.html Guiding Lights for Your Car, March/April 1997, by Herb Shuldiner, Car and Travel

Return to Table of Contents

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Traffic Signal Control Systems

CHAPTER 3

Traffic Signal Control Systems

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Traffic-signal control systems coordinate individual traffic signals to achieve network-wide traffic operations objectives. These systems consist of intersection traffic signals, a communications network to tie them together, and a central computer or network of computers to manage the system. Coordination can be implemented through a number of techniques including time-base and hardwired interconnection methods. Coordination of traffic signals across agencies requires the development of data sharing and traffic signal control agreements. Therefore, a critical institutional component of Traffic Signal Control is the establishment of formal or informal arrangements to share traffic control information as well as actual control of traffic signal operation across jurisdictions. Signal coordination systems are installed to provide access. A traffic-signal system has no other purpose than to deliver favorable signal timings to motorists. The system provides features that improve the traffic engineer’s ability to achieve this goal. These are primarily access features. They provide access to the intersection signal controller for maintenance and operations. The more complete and convenient the access, the more efficient the operator will be and the more effective the system. In addition to control of traffic signals, modern systems also provide wide-ranging surveillance capabilities, including various kinds of traffic detection and video surveillance. They also provide more powerful traffic-control algorithms, including the potential for adaptive control and predictive surveillance. SOURCES: • • • • Traffic Control Systems Handbook, February 1996, Publication No. FHWA-SA-95-032, Federal Highway Administration. Manual on Uniform Traffic Control Devices for Streets and Highways, Federal Highway Administration. Improving Traffic Signal Operations, A Primer, February 1996, Publication No. FHWA-SA-96-007. Computerized Traffic Signal Systems, Training Course, To be Published in 1997, NHI Training Course No. 13310.

3.1 SURFACE STREET CONTROL
Surface street control systems provide the majority of traffic-signal system applications. They are intended solely to provide control of networks of signal-controlled streets. When traffic-signal systems are integrated with freeway-management systems, their objectives take on a larger perspective. Integrated traffic-signal systems will be covered in a later section.

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3.1.1 TECHNIQUES/STRATEGIES
Isolated Signals
Isolated traffic signals are the basic building blocks of signal systems. Traffic signals are installed when traffic at an intersection becomes too heavy for motorists to efficiently or safely assign their own right of way. Because a traffic signal removes the motorist’s ability to coordinate his turn at an intersection, it is considered a more restrictive form of control than uncontrolled or stop-controlled intersections. For this reason, traffic signals are generally regarded as a last resort for intersection traffic control. The decision to install a traffic signal depends on the conditions at the intersection meeting one of a series of warranting conditions, as defined in the Manual on Uniform Traffic Control Devices. These warranting conditions are intended to define the common circumstances when a signal might be appropriate. In spite of these specified warranting conditions, the decision to install a traffic signal must be made by a qualified traffic engineer based on a careful study of the intersection and potentially lessrestrictive alternatives. Briefly, the conditions generally thought to warrant traffic-signal operation follow. General Traffic Volumes - When traffic volumes at most of the intersection approaches reach the point where other forms of control cannot efficiently assign right of way to the approaching motorists. Interruption of Continuous Traffic - When traffic on a major street is so heavy that traffic on a lightly travelled side street has little opportunity to cross or enter the main-street traffic. This condition requires heavier traffic on the main street than the previous condition, but allows lighter traffic on the side street. Pedestrian Volumes - When pedestrian traffic is heavy enough to justify the interruption of vehicular traffic. School Crossings - If judged necessary by the traffic engineer, a traffic signal may be used to facilitate the crossing of school children. Progressive Movement - Sometimes a traffic signal will help keep platoons of cars tightly formed to enhance the coordinated flow along a street and encourage an appropriate speed. Accidents - Traffic signals are sometimes effective in reducing accidents that result from the inability of motorists to safely assign their own right of way. These accidents typically involve right-angle collisions. Some Combination of the Above - A collection of conditions that generally comprise some of the above conditions, or when streets that are clearly major elements of a transportation network intersect. Once a traffic signal is installed, it may be operated one of two ways: pretimed or actuated. In practice, the installation of isolated pretimed intersections has become rare. Most signals in isolated circumstances control highly variable traffic, and therefore work better when actuated by traffic. a. Pretimed Operation. In this form of operation, the red, yellow, and green indications are timed at . fixed intervals. Pretimed operation assumes that the traffic patterns can be predicted accurately
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based on time of day. As previously mentioned, this predictability can usually only be achieved by controlling the traffic entering the intersection with upstream signals, as in a system. In isolated locations, however, the traffic approaching the intersection arrives randomly, and is not usually predictable enough to make pretimed operation a good choice. But pretimed operation does not require traffic detectors at the intersection, and is therefore much cheaper to install. Consequently, pretimed operation is usually used at isolated intersections only when funds do not allow actuated operation. b. Actuated Operation. Intersections with this form of control consist of actuated traffic controllers and vehicle detectors placed in or on the roadways approaching the intersection. In actuated operation, the control algorithm is primarily concerned with when green intervals terminate. With actuated controllers, green intervals may terminate in one of four ways: 1. Maximum Green Time is Reached. Usually called maxing out or timing out, this occurs when a user-determined maximum green time is reached. The interval is terminated and the next interval in the sequence is allowed to time. 2. Traffic Flow Ceases on the Approach. When a gap in traffic appears that is greater than a userdetermined threshold, the controller will terminate the green interval in favor of other movements that have demand. This form of termination is known as gapping out. 3. A Signal System Forces the Termination. When an actuated signal is part of a coordinated system, the system keeps the signal in step with the intended operation by forcing green intervals off at the intended times in the signal cycle. This is called applying a force-off. 4. The Signal is Preempted. As discussed below, when a priority vehicle approaches the intersection, nonpriority green intervals may be terminated in favor of the priority movement. In most cases, only the first two of these termination methods will be used at isolated locations. Forcing is reserved for coordinated operation, and preemption is a special case. During actuated operation, a traffic movement will be served with a green indication. This green interval will last a user-defined minimum amount of time. As long as cars continue to cross the approach detectors frequently enough, the green interval will be extended. These extensions will continue until the cars thin out sufficiently to allow the signal to gap out, or until the interval reaches the maximum time. At isolated intersections, actuated operation considers only when to terminate the current traffic movements being served. Actuated controllers do not determine whether extending the green for that movement will meet intersection-wide objectives for traffic operation, such as minimizing delay. Consequently, the objective function of normal actuated extension is to minimize unused green time. A corollary of this objective is to maximize green time that is fully utilized. At actuated signals, therefore, effective cycle lengths tend to grow uncontrollably as traffic demand nears capacity. Without signal coordination, the maximum green times are the only mechanism in the controller to impose some discipline on the cycle length. At critical intersections, good practice would dictate that maximum green times are calculated to provide effective operation under capacity-flow conditions. These conditions vary depending on time of day, and most controllers are therefore equipped with two or more sets of maximum green times to be used at different times of day.
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Interconnected Signals
a. Distributed Systems Distributed systems are those in which, generally, the intersection controller is responsible for control decisions at the intersection. Distributed systems come in many varieties, ranging from small closed-loop systems (see below) to powerful large-scale systems. When traffic signals are located close enough together that traffic remains in recognizable platoons from one intersection to the next, traffic engineers will usually seek to coordinate their operation. Signal coordination merely requires that the signal timings at multiple intersections be timed to meet networkwide objectives for traffic flow. This usually requires all signals to operate at the same or a compatible cycle length, with careful design of the time-space relationships between the intersections. The signals, therefore, need some means of staying in step with each other. At the most basic level, each intersection’s traffic signal may contain an accurate clock, with all intersections coordinated according to their internal clocks. As long as the clocks at the intersections remain synchronized with each other, the signals stay in proper coordination. This form of coordination is known as time-base coordination. Time-base coordination is used when a communications infrastructure is unavailable. When a communications infrastructure can be constructed, signals can be coordinated more effectively than with time-base operation. The differences between distributed systems and centrally controlled systems have blurred in recent years. Most modern centralized systems have many of the important features of distributed systems, and most distributed systems offer many of the most useful central control features. Distributed systems have the following characteristics: • They rely on powerful local-intersection controllers. Because the power of the system is inherent in the local controller, these controllers must have all the features desired for signal control at the intersection. Most local-intersection controllers available have sufficient power to operate effectively in a distributed system. Some of the newest systems, however, use leading-edge controllers, such as the Model 2070, which does have a cost impact on the system. They are inherently robust. Distributed systems do not transmit mandatory real-time control commands over the communications network. Consequently, the intended operation of the system can be maintained even during communications and central computer downtime. True distributed systems incorporate this characteristic more effectively than centralized systems with a time-base backup. They are always operating in time-base coordination, with the central computer and communications network used only to maintain the accuracy of the internal clock. When a failure occurs, they do not have to transition to backup operation; they are already there. They are easily expanded. Each time a new intersection is built, the computing capacity of the system, which includes the local controllers, is expanded sufficiently to incorporate the new intersection. All that must be added is communications infrastructure.

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•

They are often inexpensive. The communications network need not be reliable enough to carry mandatory real-time communications. Consequently, inexpensive communications alternatives, including wireless alternatives, are viable options that can significantly reduce the cost of a new system. The savings in communications infrastructure usually compensates for the potential higher cost of local controllers. Distributed systems typically cost between $10,000 and $30,000 per intersection. They often do not provide real-time surveillance. Distributed systems do not need real-time polling of intersections for control purposes, and some systems are installed on communications plants that do not allow real-time polling. In these cases, real-time surveillance also cannot be provided. They do not provide for centralized adaptive-control algorithms. Some adaptive-control algorithms use a centralized optimization facility that requires centralized control. SCOOT (Split, Cycle, Offset Optimization Technique) is an example of this type of system. Such operation is not possible on distributed systems that cannot provide reliable real-time control communications. The central processor in the distributed system is limited primarily to operator interface and display functions.

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•

When To Use Distributed Architectures Distributed systems may be preferred when: • • • • • • • • Powerful local intersection control is desired. Project budgets limit the installation of new linear infrastructure and fault-tolerant central computer networks. Improved reliability is required through the use of microprocessors and multiple levels of fall-back control. Existing infrastructures must be used. The signal system has few existing facilities (e.g., computers, interconnect). Wireless communications technologies must be used. Absolute real-time surveillance is not needed. Centrally optimized adaptive control is not needed.

b. Central Control Systems

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In centralized systems, a central computer makes control decisions and directs the actions of individual controllers. Each intersection requires only a standard controller and interfacing unit and does not perform any software functions. Central systems have the following characteristics: • They depend on reliable communications networks. Because real-time control commands are transmitted from the central computer to the local intersection, any interruption in the communications network forces the local controller to operate without that real-time control and revert to its backup plan. In traditional centralized systems, the backup operation was usually isolated traffic actuation. More recent systems revert to time-based coordination, but this still requires a transition from central control to local control. During this transition, signal coordination is usually lost for a short period of time. For this reason, communications networks for centralized systems usually include some form of fixed communications, with most agencies preferring to own their infrastructures. These communications media include twisted-pair copper wire and fiber-optic cable. The physical media typically provide inherent reliability of 99.995 percent to 99.99995 percent, with downtime ranging from a few seconds to a few minutes a year. In real systems, downtime is much higher because of physical intrusion on the infrastructure, though some fiber network approaches even minimize the effects of that danger. They depend on reliable central computers. Without the central computers, centrally controlled systems do not make much sense. When the central computer is down the system has the same problems as when the communications network is down, except that the problem affects all intersections, not just the few on that communications branch. Traditional centralized systems ignored this problem, and consequently earned a reputation for reliability problems. Newer centralized systems are employing advanced computer reliability techniques. The most interesting (and expensive) of these approaches is known as fault tolerance. Fault-tolerant systems employ two identical central computers networked together with a high-speed network connection. They both contain the same software, and share a joint operating system. Each computer runs in lock-step with the other, so that they operate as twins. When one computer fails the system is operated by the other computer, and the joint operating system arbitrates between the two systems during the onset of failure. They are often not easily expanded. Many traditional centralized systems are designed around a maximum network size. Increasing the size of the network requires a significant investment in central computer upgrades and often, upgrades in the software as well. They are expensive. Communications networks typically consume at least two-thirds of the cost of a system. Centralized systems require communications networks with high throughput reliability, which typically precludes the successful use of wireless communications. Consequently, the system costs include installation of a linear communications infrastructure. Centrally controlled systems usually cost between $40,000 and $80,000 per intersection. They provide excellent surveillance response time. The system’s communications network is reliable enough to allow mandatory real-time control communications. In most situations, this requirement ensures once-per-second return of surveillance information.

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•

They allow centralized control algorithms. This is the one area where centrally controlled systems have a distinct disadvantage over distributed systems. Some control algorithms, such as SCOOT, require a central computer to calculate the optimization algorithm for the entire network. Only a centrally controlled system can provide this capability.

When To Use Centralized Architectures Centralized systems can be considered when: • • • The budget allows linear communications infrastructure to each field device, in addition to the use of fault-tolerant central computer networks. Centrally optimized adaptive-control technologies are desired. The system will share resources, particularly communications and computer networks, with other systems that require high reliability, such as emergency-management systems.

Network Architectures
a. Centralized Architecture A centralized architecture is representative of the central control system in which a single central computer configuration directly controls the duration of every controller phase. The computer transmits commands that are used to terminate the existing phase to the controller. These commands are usually transmitted at a once-per-second rate. b. Distributed Architecture With Local Masters This architecture is representative of most closed-loop systems in which second-by-second commands are transmitted from local masters to the intersection controllers. The masters communicate with the central processor only when failure occurs, or when commanded to do so by the central processor. The connection between the masters and local controllers is usually made via dedicated twisted-pair cable. The connection between the masters and the central computer is usually made via dial-up telephone. In this way, it is possible to minimize the cost between remote groups of intersections and a central site. For this reason, closed-loop systems are popular with State and county agencies responsible for control of intersections dispersed over a wide geographic area. c. Distributed Architecture Without Local Masters This architecture is similar to the centralized architecture. However, its lower communication capacity requirements (i.e., sampling rate of once per minute or less) offers the ability to connect more than 100 intersections to a single voice grade facility. It is therefore practical to use a variety of alternative communications media such as radio or cable television. This architecture relies on the local controllers or communications interface devices to provide the local timing.

Special Controls
Preemption/Priority Systems
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Preemption systems started out as special hardware devices installed in controller cabinets to respond to special conditions. When those conditions appeared, the device would preempt the operation of the controller, and take over operation during the special condition. Most modern signal controllers have preemption capabilities built in, and therefore allow much greater flexibility in how preemption scenarios are operated. Priority systems came about later, and provide the capability to give special consideration to one class of vehicles without completely preempting the normal operation of the signal. The special conditions that call for preemption and priority are usually grouped into three categories: railroad, emergency vehicle, and transit vehicle events. a. Railroad Preemption. When traffic signals are placed close enough to a railroad grade crossing that conflicting signals cause a safety problem, a preemption capability is installed to take over operation of the signal while a train is near the crossing. At such a signal, the controller will either invoke flashing operation or a special preemption plan while the train is approaching or in the crossing. The special preemption plan usually starts with a track clearance interval, which allows cars that may be queued in the crossing to clear the tracks, and is followed by limited service, where the conflicting movements are red while the train is present, and nonconflicting movements are allowed to cycle. In most controllers, railroad preemption takes the signal out of coordinated operation. Controllers sense that trains are nearby by receiving a contact closure on signal lines tied into the grade crossing equipment. b. Emergency Vehicle Preemption. Many older systems were designed to provide continuous green signals along fixed emergency vehicle corridors. These corridors typically include the streets adjacent to fire stations, and these systems were often called fire routes. Fire routes are usually operated by a switch in the fire station that is manually operated by the firemen. The fire route stays in effect until the switch is turn off, or for a specified period of time. These approaches are best suited to centrally controlled systems, where the actions of the local intersections are being directed by a central computer. The fire route switch is then connected only to the central computer. More modern emergency vehicle preemption schemes are intersection-based, and use special detectors at the signal to receive coded signals from emergency vehicles. These systems preempt regular signals to allow a green signal in the direction needed by the approaching emergency vehicle. Ambulances, as well as fire trucks, can use these systems. Because these approaches are intersection-based, they are more suited to application within distributed systems. A preemption event at a centrally controlled intersection will usually be dropped by the system and picked up some time after the preemption event is over, which worsens the operational effect of the preemption. c. Transit Vehicle Preemption and Priority. Some systems employ priority schemes for transit vehicles. The objective is to maximize passenger capacity of the network by providing ridership-enhancing operational advantages to transit vehicles. When the transit vehicles are not buses, priority operation may improve safety by reducing the number of stops required by larger rail-based transit vehicles.

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Some transit schemes use preemption, but the trend is toward priority schemes that work within the signal-coordination pattern instead of removing the signal operation from the pattern. For example, if a signal detects an approaching transit vehicle, it may be programmed to see if the green for that movement can be serviced early, or held for a longer time, without forcing an interruption in the normal operation. Often, the delay to the transit vehicle can at least be reduced by using these approaches.

3.1.2 TECHNOLOGIES
Mainframe and UTCS Type Systems
In 1997, FHWA began development of the Urban Traffic Control Systems (UTCS) project. The system was installed in Washington, DC, and was used to develop, test, and evaluate advanced traffic-control strategies. The system contained 512 vehicle detectors whose outputs were used to determine signal timing at 200 intersections. Extensive data processing, communications, and display capabilities were made available to support the traffic-control strategy research. Later research efforts produced Extended and Enhanced versions of the software package that implements these concepts. Virtually all mainframe traffic-control systems in operation in the United States are based on one of two UTCS packages, originally supported and distributed by the FHWA. The Extended UTCS package, which uses a menu-type user interface, is considered by many to be the benchmark program against which features of competing programs are measured. The other package is the Enhanced package, originally developed by the FHWA to overcome shortcomings of the Extended package and to add additional features. The enhanced UTCS package was completed and demonstrated in Birmingham, AL, in 1983. Versions of the Enhanced package have been installed in Los Angeles and San Diego, CA.

Closed-Loop Systems
The closed-loop system is a distributed processor traffic-control system with control logic distributed among three levels: the local controller, the on-street master, and the office computer. These systems provide two-way communication between the local controller(s) and the on-street master(s) and between the on-street master(s) and the central computer. Typically, the local controller receives information from field devices (e.g., system detectors). The master controller receives information (e.g., traffic and/or internal diagnostics) from the local controller. The central computer enables the system operator to monitor and control the system’s operations. One major disadvantage of the closed-loop system is inability to control intersections connected to different local area masters in a unified manner. This restriction precludes extensive reconfiguring of control area boundaries in response to differing traffic conditions. Three control modes are typically found with most closed-loop systems: time of day, manual, and traffic responsive. With the time-of-day mode, the controller unit can automatically select and implement a prespecified traffic-signal timing plan and sequence (cycle/offset/split) based on the time of day, day of

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Advanced Transportation Management Technologies

week, and/or time of year. With the manual mode, the operator specifies the pattern number of the desired traffic-signal timing plan and sequence via the computer console. With the traffic-responsive mode, the computer automatically selects the predefined traffic-signal timing plan best suited to accommodate the current traffic flow conditions in the signal network. The pattern selection and implementation is accomplished through a traffic flow data matching technique executed every five minutes on the five-minute mark. Two other control modes have been used by some closed-loop systems: the controller unit parameter mode and the critical intersection control mode. The closed-loop system consists of six components:

• • • • • •

System detectors, Local control equipment, Controller-master communications, On-street master, Master-central communications, and Central computer.

a. System Detectors System detectors are used to sense vehicle presence or pulse duration and derive information on vehicle volume, occupancy, speed, queue length, etc. The detector technology has been discussed previously. However, care must be taken in the placement of these detectors to ensure the measures desired are obtained. For example, some systems select each parameter separately. The cycle length could be determined by the highest detector output level from one group of detectors while the offset could be determined by a ration of detector output values from the same or a different group of detectors. The split could be determined by a ratio of output values from still another pair or group of detectors. Other systems use various forms of pattern matching, whereby a combination of volume and occupancy values from each detector is associated with each eligible timing plan and an algorithm is used to find the best match. In general, detectors should not be located near major driveways, nor in areas where there is poor lane discipline or weaving sections. They should be placed far enough upstream from the intersection so that stopped queues normally do not extend over the detector, unless queue lengths are desired. Understanding and familiarity with the traffic responsive algorithm is a prerequisite in detector placement. b. Local Control Equipment Closed loop traffic control systems are very similar to time-based coordination technology. There are two configurations: external and internal. The external version houses the communications function and the supervisory control functions that allow the interface with the local controller on a separate chassis. The internal form is generally designed as a single module that slides into a slot in the controller chassis.
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Traffic Signal Control Systems

Unlike the external closed-loop system interface devices, the internal devices are capable of three functions: communications, time-based coordination, and local controller database modification. With the internal closed-loop system local hardware, it is no longer necessary to make a trip to the field simply to adjust a clearance interval, or a minimum green or any other controller setting. The change can be made from a computer in any location (e.g., central control, remotely). Being able to change or modify controller settings requires an intimate interface between the controller design, the communications messages and protocols, and the central controller software and database. This level of integration precludes the possibility of using one manufacturer’s local controller with another’s off-street master or central computer. The capability comes, therefore, with a stipulation that all replacement and expansion equipment must come from the original supplier. However, with the development of NTCIP applications such as the link from the field device to a hub computer or central , computer can be implemented with any combination of products and manufacturers. These standards will revolutionize the traffic-control industry and make things happen in terms of communication interfaces and proprietary product restrictions and constraints. An advantage of the external form of closed-loop systems is that the device can interface with virtually any modern controller. Many systems provide the capability to interface with three-dial, electro-mechanical controllers, as well. c. Controller-Master Communications Most of the closed-loop systems use a 1,200 bits per second, Frequency Shift Keying (FSK), Time Division Multiplexing (TDM) communication protocol. The system will work on leased telephone lines or on jurisdiction-owned cable. Most installations have been with city-owned cable. The ideal system would be where each local controller in the system is addressed once per second by the master. Typically, the data transmitted from the on-street master to the local controllers are commands to switch to a particular timing plan, or data changes to the database of a specific controller. There are three categories of return messages: status data, signal display data, and detector data. This data need not be communicated on a once-per-second basis for every intersection and, therefore, different schemes (e.g., once per 30 seconds, once per minute) could be configured to make up the 1,200 bits-per-second capacity. d. On-Street Master The primary function of the on-street master is to select the timing plans for a group of intersections, to process and store detector count information, and to monitor equipment operation. The following traffic-responsive technique demonstrates a typical algorithm used in closed-loop systems, and is found in the Computerized Traffic Signal Systems Training Course. All detectors are assigned to groups. There is one cycle group of 12 detectors. There are two offset groups (rightbound and leftbound) with a maximum of 12 detectors in each group. There are two split groups (main and cross) with a maximum of 12 detectors in each group. To select the cycle length, the highest value (some systems select the second highest or average value) of all the detectors in the group is identified. The cycle length is selected by comparing this value with parameters stored in a table that are associated with each of four cycle lengths. All systems have a form of hysteresis that prevents oscillating between different cycles when the measures are at the boundary levels.
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The offset calculation would be similar but perhaps use a ratio of directional distribution to make the selection. For example, the ratio of the highest rightbound detector to the sum of the highest detector measure in both directions could be computed. The offset would be selected by comparing this ratio with values stored in a table. Typically three or five offsets are available with the middle offset representing balanced flow. The split may be determined in a similar manner. Given below is an example that considers a twodimensional matrix: Cross Street Value Main Street Value 1 1 2 3 SP2 SP2 SP1 2 SP2 SP2 SP2 3 SP3 SP3 SP2

As with cycle and offset, the detectors in the split group are searched for the highest value. The output values are mapped to a matrix. In this example, the mainstreet detectors are used as the column pointer and the cross street detectors are used as the row pointers. The entry in the table above represents the split selection; SP1 would favor the cross streets, SP2 would be the normal split, and SP3 would be a split that highly favors the main street. A characteristic of this type of system is that when SP3 is selected, all controllers in the system must operate on split three. This is not as restrictive as it first appears, as long as one can assign different values at each intersection to be assigned as split three. In fact, is it common for closed-loop systems to code the save values for each of three splits at some intersections so that no matter what split is selected by the master, one set of timing values would be used at a particular intersection. This would likely be done at minor intersections. It should be noted that the numbers given by some manufacturers in terms of cycles that the system supports can be misleading. If one system supports 31 cycles, for example and another 15 cycles, it really does not make that much difference between systems if only three or four cycles will actually be used. Some systems state their timing plan capacity in cycles, splits, and offsets. Three cycles, splits, and offsets would correspond to 27 combinations or plans. Others count each independent set of values as a plan. e. Master-Central Communications All closed-loop systems are capable of using dialup communications between the central computer and the on-street master. With this form of communications, there is a separate telephone drop for each onstreet master. Most telephone companies charge for the field drop on the same basis as a commercial telephone. Most users install a separate dialup line for the central computer, as well. Communications between the central computer and the on-street master can take one of three forms: time synchronization, system command, and download data. A message transmission can be initiated by
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a time-of-day event schedule or by operator action. The user has the option of issuing a command or downloading data. A typical command would be to update the master time of day with the value in the central computer. Another command would be to upload (send from the master to central) a particular page of data. A command typical of all closed loop systems is to initiate monitoring of a particular intersection. This command results in an intersection graphic being drawn on the central computer and the various green movements depicted by arrows and other graphic symbols. Depending on the system, the display of the intersection monitor information places a major load on the communications capacity. Although all closed-loop systems can operate with dial-up communications, they work quite well with dedicated leased telephone lines and jurisdiction-owned cable. The dialup alternative offers the attractive qualities of being simple and generally inexpensive to install. f. Central Computer

The central computer is used to: • • Set time and date. This enables the user to reset the computer clock and automatically reset the onmaster and all local controller clocks to the same value. Display intersection. This allows a real-time display of single intersections (some systems allow the user to select a predrawn intersection from a library, and others provide the capability for the user to draw an intersection). With most systems, the communication link (telephone line) is occupied when the real-time display is ongoing. It is impossible, therefore, for the system to report any malfunctions if any are detected. The simplest way to deal with this problem is to allow the on-street master to retain the message in queue and to report the malfunction when the intersection monitoring is terminated. Modify master database. This allows manipulations of the database in the on-street master. This data is organized into five categories: the event schedule, the traffic-responsive parameters, detector processing parameters, data logging, and event logging. Modify controller and coordination data. Every point made above with respect to the master database holds true also for the controller/coordinator database. This is where first-time users of closedloop systems appreciate the usefulness of full-screen editing. Another common function is the ability to copy all or part of the database for one intersection to another. Modify system parameters. Intersection addresses, communication line and slot assignments, type of monitor and video card, and numerous other system configuration data are included in this division Monitor system. When this option is selected, the computer is monitoring the communication port. When a call comes in, the central computer receives the message and takes the necessary action. Two types of messages are received when in this mode: a system error message and detector data. Prepare reports. The data generated by the closed-loop system is converted into information required by the operators of the system.

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Figure 3.1, from the Computerized Traffic Signal Systems Training Course, provides a summary of the features for several closed-loop systems on the market today.

Traffic-Adaptive Signal Control
a. SCOOT SCOOT (Split, Cycle, Offset Optimization Technique) is the premiere centralized adaptive control scheme available. The fundamental technology of SCOOT grew from the development of the Traffic Network Study Tool (TRANSYT) in the late 1970s and early 1980s, and was developed in the United Kingdom by the Transport and Road Research Laboratory (now the Tranport Research Laboratory). SCOOT performs optimization at three levels. SCOOT measures vehicles at a detector ideally placed at least eight seconds of travel time upstream from the stop line. Every second, the central program predicts the profile of arrivals to the signal based on the profile measured at the detector. This arrival profile is compared with a departure profile based on saturation occupancy from onset of green to clearance of the queue. The lapse between departure and arrival profiles represent those vehicles delayed in a queue. These profiles are measures of a combination of detector occupancy and gaps, called link profile units. Determination of these units is one of the secrets of SCOOT. The split optimizer in SCOOT evaluates the projected arrival and departure profiles every second. Five seconds before each change of signals within the cycle, SCOOT adds the delay from all movements that will end or begin at that change of signals. This delay is compared against delay calculated with the change of signals occuring either four seconds earlier or four seconds later. Of the three, the scenario that provides the best balance of delay for the movements being optimized will be implemented. Evaluation of this balance is controlled by user-defined preferences. To track trends, SCOOT will carry over one second of the four-second adjustment to subsequent changes of the signals, although the offset optimizer may make further adjustments. At the beginning of the interval serving a user-designated combination of traffic movements, the offset optimizer projects the delay for all the movements of that intersection, based on the profiles measured in the previous cycle. This interval is called the named, or nominated, interval. SCOOT may adjust all the signal change times for that cycle four seconds sooner, four seconds later, or not at all. After this offset adjustment, the split optimizer may further adjust these signal changes based on profiles actually approaching the stop line at that time. The cycle optimizer looks at the saturation levels of all intersection movements once each cycle-control period (2.5 or 5 minutes). The intersection with the highest saturation is considered the critical intersection. If the saturation of the heaviest movements at the intersection exceeds 90 percent, the cycle optimizer will add 4, 8, or 16 seconds to the cycle depending on the length of the cycle (4 seconds for the shortest cycles, and 16 seconds for the longest cycles). If the saturation is much less than 90 percent, the cycle optimizer will subtract the increment from the cycle. Because cycle adjustments are kept very small, they can always be accommodated immediately within a few following signal intervals, and lengthy transition periods are therefore not needed. The cycle adjustment will be added to the named interval; therefore, the named interval should be the longest and most easily varied interval in the cycle (usually main-street through movements).
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Table 3.1. Features of Available Closed-Loop Systems.
Automatic Signal/Eagle Marc 360 ECONOLITE KMC - 10,000 24 240 1 5760 32 (TOD, DOW, TOY) TRSP, Manual, Flash 4 10 896** 32 (TOD, DOW, TOY) Manual, TRSP, Flash 16 14** 60 64 TCT MDM 100 32 256 2 8192 64 (TOD, DOW, TOY) Manual, TRSP, Flash SONEX S 80

On-Street Master Controller Unit

Controller Units per Master

On-Street Masters per PC

System Detectors per Master

Controller units per PC System Detectors per Master

Control Modes

960 32 per section/ 128 per master (TOD, DOW, TOY) TRSP, Manual, Flash

Field Communications • Master to Central PC • Master to Load Units • Dial-up • Twisted-pair, Fiber-optic, Radio, Coaxial & Telephone • IBM Comp. PC-XT • 512 KB RAM • 360 KB Disk Drive • 10 MB HC • RS-232C output ports • MS DOS 3.0 • CGA, EGA or VGA color monitor • Hayes Comp. 1200/2400 modem • 80-column printer • Dial-up • Telemetry, Twisted-pair, Fiber-optic, Telephone • IBM Comp. PCAT • 512 KB RAM • 360 KB Disk Drive • 20 MB HC • Communication & output ports • MS DOS • EGA or VGA color monitor • Hayes Smart Modem 300/1200 • 80-column printer

Central Computer

• Dial-up, RS-232, Leased Cable • Telemetry, Twisted-pair, Fiber-optic, Leased Telephone • IBM Comp. PC-XT/AT • 640 KB RAM • 360 KB Disk Drive • 20 MB HC • Communication & output ports • MS DOS • EGA or VGA color monitor • Hayes UDS modem • 80-column printer

• Dial-up • Twisted-pair, Fiber-optic, Coaxial • IBM Comp. PCXT or AT • 256 KB RAM • 360 KB Disk Drive • 10 or 20 MB HC • RS-232 port • MS DOS • EGA, VGA color monitor • Sonex modem • 80-column printer

Reports (local alarms, MOEs, Communication and/or Detector failures, conflict monitor report, controller status, detector count logging, power failure, etc.) Yes Yes No Yes

Yes

Yes

Time Space Diagram

No

Coordinated green up to 32 intersections Yes Yes 255 200 No No Yes Yes Yes Yes 4 Days Unlimited No

Yes Yes (EGA & VGA) ? 180 No

Monitoring • Local Intersections • System Map Max. No. of Reporting Events Stored Event Capacity for Time-based Traffic Patterns On-Line Timing Generation

Traffic Signal Control Systems

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Advanced Transportation Management Technologies

3-18

Table 3.1. Features of Available Closed-Loop Systems (continued).
TRACONEX TMM 500 TRANSYT 3800 EL 30 99 1 2970 48 (TOD, DOW, TOY) Free Manual, Pre-empt, TRSP, Flash (TOD, DOW, TOY) Manual, TRSP, Flash 512 256 1 1 Unlimited 32 (TOD, DOW, TOY) Manual, TRSP, Flash • Dial-up • Twisted-pair, Fiber-optic • Any RS232 device • IBM PC XT/AT • 512 KB RAM • 360 KB Disk Drive • 20 MB HC • CGA or EGA color monitor • Printer 16 Unlimited 32 48 31 31 1 961 16 (TOD, DOW, TOY) Manual, TRSP, Flash • Dial-up, Leased Lines • Dial-up • Dial-up • Twisted-pair, Fiber-optic, Coaxial • Twisted-pair, Radio, Fiber-optic • Twisted-pair • IBM PC XT/AT • 512 KB RAM • 360 KB Disk Drive • 20 MB HC • Output parts • MS DOS • EGA or VGA color monitor • Printer • IBM System 2 PC • IBM PC XT or AT • 640 KB RAM • 1.2 KB Disk Drive • 10 MB HC • RS 232 port • MS DOS • EGA or VGA color monitor • Hayes Modem • 80-Column Printer BI TRAN MODEL 170 WAPITI MODEL 170

On-Street Master Controller Unit

Controller Units per Master

On-Street Masters per PC

System Detectors per Master

Controller Units per PC System Detectors per Master

Control Modes

Field Communications • Master to Central PC • Master to Load Units

Central Computer

Reports (Local alarms, MOEs, Communication and/or Detector failures, conflict monitor report, controller status, detector count logging, power failure, etc.) Yes Yes No Yes

Yes

Yes

Time Space Diagram

No

No

Yes Yes NI NI No

Yes Yes NI 200 No; Comp. W/AAP

Yes Yes NI NI No

Yes Yes 200 64 No

Monitoring • Local Intersections • System Map Max. No. of Reporting Events Stored Event Capacity for Time-base Traffic Patterns On-Line Timing Generation

Traffic Signal Control Systems

Setting up a SCOOT system first involves calibrating a range of parameters for each traffic movement in the network to ensure that the SCOOT model is working properly. These parameter adjustments require about the same level of effort during initial installation as conventional signal-timing calculations. Once the movements are being properly modeled, the ranges within which the optimizers may work are defined, such as minimum and maximum cycle length, minimum movement timing, optimization preferences, etc. SCOOT provides no optimization of phase sequence, although the systems that implement SCOOT allow complete flexibility in changing phase sequences by plan. SCOOT can then be used within these plans to provide adaptive control. SCOOT detectors should be placed at least eight seconds of travel time upstream from the stop line, where possible, to allow the link profile units to be measured before the split optimizer performs its duty. Typically, these detectors are placed on the outbound lanes of upstream intersections, and tied to the upstream intersection cabinet. The assignment of a SCOOT detector for the downstream intersection is made within SCOOT. SCOOT is a centralized algorithm based on once-per-second mandatory communication with the localintersection controller. None of the optimization steps is performed in the local controller. Consequently, the SCOOT optimizer is wholly dependent on the communications network and central computer for operation. b. SCATS Sydney Coordinated Area Traffic System was developed by the Roads and Traffic Authority of New South Wales, Australia, and utilizes a distributed, three-level, hierarchical system using microprocessors and minicomputers. The system architecture consists of a central monitoring computer at the central control center, remote regional computers, and local traffic-signal controllers. For large systems with more than 400 signals, a VAX computer is recommended to provide system management support, data collection and analysis, data backup, fault analysis, and system inventory facilities. The central monitoring computer allows access to the regional computers for traffic data collection, data input, and monitoring. It performs the following functions without influencing traffic operation: • • • • Outputs traffic and equipment status for fault rectification. Stores specific traffic data for short-term or permanent record. Maintains the core image for each regional computer, and reloads the regional computer if required. Allows central control to monitor system, subsystem, or intersection, alter control parameters, manually override dynamic functions, or plot time-distance diagrams.

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Advanced Transportation Management Technologies

Each regional computer autonomously controls the intersections in its area. These computers are the heart of the SCATS system. They are usually installed at the center of the groups of traffic signals to be controlled in order to reduce the cost of the communications. They implement the signals by analysis of the detector information preprocessed by the local microprocessors. The local controller, at the traffic-signal site, processes data collected from traffic detectors, makes tactical decisions on signal operation, and assesses detector performance. It also incorporates a software method of cableless link coordination (with 11 plans) through synchronous clocks. This provides a fall-back mode of operation that enhances total system security without the need for dual computer systems. c. RT-TRACS Real-Time Traffic-Adaptive-Control System (RT-TRACS) is a project to develop and field evaluate a realtime, traffic-adaptive signal control system similar to the SCATS and SCOOT systems, and suitable for use in the ITS environment. FHWA has awarded five independent contracts for development of a realtime traffic-adaptive algorithm for use in an Advanced Traffic Control (ATC) unit. One of these algorithms is the Optimized Policies for Adaptive Control (OPAC), developed as an on-line signal timing optimization software and hardware control system. An Advanced Transportation Controller (ATC) processes data from upstream vehicle detectors and develops real-time timing plans including cycle lengths, offsets, and splits to be implemented by the local controller. The OPAC is being tested on the New Jersey State Route 18 to examine its application in a closed-loop system environment. RT-TRACS provide four levels of control: system, district, section and intersection. Each level should be able to seek optimization within the constraints imposed by higher levels. The system level is the highest level and consists of all intersections connected in the network. This level will provide the means to execute global functions. The district level will be the next level of control. The system will be divisible into geographic districts of several square miles in size. Every intersection within the system will be required to be in only one district. RT-TRACS will support 16 districts, each with the ability to support functions that address a large area of a city. A section will be a logical cluster of intersections. Intersections may be assigned to one or more sections. There will be a minimum of 256 sections, but no limit to the number of sections to which an intersection can be assigned. The intersection is the lowest level in the hierarchy. RT-TRACS will be designed to control a maximum of 5,000 intersections, in order to accommodate universal control in large urban areas. RT-TRACS will provide for short-term and long-term strategies. The short-term strategies respond to current traffic as measured by detectors, while the long-term strategies manage congestion control for fall-back to off-line optimization. In both cases, a combination of strategic and tactical control decisions will be used to identify the system control level to be used in each section and to set signal timings accordingly. RT-TRACS will consist of a variety of signal-control strategies, one of which will be dynamically selected for operation at a particular set of intersections at any given time. This selection of signal-control strategies will be changed according to the time of day, the prevailing traffic conditions, and other appropriate circumstances (e.g., holiday, special event, weather). An option for RT-TRACS will be that it could be

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Traffic Signal Control Systems

operated with only a subset of the signal-control strategies available for use in those street networks and local jurisdictions that have no perceived need for the more sophisticated range of control strategies. Owen et al (1997) describe RT-TRACS as consisting of five basic components: the first predicts traffic conditions given weather conditions, time of day, existing flows, incidents, and other traffic factors; the second component defines the sections in the network; the third component selects the appropriate control strategy for the specific section given the traffic conditions that have been predicted; the fourth component implements this strategy; and performance is evaluated by the final component. RT-TRACS will implement all three control strategies by generation: • • First-generation control strategies use a catalog of fixed timing plans, generated off-line, to control a network of intersections. Second-generation control strategies use timing plans that are generated in real-time based on predictions from detector data. These control strategies are not limited by a fixed number of timing plans. The third-generation of control strategies is the most progressive system that operates in real-time, and adjusts signal timings based on detected data in real-time (i.e., very responsive to changes in traffic conditions).

•

Owen et al (1997) discuss the five prototype third-generation control strategies being developed under contracts from the FHWA and present early results of the conceptual evaluation of these prototypes in terms of potential strengths, weaknesses, and applicability. The five prototypes follow. • University of Minnesota - Highly distributed architecture with two levels of control: Local Area Controllers (LACs) and upper level-overseeing LACs. Each LAC is managed by a controller using a program called CARS. CARS selects phase lengths for each intersection of the LAC in real-time based on mesoscopic simulation of the subnet that will influence the intersection. It adjusts the current green phase one intersection at a time, treating the intersections in user-specified order of importance. PB Farradyne Systems and University of Massachusetts - Lowel Optimization Policies for Adaptive Control (OPAC) design - Each subnetwork is considered independent and can transition between the uncongested and congested modes based on MOEs and thresholds. For uncongested networks, OPAC uses a level of control at the local intersection that determines the phase on-line and a network level for synchronization. The congestion control process in OPAC generally attempts to maximize throughput by selecting the phase that will pass the most vehicles through the intersection. University of Arizona - Composed of the main controller, called RHODES; APRES-NET, which ; simulates platoons; REALBAND, a section optimizer; PREDICT, which simulates individual vehicles; and COP a local optimizer. The prototype is a hierarchical control system and has two levels of , optimization: the global optimization and the local optimization. Wright State University Intelligent Systems Application Center (ISAC) - This prototype selects the best fixed-time plan for each independent network from a set of precomputed fixed-time plans. It then
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•

•

•

Advanced Transportation Management Technologies

modifies the current timing plan temporarily in real-time, based on local traffic detection. For local optimization, each intersection can modify the recommended fixed-time plan. For global optimization, the fixed-timing plans are generated for each network and for selected sets of conditions using an off-line, fixed-time signal network routine. • Maryland/Pittsburgh - This prototype uses a highly distributed control, with most of the intelligence residing at the local level. The network level model operates in a supervisory capacity.

Table 3.2 presents early results of the conceptual evaluation of these prototype systems. They were interfaced with CORSIM for evaluation purposes.

Traffic Controllers
Traffic controller technology has been divided into two camps represented by two different specification strategies. Both were developed in the mid-1970s, and both are now being superseded. But these two approaches represent nearly all the installed infrastructure of current signal systems. a. NEMA TS-1. The National Electrical Manufacturers Association (NEMA) developed performance specification TS-1 for traffic-actuated controllers. The specification is functional; only the operation of the controller (plus its physical and environmental requirements) are included. TS-1 describes what the controller must do, and describes the interface between the controller and cabinet. The NEMA specification does not set any requirements for user interfaces or system interfaces. Each manufacturer has developed proprietary interfaces in accordance with the need of its customers. The NEMA specification first specified a consistent approach to phasing. In NEMA usage, a phase is the sequence of green, yellow, and red intervals for an individual traffic movement. In most intersections, two compatible phases will be allowed to display green at any given time. NEMA did not specify hardware. The original TS-1 controllers used discrete solid-state electronics. Since that time, controllers have migrated to advanced microprocessors, and now provide a host of features not required by the original specification. Because the internal architecture of the controller is not specified, software for the controllers must be developed by the manufacturer and that software will work only with that manufacturer’s product. Generally, software is built into the controller and is not accessible by the user. NEMA did specify the cabinet interface. The TS-1 specification uses three round military-specification connectors to provide discrete signals to the controller field-wiring back panel. Features are manufacturer-specific, and NEMA controllers are therefore not interchangeable within systems without a separate translator device. b. Model 170. Around the same time as the NEMA TS-1 development, the California Department of Transportation, the City of Los Angeles, the New York State Department of Transportation, and the Federal Highway Administration joined forces to develop an open-architecture general-purpose microcomputer for traffic control. The resulting Model 170 controller specification requires a specific hardware architecture and processor. Improvements in the specification have been limited to backward-compatible enhancements.
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Traffic Signal Control Systems

Table 3.2 Conceptual Evaluation of the Prototypes.
Prototype Arizona Strengths Automated setup Amendable to lab testing Consistent with responsive objectives Simplicity Amendable to lab testing Weaknesses Complexity (four components) Potential excessive computational time Applicability Arterials and widely spaced grids Undersaturated conditions only

ISAC

Unspecified number of fixed-time plans required Excessive detector requirements Does not update the timing plans Inconsistent overall responsive objectives Theory not well documented Setup complicated Programming structure

Any configuration that accommodates a fixed-time plan Undersaturated conditions Act in transition between fixed-time plans and fully responsive control

Farradyne OPAC

Extension of tested isolated intersection techniques

Arterials with widely spaced intersections Undersaturated conditions with possible extension to saturated Saturated and undersaturated conditions Diamond interchange, grids and closely spaced intersections Adaptable to different intersection configurations

Maryland/ Pittsburgh

Global optimization General applicability Setup and detectorization Based on proven theory (hydrodynamic wave theory) Programming structure Not easily tested Overall design structure Distributed approach Implementation Not amendable to lab testing Questionable real-time applicability Proprietary automated setup routine

Minnesota

The Model 170 uses software developed by a third party. The user has access to the software, which work equally well with all manufacturers’ products. The specification also requires a standard serial interface for connecting the controller to systems. The interface with the cabinet is defined by a large, square connector carrying discrete signals to the controller back panel. Because the specification defines only hardware, the functionality of the controller is entirely contained with the software. Model 170 controllers have been programmed to act as traffic controllers, variable-message sign controllers, ramp meters, field masters, and other traffic-system devices. Model 170 controllers are brand-independent, and therefore provide interchangeability in all installations without the use of translator devices. In the last few years, two new controller technologies have emerged to provide the advanced functionality needed by ITS technologies.

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Advanced Transportation Management Technologies

c. NEMA TS-2. NEMA completed a specification for two variations of advanced controller in 1992. The TS-2 specification is similar to the TS-1 specification in that functionality is defined without imposing hardware standards. As with TS-1, the functionality of the controller is defined by built-in software that is not accessible by the user. The TS-2 specification defines two grades of controllers. Type 1 is a pure TS-2 controller intended for new systems and installations. The Type 2 controller provides TS-1 cabinet interfaces to ensure backward compatibility with existing cabinets. TS-2 specified a cabinet interface based on data transmission rather than discrete signals. The cabinet bus interface uses the RS-485 standard with the Synchronous Data Link Control protocol (SDLC). The cabinet bus interface is intended to connect the controller, the malfunction management unit (conflict monitor in TS-1 controllers), the detection system, and the terminals and facilities unit (the back panel). The use of the bus interface greatly reduces the complexity of signal controller cabinets by relieving the need for the hundreds of conductors required to move discrete signals around the cabinet. The TS-2 controller defines a serial connection for communications with the system, but does not specify a communications protocol for that connection. Because the software is built into the controller, the lack of a defined system communication protocol has been a gaping hole in the specification. NEMA has sought to fill this gap by leadership and active participation in the development of the National Transportation Communications for ITS Protocol. d. Model 2070. The California Department of Transportation led a loose consortium of interested users in the development of an advanced open-architecture transportation controller. The original concept was called the Advanced Transportation Controller. Eventually, the concept solidified into the now-finalized Model 2070 controller standard. The Model 2070 employs the open-architecture VMEbus industrial control computer. VME stands for Versa-Module Europe, and derives from the old Motorola Versabus. The use of an industry-standard computer architecture allows the installation of aftermarket processors and other devices in the controller. The VMEbus provides bus arbitration, which makes it possible for multiple processors to access the same resources within the controller. The Model 2070 specification includes the processor, the system communications modules, and the field I/O module. The cabinet interface is provided by a Model 170-style square plug, making the 2070 cabinet-compatible with older Model 170s. The 2070 also includes an RS-485 port, which allows interface with NEMA TS-2 cabinets (assuming the software supports the port, which is not required by the specification). System communications are handled through asynchronous serial ports. The Model 2070 controller is the first to provide a conventional real-time operating system and control programming in a high-level language. As with the Model 170, software is provided by third-party developers, and completely defines the functionality of the controller.

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Traffic Signal Control Systems

Arterial Highway Advisory Radio
The primary use of Highway Advisory Radio (HAR) is to provide real-time traffic information at key locations along major arterials. The information content of a HAR message can be much greater than that displayed on a dynamic message sign, and can use either live messages or prerecorded messages. A thorough discussion of HAR can be found in Section 2.9.

Arterial Video Surveillance
Video surveillance systems (CCTV) are systems used to verify and monitor traffic and incidents. They are also used to determine the type of assistance required. Each system consists of various elements including camera units, a controller cabinet housing the control equipment, and the communication system that connects the camera to a control center. The primary objective of an arterial CCTV system is to provide surveillance of arterial sections, intersections, visual confirmation of incidents, and information on the types of assistance that will be required. A thorough discussion of video surveillance can be found in Section 2.7. However, there are some differences between freeway and arterial video surveillance. Some applications that are unique to arterial video surveillance follow.

•

A camera viewing a single intersection in an urban area is commonly mounted on a building and might use a fixed lens. That particular camera might not need to have the capability of a remote controlled pan/tilt/zoom. Because many urban arterial are well lit, street lighting is usually available in urban intersections. This makes a color camera well suited, since these cameras require high lighting conditions. Using cameras to observe and/or verify the unused vehicle capacity on surface streets before diverting freeway traffic caused by incidents, reconstruction, special events, etc. Evaluating signal timing for arterials and verifying coordination of signals.

• • •

Arterial Video Image Processing
These detection systems use microprocessor hardware and software to extract real-time traffic flow data through analysis of video images collected by a series of cameras mounted over roadways. These detector systems are discussed in Section 2.6. However, some distinct features and applications of these systems for surface arterials follow. • Care must be taken in the mounting of the cameras, as there is a requirement that all approaches to an intersection may be observed so as to place detectors. If this is not possible with one camera, more than one unit should be placed for a larger coverage. Used for intersection detection (just like inductive loops), intersection traffic counting, intersection surveillance, queue length detection.

•

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Advanced Transportation Management Technologies

•

Intersection applications where only presence detection is required and where the intersection traffic controller handles data storage and traffic-management-center communications functions.

Arterial Detection
Detector technologies were discussed in Section 2.6, including technical sophistication, cost, and operational advantages and disadvantages. Accuracy of detection systems, as well as reliability, become important issues when dealing with arterial systems and intersection control. There is less room for error when considering intersection detection and control as opposed to the use of these detectors for freeway management and control, including traffic counting. In addition, the output type (e.g., relay, solid state) is important in arterial detection as the relay type fails on contact closure, thereby providing a constant call as opposed to no call (i.e., providing maximum green for that phase as opposed to no green at all). In addition, the location of detectors in traffic-signal control is different than when used in freeway systems. Care must be taken in selecting link, lateral, and longitudinal detector placement.

3.1.3 CASE STUDIES
City of Richardson, Texas
John Black (www.startel.net/atms/RFP .HTM) presents specifications that were used to solicit proposals for an Advanced Traffic Signal Management System in the City of Richardson, Texas. The City conducted extensive tests on the equipment submitted between the period of January to December, 1995. It negotiated a contract with Naztec, Inc. of Sugarland, Texas and began a 6 month operational test of all system hardware and software in March, 1996. Naztec passed the operational test on September 1 and all controllers, conflict monitors, modems, and system support is on order and should be fully functional by January, 1997. The specifications included such items as: • • • • • • • • • Minimum System and Controller Requirements Desirable System and Controller Features Hardware and Software Requirements Future Software Enhancements Project Requirements Controller Specification Conflict Monitor Specification CATV Modem Specification Excerpt from NTCIP Protocol

3-26

Traffic Signal Control Systems

• • • • •

Contract Requirements Specification for Traffic Signal Cabinets Specification for a NEMA Conflict Monitor Tester Specification for Loop Detector Amplifiers Annual Loop Detector Installation Contract Specs

In addition, John Black (www.startel.net/atms/COMCOST.HTM) provides a Present Value Analysis for Selecting a Communications Medium for a Traffic Signal Control System in Richardson, Texas. This analysis can be found in Appendix J.

OPAC
The Optimized Policies for Adaptive Control (OPAC), one of five candidate signal control system developed to work within RT-TRACS, has been installed and undergoing testing in Middlesex County, New Jersey. Early findings indicate that the system reduced travel time by 27 per cent on the arterial being tested and the number of stops by 55 per cent in over-saturated traffic conditions during the long afternoon peak period. Mean time for the whole route under OPAC was 783 seconds compared to 1053 seconds using regular coordinated, semi-actuated signals. Average stops per vehicle were 7 compared with 15.6. the most significant improvements were achieved in a short section of highway with traffic signals close together, while average stops dropped from 13.2 to 4.5 , and average time in this section from 730 seconds to 457 seconds (Peter Samuel, September, 1996)

SCOOT
The city of Anaheim, California is installing a SCOOT-based Urban Traffic Control System (UTCS), to form part of the city’s Advanced Traffic Control System Field Operational Test. This test will determine the benefits of adaptive traffic control compared with conventional central signal system operations, and will evaluate the use of video image processing tools to support the real-time data needs for advanced traffic control. The city’s current UTCS system will be integrated with the adaptive SCOOT system. SCOOT will be implemented at 31 intersections in the vicinity of Disneyland, the Convention Center, Anaheim Stadium, and the Arrowhead Pond Arena (Traffic Technology International, June/July 1996). San Diego’s new signal-control system, the Split, Cycle, and Offset Optimization Technique (SCOOT) responds automatically to variations in traffic flow, based on real-time information fed from detectors embedded in city roadways. A central minicomputer communicates once per second with SCOOT intersections, recalculating signal timing based on the up-to-minute information it receives. SCOOT is currently concentrated on two city roadways. One is a six-lane major arterial serving commercial and light-industry areas as well as the Miramar Naval Air Station. The other provides access to San Diego’s stadium, home to approximately 250 events each year. After San Diego evaluates these initial installations, the city will expand the SCOOT system. So far, results are encouraging: other areas with SCOOT systems report significant reductions in travel times, with decreases of up to 11 percent during peak periods.
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Advanced Transportation Management Technologies

3.1.4 EVOLVING TECHNOLOGIES
Spread-Spectrum Radio Traffic Interconnect
A Field Operational test that will evaluate the use of spread spectrum radio as a traffic signal communications device within the Los Angeles ATSAC signal system. The radios will be tested in a network of signals to determine their ability to reliably reroute communications links; work in various geographies; provide for large-scale, once-per-second communications; and determine the cost-effectiveness of using this technology.

Real-Time Traffic-Adaptive Signal Control
As discussed above, a prototype real-time, traffic adaptive control system (RT-TRACS) is under development and will be completed in 1997.

Advanced Traffic Controller (ATC)
This is a modern, open architecture, easy-to-integrate traffic control and communication system (under development) that will be deployed for most traffic control applications including: adaptive intersection control, integrated corridor management (loop detection, ramp metering, CMS control, etc.), communications, electronic toll and traffic management, video detection and surveillance, AVI, and other ITS applications. The SmartATC is being designed to Caltrans specifications and is being developed to overcome the limitations of the Model 170.

Common Information Database
Real-time management of traffic and transit operations in urban areas typically involves multiple jurisdictions and agencies, each responsible for traffic management within a defined area. Basic data needs between multiple traffic management centers may include: a center’s need to be able to monitor the operation of selected other centers; a center’s needs to be able to monitor the operation of selected field devices (transit vehicle, traffic signals, CMSs, etc.) managed by another center; a center’s need to be able to issue commands to selected field devices managed by another center.

Integration of Control/Monitoring Systems
Integration of multi-agency control and monitoring systems allows different control centers and agencies to make system decisions and disseminate information to the motorist based on conditions in other systems. SOURCES: • • An Evaluation of Real-Time Traffic Adaptive Control Prototypes, 1997, Submitted to TRB by Larry E. Owen, Charlie M. Stallard and Deborah M. Glitz. Peak Traffic Problems Reduced, September 1996, by Peter Samuel, ITS international.

Return to Table of Contents
3-28

Incident Management

CHAPTER 4

Incident Management

4-1

Advanced Transportation Management Technologies

4-2

Incident Management

4.1 FREEWAY INCIDENT-MANAGEMENT SYSTEMS
Nonrecurring problems (incidents) consisting of traffic accidents, vehicle breakdowns, spilled loads, adverse weather conditions, rubbernecking, etc., are caused by random events and thus, are unpredictable. Freeway incident management is the coordinated and preplanned approach used to restore freeway traffic to normal operation as quickly as possible after an incident by using human and mechanical resources. Incident management provides an organized and functioning system for quickly identifying and clearing crashes, disabled vehicles, debris, and other nonrecurring flow impediments from area freeways. Roadways are cleared and flow restored as rapidly as possible, minimizing frustration and delay to travelers while at the same time meeting the requirements and responsibilities of the agencies involved. The various jurisdictions and agencies responsible for operations and enforcement are working together to develop a policy and operations agreement that defines specific responsibilities of incident management. Such an agreement includes detection, verification, response, clearance, scene management, and traffic management and operation. The multi-jurisdictional operating agreement ensures cooperation, coordination, and communication among all agencies including law enforcement, fire, ambulance, highway traffic control, and maintenance, as well as environmental and other public agencies. Interagency cooperation also reduces duplication of effort in coordinating incident management activities. In addition, private sector businesses that do towing and recovery may be involved in incident clearance. SOURCES: • • • • Traffic Control Systems Handbook, February 1996, Publication No. FHWA-SA-95-032, Prepared for FHWA by Dunn Engineering Associates. Freeway Management Handbook, FHWA Publication, available Spring 1997. Inform Evaluation, Vol. 1: Technical Report, 1991, Publication No. FHWA-RD-91-075. Inform Evaluation, Vol. 2: Executive Report, 1991, Publication No. FHWA-RD-91-076. Framework for Developing Incident Management Systems, Executive Summary, August 1991, Publication No. WA-RD-224.1. Freeway Incident Management Handbook, July 1991, Publication No. FHWA-SA-91-056. A Comprehensive System for Incident Detection on freeways and Arterials, March 1995, ITS America. Automating incident Management with GIS Technology, April 1994, Paper presented at 1994 ITS America Annual Meeting. Massachusetts Incident Management Conferecnce Proceedings, June 1991, Publication No. DOT-T-92-05.
4-3

• • • • •

Advanced Transportation Management Technologies

•

Incident Management, Challenges, Strategies, and Solutions for Advancing Safety and Roadway Efficiency, Executive Summary, January 1997, American trucking Association

4.1.1 TECHNIQUES/STRATEGIES
Detection
Incident detection determines if an incident of some sort has occurred. This subsystem is responsible for identifying possible events and reporting them to system users for further disposition. The incidentmanagement subsystem will accept processed detector data, evaluate the data based on an appropriate algorithm, generate communications log entries for identified events, and enter them into the system. The information has to reach the location where response can be initiated. The most common techniques for detecting incidents are electronic surveillance, CCTV, aerial surveillance, motorist call systems (which include emergency call boxes and emergency telephones), cooperative motorist-aid systems, cellular telephone, CBs, and police and service patrol vehicles. Incident detection by electronic detectors (inductive loops) involves real-time computer monitoring of traffic data obtained from these detectors. Section 2.6 provides a thorough discussion of available detection technologies.

Verification
Since the nature for the incident cannot be determined by electronic detectors, some form of confirmation is required to determine the necessary response. This can be performed by such systems as CCTV, aerial surveillance (helicopters and small airplanes), call boxes, patrol vehicles, CB radio, cellular telephone, etc. Section 2.7 provides a thorough discussion on video technologies.

Response and Clearance
Once an incident is detected and verified, the key to minimizing congestion or other adverse impacts is the timely, safe removal of the incident and restoration of the freeway to its full traffic capacity. The longer the duration of response and clearance, the more severe the resulting congestion and delay. The single most cost-effective incident-management strategy is to reduce the response and clearance time. A response plan must be implemented immediately after detection and verification as part of the incident-management process. This plan should be developed beforehand and include, as a minimum, the following elements. a. Participating Agencies and Partners All participating agencies and partners involved in incident management must be identified with names and phone numbers. For each agency, an incident-management coordinator should be selected for notificatin during an incident. b. Interagency Communications Communication links among the participating agencies and partners need to be established. These links may take one or a combination of several forms, including: phone (e.g., leased commercial,
4-4

Incident Management

cellular); dedicated cable; radio; commercial pager; Internet. Care must be taken to ensure that the chosen communication link(s) is reliable and, if more than one is used, that they have a common functionality. For example, it is very important that an operator at a transportation-management center be able to communicate with a police officer in the field regarding the nature of the incident and the extent of the assistance (e.g., medical, rescue, hazardous material) necessary. The frequency, channel, or line for communications must be shared, as must the codes used to communicate types of incidents and assistance needed. c. Traffic-Management Procedures Establishing traffic-management and operational procedures is vital to the prompt response to and clearing of an incident. The collection of information at the transportation-management center (traffic operations center) and the coordination of activities are key elements in managing the response of incidents. Facilities and management strategies used for responding to and clearing the incident include the following. 1. Traffic Operations Center. This is a facility where, for the most part, all information is received, managed, and disseminated to various locations. This includes the communications center, the traffic-control center, the traffic-management and information center, the State police dispatch center, the maintenance dispatch center, etc. Real-time traffic information (e.g., incident location and severity) is received at this location. All communications to and from participating agencies and partners occur at this center. 2. Resources and Responsibilities. The resources to be provided by and responsibilities of each participating agency, once identified, are assigned. It is important to identify in the management plan the resources required to respond to and clear the incident. It is equally important, at the scene of the incident, for every entity involved with the incident response to know its purpose and responsibilities. 3. Securing the Scene. Securing the incident scene is particularly important in managing incidents. The field command (usually a trained service patrol) manages the scene and provides leadership in the activities that take place. He or she, with the assistance of the personnel at the scene as well as at the traffic operations center, cordons off an area, directs traffic at the scene, sets up traffic control for possible route diversion, provides emergency assistance, coordinates communications with the various participating parties, and assures that the efforts at the incident scene, as well as the traffic impacted, are operating in an orderly fashion. 4. Accident-Investigation Sites. These are special designated areas, off the freeway, where drivers exchange necessary information and police officers perform an investigation of the incident and complete all necessary reports. These areas are generally located out of the view of the freeway, so as to reduce rubbernecking and braking by passing vehicles. The benefits of an accident investigation site include reduced motorist delays, reduced vehicleoperating costs, reduced secondary accidents, reduced pedestrian exposure, and more efficient use of the public agency’s personnel.

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Advanced Transportation Management Technologies

5. Emergency Response. Emergency response techniques and strategies hasten emergency vehicles to an incident site when traffic has queued behind the incident, and help facilitate an order to the many response vehicles parked in travel lanes at the incident site. Freeway design barrier gates and emergency ramps provide emergency freeway access. These facilities are closed to regular traffic, but can be utilized by authorized vehicles through manual or electronic gate systems. 6. On-Site Traffic Control. Traffic control is required to facilitate the orderly movement of traffic past the incident site, or to coordinate route-diversion techniques due to lane closures. Channelization of traffic can be accomplished with technologies similar to those discussed in Section 2.5, Transportation Management During Reconstruction. 7. Traffic-Management and Control Strategies. These are activities to assist in the response and clearing of the incident during the incident-management process. Information on several parameters must be obtained before a response plan, consisting of the magnitude of the traffic-management and control strategies, can be selected and implemented. This information may include: • • • • • • Period of incident. Severity of incident. Anticipated duration of incident. Requirement of medical assistance. Hazardous material. Blocked lanes.

Several action plans may be selected, depending on the nature of this information. Table 4.1 shows two examples of Response Action Plans for two types of incidents: one simple, not severe, and the other severe, high priority. Depending on the incident type and severity, a compromise of these two plans may be selected and implemented.

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Table 4.1 Response Action Plans for Different Types of Incidents

Description of Incident
The incident occurred during the offpeak period, is not severe, clearing is not anticipated to have a long duration, has no injuries, does not require medical assistance, and can be cleared to the side of the road with no lanes being blocked. The incident occurred during the peak period, is severe, clearing is anticipated to have a long duration, has injuries, requires medical assistance, multiple lanes are blocked, high priority.

Action Plan
The actions to be taken might include: • Device action (e.g., commands to DMSs). • Message for device (e.g., HAR). • Text script (e.g., building of database, media). • Communications with involved parties (e.g., police).

The actions to be taken might include (*): • Device action (e.g., commands to CMSs). • Message for device (e.g., HAR, radio). • Text script (e.g., building of database, media). • Transmission of video (e.g., local TV, media). • Communications w/involved parties (e.g., police, EMS). • Route diversion for motorists. • Selection of appropriate signal-timing plans. • Selection of appropriate ramp-metering rates. • Communication w/other TMCs and possible control.

(*) In this type of Response Action Plan, a diversion route may be needed. Through the field processing units and interface with the Transportation Management Center (TMC), the status of each intersection or groups of intersections on arterials of that route, as well as timing plans needed, will be communicated to the respective TMC (e.g., signal Traffic Control Center (TCC), jurisdictional TMC, or TCC). Depending on the signal-control system controlling the intersections (e.g., closed loop), an interface to allow the TMC to poll the intersections, or masters, and to modify timing of intersections by sending a controller command request to the signal-control system is very important to manage the corridor. The TMC must be able to extract intersection status, detector data and status, and timing in effect from the signal-control system or TCC. The signal-control system or TCC must be able to extract freeway or link status and incident information from the TMC.

The dynamic nature of the incident can affect the response plan through changes indicated by monitoring of the response effort. If traffic conditions are getting worse as a result of the selected response plan, modifications to the plan may be in order. The following response actions portray a typical scenario of incident management.
A freeway TMC detects an incident that creates a major bottleneck downstream of the off- and on-ramps. With the use of the video surveillance cameras (used and controlled from the TMC workstation) and an incidentmanagement decision support system, the operator of the workstation can select an appropriate response plan and issue appropriate commands to DMSs and other traveler-information systems on the freeway to direct traffic to alternative routes. Commands are also sent from the freeway TMC workstation to workstations of surface streets (e.g., traffic-signal control center, local traffic control center), to adjust signal-timing patterns, local advisory radio messages, and DMSs on the parallel arterial roadways to which traffic typically diverts during such an incident. Computer workstations in the TMC or other TMCs and/or TCCs may be able to continuously 4-7

Advanced Transportation Management Technologies

and automatically exchange data, thereby allowing a workstation to monitor the operation of and issue commands to any device managed by any other workstation. Specification for the type of data to be exchanged, under what circumstances, and what commands will be sent from one workstation to the other(s) must be designed in advance. A particular workstation will have to determine what data or information it needs for a particular purpose at any given time. It will then request that information from the appropriate workstation(s). The signal-timing patterns implemented are designed in advance to meter diverting traffic and provide maximum capacity for the diversion route, to avoid gridlock. The signal-coordination pattern selection in response to traffic volumes building and dissipating during the incident may be made by either the freeway or the local arterial workstations. Either workstation may be able to manage and control traffic and devices on the surface streets. DMSs on the arterial roadway and local advisory radio messages can be used to direct traffic to the first clear on-ramp downstream of the incident, to minimize any unnecessary off-freeway travel by motorists who are not aware of the exact location and conditions of the incident. These DMSs and any other traveler information may be controlled by either the freeway or surface street workstation.

This type of a platform demonstrates not only the integration of technologies and the management and control of devices from a single point (the workstation), but also the integration of traffic-operation systems and the networking of workstations, which really demonstrates the network and integration of multiple traffic-management centers. Field devices could also operate in a network fashion. For example, a field device connected to a specific local workstation but which another workstation (freeway) needs to monitor or control for regional application can be treated as a system. The system can use the integration network for communication with such a device, rather than using a direct communication channel. In this manner, the workstation will not be communicating directly with the remote device but with the workstation that has direct connection to the device, which in turn will relay the information to the other workstation. Depending on the actions taken for a response plan, a diversion-route selection may result in various coordinated plans where the integration of ramp meters with signal control is realized. Following are several examples of coordination plans. Coordination Plan Example 1: No Coordination. The conditions as they exist will be used. The ramp-metering rates and signal-timing plans stored in the controllers for that time of day, at each site, will be used. There will be no coordination between the freeway ramp and arterial street system. Coordinated Plan Example 2: Minimum Coordination. Traffic-responsive ramp control will be applied at the location upstream of the incident. As levels (occupancy or volumes) on the mainline freeway change, the metering rates on the ramp are changed accordingly. This approach utilizes nearby detectors on the freeway and the entrance ramp, and a controller to determine an appropriate metering rate. Traffic-signal timing will be adjusted on the arterials. After occurrence of an incident, one-way arterial progression plans will be used to maximize the traffic operations.
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Coordinated Plan Example 3: Maximum Coordination. Integrated area-wide ramp control will be in effect. Queue override will also be implemented for each entrance ramp. The entrance ramp immediately upstream from the incident area will be closed after the incident occurrence. Maximum priority will be given to the ramp traffic both from the exit ramps and onto the entrance ramps, as shown below. • Off-Ramp Priority - The traffic-signal settings will be adjusted to provide the maximum time possible to the signal phases that serve the off-ramp traffic, and less green time to the other signal phases. The cycle lengths and offsets will remain the same. However, the split will be adjusted. On-Ramp Priority - This will provide maximum possible flow onto the freeway. The diverted traffic will return back onto the freeway through an interchange downstream from the incident. Ramp metering immediately downstream of the incident will be shut off, and the signal timing plan will favor the phases that facilitate traffic flowing on the on-ramp. All ramp controllers downstream of the incident will be assigned the maximum allowable metering rates using the area-wide control system.

•

The exit-ramp queue detector will be monitored to avoid spillback onto the freeway. This detector activates the signal at the interchange to allow vehicles on the ramp to dissipate faster. On the arterials, maximum one-way signal progression will be provided for the diverted priority traffic coming from the freeway. The cross streets will receive less green time. Traffic flows and patterns along the diversion path will be monitored regularly during incident management, and signaltiming plans will be updated as necessary. Queue detectors on the on-ramps in the diversion area will be activated to avoid any possible vehicle spillback from the on-ramp onto the surface streets. 8. Vehicle Removal and Towing. This involves the fast removal of disabled, abandoned, or damaged vehicles by tow trucks. Towing is most commonly provided by a rotation call out. Rotation towing should include both heavy-duty and light-duty rotation lists. Many larger urban areas are entering into contract towing. Contracts are usually awarded on a zone basis and cover response-time requirements, training, equipment, insurance, storage, and other items. The cooperation of the public is vital in removing vehicles involved in minor accidents. Fast vehicle-removal legislation policies have been enacted to reduce the impact of incidents and increase motorist safety. There are two types of vehicle-removal legislation, one addressing motorists involved in minor accidents and one addressing agencies involved with incident management. The first type, often included in State vehicle laws, requires motorists involved in noninjury accidents to move their vehicles off the roadway. Texas adopted a “Move-It” public education program to encourage drivers involved in minor accidents (e.g., no injuries, drivable vehicles) to move the vehicles from the travel lanes before exchanging information or calling the police. Other States have followed with similar programs. Georgia, for example, has a program called “Steer It—Clear It.” Several examples of removal legislation are provided below.
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Section 42-4-1602 of the Colorado Motor Vehicle Code is vehicle-removal legislation intended for motorists and States:
(1) The driver of any vehicle directly involved in an accident resulting only in damage to a vehicle which is driven or attended by any person shall immediately stop such vehicle at the scene of such accident or as close thereto as possible but shall immediately return to and in every event shall remain at the scene of such accident, except in the circumstances provided in subsection (2) of this section, until the driver has fulfilled the requirements of section 42-4-1603. Every such stop shall be made without obstructing traffic more than is necessary. Any person who violates any provision of this subsection (1) commits a class 2 misdemeanor traffic offense. (2) When an accident occurs on the traveled portion, median, or ramp of a divided highway and each vehicle involved can be safely driven, each driver shall move such driver’s vehicle as soon as practicable off the traveled portion, median, or ramp to a frontage road, the nearest suitable cross street, or other suitable location to fulfill the requirements of section 42-4-1603.

Section 42-4-1603 of the Colorado Motor Vehicle Code is vehicle-removal legislation intended for incident-management agencies and States:
Whenever any sheriff, undersheriff, deputy sheriff, police officer, marshal, Colorado state patrol officer, agent of the Colorado bureau of investigation or an agency employee finds a motor vehicle, vehicle, cargo, or debris, attended or unattended, standing upon any portion of a highway right-of-way in such a manner as to constitute an obstruction to traffic or proper highway maintenance, such officer or agency employee is authorized to cause the motor vehicle, vehicle, cargo, or debris to be moved to eliminate any such obstruction: and neither the officer, the agency employee, nor anyone acting under the direction of such officer or employee shall be liable for any damage to such removal. The removal process is intended to clear the obstruction, but such activity should create as little damage as possible to the vehicle, or cargo, or both. No agency employee shall cause any motor vehicle to be moved unless such employee has obtained approval from a local law enforcement agency of a municipality, county, or city and county, the Colorado bureau of investigation, or the Colorado state patrol.

A Texas Senate Bill, 312 Article 6673g, intended for incident-management agencies and States:
The state Department of Highways and Public Transportation may remove obstructions from the roadway without the consent of the owner or carrier of spilled cargo or other personal property on the right-of-way or any portion of the roadway of the state highway system in circumstances in which, as determined by the department, the cargo or property is blocking the roadway or may otherwise be endangering public safety. The department and its officers and employees are not liable for any damages or claims of damages to removed cargo or personal property that resulted from removal or disposal by the department unless the removal or disposal was carried out recklessly or in a grossly negligent manner.

Virginia Section 46.2-1212.1. Authority to provide for removal and disposition of vehicles and cargos of vehicles involved in accidents, for States:

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A. As a result of a motor vehicle accident or incident, the Department of Sate Police and/or local law enforce ment agency in conjunction with other public safety agencies may, without the consent of the owner or carrier, remove: 1. A vehicle, cargo or other personal property that has been (1) damaged or spilled within the right-ofway or any portion of a roadway in the state highway system, and (2) is blocking the roadway or may otherwise be endangering public safety; or 2. Cargo or personal property that the Department of Transportation, Department of Emergency Services, or the fire officer in-charge has reason to believe is a hazardous material, hazardous waste or regulated substance as defined by the Virginia Waste Management Act or a hazardous waste or regulated substance as defined by the Hazardous Materials Transportation Act, or State Water Control Act, if the Department of Transportation or applicable person complies with the applicable procedures and instructions defined either by the Department of Emergency Services or the fire officer in-charge. B. The Department of Transportation, Department of State Police, Department of Emergency Services, local law enforcement agency and other local public safety agencies and their officers, employees and agents, shall not be held responsible for any damages or claims that may result from exercising authority granted under this section, provided they are acting in good faith. C. The owner and carrier, if any, of the vehicle, cargo or personal property removed or disposed of under the authority of this section shall reimburse the Department of Transportation, Department of State Police, Department of Emergency Services, local law enforcement agency and local public safety agencies for all costs incurred in the removal and subsequent disposition of such property.

Driver Information
As part of the incident-management plan, the dissemination of accurate information to the motorist in a timely manner is crucial. The motorist needs to be informed as to the nature and the extent of any delays that he or she encounters. Warning the motorist well in advance of an incident will result in greater tolerance for any delay, will encourage the motorist to take alternate routes, and will reduce the number of secondary incidents, as motorists are more alert.

4.1.2 TECHNOLOGIES
Detection and Verification
a. Detection Algorithms Automatic vehicle detection consists of two major elements: a traffic-detection system that provides the data (such as volume, speed, occupancy); and an incident-detection algorithm that interprets the information and determines changes in certain traffic-flow variables, thus determining presence or absence of capacity-reducing incidents. Loop detectors and video detectors are used extensively for data acquisition. In general, incident-detection algorithms are grouped into three main categories:
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1. Pattern-Recognition Algorithms. Pattern-recognition algorithms use data concerning current traffic patterns, such as traffic occupancies, to sense congestion changes (e.g., the California comparative algorithm). This algorithm consists of three simple comparisons to some predetermined thresholds. An incident is detected when upstream occupancies are significantly higher than downstream relative to upstream occupancy thresholds, and the downstream occupancies have decreased significantly during the past two minutes. The algorithm takes the occupancy data and calculates the following traffic measures: • • • • Spatial difference in occupancies; Relative temporal difference in downstream occupancy; Relative spatial difference in occupancies; and Downstream occupancy.

2. Time-Series (Smoothing) Algorithms. Such algorithms use forecasting techniques to identify traffic changes. Significant differences between the observed and the forecasted values are the result of incidents (such as the Autoregressive Integrated Moving Average [ARIMA], by which a 95-percent confidence interval of the forecasts is constructed for comparison purposes and any observed value outside the confidence interval is considered an incident). 3. McMaster Algorithm (Point-Based Detection). The McMaster Algorithm separates the flowoccupancy diagram into four areas corresponding to different states of traffic conditions. Changes of the different states of traffic in a short time represents incidents. Statistical data smoothing has been performed on data for incident detection to suppress the randomness in the data (variations). Various smoothing techniques have been used, such as simple running averages (the California algorithm) and exponential smoothing. Travel time is the primary statistic (variable) in an incident-detection algorithm for all loop configurations, due to a smaller dispersion present in the raw data. In addition, on-line decision support systems, such as KBES (Knowledge-Based Expert Systems) have been used (as a series of rules or heuristics) by control center personnel to detect, verify, and respond to traffic incidents. These expert systems have been designed (e.g., Santa Monica Smart System) to solve problems whose solutions require expertise. It is a real-time, on-line computer system supporting the traffic manager in: screening large amounts of data; analyzing the real-time traffic data and responding consistently across the operators; and as a training tool used off-line by managers for a variety of traffic-incident scenarios. These systems use incident-detection algorithms based on realtime volume and occupancy data from the mainline detector stations, and compare data against user-specified thresholds for incident identification. Advantages: • •
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Incident-detection algorithms use traffic parameters and data to identify incidents. They use detectors to provide quick indication of incidents.

Incident Management

Disadvantages: • • • Incident-detection algorithms do not detect incidents; they use traffic data to detect congestion. Incident-detection algorithms have a high false-alarm rate as recurring congestion increases. They can only detect incidents that impact traffic flow.

Detection Algorithm Case Studies TransGuide - From the TransGuide ITS Design Report (transguidewwwserver.datasys.swri.edu:80/ articles/designreport.html ) Detection Algorithms Various algorithms have been used to detect incidents in systems based on loop detectors. Manyof the algorithms are flexible in some ways and each has advantages and disadvantages. The designers of the TransGuide system have designed the system so the data necessary for several of the available algorithms is continuously collected. The system was also designed so the specific algorithm being used to detect an incident could be investigated using real-time data and, if desired, could easily be changed. The selection of an initial incident detection algorithm focused specifically on the ability of the algorithm to rapidly detect incidents, even at the risk of a relatively high level of false alarms. The capability of the TransGuide system to verify incidents via the video subsystem is another reason that rapid detection of incidents has a higher priority than making sure that each alarm is actually an incident. Since the video subsystem is used for classifying incidents, there is also no requirement for the selected algorithm to do so. It is sufficient for the algorithm to detect incidents. The algorithm used to generate alarms is flexible and can be tuned to trade off detection time and false alarm rate. The computer polls each LCU on a periodic basis þ the period of the poll defaults to 20 seconds, but can range from 10 to 60 seconds in 10 second increments. The computer generates an alarm based on a moving average of speed or occupancy þ the period of the moving average can range from 1 to 10 minutes, but defaults to 2 minutes. The moving average is compared with a threshold, which can be a default value or a defined value. Thresholds can be defined for detectors based on the specific time of day, day of the week, or day of the year. For each detector or set of detectors, there are up to four thresholds at which alarms are generated. A minor alarm will be generated when the average speed is less than the speed minor alarm threshold. The speed minor alarm threshold defaults to 45 mph. A minor alarm will also be generated if the occupancy is greater than the occupancy minor alarm threshold, which defaults to 25 percent. A major alarm will be generated when the speed is less than the speed major alarm threshold, which defaults to 30 mph. A major alarm will also be generated if the occupancy is more than the occupancy major alarm threshold, with a default of 35 percent. These thresholds can be adjusted at 15-minute intervals to values derived from historical data. The algorithm described is expected to provide flexible, rapid detection of traffic incidents. Ananalysis
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being conducted as a separate part of the current operational test includes additional work on optimizing the detection algorithm. This analysis will also consider properties and capabilities of other existing algorithms. Divert Divert, a Minnesota Guidestar project, redirects traffic around freeway incidents by sending motorists off the freeways onto surface arterials and than back again. The system uses inductive loop detectors, CCTV, DMSs, and signal timing devices to direct traffic and lighten congestion (ITS World, Jan/Feb 1997). Montgomery County To rapidly identify and clear incidents, Montgomery County has established an advanced transportation management system that supports up to 1,500 traffic signals, 200 video surveillance cameras, and 3,000 sampling detectors in the roadways. Enhancing the monitoring capabilities of this system with a critical bird’s-eye view is an aerial surveillance program, in action each morning and afternoon, that transmits live video footage of incidents and bottlenecks directly to the county’s transportation management center. Staffed with a pilot and a traffic technician, a government airplane circles the county, spotting incidents and quickly identifying their locations and circumstances. This instantaneous and precise information, fed automatically to the police and fire computer-aided dispatch system, alerts emergency agencies to the need for immediate response. The real-time information may also direct the transportation management center to optimize traffic flow with changes to traffic signals and variable message signs. During snowstorms or other crises, the transportation management center takes over a local cable television channel and updates conditions around the clock with video footage from aerial and ground cameras, sharing real-time traffic information with the traveler. Radio also broadcasts current traffic conditions. b. Electronic Sensors Electronic sensors are devices placed along the roadway to detect the presence of vehicles, speeds, occupancies, etc. This real-time data is then processed, using automatic processing techniques (e.g., detection algorithms, knowledge-based expert systems) to identify congestion resulting from incidents (nonrecurring congestion). The types of sensors used can be found in Section 2.6. The most commonly utilized detector for incident management is the inductive loop. Advantages: • • Capable of continuously monitoring entire roadway section. Provides rapid detection, especially in high-volume conditions.

Disadvantages: •
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Requires large capital investment.

Incident Management

• • • • •

Long lead time involved in designing and implementing system. High maintenance costs. High false alarms in congested areas. Cannot detect non-congestion-causing incidents. Verification is necessary before any response plan is implemented.

c. Motorist Devices Motorists use such devices as call boxes, CB radios, cellular phones, and other telephones at roadside to report incidents using special numbers. Advantages: • • • • The devices that the motorist uses to report incidents are very accessible. Fast identification of incidents. Low false-alarm rate. High detection rate.

Disadvantages: • • • Dependent on motorist input. Multiple calls may be received at the control center for the same incident. Information provided concerning the location and severity of incident may be unreliable.

d. Freeway Service Patrol and Courtesy Vehicles These are special vehicles that patrol or circulate throughout an area to report incidents to the control center, as well as to assist vehicles that experience minor breakdowns. Advantages: • • • • Such vehicles provide continuous patrol. Detect and verify incidents that occur on their path. Provide reliable information on location and severity of incidents. Can address minor incidents with no further assistance.

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Disadvantages: • • • • • A large amount of personnel is required to cover congested areas. Detection of incidents is a function of the headway between patrols in an area. Cannot detect incidents not on their route. Patrol vehicles also affected by congestion. May not be able to reach an incident if delayed by congestion.

e. Fixed Observers These are personnel stationed in towers and/or tall buildings along congested highways for the purpose of observing traffic and identifying incidents. These observers report incidents to the control centers for further action. Advantages: • • • Fixed observers are a useful interim measure. Useful for special events or highway reconstruction. Reliable information.

Disadvantages: • • • • f. A large amount of personnel is required to cover congested areas. Detection of incidents is a function of the area covered. Detection is affected by severe weather conditions. May require construction of facilities where observers are stationed. Aerial Surveillance

Aerial surveillance systems use fleets of aircraft (e.g., helicopters, small planes), usually retrofitted with video cameras, circulating above a metropolitan area during peak periods, to identify and report incidents, as well as to provide live video pictures. Advantages: • • • Aerial surveillance can cover a large area. Identifies and verifies incidents with the aid of video images. Reliable information.

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• •

Can be used not only for detection of incidents, but also for obtaining information concerning traffic conditions on other roadways for possible traffic diversion. Can assist media in disseminating traffic information to the motorist.

Disadvantages: • • • • High capital cost. Costly to cover a large area for long periods of time. Affected by severe weather conditions. Time of detection is a function of headway of aircraft.

g. CCTV CCTV surveillance systems, installed at numerous locations in the highways, use television cameras to detect and verify incidents. Section 2.7 provides a thorough discussion of these systems. Advantages: • • • • • CCTV systems can cover a large area, depending on installations. Effective verification method. Provide reliable information. Current technology of cameras has made it possible to receive good video images in severe weather conditions. Can use video images in disseminating information to motorist.

Disadvantages: • • • High capital cost to cover a large area. Incident identification is a function of coverage. Can be used for incident identification, but this is a labor-intensive process.

CCTV Case Studies TransGuide - From the TransGuide ITS Design Report (transguidewwwserver.datasys.swri.edu:80/ articles/designreport.html ) Video as Incident and Message Verification Once an alarm has been generated, the TransGuide video facilities will be used to verify and characterize the incident and to drive the dispatch of any necessary emergency services. The video
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capabilities of the system are based on a user controllable camera and lens system, which is used by the operators to view the scene of the incident. The video signal generated by the camera is converted for communications to the control center by video coder decoders (codecs). The video signal is reconverted and displayed on workstation Cathode Ray Tube (CRT) screens or on arrays of screens making up the video wall in the control room. The video system provides the operators with a color, detailed view of an incident in daylight or at night. Multiple operators, such as police and VIA Metropolitan Transit Authority dispatchers, as well as TxDOT operators, can access a view of the scene simultaneously. The use of the system’s video capabilities is fundamental to the successful operation of TransGuide. Several combinations of cameras, lens systems, codecs, monitors, and video display units were investigated by TxDOT. The subsystems selected satisfy the demanding video requirements of the TransGuide ITS.

Response and Clearance
a. Communications The inability to communicate at the incident scene or to coordinate response among the agencies is one of the most common problems in incident response. It is caused by the absence of compatible communications equipment and by lack of knowledge of the response and communications protocols and procedures of other responding agencies. Jurisdictional and institutional turf issues often prevent or inhibit on-scene and off-scene communication necessary for the incident to be cleared efficiently, between participating agencies. A lack of understanding of the roles, resources, and abilities of the other agencies contributes significantly to the lack of willingness to communicate. Incompatible or antiquated communications equipment or lack of equipment prevents communication. Furthermore, the types of communications needed by agencies working together at the scene of an incident may be different or may require different protocols than those needed for routine communications within an agency. Communication links needed to convey information quickly and accurately include: field-to-field (communications among personnel at the scene); field-to-dispatch (communications between personnel at the scene of an incident and personnel at their agency’s dispatch or operations center); and dispatch-to-dispatch (communications between dispatch or operations centers of responding agencies). 1. Conventional Radio - often incompatible among agencies and may be antiquated. In addition, agencies need to coordinate purchases to ensure compatibility 2. 800 MHz Radio - increasingly popular, with many agencies using this method of communication. It provides more capacity. There are, however, some compatibility problems and agencies still need to coordinate purchases to ensure compatibility. Also, this frequency makes it difficult for traffic reporters to scan communications. 3. Single Emergency Frequency - used to facilitate management of major incidents; however, protocols and conditions for use need to be defined. 4. Cellular Phone - can be of particular benefit for command-level persons to facilitate communications.
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Driver Information
a. Media Most motorist information is now broadcast over commercial AM and FM radio stations or on television newscasts. Cable television stations in some markets carry traffic information. In most major urban markets there are one or more radio/television stations that provide aerial coverage of traffic. Private traffic-reporting firms collect, package, and sell traffic information to the broadcast media in many urban areas. The media market is extremely competitive and many media outlets find that maintaining their own traffic-reporting services (e.g., airplanes) is too costly. b. Highway Advisory Radio These stations are primarily broadcast at 530 or 1610 kHz on the AM broadcast band, although the FCC will allow the use of other frequencies that are available. There are many users of traditional HAR frequencies in urban areas (e.g., airports, amusement parks) that can conflict with highway usage, and the range of broadcasts is usually limited. For more information on HAR, see Section 2.9. c. Dynamic Message Signs Dynamic message signs can be at fixed locations or they can be portable. They provide guidance information about diversions (e.g., local and regional information, alternate route information), warning of conditions ahead (e.g., incidents, congestion, long delays, lane closure), and dynamic information regarding unusual conditions (e.g., incidents, construction and maintenance activities, special events). For more information on DMSs, see Section 2.8 d. In-Vehicle Displays These systems provide real-time information in the vehicle about traffic and road conditions to drivers by voice, video, or combination messages. For more information on in-vehicle displays, see Section 2.11. e. Videotext Videotext is the use of the vertical blanking interval in television broadcasts to transmit information. f. Telephone Dial-In

Some areas (e.g., Boston) have telephone numbers for traffic information prepackaged to be routeor trip-specific. Listeners do not have to listen to traffic conditions across an entire area to choose the routes of interest. Other areas (e.g., Chicago) have traffic telephone numbers providing area-wide real-time information. g. Information Kiosks These are automated traffic-information units usually displayed on video monitors. They are typically located at shopping centers, employment centers, airports, hotels, car rentals, etc.
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h. Internet The Internet is fast becoming the information medium. Real-time traffic and road conditions are beginning to appear on the Internet as State and local agencies attempt to use this fast-expanding resource to provide motorists with information.

4.2 SURFACE ARTERIAL INCIDENT-MANAGEMENT SYSTEMS
Unlike freeway incident management, not much work has been performed in the research, development, and implementation of surface street incident-management systems. The issues involved in the detection of incidents on surface streets have not been clearly defined. As previously discussed, freeway-incident detection employs algorithms to identify incidents by using real-time traffic information (e.g., volume, occupancy, speed). On surface streets, such measures of traffic flow fluctuate continuously due in part to traffic signals, driveways, and other stops that disturb traffic flow. Other characteristics of surface streets that make incident detection at those locations different than freeways include: multiple access, interrupted flow, geometric constraints, control measures, operating conditions, and detector configurations. With the development of and increasing interest in the deployment of the metropolitan intelligent transportation infrastructure, there is a push toward integrated systems. In a workshop on Surface Street Incident Detection held in Scottsdale, Arizona, on August 4-6, 1996 (sponsored by the FHWA and hosted by Oak Ridge National Laboratory), the need for research and development on incidentmanagement systems for surface streets was the theme. Under the emerging concept of integrated traffic-management systems, surface street incident detection is receiving increasing attention. It is envisioned as an integral part of the metropolitan intelligent transportation infrastructure. Also, the evolving technologies and popularity of them on detection and surveillance systems (e.g., video image processing, wide area detection, cellular telephones, fuzzy logic) are providing new and exciting potential for the development of these systems. Several algorithms have been developed for surface street incident detection. One such incidentdetection system has been developed for the ADVANCE project discussed by Bhandari et al (1995). The components of the incident-detection system follow. • • • • Fixed-detector algorithm uses real-time and historic data provided by fixed detectors located on major arterials to classify conditions on the detectorized street as incidents or non-incidents. Probe vehicle algorithm uses travel time reports by probe vehicle and historic travel times on these links to interpret traffic conditions as incident or non-incident. Anecdotal algorithm uses information provided by emergency personnel and other motorists on the network to detect incidents in real time. Data fusion algorithms combine the output from the fixed detector, probe vehicle, anecdotal algorithms, and the operator interface.

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• •

Duration and impacts module determines the expected duration of the incident and the impacts on the incident link travel times. Operator interface allows the Traffic Information Center personnel to view the output from the data algorithms, and to key-in incident reports from other sources. The output from the duration and impacts module will be available to the operator for review.

The Smart Diamond project by the Texas A&M University, ITS Research Center of Excellence, is a research project on incident detection in a real-time traffic-adaptive control system using a fuzzy logic modeling technique. The model distinguishes abnormal conditions from random fluctuations under normal conditions by looking for abrupt changes in traffic measures. Measures employed include: queue length, speed, occupancy, and turning movements.

4.2.1 CASE STUDIES
Smart Corridor
The official opening of the Santa Monica Smart Corridor in Los Angeles was October 1996. The key element of this ITS demonstration project is incident management and the interagency coordination that occurs to make this happen. The agencies that have access to the Smart Corridor system are Los Angeles DOT, Caltrans, California Highway Patrol, Culver City, Beverly Hills, Santa Monica, and the Los Angeles County Metropolitan Transportation Authority. The surface street incident-detection system covers 800 instrumented links and more than 1,900 detectors. An expert decision support system develops incident responses in realtime that are based on changing traffic conditions. Alternative route diversions are displayed on DMSs, broadcast on HARs, and publicized through the media. In addition, signal timing plans and ramp-metering rates are changed to accommodate diversions. The Arterial incident Detection system works by a method of time weighted data analysis. Volume and occupancy data from each system detector is gathered from the real-time traffic control system on a minute-by-minute basis and transmitted to the Smart Corridor system. The detector data is then combined into link data which is smoothed with data from the previous four minutes to obtain a sliding five minute average link value. This five-minute average link data is then compared to a matrix which represents the normal, congested, and maximum traffic values expected on this particular link. Data values outside the acceptable range are ignored, and those within range are given a persistence value. Over time, if traffic conditions warrant, the persistence value will increase, and ultimately an incident will be identified (David Roseman and Sean Skehan, 1995).

4.2.2 EVOLVING TECHNOLOGIES
Incident Management Algorithms
Automatic incident detection involves the collection of real-time traffic information and algorithms that interpret this information and establishes the presence of incidents. The algorithms most commonly used today are: the California and the McMaster algorithms. These algorithms have not been
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received and used widely by the traffic management industry as they have not performed favorably. New algorithms have been and are continuously being developed to overcome the deficiencies of the other algorithms. These are: statistical test (time-series smoothing analysis and filter theory to model traffic flow); knowledge-based expert systems (automated response); neural networks; image processing with artificial intelligence; fuzzy set theory. SOURCES: • • • Automated Arterial Incident Detection: Santa Monica Freeway Smart Corridor, 1995, by David Roseman and Sean Skehan, ITE Compendium of Technical Papers. Incident Management: Challenges, Strategies, and Solutions for Advancing Safety and Roadway Efficiency Executive Summary, January 1997, by American Trucking Association Foundation. Arterial Incident Detection integrating data from Multiple Sources, January 1995, a paper Presented at the 1995 TRB Annual Meeting, by Nikhil Bhandari, Frank Koppelman, Joseph Schofer, Vaneet Sethi, and John Ivan. Arterial Incident Detection Using Fixed Detector and Probe Vehicle Data, December 1994, a paper Presented at the 1995 TRB Annual Meeting, by Nikhil Bhandari, Frank Koppelman, Joseph Schofer, and Vaneet Sethi. Traffic Flow Characteristics of Signalized Arterials under Disturbance Situations, June 1990, by Lee D. Han and Adolf D. May, Publication No. UCB-ITS-RR-90-12. Automatic Detection of Traffic Operational Problems on Urban Arterials, July 1989, by Lee D. Han and Adolf D. May, Publication No. UCB-ITS-RR-89-15. Proceedings of the Workshop on Surface Street Incident Detection, August 4-6, 1996, Scottsdale, Arizona, by Oak Ridge National Laboratory.

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Return to Table of Contents

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Electronic Toll - Collection System

CHAPTER 5

Electronic TollCollection System

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Electronic Toll and Traffic Management (ETTM) is an element of ITS that allows for nonstop toll collection and traffic monitoring. ETTM utilizes vehicles equipped with transponders (electronic tags), wireless communication, in-road/roadside sensors, and a computerized system (hardware and software) to uniquely identify each vehicle, electronically collect the toll, provide general vehicle/traffic monitoring and data collection. ETTM technologies and infrastructures provide the necessary capabilities for future applications such as incident management, alternate route guidance, and travel demand management. Properly implemented, ETTM can reduce congestion, increase operating efficiency, improve travel time, reduce pollution, and improve safety of the roadway facility and surrounding corridors.

5.1 ETTM COMPONENTS
A major component of the ETTM is Electronic Toll Collection (ETC). ETC is combination of techniques and technologies that allows vehicles to pass through a toll facility without requiring any action by the driver (i.e., stopping at toll plazas to pay cash). In fact, today’s conventional toll plaza in not necessary in a fully dedicated ETC facility. ETC components can be categorized as in-lane/roadway components and Facility Management and/ or Customer Service Center components. Three major in-lane/roadway components are required for the successful implementation of an ETC. These components are:

• • •

Automatic Vehicle Identification (AVI); Automatic Vehicle Classification (AVC); and Video Enforcement Systems (VES).

All in-lane/roadway components are in communication with and controlled by a computer called the “lane controller.” The lane controller takes input from the AVI, AVC, and VES components. Its database, through which a list a valid tags is maintained, is used to validate the AVI and charge the customer’s account. The information from each lane controller is passed on to a plaza host computer. Each plaza host computer is in constant communication with the central computer in the Facility Management and/or Customer Service Center, thereby consolidating the database, as well as equipment requirements. The Customer Service Center manages the accounts, enrolls customers and issues tags, processes the violations, handles all inquiries, and serves as the facility management center.

5.1.1 AUTOMATIC VEHICLE IDENTIFICATION
Automatic vehicle identification refers to various components and processes that allow for the identification of vehicles and and their owners for the purposes of charging the toll to the customer and providing mechanism for data collection for various traffic-management strategies. AVI technology can be broken into two main categories: laser and Radio Frequency (RF.) Laser systems utilize a barcoded sticker attached to the vehicle and read by a laser scanner as the vehicle passes through the toll lane. Laser technology has several drawbacks that limit its use in the open-road toll collection
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environment. Chief among these are sensitivity to weather and dirt, ease of forgery, and location and installation of the scanner in the close proximity of the toll lane. On the other hand, RF systems utilize a transponder (or electronic tag). An RF tag is a device located in or on the vehicle that is used in conjunction with an in-lane RF antenna-reader to communicate identifying information about the vehicle and customer to the toll system. Each toll lane is equipped with an RF “antenna,” usually mounted in the center of the lane above the roadway (however, there are implementations where the antenna is mounted in the roadway itself). Each antenna is connected to a “reader,” which controls communications between the tag mounted on the vehicle and the antenna in the lane. The reader sends out a signal (via the antenna) to the tag that lets the tag know it should begin communication. The tag returns a unique ID number used to identify the vehicle (customer) to the ETC system. In the case of read/write tags, smart tags, or smart cards with transponders, additional information may be transmitted by the tag (such as account balance, point of entry, etc.) and the reader may send back updated information to be encoded on the tag/smart card.

5.1.2 AUTOMATIC VEHICLE CLASSIFICATION
Automatic vehicle classification refers to the various components and processes of the toll-collection system with which the toll equipment is able to determine the configuration of the vehicle in order to determine the appropriate toll to charge. Vehicles are segregated into classes, such as cars, trucks, and buses, primarily to charge different tolls by such classes. AVC systems, of which there are many variations, consist of various in-lane devices that measure the physical characteristics of vehicles and an AVC processor that uses the outputs of those devices to categorize vehicles into distinct classes. In manual toll-collection systems, AVC systems are used to verify the classifications assigned by toll collectors. In electronic toll-collection systems, AVC systems are used to calculate the amount of toll due or to verify precoded classifications on vehicle tags. An automatic vehicle classification may need to determine vehicle height, number of axles, presence of dual tires, and vehicle weight to distinguish between vehicles and assign the correct class. In addition, automatic vehicle classification must provide for vehicle separation (i.e., assigning the various class determinants to a single unique vehicle). When a vehicle’s class is dependent on the number of occupants of a vehicle, there is no practical way to determine the class by automated means. Similarly, there is no way to automatically determine the purpose for which a vehicle is being used (e.g., a taxi cab cannot be distinguished from a private passenger car). Determinants of vehicle class may include: • • • • Number of axles and/or tires of a vehicle. Dimensions (e.g., height, length, wheelbase, height over first axle) of a vehicle. Weight of a vehicle. Number of occupants in a vehicle (e.g., a special class assigned to commuter pools with a minimum number of occupants).

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•

Purpose for which a vehicle is being used (e.g., a special class assigned to taxi cabs).

5.1.3 VIDEO ENFORCEMENT SYSTEMS
The term “video enforcement systems” or “violation enforcement systems” refers to the various components and processes of the toll collection system with which the toll equipment is able to capture information on vehicles that have not paid the proper toll. VES is used to capture images of the license plates of vehicles that use ETC lanes without valid ETC tags. These images are used to extract the license plate number and State (either by an automatic system or manually) and that information is used to perform a search of the applicable State’s motor vehicle records to determine the registered owner of the vehicle. A notice is then sent to the owner, indicating that a toll is due. Most agencies also levy a processing fee that, relative to the toll, can be very high. The main purpose of the fee is to deter motorists from habitually violating the toll and to offset the cost of processing the violation. In the event that the owner does not pay the toll, agencies can forward the matter to the local judicial system for resolution. If patrons believe that an ETC lane is operating without VES, they will take advantage of the situation and violation rates will increase. VES is necessary to record the image information needed for the agency to pursue evaders, recover tolls and issue fines, thereby deterring toll evasion.

5.2 TECHNOLOGIES
5.2.1 AVI TECHNOLOGIES
Inductive-Loop Systems
The only AVI technology that employs very low frequencies is the inductively coupled system, which uses a loop antenna embedded beneath the surface of the roadway to communicate with a tag mounted on the underside of the vehicle. The roadway antenna sends out an interrogation signal and the tag returns with a signal containing data stored in the tag. This is normally an active (as opposed to a passive) system since the tag normally transmits its own signal (rather than reflecting the interrogation signal). The system is the earliest of the AVI technologies. Advantages: • • • • Proximity of loop antenna and tag provides potential for increased reliability. Simple serviceability. Low potential for electrical interference. Short coupling range decreases potential for interference from adjacent lanes.

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•

Advanced traffic-management and traveler-information systems can also use inductive loop, so the infrastructure is already in place for other ITS-related applications.

Disadvantages: • • • • • Low frequency results in lower maximum data rate, although it is fast enough to allow multiple transmissions to increase reliability. Moderate difficulty in duplicating tags. Tag usually requires power from vehicle (active tag). Tag installation is not as convenient as that of a windshield-mounted tag. More sensitive to environmental conditions.

Optical Systems
Two types of AVI technologies employ optical or near-optical frequencies to identify vehicles. The first system, optical license plate identification, reads license plates directly and identifies the vehicle from a database. As the vehicle passes the toll booth a video camera forms an image, which is digitized and processed to extract the license plate number. Typically, the image processing can take nearly one second, precluding multiple reads for improved reliability. The second type of optical or near-optical system, bar coding, employs a vehicle tag that is simply a bar code. A laser scans continuously over the area where the tag is expected to be and the reflected signal is processed to extract the code. This image processing is much simpler than trying to read a license plate since the reflected laser signal represents a one-dimensional image, whereas the video image of the license plate must be processed in two dimensions. a. Optical License Plate Identification Advantages: • • • No special vehicle tag is needed. License plates are not likely to be duplicated. There is no chance of interference between adjacent lanes.

Disadvantages: • • • The processing algorithms are computation intensive. The relatively long time required for image processing precludes multiple reads to increase reliability. The system is subject to failure due to dirty or damaged license plates, the presence of bumper stickers and similar text on a vehicle, and reduction of visibility caused by rain and fog.

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Electronic Toll - Collection System

• •

Low (80 to 90 percent) reliability because of the complexity involved in image processing. Typically requires highly reflective license plate.

b. Bar Coding Advantages: • • • • Greater reliability than systems reading license plates because of the single dimension. Simple vehicle tag consists only of a bar code imprinted on an adhesive strip. Low potential for lane-to-lane interference because of limited range. Much faster than systems that read license plates.

Disadvantages: • • • • Tags are easier to duplicate compared to other AVI technologies. Susceptibility to failure caused by rain, fog, dirt, or moisture on tag. Finding the returned signal through image processing results in less reliability than systems employing transponders (microwave systems). High restrictions on the position and speed of the vehicle as it passes the reader.

Active RF/Microwave Systems
Active radio frequency AVI systems employ microwave frequencies for communications to and from the vehicle. All active RF systems have high data rates that allow multiple transmissions (redundancy), resulting in increased reliability. These transmissions are commonly known as “handshakes” in the industry. Active RF/microwave systems may be divided into those in which the tag generates its own microwave signal (active tag) and those in which the tag simply reflects the microwave signal that it receives (passive tag). Active tags require a power source (battery connection to vehicle power), while passive tags may or may not require a power source. In an active vehicle tag system, the transmitter sends out a short interrogation signal, which triggers the circuitry in the tag. The tag responds by generating a microwave signal containing the data stored in the tag. This signal is transmitted to a receiver that decodes the data and sends them to a computer for identification. Advantages: • • • Greater operating range than a passive system because the tag is not powered by interrogating beam. Greater reliability than a passive system because the return signal from the vehicle is stronger. Less chance of electrical interference than a passive system because of the stronger signals.

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Disadvantages: • • • Greater complexity in the tag circuitry, resulting in higher manufacturing costs. Greater probability of lane-to-lane interference due to stronger signal. The tag must have a battery or be connected to vehicle power.

Passive RF/Microwave Systems
In a system that employs a passive vehicle tag, the transmitter usually transmits a signal continuously. This signal is intercepted by the tag and reflected to a receiver. The amount of reflection varies (the reflected signal is modulated) according to the data stored in the tag. The received signal is decoded to recover the data, which are then sent to a computer for identification. Passive RF communication is sometimes called the “backscatter” method. Advantages: • • The tag does not need to be connected to vehicle power. The tag is less complex than in an active system.

Disadvantages: • • • Lower reliability than an active system. Greater susceptibility to electrical interference because of lower signal levels. Shorter operating range because the tag is powered by the interrogating beam.

Surface Acoustical Wave
Surface Acoustical Wave (SAW) technology operates at much the same frequency as RF systems. The primary difference between SAW and RF microwave systems is that the SAW transponder is nonprogrammable. With the SAW technology, a low-power radio frequency signal from the AVI reader is captured by the transponder antenna and energizes a lithium crystal, generating an acoustical wave along its surface. This acoustical wave travels along the surface of the crystal so that etched metal taps can be used to send back a series of time-delayed reflections of the original signal that uniquely identifies a tag. Advantages: • • • It is virtually impossible to duplicate the vehicle tag. The tag circuitry is much simpler, thus lower in cost. No power is required to operate the tag.

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Electronic Toll - Collection System

Disadvantages: • • • A limited operating range (up to 15 ft.), since it is typically part of a passive system. A limited data transmission rate because microwave energy must be converted to mechanical energy. The tag cannot be programmed.

5.2.2 ELECTRONIC TAGS/TRANSPONDERS
RF Tags
The information stored in the tag is fixed (read only) and cannot be changed and the tag does not have any processing capabilities. These tags are often referred to as Type I tags. However, some tags contain an updateable (read/write) area on which the antenna/reader may encode information (such as point of entry and date/time of passage.) These tags are often referred to as Type II tags. RF tags have been in use for several years at many installations both in the United States and around the world. RF tags operate in half duplex mode, meaning that they cannot send and receive data at the same time. They generate the signal used to communicate with the antenna/reader in one of two ways: actively, whereby the RF tag contains a transmitter and generates its own RF signal; and passively, whereby the RF tag reflects the signal it received from the antenna/reader (and, as such, the tag does not contain a transmitter). Three frequency ranges are used by RF tags: • • • 900 to 928 MHz 2.45 GHz 5.8 GHz

Only the 900 to 928 MHz frequency range is used in the United States, with the other frequencies in use in other parts of the world. The maximum read/write range of RF tags does not extend much beyond 100 feet and in actual use they are usually within 20 or 30 feet of the antenna during communications. The RF tag contains from 128 bits to 512 bits of memory in the form of EPROM and/or EEPROM. However, some RF tags can be augmented to contain as much as 16 megabits of memory. The RF tag also contains a battery that is not user replaceable and has a useful life of between 5 and 10 years. Other features of RF tags include: • • LED, controllable via the reader to indicate information to the driver. LCD, controllable via the reader to display a message to the driver.

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• • •

Buzzer (or other sound generating device), to alert the driver. Scroll buttons - to allow the driver to scroll through messages received from the reader. Communication ports, to allow the tag to communicate with other devices in the vehicle. Note that tags with this feature are often referred to as Type III tags.

Among the many communications standards supported by RF tags are: • • • • • • Crescent HELP; ATA 5/16/90; ISO 10374.2; AAR S-918-92; ANSI MH5.1.9-1990; and California Title 21.

RF Smart Tags
An RF smart tag is an RF device, located in the vehicle, that is used in conjunction with an in-lane RF antenna/reader to communicate identifying information about the vehicle, customer, and account balance information to the toll system. Some portions of the tag information are fixed (such as vehicle and customer data) while others are updateable (such as balance information). The smart tag contains a microprocessor, which maintains account balance information updated each time the smart tag is used. RF smart tags have not been used extensively either in the United States nor around the world. RF smart tags operate in full duplex mode, meaning that they are able to send and receive data at the same time. They actively generate the signal used to communicate with the antenna/reader via a transmitter. Three frequency ranges are used by RF smart tags: • • • 900 to 928 MHz 2.45 GHz 5.8 GHz

Only the 900 to 928-MHz frequency range is used in the United States with the other frequencies in use in other parts of the world. The maximum read/write range of RF smart tags is greater than that of RF tags (owing to their use of active transmission); however, in actual use they are usually within 20 or 30 feet of the antenna during communications.

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The RF smart tag contains from 16 kilobits to 64 kilobits of memory in the form of EPROM, EEPROM, ROM, and/or RAM. The RF smart tag also contains a user replaceable battery that generally has an operational life of between one and two years. Other features of RF smart tags include: • • • • • LED, controllable via the reader to indicate information to the driver. LCD, controllable via the reader to display a message to the driver. Buzzer (or other sound generating device), to alert the driver. Scroll buttons, to allow the driver to scroll through messages received from the reader. Communication ports, to allow the tag to communicate with other devices in the vehicle.

At this time, RF smart tags utilize proprietary communications standards.

Smart Cards With RF Transponders
For toll collection, use of smart cards use actually requires two components: the smart card itself and a separate RF transponder (tag). The smart card is an Integrated Circuit (IC) device that contains a microprocessor and memory and stores account balance information. The RF transponder is an RF device, located in the vehicle, that interfaces to the smart card and allows the smart card to communicate with the in-lane antenna/reader. Often, this RF transponder is actually a Type III RF tag. In addition, the RF transponder contains information about the vehicle that it transmits to the antenna/ reader along with the smart card information. Smart cards with RF transponders are undergoing extensive trials in Europe. The tags used with smart cards employ either full or half duplex communication with active or passive transmissions. The frequency ranges used conform to those of other RF tags, as do their communication ranges and other features.

5.2.3 AVC TECHNOLOGIES
Various equipment used to determine vehicle classification include:

Inductive Loops
Inductive loops are wires placed in channels cut into the road bed and used to detect vehicle presence by sensing the metallic mass of the vehicle.

Treadles
Treadles are pressure-sensitive devices placed in frames installed in the road bed and used to determine the number of axles, number of wheels, and direction of a vehicle crossing the treadle. A parallel series of sensor devices detects the direction of axle movement by the sequence of sensor activation. Treadles can be classified into several types based on the physical principle used to convert the pressure of a vehicle’s wheel into electrical signals recognized by the logic units of the treadles.
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a. Electromechanical Treadles - These devices are simple electromechanical devices in widespread use for low-speed applications; however, they are reported to be inaccurate at speeds of above 55 mph. They also have a high maintenance cost. b. Resistive Rubber Treadles - These devices are similar to electromechanical treadles, but use resistive rubber rather than metal for contact closure. They are specified to operate accurately at speeds from 2 to 80 mph. They also have a lower maintenance cost than metallic units. c. Optical Treadles - These devices utilize infrared beams inside a tube. The beam is broken and an electrical signal is generated when an axle crosses the treadle. These devices are reported to be accurate at higher speeds and have a long life and low cost of maintenance. They can be installed in standard treadle frames. d. Piezoelectric Treadles - These devices utilize special material inside a tube. The material generates an electrical current when subjected to pressure caused by an axle crossing the treadle. The devices are reported to be quite accurate at speeds of above 5 mph, but not accurate at speeds between 0 and 5 mph.

Weigh-In-Motion Devices
These are pressure-sensitive devices generally placed in frames installed in the roadbed and used to determine the axle weight of vehicles. Many of the sensors used in weigh-in-motion devices are the same as those used in treadles. They differ in that treadles utilize a series of sensors to detect the direction of axle movements. a. Bending Plates - These devices utilize a bending plate to determine the axle weight of a vehicle. The device generates an electric current when subjected to pressure caused by an axle crossing the plate. b. Capacitive Strip - The degree of pressure on strip as axle crosses strip allows calculation of axle weight. c. Piezoelectric Sensors - These devices utilize special material inside a tube. The material generates a varying electrical current proportional to the weight of the axle crossing the sensor.

Light Beams
These are devices consisting of a single infrared light beam that is broken as a vehicle passes through the beam. They are used to detect vehicle presence and vehicle height. The functionality of light beam devices is limited in that they cannot accurately separate vehicles with trailer hitches or provide a profile of the vehicle. Another disadvantage of light beams is that the single beam of light is transmitted through vehicle windows without impediment, thereby causing the appearance of a separation of the vehicle where none exists.

Light Curtains
Light curtains emit multiple horizontal light beams to measure vehicle presence and profile. A transmitting tower sends light beams across the lane to a receiving tower. As a vehicle breaks the light
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beams, a two-dimensional profile of the vehicle can be produced. Objects such as trailer hitches can be detected down to approximately one-half inch.

Scanning Devices
These devices generate radiation at various frequencies to detect vehicle presence and profile. Scanning devices that may be useful in AVC applications include the following. a. Ultrasonic Scanners - These devices emit ultrasonic waves that are reflected back to the transmitting device to detect vehicle presence and two-dimensional profile. Ultrasonic devices are subject to distortion from air turbulence and changes in temperature and humidity. Despite this, Japan uses ultrasonic technology extensively for vehicle classification. b. Infrared Scanners - This technology is used to separate and profile vehicles using a vertical or horizontal infrared scanning camera system. Output from the equipment is processed to produce two-dimensional images, which are compared to vehicle class templates to determine vehicle classification. c. Laser Scanners - Laser scanners use scanning laser beams to detect and classify vehicles operating in high-speed, high-volume conditions. Output from the device is processed to produce threedimensional images, which are compared to stored templates of various vehicle profiles to determine vehicle classification.

Video Image Processing
These devices use video cameras to scan traffic and use built-in software to determine vehicle profile information such as length, width, and height from the scanned vehicle images.

5.2.4 VES TECHNOLOGIES
Photographs
The very earliest video enforcement systems utilized cameras to take photographs of toll-evading vehicles. This approach was soon abandoned because of the labor-intensive, manual extraction of plate information from the photographs. Other problems, such as triggering the camera, image correlation with lane, date, and time, and storage of photographs, made this approach unacceptable. This approach generally required each lane to be equipped with a camera and film storage device.

Videotape Recording
Videotape recording devices (VTR/VCR) were subsequently used to capture images of vehicles going through the lane. The videotape would be replayed at a later time to review the images and extract license plate information. Image review was a time consuming activity that was done using a standalone videotape playback unit. Several implementations of this technology added lane number and date/time information, which was overlaid onto the tape. For image retrieval and ease of locating
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images, the relationship between an image number and the tape position information was recorded. Also, the recording was done with a dual tape speed to allow for greater image storage and for more efficient post-processing image review. Besides the potentially large amount of storage space required, this approach required manual handling of tapes from the image capture location to the violation processing location. This approach, while still in use today, is still labor intensive. This approach generally required each lane to be equipped with a video camera as well as a dedicated VTR.

Digital Imaging
The latest implementations of VES are video-based systems that utilize digital capture and storage of images. Digital systems feature the ability to digitize images, store them electronically, and transmit them to remote locations. In addition, digital systems can be enhanced through the use of License Plate Recognition (LPR) systems. LPR allows the VES to automatically determine where in the image the license plate is located, read the license plate number and State, and store this information on the transactions. This can alleviate the need for manual intervention in the violation process and greatly reduce the operating cost of the electronic toll-collection system. This approach generally requires each lane to be equipped with a camera; however, the images can be stored in the lane or several cameras can be connected to a central image storage location.

License Plate Recognition
VES has one primary objective — to capture an image that has high enough quality to allow for the extraction of the license plate data. This data includes the plate number and the State that issued the plate. With this information the owner of the vehicle can be identified by searching for a match in a local vehicle plate database or by obtaining this information by some arrangement with the associated State division of motor vehicles. The challenge is the accurate and cost-effective extraction of the plate information. Currently, most systems rely on a human being to review the image and key in the plate number and State. This manual method is labor intensive and allows the possibility of incorrect image reading or keying of the information. However, Optical Character Recognition (OCR) technology has advanced to a level where some vendors are proposing and actually building systems that incorporate automatic recognition of the license plate and OCR to extract the license plate number and State from the image. The major problem with automatic LPR extraction is its level of inaccuracy. There is not necessarily a problem with the technology itself, but rather a combination of factors inherent in the way license plates are designed, issued, and used. Among these factors are: • • • •
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Lack of standards for license plate uniformity. Dirty plates, damaged plates, and obstructions. Plate is mounted incorrectly or missing; temporary tags. Supplemental lighting systems aren’t effective for all plates (e.g., those with plastic covers).

Electronic Toll - Collection System

• •

Differences in vehicle design and license plate position. Ambiguity and similarity of letters/numbers cannot be explicitly determined (such as the letter O and the number 0).

As a result of these factors, LPR systems often still require manual intervention to read images and confirm the results. To improve the overall results, some vendors have provided the capture of multiple images with LPR run on several images. If the LPR determines the same plate information over multiple images, the confidence level of the data is improved and manual review may not be required. Any discrepancy is placed into a manual review queue or treated as a lost-revenue transaction. These limitations have constrained the use of LPR in VES, and most system in use or under development do not use LPR. SOURCES: • • • • An ETTM Primer for Transportation and Toll Officials, March 1995, ITS America, ETTM Task Force. Electronic Toll & Traffic Management (ETTM) User Requirements for Future National Interoperability, January 1995, ITS America, Standards and Protocols Committee. ETTM - An Early ITS Winner, ITE Journal, December 1995, Lawrence Yermack, Maureen Gallagher, K.R. Marshall. Electronic Toll and Traffic Management (ETTM) Systems, NCHRP Synthesis of Highway Practices 194, 1993, Michael C. Pietrzyk, Edward A. Mierzejewski, Transportation Research Board.

5.3 CASE STUDIES
FasTrak
The Transportation Corridor Agencies opened the San Joaquin Hills corridor in California and uses the FasTrak electronic toll collection system to allow commuters to use the same transponder that they use on other toll roads in the state. The system will work with SR-91 express lanes and various others in the state.

Fastoll
Fastoll is Virginia’s toll collection system, operating on Virginia DOT facilities, the Dulles Toll Road, and the Coleman Bridge. Within five months of the Fastoll opening, in April 1996, over 50,000 Fastoll transponders were issued and 35,000 acounts opened. More than 60,000 toll accounts are being processed each day. Fastoll patrons are able to open accounts via prepaid mail-in applications, tollfree telephone calls, or via an internet application form, or by visiting one of the service centers in person (Traffic Technology International, Dec 1996/Jan 1997).

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Oklahoma
The Oklahoma Turnpike Authority manages 10 turnpikes each with some Electronic Toll Collection. The system has been operating since 1991, and is claimed to have 99.5 per cent accuracy. Currently, there are about 310,000 toll tags in circulation, representing 165,000 accounts with the turnpike authority. On interstate highways there is as little as 25 per cent Electronic Toll Collection while in local commuting routes the per cent is about 70. To encourage users to adopt Electronic Toll Collection, a 10 per cent discount applies and during hiliday periods Electronic Toll Collection users save 10 to 15 minutes per trip (TollTrans, Oct/Nov 1996).

Illinois I-Pass
The Illinois I-Pass began in 1993 and initially had 30,000 transponders. An expansion to the system, July 1998, will add another 250,000 transponders and will include 513 electronic lanes. It uses an axle-based classification system and features open tolling and barrier plazas. Each transponder is programmed for a specific class of vehicle based on the number of axles while each toll lane has an embedded axle counting device. In addition, for the expanded system, an auto-credit feature of the system will be enabled. When the system senses that a pre-approved motorist’s account has dropped below $10, it will automatically replenish that account by $40, charging the additional amount to the individual’s major credit card. The information from the I-Pass toll plazas is transmitted back though the Toll Operation Management System networks which relays the data to the host, a mainframe located at the Illinois Toll Authority’s central administration office. (Katie Brazel, 1996).

TransPass
The Maine TransPass system, currently with 122 automated toll collection lanes, has purchase 60,000 transponders with plans to purchase more. The system is very similar to the Illinois I-Pass.

E-ZPass
The E-ZPass, by year 1999, will be available at all participating toll facilities in the New York, New Jersey, Pennsylvania, tri-state region. The New York State Thruway Authority reports that approximately 40 per cent of all their toll transactions are made using E-ZPass transponders. At the Tappan Zee Bridge 75 per cent of the a.m. peak period transactions are made through E-ZPass. On the New York State Thruway west of the Tappan Zee Bridge, vehicles equipped with E-ZPass transponders have recently been detected at a rate of 19,500 per hour. On average, TRANSCOM’s System for Managing Incidents and Traffic (TRANSMIT) counts over 400,000 reads per day on the New York State Thruway and Garden State Parkway.

Metro-Dade County, Florida
To facilitate faster passage through the toll area for both residents and visitors, Metro-Dade County implemented an electronic toll system. With transponder devices (looking much like bar codes, but essentially wireless radios) affixed to their windshields, vehicles can cruise through the toll plaza. The toll road’s eight lanes are equipped with custom-designed transponder technology capable of detecting and reading information from moving sources-in this case, the number of axles on each passing vehicle, used to calculate toll fares for electronic collection-at speeds of up to 55 miles per hour. The
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system has a useful life of 12 to 15 years and can be technologically upgraded as needed or appropriate. Additional lanes offer customers more traditional payment options, such as paying a toll attendant or tossing coins in a basket. The electronic system has several advantages. Since users of the transponder devices must establish pre-paid accounts with the county, Metro-Dade collects toll revenue in advance and in greater increments, instead of dollar by dollar. The electronic system improves traffic flow, minimizes delays due to toll-collection procedures, and enhances collection accuracy and revenue projections for the jurisdiction.

California SR-91
The State Route 91 Variable-Toll Express Lanes is the first fully automated toll road in the world. It opened for revenue service on December 27, 1995. The four-lane toll facility is located in the median of the existing eight-lane Riverside Freeway in Orange County, California, between the City of Anaheim and the Riverside County line. Unlike other variable-toll roads which exist in Singapore, Scandinavia, France, and elsewhere, the SR-91 project is a single highway section serving an urban commute corridor, where a free, although congested alternative route is readily available. The privately built and operated facility charges tolls which vary with the time of day, reflecting the travel time saved by toll lane customers compared to users of the adjacent public freeway. The greater the traffic delays on the adjacent freeway lanes, the greater the toll. Currently, tolls follow a published schedule, although the technology would permit the toll levels to vary dynamically if this should someday be desired. All tolls are collected by Automatic Vehicle Identification (AVI), in part because there is not enough space in the freeway median for conventional toll booths. Non-AVI-equipped vehicles are prohibited from the facility. The electronic toll-collection concept is marketed regionally as the FasTrak. The FasTrak system on State Route 91 is inter-operable with FasTrak lanes on the other publically operated toll roads in Orange County, where conventional toll booths are also provided. Rideshare groups with three or more persons (HOV-3+) currently travel toll-free, although they may be charged a discounted toll sometime in the future. A special lane is provided for HOV-3+ vehicles to bypass the electronic toll-taking which occurs about halfway along the length of the facility. Proper use of the automated toll lanes is enforced by the California Highway Patrol (CHP), under contract to the California Private Transportation Company (CPTC), and through the use of video surveillance equipment. The CPTC operates the toll lanes on land leased from the State of California. The CPTC has thirty-five years to return a profit to its investors, after which time the toll lanes revert to full state control (airship.ardfa.calpoly.edu/~jwhanson/sr91info/sr91info.html).

Sullivan (1997) summarizes some early findings which have emerged to date from approximately one year’s experience with the SR 91 toll facility:
• The SR 91 toll lanes have been an early market success. By the end of the first year, peak period traffic had increased to the level where a toll increase was warranted to protect the toll lanes from the onset of congestion.

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• • • Even though 75-80% of peak period travelers on SR 91 are engaged in home-to-work trips, most customers do not use the toll lanes on a daily basis. Overall traffic volumes on SR 91 appear to have increased only a small amount during the first months of toll lane operation. The capacity increase due to adding two new toll lanes in each direction on SR 91 has resulted in substantially reduced peak period congestion which has encouraged some traffic shift back to the freeway from parallel arterials. Preliminary indications are that many toll lane users choose to enter the toll lanes under conditions where the expected value of their time savings is apperntly less than the tolls paid. Prior to and since the opening of the variable-toll lanes, average vehicle occupancy in the SR 91 and SR 57/60 corridors has changed very little. Initial post-opening results show an increase in the percentage of HOV-3+ vehicles in the SR 91 traffic stream, perhaps reflecting the fact that HOV-3+ toll lane users pay zero tolls. Commuters who use the toll lanes most frequently have higher income distributions than commuters who use the lanes less frequently or not at all. Surveys conducted in November-December 1995, April-May 1996, and late 1996 explored the traveler’s degree of approval of congestion-based tolls. Through all the surveys, the idea of providing additional toll-financed laned to bypass congestion consistently met with ap proval in the 60-80% range. However, the idea of varying tolls based on the severity of the congestion bypassed was not initially very popular, registering about 45% approval rating. Approval levels for operating the highway as a private business were in the 35-45% range both before and five months after the facility’s opening. The most recent survey in the winter of 1996 shows that travelers appear to be getting used to this innovative idea, and approval levels for most traveler categories increaed to the 50-60% range.

• •

• •

•

I-15 ExpressPass
The I-15 ExpressPass is a three-year pilot program funded by the FHWA and developed by the San Diego Association of Governments (SANDAG) in cooperation with Caltrans. The goal of the program is to reduce rush hour congestion on I-15 by making the maximum use of all traffic lanes. ExpressPass will allow a limited number of solo drivers to use the two reversible lanes normally reserved for carpools. These lanes stretch 8 miles down the middle of I-15 between State Route 56 and 52. I-15 ExpressPass is a monthly subscription program that allows single drivers to pay a monthly fee in order to use the I-15 Express Lanes carpool facility. To participate, drivers must have an ExpressPass account and display a permit in their windshield when theu use the lanes. Early observations of the program include: express lane traffic continue to remain free-flowing; actual expressPass use is less than expected; HOV use of the express lanes has increased; express lane violations have declined; customer satisfaction with the program is very high; perceived travel time savings is high; primary purpose of using the ExpressPass is work.
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5.4 EVOLVING TECHNOLOGIES
Intelligent Tags
These tags can perform computations on tolls and maintain customer accounts. These tags do not require validation based on a centrally-maintained database. Validation is done in the individual microprocessor-based transponders. Some systems can also interface with external peripherals to receive on-board displays. SOURCES: • • • • • • • • • An ETTM Primer for Transportation and Toll Officials, ITS America, ETTM Task Force, March 1995. Electronic Toll & Traffic Management (ETTM) User Requirements for Future National Interoperability, ITS America, Standards and Protocols Committee, January 1995. ETTM - An Early ITS Winner, Lawrence Yermack, Maureen Gallagher, K.R. Marshall, ITE Journal, December 1995. Electronic Toll and Traffic Management (ETTM) Systems, Michael C. Pietrzyk, Edward A. Mierzejewski, NCHRP Synthesis of Highway Practices 194, Transportation Research Board, 1993 Embracing ETC, October/November 1996 by Katie Brazel, TollTrans Electronic Toll Collection Systems (ETC), 1996, US Department of Transportation, www.its.dot.gov/docs/itibeedoc/etcs.htm Electronic Toll Collection, California PATH, //pelican.its.berkeley.edu/path/dss/etc.html Electronic Toll Collection (ETC), www.ettm.com Impacts of Implementing the California Route 91 Variable-Toll Express Lanes, Edward C. Sullivan, 1997

Return to Table of Contents

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CHAPTER 6

Transit-Management Systems

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Advanced Transportation Management Technologies

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Transit-Management Systems

The Advanced Public Transportation Systems (APTS) is a Federal Transit Administration sponsored program to encourage development and implementation of innovative technologies and strategies to improve public transportation and ridership. APTS is an integral part of the ITS initiative and allows for the integration of highway and public transportation intelligent transportation systems to take full advantage of the existing transportation infrastructure. APTS incorporates state-of-the-art computer, telecommunications, and navigational technologies to improve the service and safety of public transportation. Most recent FTA reports categorize the APTS according to four sets of services/ technologies: Fleet Management, Traveler Information, Electronic Fare Payment, and Transportation Demand Management. Not all of these categories and services will be discussed in this handbook, but operational strategies and technologies related to congestion management are discussed in this chapter. Transit management supports fleet management capabilities by monitoring both the location and performance of vehicles. Transit vehicles equipped with Automatic Vehicle Location (AVL) technology provide the basis for vehicle tracking. AVL provides information regarding the real-time position of a vehicle that may be used to monitor schedule adherence and provide travelers with information concerning the location of transit vehicles. Providing accurate information concerning the status and location of transit vehicles to travelers may improve customer satisfaction and increase ridership. Location information provided to dispatchers can be used to conduct advanced demand-responsive computer-aided routing and scheduling and may be used to manage fleet resources in response to events that impact schedule adherence. Information describing the current location of a transit vehicle is transmitted to a centralized dispatcher, who then compares the actual location with the scheduled location. Depending on the variance between the actual and scheduled locations, actions may be taken to improve schedule adherence and to transfer information to travelers. Transit vehicles equipped with Automatic Vehicle Identification (AVI) technology can request trafficsignal priority along signalized routes to improve transit route running times. AVI-equipped transit vehicles can also serve as probe vehicles to prove real-time data concerning the performance of the roadway system

6.1 TECHNIQUES/STRATEGIES
6.1.1 FLEET MANAGEMENT
Fleet management focuses on the operation of the vehicles and technologies that can be applied to improve vehicle and fleet planning, scheduling, and operations. Fleet management can improve the efficiency and safety of the vehicles, which results in a reliable system that could attract new ridership and help the operation become more cost-effective.

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6.1.2 COMMUNICATION SYSTEMS
As with any other component of an ITS, communication is a vital component of an APTS. Various communication techniques and technologies are required to meet the communication needs of such integrated functions as the following. • Bus and control center communications. - Voice - Data - Emergency • • • • • • Fare payment. Park and ride operations. HOV / express bus lane access. Adaptive signal system. Intermodal communications. Traveler information system.

Bus and control center communications are the critical link to a successful APTS implementation, and often require bandwidths to transmit significant amounts of information over a large metropolitan area. In most instances, these requirements can only be met through the use of a dedicated FCC, licensed service. Other innovative methods, such as transmission overlay of APTS information by commercial FM radio station transmission or use of Radio Data Systems (RDS), have demonstrated capabilities for use as APTS communication technologies.

6.1.3 GEOGRAPHIC INFORMATION SYSTEMS
Geographic Information Systems (GIS) are computer-based systems that combine hardware, software, and procedures to capture, manage, manipulate, analyze, and display spatially referenced data. GIS has been extensively used in transportation-management systems. It is a tool that may be used for planning, operation, management, and maintenance of a public transportation system. Transportation is an ideal GIS application due to the fact that a transportation system and its associated components are spatial in nature. Applications of GIS in transit management include: • Service and facility planning for bus routes, bus assignments, scheduling, ridership, parking lots, facilities, shelter locations, running times, accident analysis, and customer complaints.

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Operations using street and route maps, service performance monitoring, emergency call location identification, and vandalism location and history. Market development using maps and data that identify land uses, employment sites, demographics, and travel patterns. Customer information and service through bus route maps, trip planning and route selections, on-time performance data, and customer data. Transportation service analyses such as service performance statistics, origin and destination of ridesharing applicants, adherence to the Americans with Disabilities Act, and HOV violations. amount of data using a relational database and an electronic map. GIS-based systems have shown to be user friendly in terms of interface and operation. with an electronic map and a relational database. GIS software can run on PCs to mini-computers and workstations. Hardware selection is dependent on the software vendor, size of the geographic

6.1.4 AUTOMATIC VEHICLE LOCATION SYSTEMS
Automatic Vehicle Location systems (AVL) are computer-based vehicle tracking systems. These systems have been used extensively in military and civilian applications such as commercial vehicle fleets, police and fire services, and transit operations. AVLs have many inherent benefits, and depending on the type of technology, can provide the basis for implementation of other APTS components. AVL use in transit operations has significantly increased with the introduction of ISTEA and the Clean Air Act, policies that reorganized the funding structure and parameters for many urban areas. AVL is expected to have many benefits, including: • • • • • • • • Increased operating efficiency. Increased service reliability. Improved response to service disruptions. Improved detection of mechanical problems. Improved driver and passenger safety and security. Input to passenger information systems. Input to preferential traffic-signal actuators. Improved database.
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Although AVL are primarily used to identify the location of the vehicle, they are often used in conjunction with other applications. The amount of information that may be transmitted between the bus and the management center is a function of the selected hardware and software systems and the data transmission techniques. Other APTS applications that are often implemented in conjunction with AVL are: • • • • • • • • Schedule adherence monitoring. In-vehicle silent alarms. Automatic traveler information system. Vehicle component monitoring (i.e., engine components, brakes, etc.). Automatic passenger counters. Computer-aided dispatch. Preferential traffic-signal systems. Automatic fare-payment systems.

6.1.5 TRANSPORTATION-MANAGEMENT CENTERS AND TRANSIT-OPERATION SCHEDULE
Transit-management software is designed to optimize the use of all implemented technologies. Transit-management software has been used for computer-aided dispatching, computer-aided service restoration, and service monitoring. Service monitoring is performed through collection of operational data such as vehicle positions, passenger data, traffic and weather conditions, vehicle and driver performances, alarms and calls. This information is then analyzed using various routines in the software to determine such information as schedule adherence, route adherence, status of vehicle components, estimated time of arrivals, service requests, statistical information, and emergencies. In case of an emergency or a service call, the system can determine the best course of action and recommend alternatives for restoring service. Once the plan of action is approved, the system can assist in quickly dispatching appropriate services to the location and rerouting or rescheduling the system to handle the emergency. Using the traveler information system, the system can inform the transit users of the system status and provide alternatives. Transit-management software is part of an integrated management system often located in Transportation/Transit Management Centers (TMC). A transportation management center can be described as a facility that manages, operates, and maintains a multimodal transportation system. TMCs use a wide range of technologies to manage and control a transportation network that facilitates the movement of goods and people using various modes of transportation. There are two basic tasks performed by a TMC. One is to plan, manage, and operate the transportation system, and the other is to provide information to the users. TMCs may use various technologies to gather and disseminate information. For example, an AVL-equipped
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bus may provide information about its location. The TMC can use this information to estimate the time of arrival at the next stop and automatically display this information on the wayside and/or onboard electronic signs. More detailed information regarding TMCs is their operation is available in Chapter 7.

6.1.6 TRAVELER INFORMATION SYSTEMS
Traveler information systems provide the transportation-system user with information regarding one or more modes of transportation. This information can be provided pre-trip or en-route. The user may access the information at home, work, a transportation center, wayside stops, on board the vehicle, or through various technologies while traveling. Information that may be provided to the users is grouped into three categories: General Information. The user is provided with information on available transportation services in the region. Information that may be identified includes transit services, bus or rail, taxi services, major roadways, attractions, and other such information on operating agencies, telephones numbers, and automated linking to agencies’ home pages. Schedule Information. The user is provided with a time table/itinerary for a given trip. Information may include details about the route, fare, schedules, transfer requirements, bus stop locations, and maps. Operational Information. The user is provided with real-time status of the transportation system or services. In the case of a transit agency, the patrons may obtain information regarding expected arrival/departure times, delays, passenger loading, and congestion so that the user may an informed decision with regard to their trip and available alternatives. Pre-trip information may be used to plan the mode of travel and/or best route. The pre-trip information may be accessed through the use of: • • • • • • • Cable television. Radio broadcasts. Personal computers. Personal communication devices. Telephone. Information kiosks. Non-interactive displays.

Many jurisdictions have access to cable television through Government Access Channels. Such channels can be used to display real-time information regarding the transportation network. Radio
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broadcasters are often interested in getting first-hand information from transportation managers to keep the listeners informed. Personal computers and the Internet have opened a whole new world for exchanging information. Internet and personal computers allow for a large-scale access to userspecific information. Other information technologies that lend themselves to automation are telephone systems, information kiosks, and personal communication devices. En-route information can be communicated to the user through: • • • • • • Personal communication devices. Radio broadcast. Electronic signs (wayside and on-board). Dynamic message signs. Highway advisory radio. Kiosks.

The most commonly used en-route information systems for transit applications are wayside and onboard electronic signs. Using some of the technologies already discussed, such as AVL and on-board vehicle logic units (VLU), electronic signs can display real-time route-specific information, such as estimated arrival/departure times and cause/duration of delay. Kiosks can be used at transportation centers or major employment or retail centers to provide specific or network-wide information regarding transit services and the transportation network to assist the user in making an informed decision about their trip.

6.2 TECHNOLOGIES
6.2.1 FLEET MANAGEMENT
Technologies used in fleet management include communication systems, automatic vehicle location, automatic passenger counters (not discussed in this handbook), and transit operations software.

Communication Systems
Alternative communication techniques being used or developed to meet future needs of the APTS include:

•
•

Low-earth-orbit satellite services, which rely on satellite communication services to transmit information. Analog/digital cellular. Cellular services provide excellent coverage in most metropolitan areas. Although conventional analog systems are nearing capacity, digital systems may provide some additional capacity.

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•

FM sub-carrier radio data systems. These systems allow for the overlay of traffic and other information in the frequency sidebands (unused portion of the frequency) of commercial FM radio stations. Personal communication services. This technology is still in development. Spread spectrum systems. These systems use a low power signal to transmit over a band of frequencies. The system selects which band to use based on availability. Because of this, lowpower signal spread spectrum systems do not require FCC licensing. However, these types of systems have limited range and may require numerous antennas and repeater stations. Shared spectrum technology is sharing a spectrum with other public agencies using digital features of trunking. Examples of these systems are 800- and 900-MHz systems. Wireless data services. This is the utilization of wireless data services such as Cellular Digital Packet Data (CDPD) and commercial services such as ARDIS. Commercial mobile radio, which has limited use. Integrated communication systems. These systems may include a combination of mobile radio and other technologies listed above.

• •

• • • •

Although each of these technologies may be used in APTS applications, selection depends on the performance requirements, cost of operations, and the availability of spectrum.

Automatic Vehicle Location
An AVL system may be thought of as two components: the location technology and the data transmission methodology. Location technology include hardware and software that are required to determine the vehicle location. Data transmission methodology determine the process by which the vehicle and the management center exchange data. Location Technologies An AVL system may employ one or more of the following technologies discussed in this section. Often AVL systems, especially in large urbanized areas, require the use of more than one location technology to meet the requirements of the system. a. Signpost and Odometer Sign and odometer technology required the installation of signpost (electronic transceivers) along bus routes, installation of an on-board computer and transceiver in each vehicle, and means to transmit information from the signpost to the traffic management center. The signpost, normally mounted on utility poles, communicates with the vehicle using a low-powered signal. The information may be exchanged as the vehicle passes a signpost. One method is that the signpost transmits its unique identification information to the vehicle. The onboard computer uses the information about the signpost location and the vehicle information to calculate the vehicle’s location and transmit this to the managment center. By another method, the vehicle has a transmitter with a unique ID that it
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transmits to the signpost as the vehicle passes by. The signpost then transmits the information back to the managment center for processing. The first method allows for locating the vehicle at any time, while the second method can only identify the status of the vehicle at the last signpost. It should be noted that the second method does reduce the radio traffic and the need for reserved frequencies. Although signpost and odometer technologies have been well-tested and proven, there have some drawbacks. Some limitations of this type of AVL system are that the routes are fixed and modifications to the route require additional equipment; the amount and type of field equipment could introduce significant maintenance issues; and coverage is available along the route only, thus, the system is incapable of tracking vehicles that stray off-route. b. Global Positioning System Global Positioning system technology uses signals transmitted from satellites in orbit. The information is received through the on-board receiver and computer, and can be transmitted to the management center. GPS works anywhere a satellite signal can reach. However, the signal cannot penetrate tunnels, buildings, and/or foliage. For this reason, many systems that utilize GPS technology utilize a secondary system to complete the coverage where urban structures and heavy foliage could interfere with the satellite signals. Any of the other location technologies may be used to complement the GPS system. The recent implementation of AVL in the Atlanta MARTA system used dead-reckoning technology to supplement the GPS system. Although there are systems under design using signpost technologies, most of the new AVL systems are being designed using the GPS technologies. This can be attributed to the GPS flexibility, lower maintenance requirements, broader coverage area, and added security due to consistency of surveillance. c. Radio Navigation/Location Ground-based radio includes Long Range Aid to Navigation (Loran-C). Loran-C uses low-frequency waves to provide signal coverage. It determines location based on the reception of transmissions and the associated timings from various transceivers. Its performance is significantly reduced in urban areas, and is highly susceptible to radio frequency and electromagnetic interference from power lines and substations in urban and industrial areas. However, there are private providers of radio-locating services that operate very effectively in an urban area due to blanketed coverage using an 800- or 900-MHz band. Often, these are cellular providers that have already made a significant investment in building an infrastructure to support this type of activity with minor modifications. Multiple users and users of the radio towers tend to keep the subscriber’s rates affordable. d. Dead-Reckoning Dead-reckoning utilizes the odometer reading of the vehicle, and may include an on-board gyroscope or compass and a computer to determine the vehicle’s location in reference to an established station. Dead-reckoning technology is often used to supplement one of the other location technologies and is not used as the primary system. If the GPS or radio signal is lost due to obstructions (e.g., tall build6-10

Transit-Management Systems

ings, tunnels, bridges, foliage), the vehicle can still be located with some degree of accuracy, using dead-reckoning technologies, until the signal transmission can be reestablished.

6.3 CASE STUDIES
6.3.1 CALIFORNIA ADVANCED PUBLIC TRANSPORTATION SYSTEMS
In partnership with both the Federal Transit Administration and the Federal Highway Administration, the California Department of Transportation (Caltrans) has established the California Advanced Public Transportation Systems (CAPTS) program. This program and its resultant public/private partnerships may soon enable attainment of a cost-effective personalized public transportation system that is competitive with the private automobile. The CAPTS projects are among the various field operation tests underway throughout California.

The Los Angeles Smart Traveler (Test Over)
Smart Traveler operational test partners include Caltrans, California’s Health and Welfare Agency, the Los Angeles (L.A.) Metropolitan Transportation Authority (MTA), and private sector affiliates Pacific Bell Telephone, International Business Machines (IBM), and Commuter Transportation Services (CTS), Inc. Smart Traveler brings together a number of existing systems from different agencies. Caltrans maintains a freeway conditions map that provides traffic speed information from more than 1,000 points on the freeway system, and presents it in the form of a color-coded map updated approximately every 30 seconds. MTA has a transit database which provides route, schedule, and fare information for all bus and transit lines serving L.A. County. CTS maintains the region’s ridesharing database, that contains origin/destination information on individuals interested in carpooling or vanpooling. These three agencies are linked electronically to provide the user with information from each of them via any Smart Traveler communications interface. Pretrip and en-route Information is available to travelers who wish to plan or reroute their trip, reschedule it, or choose another mode of travel based on projected delays. Ride matching and reservation services are available through a toll-free telephone number with a bilingual audiotext, touchtone responsive information system. Callers are able to register with CTS over the phone; once registered, they are able to hear a list of trip-matching registrants read back to them over the phone. They are also able to record a voice message to be automatically sent over the phone to all those who appear on their matchlist.

Los Angeles Smart Traveler Kiosks (Test Over)
Seventy-eight bilingual, automated, multimedia kiosks were installed within the greater Los Angeles area of California as part of the Los Angeles Smart Traveler field operational test being carried out by the California Department of Transportation’s Advanced Public Transportation Systems Group. As a consequence of the Northridge earthquake, the Smart Traveler Kiosk element was expanded from a limited test to an extensive network of kiosks providing area travelers with information on transporta-

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tion options. One of the principal objectives of the field operational test is to assess the effectiveness of this method of disseminating traveler information to influence travel behavior. The kiosks utilize a personal computer-based system, connected via dedicated digital telephone lines to a telecommunications system established by California’s Health and Welfare Agency Data Center in Sacramento. This system accesses the rideshare, transit, and freeway-conditions information residing in databases maintained by Commuter Transportation services, Inc., Los Angeles County Metropolitan Transportation Authority, and CalTrans Transportation Management Center in Los Angeles. The kiosks provide personalized transit itineraries including routes, fares, schedules, and origin-to-destination travel times; carpooling possibilities; real-time freeway conditions; and videos on various transportation topics such as “driving tips” and “effect on the environment.” The user interface is a touchscreen monitor. Freeway flow status is displayed on a map. The videos are stored on a laser disc within the kiosk. All other information is displayed in textual form. Carpool match lists and transit information can be printed by the kiosk.

Caltrans’ Automated Transit Pass - The Los Angeles Smart Card (Test Over)
Partners in this field operational test include Caltrans, the L.A. Metropolitan Transportation Authority, the L.A. Department of Transportation, the City Transit Departments of Torrance and Gardena, and Echelon Industries, Inc. Electronic Payment Services allows travelers to pay transit bus and rail fares, parking fees, and road tolls without using cash. The smart card is more convenient, reduces the delays caused by travelers queuing up to pay, and increases security by reducing cash on hand. Eventually, card functions may increase to cover purchases such as gasoline and snacks, much as a bank Automated Teller Machine (ATM) card can be used now. System components include passenger transaction cards, an automated card reader/writer on board the bus, a downloading device for daily or weekly information retrieval, the central processing system, centralized funds transfer and processing functions, and a mobility management center for dissemination, renewal, and security of cards.

Santa Clara County Smart Paratransit Demonstration
Smart Paratransit Demonstration partners include Caltrans, Santa Clara County Transit District, Outreach Paratransit Broker, Trimble Navigation, UMA Engineering, and Navigation Technologies. When travelers with disabilities request transportation from the regional paratransit dispatch center, the system makes a reservation and routes a vehicle to them. For cost-effectiveness, the traveler is transferred to a fixed-route mode as soon as is practical. Personalized public transit service thus provides disabled travelers with transit access to previously unreachable locations, and acts as a specialized feeder service to regular mass transportation lines. Personalized public transit service is especially valuable in rural areas, where fixed-route service is too costly to maintain. The service is enabled by automatic vehicle location technology, demand responsive dispatching software, and a navigable map database. These advanced technologies allow the dispatcher to locate the closest vehicle to the requester and to route it via an in-vehicle display to guide the driver.

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Ventura/Lompoc Smart Card (PASSPORT)
The Ventura/Lompoc Smart Card Demonstration project is an expansion of the Los Angeles Smart Card Field Operational Test. Its purpose is to complete the development of the comprehensive, integrated Passenger Transaction Unit and Vehicle Monitoring System. This project researches an advanced transit fare payment media (Passport), automated passenger counters, improved radio communications for demand-responsive operations, speech systems and displays for bus stop announcements, and high speed printers for transfers. Ventura County’s Smart Cart (Passport) is a high-tech, prepaid bus pass that lets the user get around all of Ventoura County. The Passport may be paid for and “recharged” by telephone or mail. As of January 1996, the Smart Passport was valid on every public transit system in the County. In Ventura, seven transit operators have been supplied with systems to track vehicle location, produce synthesized speed messages, utilize local area radio for up and down-loading data in their garages, as well as fare transaction units for both passengers and drivers on a total of 75 vehicles. In Lompoc, 10 vehicles have been supplied with fare transaction units and radios. An area-wide radio-based station to accommodate centralized dispatching operations has been developed with an interactive, graphicbased system integrated with fare transaction system.

The Ventura/Lompoc Smart Card demonstration project is funded by the FHWA, the FTA and Caltrans.

Transit Probe
The transit probe project is a multi-jurisdictional transit effort whose vision is to integrate transit and traffic management with Advanced Traveler Information Systems (ATIS) to benefit transit agency operations and partner with traffic management agencies. It will provide the public transit rider with real-time transit information from which better informed travel plans can be made. Transit Probe calls for fixed-route transit vehicles to be equipped with GPS receivers, and will travel along bus routes within Orange County as probes and will provide highly accurate location, speed, and time data to a central dispatch station. Value-added information such as arterial freeway congestion, incident data and transit information will be derived from GPS data and disseminated. Transit information will be dispersed to the general public via strategically located kiosks throughout Orange County. Traffic related information will be transmitted via TravlTIP to partner agencies (Caltrans District 12, the City of Anaheim, and the City of Santa Ana) to enhance arterial and freeway traffic operations and management.

Transit Probe, a $3 million demonstration project, is sponsored by the FHWA and Caltrans.

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6.3.2 DENVER SMART VEHICLE SYSTEM
The Regional Transportation District (RTD) in Denver has implemented an Automatic Vehicle Location Management and Monitoring System (AVL/MMS) operational test. This project is sponsored by the Federal Transit Administration under its Advanced Public Transportation Systems (APTS) Program. Westinghouse Electric Corporation was awarded the contract for implementation of the AVL/MMS. Their proposal incorporated a global positioning system GPS for vehicle location. RTD’s major objectives in implementing the AVL/MMS are: • • • • To improve the ability of dispatchers to adjust on-street operations. To provide accurate and real-time information to the riding public. To increase safety through better emergency management. To develop more efficient schedules.

RTD provides public transit services to six counties in the Denver region, covering an area of about 2,300 square miles. RTD operates more than 800 buses. The heart of the new communications system is the Operations Center, where fleet activity is controlled. The Operations Center is equipped with state-of-the-art dispatch consoles and computer work stations. The CAD feature gives the dispatcher greatly improved awareness of what is happening on the street and the ability to take quick action to rectify service anomalies. The MMS receives location and schedule-adherence information from each vehicle. The vehicle is displayed on a computer monitor as an icon overlaid on a map of the Denver area. Each bus icon is color-coded to indicate the degree of schedule adherence. Vehicle location is updated on the dispatcher’s monitor every two minutes under normal conditions. Other route, schedule, and incident data are reported to the dispatchers on an exception basis and displayed on a separate monitor. Each RTD vehicle is equipped with an integrated radio/AVL package, which consists of a conventional mobile radio, an onboard processor, a driver interface, and a GPS antenna. The vehicle odometer is connected to the onboard processor to provide movement/distance data to the system for the dead-reckoning feature, which supplements the satellite information in areas where satellite signals cannot be reliably received. The onboard processor receives the GPS information, calculates the vehicle’s position, and compares that position to the schedule. The vehicle position and scheduleadherence information is transmitted routinely to the Operations Center during the regular reporting sequence. Exceptions or incidents are transmitted immediately. The onboard processor also serves as an interface and distribution center to control the radio, switch signals from voice to data, and send/receive signals to/from various input/output devices such as the driver console, handset, external microphone, and public address system. The driver console (called the Transit Control Head) allows the driver to communicate with the dispatcher or send various preset messages. In case of an emergency, the driver can activate a silent alarm switch to alert the dispatcher. The dispatcher can then activate a covert microphone located

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on the bus to monitor the emergency situation. At the same time, the onboard processor will report the bus position at a more frequent interval to allow more accurate tracking of the vehicle in distress. The system uses nine radio channels, two for data and seven for voice. Transmitters are located at three different sites in the Denver metropolitan area. The CAD system selects the site and the available channel for best reception and channel utilization. Information generated by the system will be used to generate reports for use in evaluating transit system performance and providing data for operational and policy decision making. Real-time information obtained through the AVL/MMS will be used to update the arrival/departure time information displayed on signboards at the two downtown transit terminals. It will also be channeled to RTD’s Telephone Information Center (TIC) for use by the operators in providing real-time information to customers. In addition, as part of another ITS operational test, information kiosks providing real-time transit information are installed at the new Denver International Airport and selected bus terminals and park-and-ride lots.

6.3.3 MILWAUKEE SMART VEHICLE
The Milwaukee County Department of Public Works Transportation Division (MCTD), is deploying an Automatic Vehicle Location (AVL) system. On 602 buses, MCTD is installing a Global Positioning System (GPS) based AVL system-a 15 channel trunking radio system (800 MHz) and onboard computer that controls all vehicle subsystems. The AVL system tracks vehicle locations. By integrating the CAD software with the AVL system, MTCD has the capability to dynamically route and schedule vehicles. Phase 2 testing is underway and is scheduled for completion by Fall 1996. During this testing period, all system functions are being exercised. After phase 2 testing, the system will be tested under normal operating conditions for a period of 30 days. MCTD plans on disseminating real-time transit information through various traveler information systems and may test flexible-routes and bus signal priority (September 1996).

6.3.4 MARYLAND
Montgomery County is installing GPS-based fleet-management equipment on 250 of its buses, to allow monitoring of traffic congestion, bus schedule and route adherence, and increase vehicle security. Transit data will be gathered at the Montgomery County’s Transportation Management Center and fused with data being gathered by the traffic management system. This data will form an intermodal database that will be used by traffic and transit managers for operation, and provided to the public via Internet, pager network, telephone, and television. This system integrates both traffic and transit data in one common intermodal database. Dispatchers can view transit vehicle locations as well as traffic-signal information on a single map, providing them with true intermodal information. In Baltimore, the Light Rail System running up and down Howard Street (downtown Baltimore) is equipped with signal-preemption equipment. The system is based on AVL using GPS, and will enable the light rail vehicle to determine its position autonomously and request a green light as it approaches the next traffic signal. Subsystems are installed on the vehicle, on the wayside, and at intersections.
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The traffic-control equipment communicates with the wayside equipment and the Baltimore Traffic Control Center, incorporating schedule-adherence and vehicle-status reporting.

6.3.5 OREGON
In Portland, OR, an AVL system relies on GPS location data and radio-based voice and data communications to collect and deliver data that helps keep buses on schedule, in turn making bus service more reliable for riders. The system also keeps the Tri-Met customer service operators informed of bus locations so that they can notify callers when a bus is running behind schedule and suggest an alternative route. It also collects operations data, such as bus arrival times, that the Tri-Met can use later to improve bus scheduling (ITS World, Jan/Feb 1997).

6.3.6 KANSAS CITY
The Kansa City Area Transportation Authority is using AVL technology to track its fleet of 280 buses. It has installed an automatic vehicle locator on each, and “smart” signposts along the roadways to read and communicate bus locations directly to the computer-aided dispatch center. Dispatchers and drivers work together to stay on schedule. At dispatch headquarters, a console monitors the real-time, precise position of each bus and compares it with the bus’ planned route and schedule. Dispatchers can focus on those buses that are ahead of or behind schedule and make appropriate adjustments. A digital readout in each bus provides the driver with the same real-time information, indicating whether he or she is running early or late on the scheduled route. The system also equips each bus with a silent alarm for emergency communications. Under the AVL system, on-time performance of the transit system rose from 78 to 95 percent. Buses on schedule 95 percent of the time are more reliable and, consequently, more attractive to commuters and other customers. With this greater efficiency, Kansas City was able to eliminate seven buses from its routes without adversely affecting service to its passengers—and save more than $400,000 in annual operating expenses. The system provides another benefit: fast response in the event of crime, medical emergency, or other crisis. By pinpointing bus locations, the system slashes a response time of 3 to 10 minutes to approximately 1.

6.3.7 ANN ARBOR SMART INTERMODAL
Ann Arbor Transportation Authority (AATA) is deploying the Smart Bus concept—Automatic Vehicle Location (AVL) and Computer Aided Dispatch (CAD) system, vehicle component monitoring, Automated Passenger Counters (APC), Electronic Fare Payment (EFP) system, and in-vehicle video surveillance system. On 76 buses and 5 paratransit vehicles (subcontractor), AATA is installing a Global Positioning System (GPS) based AVL system-a trunking radio system (800 MHz) and onboard computer that controls and monitors all vehicle subsystems. The AVL system tracks vehicle locations, provides real-time data to traveler information systems, and triggers digital announcements and
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internal displays in the bus. AATA is disseminating real-time transit information via the Internet, kiosks, and cable television. By integrating the CAD software with the AVL system, AATA has the capability to dynamically route and schedule buses. The status of critical engine components is also monitored by the onboard computer. Electronic sensors installed within the engine continuously monitor critical vehicle components and report any out of tolerance conditions to the onboard computer which relays the information to the dispatch center via the data channel. Finally, AATA is installing a three camera video surveillance to increase driver and passenger safety (September 1996).

6.3.8 BALTIMORE SMART VEHICLE
Maryland’s Mass Transit Administration (MTA) is implementing an Automatic Vehicle Location (AVL) system and Computer Aided Dispatch (CAD) system. A prototype AVL system, LORAN-C receivers and 800 MHz radio, was previously tested on 50 buses and was successful. However, due to emerging AVL technologies, Maryland MTA is installing a new AVL system. On 200 transit vehicles (165 buses and 35 light rail vehicles), Maryland MTA is installing a Global Positioning System (GPS) based AVL system-a trunking radio system (800 MHz) and onboard computer that controls all vehicle subsystems. The AVL system tracks vehicle locations. By integrating the CAD software with the AVL system, Maryland MTA will have the capability to dynamically route and schedule vehicles. TMS Engineering has finished upgrading the microwave and communication systems. The communication system has been trunked to include a data channel. Currently, the AVL system has been installed on twenty buses. Additional buses are slowly being added, one to two a week, to ensure that the communication systems does not collapse. Maryland MTA has finished surveying the light rail vehicles. Installation of the AVL system on light rail vehicles is scheduled to commence in June 1996. The installation of the entire AVL system is scheduled to be completed by December 1996. The CAD software is undergoing field testing. In a future project, Maryland MTA plans on disseminating real-time transit information via kiosks and the Internet. Maryland MTA will provide this information to Capital Beltway Showcase’s Central Traveler Information System, a $4 million Advanced Traveler Information Systems (ATIS) and Advanced Transportation Management Systems (ATMS) project in the Baltimore/Washington, D.C. corridor. Maryland MTA may expand the AVL/CAD system to the entire transit vehicle fleet. In addition, Maryland MTA may test flexible routes and bus signal priority (September 1996).

6.3.9 CHICAGO SMART INTERMODAL
The Chicago Transit Authority (CTA) is deploying their Bus Emergency Communications System (BECS) and Bus Service Management System (BSMS). The BECS is a comprehensive communications base designed to support more effective delivery of bus service. New two-way voice and data radio system, and location capabilities are the main features of BECS. Under the BSMS, CTA is installing additional hardware and software modules to support Computer Aided Dispatch (CAD) software, transit priority movements at five signalized intersections, electronic traveler information way-side
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signs at two major bus stops, and enhanced data reporting system. Modules are only being installed on buses assigned to the 77th Street garage. CTA awarded the contract to OSC in February 1996. The new fixed voice and data radio infrastructure is scheduled to become operational in early 1997. All 264 buses are scheduled to be equipped in early 1998. CTA plans on deploying the BECS and BSMS to the entire bus fleet, approximately 1,800 buses. After systemwide deployment, some possible future enhancements are Computer Aided Service Restoration (CASR), automatic passenger load estimation, onboard electronic signs and annunicators, Electronic Fare Payment (EFP) system, and Automatic Passenger Counters (APC) (September 1996).

6.3.10 DALLAS PERSONALIZED PUBLIC TRANSIT
Dallas Area Rapid Transit (DART) is testing flexible-route buses on a regional crosstown route in the Dallas metropolitan area to determine if flexible service can increase ridership. By integrating DART’s existing Automatic Vehicle Location (AVL) system and an off-the-shelf Computer Aided Dispatch (CAD) software, slack in a bus’ schedule can be calculated. If there is sufficient slack, a fixed-route bus may deviate and pick up off-route passengers at a designated location. DART’s Geographical Information System (GIS) is used to identify the exact location of the off-route passenger pick-up point. The maximum route deviation is one mile. In April 1996, FTA awarded the cooperative agreement to DART. DART is currently developing a technical work plan and project schedule. DART may expand flexible-routes to other areas (September 1996).

6.3.11 DALLAS SMART VEHICLE
DART is also implementing an Automatic Vehicle Location (AVL) system. On 823 buses, 200 paratransit vehicles, and 142 supervisory and support vehicles, DART is installing a Global Positioning System (GPS) based AVL system-a 12 channel trunking radio system (900 MHz) and an onboard computer that controls all vehicle subsystems. The AVL system tracks vehicle locations. Final acceptance of the system occurred in February 1996. Electron Automation is still fine tuning the system. A major concern is maintenance of the route and schedule software because different databases feed the software. During the next three months, new software is being written to resolve the problem. The project is 99 percent complete. DART plans on disseminating real-time transit information through the Internet and kiosks and may test bus signal priority (September 1996).

6.3.12 DELAWARE COUNTY (PENNSYLVANIA) RIDETRACKING
Delaware County Community Transit (DCCT) is deploying a ridetracking system-automated identification cards, Mobile Data Terminals (MDT), automated scheduling and dispatching, and radio fre-

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quency data communications. The automated identification cards certify that the card holder has access to service and ensures that the parton’s sponsoring agency or agencies are charged appropriately for the trip. The identification card interacts with the MDT to identify the customer to the driver and to verify trip eligibility. Furthermore, the card creates a trip record-trip length and duration-that is used in the billing process to reconcile scheduled trips versus actual trips. Automated scheduling and dispatching and radio frequency data communications improve the ridetracking system’s efficiency (September 1996)

6.3.13 NORTHERN VIRGINIA SMART ROUTE SYSTEM
Potomac-Rappahannock Transportation Commission (PRTC) is deploying their Smart Flexroute Real-time Enhancement System (SaFIRES)-Automatic Vehicle Location (AVL) system, Computer Aided Dispatch (CAD) software, Mobile Data Terminals (MDT), and Geographical Information Systems (GIS). SaFIRES assigns the most appropriate vehicle-fixed and flexible-route buses, and health and human services transportation-to respond to a transportation request in a low density environment. On 50 vehicles, PRTC is installing a Global Positioning System (GPS) based AVL system—a threechannel trunking radio system and onboard computer that controls and monitors all vehicle subsystems. The AVL system is used to monitor bus locations and triggers digital announcements in the bus. By integrating the CAD software with the AVL system, PRTC has the capability to dynamically route and schedule buses. PRTC is also testing flexible-routes to determine if this type of service can increase ridership. If there is sufficient slack, a fixed-route transit vehicle may deviate from its route and pick up off-route passengers. PRTC’s GIS is used to identify the exact location of the off-route passenger pick-up point. The maximum route deviation is three-fourths of a mile. Finally, SaFIRES streamlines the National Transit Database reporting process and tracking of health and human services transportation ridership. The AVL system and MDT have been installed on 22 vehicles. The CAD software is being tested and debugged. Testing of the communications system was scheduled for July 1996 (September 1996).

6.3.14 WINSTON-SALEM MOBILITY MANAGER
Winston-Salem Transit Authority (WSTA) is testing the Mobility Manager concept by implementing the Paratransit Automated Scheduling System (PASS). PASS is a software package that automates the dispatching of paratransit service and is a comprehensive management information system that automates the reporting and billing of paratransit service. On three paratransit vehicles, WSTA is installing an Electronic Fare Payment (EFP) system and a Global Positioning System (GPS) based Automatic Vehicle Location (AVL) system-a trunking radio system and onboard computer that controls and monitors all vehicle subsystems. The AVL system tracks bus locations. With the project in Phase Two, fixed-route buses, vanpools, carpools, and taxis are being incorporated into the Mobility Manager. WSTA plans on disseminating real-time transit information through various traveler information systems and may test bus signal priority. WSTA may expand the AVL system to the entire fixed-route and paratransit fleet (September 1996).

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6.4 EVOLVING TECHNOLOGIES
Automatic Vehicle Location (AVL)
Global Positioning System (GPS)-based AVL systems are used for transit fleet management to monitor transit vehicles along routes, permitting quick response to changing needs, breakdowns, and vehicle or passenger emergencies.

Real-Time Computer-Aided Dispatch
Real-time computer-aided dispatch is an integrated transit scheduling and recutting system that provides real-time information to dispatchers.

On-board Sensor
On-board sensor systems automatically monitor passenger loadings, location of the vehicle, fare box revenue, operating condition of the engine, and other equipment.

Smart Traveler Technologies
These systems (e.g., kiosks, interactive displays on computers, cable TV) provide real-time information to travelers at home, the workplace, or transit centers that help travelers choose their mode of travel or alter their route due to delays.

Smart Intermodal Systems
Smart intermodal systems involve integrated electronic payment for transit, highway tolls, and parking all through one payment medium for a range of intermodal services. This involves imaging technologies as well as smart cards, tracking, and AVL systems.

Dynamic Ride Sharing
Dynamic ride sharing is intended to match travelers to drivers forming carpools dynamically. Etak, Inc. has developed SkyMap, a complete map and satellite navigational system that works with a personal computer. Priced around $400, SkyMap features a digital map database, comprehensive traveler information, a global positioning system antenna that includes a PCMCIA card connection, and a remote control. The new system converts a laptop PC into a complete mobile navigation guide, tracking a traveler’s progress in real-time on detailed “moving maps” that display cities, major streets, and highways throughout the continental United States. (www.itsonline.com/attn/ msg00010.html) TranSmart Technologies, Inc. recently released TrafficOnline (TOL) V1.0. The company calls this “the first tool for receiving customized real-time traffic information for major U.S. cities.” TOL is an interactive Internet shareware program that uses patent-pending technologies to provide, via personal computer, customized, route-specific and point-to-point real-time information on travel time, speed, incidents, construction and weather; clickable real-time congestion maps of major city highways;

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automatic warning of abnormal route travel times via TOL or automatic e-mail; and automatic updates of real-time traffic information (www.itsonline.com/attn/msg00009.html). Etak has partnered with Metro Networks to provide “the first nationwide real-time traveler information system.” Traffic information will be delivered via multiple technologies, including wireless products (e.g., palmtop computers, pagers, cellular phones) and fixed devices (e.g., home computers, interactive TV, interactive kiosks) (www.itsonline.com/itsnews.html).

Radio Broadcast Data System
Radio Broadcast Data System (RBDS) is able to receive traffic announcements that are broadcast even when the traveler is listening to another station or to a cassette or CD. The broadcaster can send a signal to the RBDS radio to “break-in” to whatever the traveler is listening to and announce the traffic information. At the end of the announcement the radio will switch back to whatever the traveler was listening to before. Conventionally, radios display the frequency of the station you are listening to. On RBDS radios, the name of the station (rather than the frequency) is displayed. In the future one will see a display of short messages, such as song titles, artist information, and inevitably advertising messages (www.dungeon.com/~start/rdsst.html). RBDS technology is a way of sending information directly to wireless receivers. One of the initial uses for this technology is to broadcast accurate real-time traffic information directly to vehicles or smart information kiosks. Another use for RBDS is to broadcast differential correction information for use by global positioning system receivers. Currently traffic information is widely available through commercial broadcast radio; however, it does not always reach the traveler at a time or location where the information is useful. By using RBDS technology, timely traffic information is delivered directly to an instrumented vehicle or kiosk. Thus, relevant traffic information is always available to the traveler.

The Phoenix Deployment Test
Real-time traffic information is gathered from the Arizona Department of Transportation, city of Tempe, Metro Networks and Skyview Traffic Watch Inc. Crusader Software (PC NT 3.51) developed by Daltek AB is used to encode the traffic information. Differential Corrections, Inc. broadcasts the encoded information from KSLX FM 100.7 radio station. Volvo systems (Dynaguide in-vehicle and PC-based units) overlay the traffic information onto Maricopa County Department of Transportation maps of the metropolitan Phoenix area. Retki software developed by Liikkuva (running on notebook PCs) overlays the traffic information onto Etak maps of the metropolitan Phoenix area (www.azfms.com/About/rbds.html). SOURCES: • Advanced Traveler Aid Systems for Public Transportation, September 1994, Publication No. DOTT-95-07.

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• • • • • • • • • • • • • • • • • • •

Advanced Public Transportation System: The State of the Art, Update 96, January 1996, Publication No. DOT-VNTSC-FTA-95-13. Internet Address http://www.fta.dot.gov/library/technology/APTS/update/index.html Building the ITI: Putting the National Architecture into Action, April 1996, Publication No. FHWAJPO-96-011. Review and Assessment of En-Route Transit Information Systems, July 1995, Publication No. DOT-T-96-03. Review of and Preliminary Guidelines for Integrating Transit into Transportation Management Centers, July 1994, Publication No. DOT-T-94-25. Advanced Public Transportation Systems Deployment in the United States, August 1996, Publication No. FHWA-JPO-96-0032. National Transit GIS Guidelines, Standards, and Recommended Practices, January 1996, U.S. DOT Publication No. DTRS57-95-P-80861. Internet Address: http://www.fta.dot.gov/fta/library/technology/GIS/ntgistds In-Vehicle Navigation Devices, Internet Address: http://www.its.dot.gov/app3.htm Assessment of Intelligent Transportation Systems Benefits: Early Results, August 1995, Publication No. FHWA-JPO-96-001 Implementation of National Intelligent Transportation Systems Program: A Report to Congress, January 1996, Publication No. FHWA-JPO-96-004. Internet Address: http://www.its.dot.gov/congress.html Intelligent Transportation Infrastructure Deployment Database: Interim Report, June 1996, Publication No. FHWA-JPO-96-0018 Intelligent Transportation Systems Projects, January 1996, Publication No. FHWA-JPO-96-0003. Intelligent Transportation Systems: What are the Benefits of the Transit Components of Intelligent Transportation Systems, April 1996, FHWA Publication No. is not available. Operation TimeSaver: Intelligent Transportation Infrastructure Benefits: Expected and Experienced, January 1996, Publication No. FHWA-JPO-96-0008. Internet Address: http://www.its.dot.gov/docs/itibeedoc/ Transit Geographic Information Systems, August 1995, Publication No. FHWA-JPO-96-0009. Telecommunication in Transportation: Key Issues and Best Practices, September 1996, Publication No. FHWA-JPO-96-0034.

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• • • • • Advanced Public Transportation Systems: Project Summaries, April 1996. Internet Address: http://www.fta.dot.gov/library/technology/APTS/iti/project9.htm Advanced Public Transportation Systems Publications Catalog, March 1996, FTA Publication with no Publication No.. Intelligent Transportation Systems/APTS, www.fta.dot.gov/library/technology/APTS/t_its.htm Advanced Public Transportation Systems (APTS): Project Summaries, June 1996, www.fta.dot.gov/ library/technology/APTS/iti/project9.htm#TRANSIT

Return to Table of Contents

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CHAPTER 7

Regional Multimodal Traveler Information Center

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Advanced Transportation Management Technologies

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Regional Multimodal Traveler Information Center

7.1 BACKGROUND
The regional multimodal traveler information center is the transportation-management system’s centralized source of road and transit information. The center is the focal point for information collection and dissemination. Each center’s and agency’s facility is just a part of the total regional transportation network covering all modes (road and transit), all types (freeways and arterials), and all areas (adjacent cities and counties). Operational decisions made by one agency impacts facilities operated by other agencies. It is important to collect and coordinate the information and response of different management and control systems by different centers and agencies. This requires interconnection of the traffic-management centers and the exchange of real-time data. Traffic-management centers need to be able to exchange real-time status data in order to monitor the condition of facilities under the management of other centers. In addition, the interconnection of centers needs to enable a computer or operator at one center to make changes in the operation of field devices managed by another center. Where decisions are made by one center, such as to change the signal-timing plans based on detector data, it is necessary that other affected centers implement actions in tandem with that decision. This requires the ability of one center to issue commands to other centers. There is a need for a centralized source of real-time roadway and transit information to provide a comprehensive and integrated view of the road and traffic conditions throughout the metropolitan area or region. Potential users of this information include both the end users (e.g., travelers, traffic managers, transit operators, private sector transportation-intensive businesses) and the private sector value-added resellers of the information and related traveler services. This information repository may be either a centralized or an interconnected set of data management facilities that directly receive real-time information from the various roadway detection and surveillance systems and other information sources, either public or private. The Regional Multimodal Traveler Information Center combines this information, packages the information in a variety of formats, and provides the information to users through different distribution channels (e.g., telephone voice and data services, radio and television broadcasts, kiosks, HARs, computer-based Internet services, in-vehicle devices, DMSs, etc.). The information may be provided both directly to the public and to private sector information service providers that will supplement it with additional information, features, and services, and market the enhanced service products. The center links data provided by other advanced transportation systems into a comprehensive regional information system. The Regional Multimodal Traveler Information Center is capable of providing automated feeds of traffic, transit, and other transportation-related information to the appropriate distribution channels. Basic information may be made available directly to communications outlets, (e.g., HAR) while specialized feeds to users are provided by private sector information service providers. The type and volume of information can be tailored to the user population, the type of distribution media employed, and the users’ special devices (e.g., pagers, radios, telephones, in-vehicle navigation devices, etc.) for receiving and displaying that information. The Regional Multimodal Traveler Information Center provides/supports a level of data integration (fusion) to clearly reflect the status of the road network (travel times, environmental conditions, special events or conditions, etc.) and transit schedule information. Metropolitan areas generally consist of multiple local jurisdictions and State-level organizations, each responsible for providing some level of traffic surveillance, management, and control. The Regional
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Multimodal Traveler Information Center supports interjurisdictional coordination involving activities segments of the metropolitan area (e.g., HAZMAT incident response, special events, weather-related or maintenance operations, etc.). Managers of the traffic network, as well as the organizations efficiently coordinate plans when assisted by common access to the information within the Regional Multimodal Traveler Information Center databases. Provider (ISP) subsystem; the Remote Traveler Support (RTS) subsystem; and the Personal Information Access System (PIAS). Traffic and transit data are input, processed, and stored by the ISP The ISP . managed in separate facilities). The other two subsystems, RTS and PIAS, request information from the ISP and provide it to the traveler. provided by both public and private-sector entities. The ISP is capable of combining data from different sources, packaging the data into various formats, and providing the information to a variety The RTS subsystem disseminates the information at fixed sites, such as transit stops, kiosks, shopping malls, and other public places. The PIAS subsystem disseminates traveler information in the home, ture for a corridor-wide traveler information system was developed for the I-95 Corridor Coalition and can be found in Appendix K). in-vehicle products) and provides analysis of its future potential. The following are summaries of market overview. Advisory systems (i.e., systems consisting of all the features of autonomous systems such as vehicle navigation and destination directory-type information, as well as additional communica1995). • with roadside beacon-based infrastructure to integrate latest traffic information, real-time, into the suggested route calculations), advisory systems are projected to account for an increasing per• • In 1991, approximately 650 units were shipped throughout the United States and this quantity In 1991, the average system price was about $2,500. In 1995, the price decreased to $1,600.

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Regional Multimodal Traveler Information Center

•

Market projections forecast a total estimated market of $210 million in 2001, representing approximately 260,000 unit shipments per year.

Kenneth Orski (http://www.itsonline.com/ko_atis.html) discusses traveler information services as follows: Live traffic reports on commercial broadcast radio are the most widely used medium to communicate with the traveling public. A 1993 University of California study revealed that 94 percent of motorists obtain traffic information from their home or car radio. Today, traffic information is broadcast commercially over 860 radio and TV stations in 54 cities to a listening audience estimated at 120 million. Commercial traffic information providers rely on state-of-the-art technology and a variety of information sources, including aerial surveillance, State and local police agencies, local traffic operation centers, and on-the-scene reports from passing motorists. Commercial TV channels and cable TV are not far behind. Morning and afternoon TV news shows offer a steady stream of traffic reports, utilizing sophisticated graphics and live video. The viewing audience is estimated at 120-150 million. The Internet has become another rich source of transportation-related information. “Commuter Pages” on World Wide Web have been set up by State and local transportation agencies in a number of metropolitan areas. The Web sites provide color-coded maps depicting traffic conditions. They are supplemented in some cases by still images of critical road segments from video surveillance cameras. Most Web pages also offer information about transit services and alert commuters about road detours and major incidents. Workplace-based travel information systems are likely to become commonplace in the future. Their precursor is the Chrysler Tech Center Employee Network, an internal cable system that disseminates traffic information over 500 TV monitors located throughout the giant CTC facility. Congestion maps, obtained from the county-operated traffic-management center, are updated continuously, providing departing employees with up-to-the-minute reports on traffic conditions throughout the region and allowing them to determine the best route home — or postpone their time of departure in case of a major incident. Eventually, employees will also be able to access this information through their desktop computers The public sector is also in the business of communicating travel information to the public. Examples include Montgomery County’s (MD) traffic bulletins and live video images on the county’s public access channel; Minnesota DOT’s traffic reports broadcast over a public radio station; and Georgia DOT’s statewide network of travel information kiosks. In addition, numerous State highway departments, toll road authorities, and airports beam service announcements to the driving public over Highway Advisory Radio (HAR) transmitters. Electronic dynamic message signs, utilizing modern LED technology, are employed extensively to inform motorists of traffic congestion and accidents ahead, hazardous road and weather conditions, road construction, and other safety-related conditions.

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7.2 CASE STUDIES
The following case studies detail deployments and/or operational tests that apply state-of-the-practice and advanced technologies in Multimodal Traveler Information Systems.

7.2.1 WASHINGTON METROPOLITAN TRAVELER INFORMATION SERVICE (WMTIS)
Overview
The Washington Metropolitan Traveler Information Source (WMTIS) project implements a Regional Multimodal Traveler Information System that will become the source for a broad range of current realtime information on traffic and transportation conditions including congestion, speed and incident data, public transit data, etc. It is a regional system in that the participants form a coalition of transportation agencies and private partners throughout the region, and information will be collected, processed, and disseminated throughout the entire region. It is multimodal because it involves both traffic and public transit agencies and services. Through the Traveler Information Center with the central server and on-site operators, it will provide a complete variety of voice, data, video, and graphical forms of traveler information and deliver them on technology platforms ranging from no- or low-cost approaches, such as audiotext telephone, on-line services, and advertising-funded kiosks, to state-of-the-art in-vehicle devices and full-featured personal digital assistants. It allows participating transportation agencies to share information through a central source of transportation data collected from agencies throughout the region. The Traveler Information Center serves as a clearinghouse for and disseminator of relevant information that can be used to improve agencies’ operations. In addition, public agencies are able to take advantage of traffic data from the privately financed supplementary surveillance equipment deployed as part of this project, and use that information for real-time management and scheduling of their systems. It also stimulates a thriving market for traveler information services by making the information available to all potential service providers in the region. Independent Service Providers (ISPs) have equitable access to the real-time information, on a fee basis, and benefit from the open architecture and industry standards upon which the design is based. The Washington Metropolitan Traveler Information Service program is a true public/private partnership in that a third of the project funding comes form private contributions. In addition, beyond three years of operation, the public agencies and traveling public will continue to receive the benefits of the system without any public sector funding; all systems will be operated as a profit-making business in which no public funding is required for continued operation.

Services to be Provided
The Technical Team developing this project laid out the elements of the WMTIS deployment as follows: • A fully staffed Traveler Information Center will be developed, totally financed by private contributions, to receive and process travel data and to disseminate traveler information.

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Regional Multimodal Traveler Information Center

•

A data gathering system that capitalizes on a combination of currently collected public sector data and a private data-collection network designed to fill the gaps in the public sector data collection network. A dissemination program consisting of the SmartTraveler audiotext, a telephone-based system that will service every citizen of the metropolitan area with access to a landline or cellular telephone; on-line services; commercial vehicle operations; broadcast media; and cable television capability. A public agency information-exchange network to improve incident-management procedures, relying on the Internet and the I-95 Corridor Coalition’s Information Exchange Network.

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The Traveler Information Center will contain the following hardware configurations and systems: • Hardware and software necessary to gather data from public sector agencies in an automated fashion for compilation into the Traveler Information database. Existing software and databases will be used and built upon rather than developing new software for all efforts. Team members will provide their previously developed softwares under a license agreement. Systems required to allow public sector agencies to exchange information among themselves on a real-time basis.

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Information delivery platforms needed to service the following Independent Service Provider categories. • • • • • In-vehicle device; Personal digital assistants; Pagers; Interactive television; and Multimedia on-line services with full-motion video.

Public/Private Partnership
This project has been designed to have substantial coordination, data sharing, and cost sharing between all partners. The guiding principle for the system design is one in which “public and private funds are both employed, but there should be the absolute minimal use of public funds to create the system and all private financing once it becomes operational.”

Dissemination of Information
The technologies used for dissemination of information include the following. a. Audiotext Service - A telephone-based, multimodal Advance Traveler Information System that will disseminate up-to-the-minute, route-specific, on-demand information to travelers from both landline and cellular phones. Two similar systems have been implemented by SmartRoute Systems

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and are operational in Boston, MA, and Cincinnati, OH. This service is designed to meet the need for basic travel information available to all income groups at no cost to the consumer. The service provides both pretrip and en-route dissemination. The Boston audiotext service currently receives five million calls per year It has a huge installed base that includes practically all homes and offices, and 20 percent of all vehicles and all income levels. It is easy to use and requires very little or no training. b. Radio Broadcast and Cable TV - The Traveler Information Center will offer services to the radio and cable TV media from a privately financed facility. They will be paid for directly by the media outlets. The real-time traffic and public transit information provided by the public agencies will be available to any private firm for dissemination to the public. Numerous television and radio markets have the infrastructure to receive and distribute the information from the Traveler Information Center. Some markets have exclusive channels for travelers or community channels like the Cable TV channel used by the Montgomery County Advanced Transportation-Management Center. The television programming can be shown continuously for a traffic channel in homes, offices, parking garages, lobbies, etc., or it can be incorporated in other programming by broadcasters for traffic reports at regular intervals. c. On-Line Services - Internet services that have the capacity to carry very detailed information and can support personalized, interactive applications. Numerous independent service providers will undoubtedly take the opportunity to integrate this information with their own proprietary information and services and provide it to users. In Boston, for example, the on-line service provided by SmartRoute Systems through AOL’s Digital Cities program is the most frequently utilized service within the program. These Internet on-line services will be supported by advertising revenues and will include such information as destination finding and route guidance, digital yellow page listings, and real-time information (e.g., traffic conditions, accidents, incidents, special events, weather conditions, road maintenance, and video images). d. In-Vehicle Information/Navigation Systems - device platforms have been developed to receive traveler information for en-route travel planning. Market research performed for the in-vehicle device manufacturers indicates consumers’ strong desire to have this type of traffic information. e. Commercial Vehicle Operations - Advanced traveler information will be provided to commercial vehicles. Such a system will be similar to the Boston implementation and will include cellular phone, pager, two-way radio, and a mobile data terminal. f. Personal Digital Assistants - These devices are similar to the ones used in the Atlanta Traveler Information Showcase utilizing Hewlett-Packard palm-top computers interfaced with SkyTel twoway pagers. Map databases and software are stored on a SanDisk memory card. Features include: scheduling and planning functions, the SkyTel news report, two-way personal paging and two-way personal text messaging, travel destinations, on-request real-time traffic speed and incident data, traffic-dependent personal routing, transit information.

g. Kiosks - Map-based information kiosks are being developed that can receive information from the Internet or FM subcarrier broadcasts. Also, travel information will be provided to kiosks being planned by participating public agencies. The kiosks will be placed in hotels and business lobbies,
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visitor centers, and transportation terminals. Initially the Traveler Information Center will provide information to the independent service providers as a public service with longer term agreements to share revenues as these services become self-sustaining. h. Wireless Communications to Portable and Fixed Computers - Several wireless information providers (FM subcarriers, two-way paging, cellular telephone) will provide bundled wireless receiver/ software products to enable owners of portable and fixed PCs to receive traveler information by plugging wireless receivers into a serial port on their computers. It will provide personal messaging, news, weather, real-time traveler information, plus other services. The wireless technology does not require the user to connect to a phone line. This same service can be used to provide information via kiosks as well as message signs located in public places. Just like the other services, the Traveler Information Center will receive a portion of the revenues generated by these products and services in exchange for the information provided to the independent service providers. i. Personalized Paging - Personalized paging services are offered whereby the regular travel and/or commute patterns of pager users are stored in the Traveler Information Center systems and the customers are individually paged to alert them of incidents or conditions that would affect their regular travel. This is similar to the personalized paging service being provided for the SWIFT system in Seattle, WA. Interactive Television - This is similar to the services being provided for the Atlanta Traveler Information Showcase where users (e.g., hotel guests, home cable viewers) are able to request realtime traffic and transit information from the television.

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7.2.2 ATLANTA TRAVELER INFORMATION SHOWCASE
Overview
The Atlanta Traveler Information Showcase provides timely transportation information to travelers in the Atlanta metropolitan area through the use of personal communication devices, in-vehicle navigation devices, on-line computer information services, interactive television in selected hotels, and cable television. This information is available to both residents and visitors for trip planning purposes. The project was operational before, during, and after the 1996 Summer Olympic Games. The Traveler Information Showcase includes information on multimodal travel options, including bus, rail, and air travel.

Devices
a. Personal Communications Devices The pen-based Envoy runs on General Magic’s Magic Cap graphic operating system. Users touch icons on the Envoy screen with a stylus to access a map of Atlanta showing real-time traffic information, electronic yellow pages, and other services. Navigation Technologies supplies the map database and electronic yellow page database; Etak’s map database and electronic yellow pages software is being integrated with Hewlett-Packard’s HP200LX palm-top computer and SkyTel’s two-way paging
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network. The HP200LX runs on MS-DOS. The windows-like operating system guides users step-by-step through the pull-down menus and icons to access real-time traffic information, electronic yellow pages, and other services. The user enters their query for specific information into their hand-held device, which transmits the request to the fixed-end server located in the Transportation Management Center in Atlanta. From its own data sources and the Georgia Department of Transportation’s Advanced Transportation Management System computers, the fixed-end server retrieves the requested information and transmits it via dedicated phone lines to wireless data network or paging facilities where it is then broadcast back to the user. Services provided include: traffic congestion and incident location and type; sites of scheduled road maintenance and construction activities (including project start and end dates and times); travel speeds and parking availability by locations; MARTA transit bus and train frequency, fares, and routes; schedules and locations for sporting and other events; wide area bus, train, and airline route and fare information; route guidance for automobiles; electronic yellow pages detailing information and locations of restaurants, hotels, theaters, museums, historical sites, shopping centers, automated teller machines, gas stations, hospitals, police and fire stations, emergency medical services and taxis. All services are available throughout the greater Atlanta metropolitan area. Many of the functions reach throughout Georgia to cities like Athens, Savannah, and Columbus. b. In-Vehicle Devices Siemens provides the in-vehicle computer and the visual display unit. The computer unit, which includes the main processor, mass storage device, inertial gyroscope and dead-reckoning device, is mounted in the trunk of each vehicle; Navigation Technologies supplies the digitized map database and an electronic yellow pages and point of interest database; DCI delivers real-time traffic information to the vehicles via FM subcarrier broadcast. DCI also provides the radio receiver and antenna that allows the vehicle to receive the FM subcarrier broadcast. The Showcase fixed-end server receives a constant stream of real-time messages on traffic congestion, incidents, planned and unplanned road maintenance, planned events, and parking lot capacity from the Georgia Department of Transportation’s Advanced Transportation Management System database and network. This information is sent to DCI where it is formatted and transmitted to FM stations in the Atlanta metropolitan area. The information is transmitted via FM subcarrier technology to the vehicles equipped with the in-vehicle devices. To use the system, the driver enters his/her destination into the visual display unit mounted on the dashboard. Because the vehicle’s origin is determined by an on-board satellite-based global positioning system, the route to the chosen destination can be calculated automatically. The driver can also stipulate that certain conditions such as “maximize freeway use,” or “shortest time travel” be factored into the system’s computation of the route. The system allows the driver to choose between screens showing turn-by-turn route guidance or a map display of the area. On the turn-by-turn screen, an arrow will point left or right at the next turn and count down the distance to that intersection. An audio command will also alert the driver to an imminent change of direction. On the map screen, a triangle representing the vehicle will move along the programmed route, which is in brightly colored
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overlay. Icons show locations in the coverage area where there are incidents or indicate traffic speed and parking lot capacity. A red “x” indicates that a road is closed. Information transmitted to the in-vehicle device is updated every 90 seconds, depending on the volume of data being transmitted; DCI has agreements with five local FM stations that will give the system coverage in a roughly 100-mile radius around Atlanta. c. Cable Television Etak provides the map database and the system integration; Georgia Public Television distributes the traffic information programming to cable systems throughout the State via a digital satellite uplink. The information available to viewers includes: maps with icons showing incident locations and colorcoded segments that indicate traffic speeds, live surveillance video feeds from cameras placed along interstate highways and major arterials throughout the metropolitan area, and traffic advisory bulletin boards will form the backbone of the visual presentation. During peak morning and evening rush hours, a Metro Networks staff member is in a production room in the Georgia Department of Transportation’s Transportation Management Center to narrate the live broadcast. This person is able to manually direct the system to pause on the video shot of a particular incident for an extended report. The Showcase fixed-end server receives a stream of information from the Georgia DOT’s Advanced Transportation Management System’s video surveillance cameras, radar detectors, and other sensors. The information is processed in the Showcase fixed-end server for distribution to the cable TV programming system data server. Once the information has been processed, it is distributed to a multi-media computer that automatically calls up pregenerated broadcast quality maps and pairs them with live traffic video surveillance feeds. This final presentation is converted to a broadcast signal and transmitted to the Georgia Public Television’s satellite transponder over a fiber-optic line for distribution to cable companies throughout the metropolitan area. Following an opening segment, viewers see an overview map of Atlanta with color-coded highway segments that indicate the speed at which traffic is moving. A second overview map uses icons to place incident locations. A prerecorded message tells viewers what the color coding means and to stay tuned for more detailed information. The system reports individual incidents and provides a detailed incident location map as well as textual descriptions. Live video (if available) of the incident and narration that describes the nature of the incident follows the incident map. A scrolling text bulletin board provides special traffic and transit advisories. d. Interactive Television T Network, a Source Media company, provides the interactive computer system with the set top boxes and the remote control end-user units. Etak supplies the digitized map database and a data server at the transportation management center, which distributes real-time traffic information to the hotel interactive television system. The Crown Plaza Hotel, Ravinia, hosted the demonstration. Guests use the remote control unit in their rooms to request information. Upon each television in the interactive television demonstration sits a set top box that is linked through the room’s telephone line
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to a head-end computer located in the hotel. This computer is linked with the Etak data server in the Georgia DOT’s Transportation Management Center through a dedicated telephone line. The Etak computer receives a constant stream of traffic information from the Showcase fixed-end server, which is also situated in the TMC, processes the data and then distributes it to the hotel computer. The set top box receives the guest’s request from a remote control for information and relays the message to the hotel head-end computer, which processes the inquiry and returns a multi-media response (maps, color slides, voice) for display on the television set. Using the room’s remote control unit, the guest signs onto the interactive channel. Choosing from a list of programming options from a graphical menu, the user pushes the number on his/her remote control unit that corresponds with the desired service. The system is designed in such a way that no user instructions are needed to determine how to navigate the system once the user is signed on. The interactive programming menu includes: 1. Traffic incidents; 2. Highway speed; 3. Public transportation; 4. Special events; 5. Area attractions; 6. Restaurants; 7. Hotel services; 8. Weather; 9. Yellow pages; and 10. Tutorial. By selecting “traffic incidents” on-screen, the viewer sees an overview map of Atlanta that is divided into nine zones. Incident locations are marked on the map by icons; highway segments are color-coded to indicate traffic speed. The viewer can use the remote control unit to specify a particular zone or corridor of interest. Incident icons are numbered, which allows the viewer to request a brief description of the incident printed as text along the bottom of the screen. By selecting “highway speed,” the viewer sees an overview map of Atlanta with color segments and dots indicating current travel speeds. Clicking on the Public Transportation tile, the guest can request MARTA and Cobb Community Transit bus and train operating hours and general transit information, wide-area travel information, and a list of MARTA and Olympic park-and-ride lots. When information is requested from the Yellow Pages function, the guest receives the name, address, phone number, and other pertinent information for each entry. The tiles Area Attractions and Restaurants present multi-media presentations that include
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color pictures, audio, location maps, and driving and transit instructions to selected restaurants and points of interest in the Atlanta area. Guests requesting route guidance can have the information printed and can pick it up at the bell captain’s stand in the main lobby. A printed map and instructions can be requested under Area Attractions, Restaurants and Yellow Pages services. The printout will be ready for pickup at the bell captain’s stand. e. On-Line Services Several partners are involved in providing on-line services. Maxwell Labs has developed an Internet World Wide Web site. Navigation Technologies provides the map database for driving route planning support and yellow pages information services. MARTA provides the transit itinerary planning service. The information provided includes: travel speed/congestion; real-time incident, maintenance, road closure information; MARTA and Cobb Community Transit bus and train service information; widearea travel (Amtrak, airlines, Greyhound) information; planned public events; Atlanta-specific electronic yellow pages; auto and transit route planning support. Maxwell Labs’ Web server receives traffic data from the Showcase fixed-end server, both of which are located in the Georgia DOT’s Transportation Management Center in Atlanta. The Showcase fixed-end server receives a continual flow of real-time traffic and transit information from Georgia DOT’s Advanced Transportation Management System computers. Users request information through the Internet Web server, which relays data from Showcase fixed-end server. For instance, to receive route guidance, a user types in their origin and destination and then selects their mode of travel (drive, transit, intermodal). The routing directions are returned to the user in text format. Maps containing speed and incident information are generated by the Web server based on current traffic data received from the fixed-end server. When users select real-time traffic information under the Transportation tile, a map of Atlanta with traffic speeds represented by color-coded segments and dots appears. Icons on the map pinpoint the locations of traffic incidents, maintenance, and planned events. A text description is provided if the viewer clicks on either a speed segment or an incident icon. Other information that will be available on the Web site includes: the traveler newsletter, press releases, and other promotional materials; descriptions of the Showcase program, technologies and the participating government agencies and companies; hyper-text links with the participants’ company home pages; and links with special events Web sites, as well as other transportation Web sites. f. Information Kiosk

Partners involved in providing information kiosks include: the Georgia DOT, which provides project supervision; JHK & Associates, which integrated the system; Navigation Technologies, which provides the map database; GeorgiaNet Authority, which will maintain the entire system once it has been implemented. When travelers request traffic and travel information, Advanced Transportation Management System servers respond to the query. The Showcase fixed-end server responds to non-traffic information

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queries (Olympic Games park-and-ride lot status) only. The fixed-end server responds with data tables, which the kiosks process for specific usage. The information available includes: real-time traffic speed and incidents by location; turn-by-turn automobile route planning support; MARTA bus and train schedules plus transit route planning; tourism information, including attractions, lodging information, and a hotel reservation system; weather forecasts; airline information; rideshare, vanpool, and park-and-ride options; special event information. The kiosks are installed in transit stations, hotels, visitor centers, hospitals, airports, public and private office buildings, rest areas, and shopping centers in and around Atlanta. Also, real-time traffic conditions will be displayed on a map of the Atlanta region with color-coded segments indicating traffic speeds. The Showcase web site is http://www.georgia-traveler.com.

7.2.3 BOSTON SMART TRAVELER SYSTEM
Overview
In 1992, the Federal Highway Administration and the Massachusetts Highway Department awarded SmartRoute Systems a project called SmartTraveler, to provide real-time traveler information services. Designed around a sophisticated network of live and slow-scan TV cameras located at crucial intersections throughout the metropolitan area, an elaborate network of regularly scheduled two-way radio and cellular phone probes, electronic scanners, fixed-wing aircraft, direct communication links with a number of public agencies, plus an evolving network of over-the-road traffic sensing technologies, the SmartRoute Systems Operation Center collects and manages real-time traffic, transit, and other related traveler information in a proprietary network of data fusion and dissemination technologies. Traveler information from the SmartRoute Systems database is presently sold and delivered to the public via landline telephone, cellular carriers, cable TV, traditional radio and TV, pagers, and now the World Wide Web and online providers. New delivery systems and joint marketing relationships are being developed for servicing personal digital assistants, alternative telephony providers, interactive television, and in-vehicle navigational devices. SmartRoutes collects, processes, and delivers a broad range of traveler information to consumers through existing and evolving electronic media, including cellular phone, on-line services, paging devices, landline telephone, and cable TV. The system includes a fully staffed traffic operations center, and numerous stationary and rotating video cameras, which provide real-time information that is processed through SmartRoutes proprietary traffic-management software. This data, which is combined with information from electronic sensors, mobile probes, in-flight monitors, public highway and mass transit sources, and much more, is then available for dissemination through both public and private channels of communications. Englisher et al (1996) assessed public acceptance of the information provide by SmartTraveler during its second year of operation in 1994. The evaluation showed the following:
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• • • • • • • • • • • • •

The number of calls averaged more than 3,000 on a typical weekday, while the number of individual users accessing the service during an average week was 7,500. SmartTraveler users were more likely to be making trips of more than 50 miles. Weather was the most important factor influencing people to call SmartTraveler before leaving work in the evening. Users are more likely to be male, to be over the age of 35, and to have annual household incomes exceeding $50,000. Approximately two-thirds of users have access to cellular phones, compared with 30 percent of those in the target market. Cellular calls make up a disproportionate share of the SmartTraveler market (61 percent of the calls). More than 80 percent of users surveyed were “very satisfied” and less than 2 percent were “not satisfied.” Users were most satisfied with SmartTraveler’s ease of use, availability, and route coverage. Users were least satisfied with the attribute “suggestion of alternate route.” SmartTraveler users ranked the service higher than broadcast media travel information on every characteristic surveyed. Many SmartTraveler users have decreased their reliance on the broadcast media for traveler information. All of the first-time users surveyed reported that they will call again, although more than two-thirds expected to call SmartTraveler fewer than five times per week. Most SmartTraveler users were extremely sensitive to cost: a hypothetical 10-cent charge per call caused respondents to reduce use of SmartTraveler by 36 percent; when asked about a flat monthly subscription of $2.50, about half of the respondents said that they would be very unlikely to subscribe, and virtually none of the users would be willing to pay $10.00 per month. Only 6 percent of the SmartTraveler users pay for the service now.

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In a follow-up survey (1995) the following were observed: • • • Cellular phone customers were given free service and the opportunity to dial using *1 instead of *ST1 previously used. SmartTraveler was receiving nearly 57,000 calls per week. Changes in the mix of calls from 1994 to 1995 were: conventional phone 39 percent to 16 percent; NYNEX cellular phone 57 percent to 43 percent; Cellular One 4 percent to 41 percent.
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The SmartTraveler web site is http://www.smartroute.com.

7.2.4 ADVANCED REGIONAL TRAFFIC INTERACTIVE MANAGEMENT & INFORMATION SYSTEM (ARTIMIS)
The Greater Cincinnati and Northern Kentucky areas have implemented Phase One (called SmartTraveler) of ARTIMIS, a cooperative project of the Kentucky Transportation Cabinet (KTC), Ohio Department of Transportation (ODOT), and the Ohio/Kentucky/Indiana (OKI) Regional Council of Governments. SmartTraveler, like Boston’s project, uses state-of-the-art technology to help local drivers avoid traffic tie-ups, facilitate smoother traffic flow through the area, and help reduce traffic accidents, fuel consumption, and hydrocarbon/nitric oxide emissions. SmartTraveler, is a regional transportation information telephone service that began operation June 28, 1995. It provides 24-hour, up-to-the-minute, route-specific traffic information to travelers in the Greater Cincinnati/Northern Kentucky, I-275 beltway. One local phone call links travelers to a central traffic-management station where traffic managers operate a high-tech network of remote control cameras, radio- and cellular-phone-equipped drivers, aircraft, radio monitors, and computerized traffic data. Travelers can access information on traffic conditions anywhere within the I-275 loop via SmartTraveler by dialing 333-3333 from any touch-tone phone, or 311 from any mobile phone. The system’s audio menu allows them to select specific information on any of the 16 travel routes within the area. They can also receive schedule information for Metro, TANK buses, Jetport Express airport shuttle service, RIDESHARE car pools and, where appropriate, travel alternatives. SmartRoute Systems, Inc., of Cambridge, Massachusetts, provides the SmartTraveler System. Estimated total cost for ARTIMIS: $35 million, provided to the States of Kentucky and Ohio by the Federal Highway Administration via the Intermodal Surface Transportation Efficiency Act (ISTEA) of 1991’s Congestion Mitigation and Air Quality (CMAQ) Improvement Program Funds. Kentucky and Ohio also provide State funds.

7.2.5 ADVANCED TRAVELER INFORMATION SYSTEM (ATIS) GRANT
On May 16, 1995, the North Dakota Department of Transportation (NDDOT), acting administratively on behalf of the University of North Dakota’s Regional Weather Information Center, was awarded a $750,000 Federal ITS grant for an “Advanced Traveler Weather Information System (ATIS)” Operational Test Project. The project is a partnership between FHWA, North Dakota DOT, South Dakota DOT, the University of North Dakota, the National Oceanic and Atmospheric Administration, US West Communications, and other public and private partners, to apply the ATIS technology to the I-29, I-90, and I-94 corridors in North and South Dakota. The goal of the project is to demonstrate how advanced technology in weather analysis, forecasting, and communication can be used to produce precise weather information for integration into an ATIS support system. Such integration is intended to produce safer and more efficient highway operations.
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In FY 1996, the project received a $1 million earmark from the U.S. House of Representatives.

7.2.6 HERALD EN-ROUTE DRIVER ADVISORY SYSTEM VIA AM SUBCARRIER
This operational test will disseminate important traveler information in difficult-to-reach, remote, rural areas (Iowa and Colorado) using a subcarrier on an AM broadcast station. System components — message generation, transmission, and reception — were developed by the multi-state organization Enterprise (which includes AZ, CO, IA, MI, MN, NC, WA DOTs, and the Dutch Ministry of Transport, Ministry of Transportation of Ontario). The project will determine system performance and analyze its impact on broadcasters, travelers, and equipment manufacturers. The primary objective is to assess real-world impacts of the system related to transmission of traveler information in challenging terrain (like that found in Colorado) and potentially interfering environmental conditions (such as those in Iowa), improvements to safety, and the overall marketability of the system.

7.2.7 HOUSTON SMART COMMUTER
Overview
This project aim of Houston Smart Commuter is to increase bus, vanpool, and carpool use by providing real-time traffic and transit information to travelers at home and work. Two components make up the Smart Commuter project. 1. The bus component encourages commuters to ride the bus instead of driving alone, focusing on the traditional suburb-to-downtown travel market in the IH 45 North corridor. Hardware and software for the transportation-information devices is in development and should be completed in April 1996. In-home information devices will be installed by April 1996 for each of the 700 test and control participants recruited. The operational test will begin in May 1996 and will last one year with semiannual evaluations. 2. The ridesharing component encourages commuters in the IH 10 West corridor to join carpools by using a ridematching service. METRO is integrating the rideshare system with its global information system map. System integration will be complete in early 1996; 2,500 drivers and ride seekers will be recruited in mid-1996. The Federal Transit Administration, FHWA, Texas DOT, METRO and Texas Transportation Institute are partners in this test.

7.2.8 TRAV INFO
The TravInfo project developed and implemented a multimodal transportation information center to integrate transportation information from a wide variety of sources making it available to the general public, public agencies, and commercial (value-added) vendors in the San Francisco Bay Area. The Traveler Information Center (District 4, Oakland California) began operation for testing purposes in May 1996, and started live operations in September 1996. The comprehensive, region-wide traveler
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information system supplies a broad array of devices and users with transportation information both before and during trips. System architecture is to remain “open-access” for all system aspects, to allow future growth and the transfer of technology. TravInfo has access to the Caltrans Traffic Operations Center, the California Highway Patrol computer-aided dispatch system and other local data sources as well as the Transportation Management Center’s regional database on mass transit fares, schedules and routes. The TravInfo Traveler Information Center is public entity but operated under contract by Metro Networks, Ink. Metro is in charge of supervising the staff, operating and managing the data collection, fusion and dissemination processes of the TravInfo system, and supporting the necessary security and telecommunications systems. TravInfo is sponsored by the Federal Highway Administration and Caltrans. It is being implemented through a partnership of public agencies, private firms and nonprofit organizations. It is led by the Metropolitan Transportation Commission, the regional transportation planning, financing and coordinating agency for the nine-county San Francisco Bay Area.

7.2.9 TRANSCAL
TransCal consists of three test projects: the Interregional Traveler Information System (IRTIS); the design and testing of a satellite-based Emergency Notification System for travelers to use to summon aid in emergency situations; and the Tahoe Frequent Passenger project which involves the unique use of smart cards, smart readers and a consumer incentive program to encourage the use of public transportation within the Lake Tahoe Basin. IRTIS integrates and delivers road, traffic, transit, weather, and value-added traveler service information from across the entire region to fixed and en-route travelers via various user devices including telephones, personal digital assistants, in-vehicle navigation/display devices, and interactive kiosks. It showcases emerging capabilities in computing, communications, and consumer electronics that can improve the availability and quality of traveler information. The project assesses the ability to integrate information from multiple regions, and to integrate traveler services and transit information with real-time regional congestion and incident content. IRTIS’ real-time traveler information database was created from data provided by California Department of Transportation Traffic Operations System, the California Highway Patrol, the Nevada Department of Transportation, the Nevada Highway Patrol and the National Weather Bureau. TransCal has a computer-to-computer link with TravInfo and is capable of interfacing with other advanced traveler information systems. The TransCal Traveler Information Center, in Sacramento, is operated by Metro Network, Inc. The service operates along the I-80/US 50 corridor between San Francisco, CA, and Lake Tahoe/Reno, NV. A satellite-based MAYDAY system also provides low-cost coverage.

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Traveler information is made available through three information channels that service four types of information access devices. The one most accessible to the general public is the Traveler Advisory Telephone Systems (TATS), which allows anyone with a touch-tone telephone to call a special number to get access to an audio version of current traveler information. Another way is to become a registered TransCal user and gain access through the Landline Data Service (LDS), which is for people who have a computer and a modem. Participation by private sector firms, known as Value-Added Resellers (VARs), will further enhance the TransCal system. Companies willing to take part in the project as VARs will formally register as participants. These participants will generate their own infomration, as well as develop market products and services that utilize the TransCal data. By Summer 1997, there will be at least eleven traveler information kiosks dispersed throughout the TransCal region allowing the general public to access the information. Each kiosk will disseminate traveler information for the entire TransCal region as well as information of local interest. TransCal is sponsored by the Federal Highway Administration and Caltrans. It was created through a partnership of public agencies, private firms and nonprofit organizations.

7.2.10 YOSEMITE AREA REGIONAL TRANSPORTATION INFORMATION SYSTEM
The Yosemite Area Traveler Information (YATI) project, funded by the Federal Highway Administration and Caltrans, employs perhaps the largest and most diverse governmental partnership of any existing field operational test. It is a cooperative effort by local, state, and federal agencies to provide travelers with up-to-the-minute information about traffic and weather conditions, as well as the status of transportation and recreational facilities in the entire Yosemite region. Partners include Caltrans, the Federal agencies of the National Park Service, Forest Service, and Bureau of Land Management; and the county Regional Transportation Planning Agencies of Madera, Mariposa, Merced, Mono, and Tuolumne. In addition, a committee to ensure that local citizens’ concerns about the project are heard and taken into account is in existence, as is a technical aspects advice committee. Pretrip travel information is available through the use of a touchtone phone, personal computer, and/ or multimedia kiosk. Travelers are able to obtain information on such diverse topics as mode options, regional road conditions, campground facilities, lodging, and tourist attractions prior to beginning their trip. En-Route driver information provides portions of the same data via highway advisory radio, changeable message signs, and cellular telephone. Multimedia kiosks located at visitor centers and other tourist stops along the entrance corridors also provide en-route information to travelers. Thus, those who do elect to drive their own vehicles into the region can obtain up-to-date information that will enable them to make easier and more informed travel and itinerary choices.

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7.2.11 DIGITAL DJ
Digital DJ, a San Jose startup backed by several Japanese manufacturers, will start broadcasting traffic data and other information in the San Francisco area. High-speed FM subcarrier technology already in use in Japan will allow participating radio stations broadcast data to receivers equipped with decoders and screen displays. Digital DJ will offer some services for free and others (including route guidance) on a subscription basis. Digital DJ will not lease broadcast capacity from radio stations but will assemble information on its own servers and disseminate customized subsets of that database to participating radio stations. The stations will receive the information on a “DDJ Workbench” computer that will reorganize it for local broadcast.

7.2.12 SHOWCASE INTERMODAL TRANSPORTATION MANAGEMENT AND INFORMATION SYSTEM (ITMIS) AND EARLY START PROJECTS
Traveltip
Traveltip, an Intermodal Transportation Management and Information System ( ITMIS) project, developed and deployed under the Showcase initiative, was funded in fiscal year 1995 and will provide for an inter-regional multimodal advanced traveler information system in the Orange County region. The project will deploy technology used to improve traffic and transit operations, and provide information to transportation managers, travelers, and third-party users to enhance decisions on transportation management, route selection, and mode choice. Traveltip is a smaller version of what is envisioned for the entire corridor. Four projects for the San Diego area have been identified and funded in fiscal year 1995 through the Showcase Early Start Program: (1) Transit Management Information System (Phase One); (2) Emergency Computer Assisted Dispatch; (3) Jack Murphy Stadium Traveler and Traffic Information System; and (4) San Diego Intermodal Transportation Management and Information System (Phase One).

7.2.13 SEATTLE WIDE-AREA INFORMATION FOR TRAVELERS (SWIFT)
Seattle Wide-Area Information For Travelers (SWIFT) is an advanced traveler information system operational test that was selected for implementation during 1994. The project team consists of the following members: • • • • • Delco Electronics Corporation (General Motors Corp. subsidiary); ETAK, Inc.; Federal Highway Administration (FHWA); IBM Corp; King County Dept. of Metropolitan Services;

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• • • •

Metro Traffic Control; Seiko Communications Systems, Inc.; University of Washington; and Washington State Department of Transportation.

SWIFT is intended to provide an ATIS capability for the Seattle metropolitan area using a high-speed data (FM-subcarrier radio) system communicating to receiver devices capable of receiving the FM-subcarrier communications. These devices will receive a variety of traveler information types, including traffic advisories, personal pages, transit locations and schedules, and other relevant information. The receiver devices being tested are: • • • Delco radio receivers; IBM portable computers; and Message WatchTM.

The portable computer devices will be capable of receiving a map display of current traffic information, bus positions and schedules, and rideshare information . The other planned devices will not support this capability. The pertinent SWIFT data will be collected by a variety of organizations and processed (validated, integrated and/or fused and formatted) by the University of Washington. The data types being collected are freeway loop-sensor information, ride-share information, traffic advisories, incidents, scheduled events, bus locations and schedules, and personal paging messages, as well as differential global positioning satellite data. The processed data will be formatted and placed into message frames for transmission to the appropriate receiver devices. The radio transmission system provides a wide-area capability that incorporates forward error correction and multiple transmission of data to increase the probability of correct reception of data. The system has a raw transmission rate of 19,200 bits per second, which after error correction and overhead provides usable information transmission rates of approximately 8,000 bits per second. If multiple transmissions of data are included, the final “real” information rate will be further reduced accordingly. Messages will be able to be individually addressed as in current pager systems, or groupaddressed to a common set of receiver devices. Plans call for the test to include a total of 700 devices, made up of 500 Seiko Message WatchesTM, 100 Delco radios, and 100 IBM portable computers. Users will be recruited to participate in the test, according to a plan developed by the evaluation contractor. A variety of technical performance, institutional, and user acceptance issues will be studied during this operational test.

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7.2.14 BUSVIEW
Busview is a cooperative effort between King County Metro Transit, the University of Washington, and the Washington State Department of Transportation. It takes existing Metro bus AVL (automatic vehicle location) data combines it with a GIS (global information systems) map database and delivers real time bus location information in a graphical format to transit users over the World Wide Web.

7.2.15 RIDERLINK
Riderlink is a project that delivers a comprehensive collection of information to transit users, as well as car- and vanpoolers, over the Internet. Information includes transit route maps and schedules, ridematching service, HOV (high occupancy vehicle) lane information and usage, and other information for those choosing non-SOV (single occupant vehicle) travel. An enhanced Riderlink project called the Easy Rider project will allow information from four transit agencies and the Washington State Ferries to be integrated into the system. Kiosks will be located at Boeing facilities, on ferry vessels, in ferry terminals, and at transit centers.

7.2.16 INFORMATION EXCHANGE NETWORK
Overview
The Information Exchange Network is a wide-area network of interconnected transportation management centers sharing real-time traffic information, but will also include transit, airports, rails, and motor carriers. The information that is to be exchanged among participating Coalition member agencies (e.g., New York, Philadelphia, Boston, Washington, D.C., Baltimore, Norfork, Providence, and Hartford) include: incident management (e.g., exchange of real-time information on incidents and support of interagency incident-management activities); digital message signs and highway advisory radio (e.g., location, status and current messages); construction events (e.g., sharing information about existing as well as planned construction activities in the area); real-time traffic condition and status (e.g., volumes, speeds, occupancy, congestion levels, transit schedules, pavement conditions); historical data to be used for transportation planning, congestion-management systems, etc.; traveler information made available to the private sector (e.g., media, traffic reporting companies); commercial vehicle operations; and video sharing. In a comprehensive study that was conducted by the I-95 Corridor Coalition to assess the user information needs, Patel and Kraft (1996) report on the survey (e.g., focus groups, individual interviews, phone surveys, mail surveys) results: • • Respondents consider information on weather conditions, traffic conditions, and construction activities and their locations as either very or somewhat important. More than 80 percent of the respondents consider information on construction, alternate routes, weather, and traffic conditions as either very important or somewhat important while they are enroute.

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•

More than 80 percent of the en-route respondents think that an in-vehicle system that warns of approaching hazards is either very or somewhat important to have. Also, 60 percent of the same survey respondents are willing to pay up to $500 and $1500, respectively, for in-vehicle emergency systems and automatic signal devices for help (MA AY For long-distance travelers, more than 80 percent considered information on weather and tion on traffic conditions and directions either very or somewhat important during pretrip planning. For the en-route travelers, more than 90 percent thought that information on alternate tion on traffic conditions.

•

• of arrival, traffic delays, and weather conditions. • information. • companies are responsible for providing this information. SOURCES: • ITS Program of the I-95 Northeast Corridor Coalition, April 15-18, 1996, Proceedings of the 1996 Annual Meeting of ITS America, Raman K. Patel, and Walter H. Kraft

7.2.17 MINNESOTA GUIDESTAR - TRILOGY
The Trilogy project is part of the Minnesota statewide ITS program, Guidestar. It will provide traveler information through different communications techniques: the Radio Broadcast Data System-Traffic Message Channel (RBDS-TMC) and a high-speed FM subcarrier. The primary objective of Trilogy is to test and compare a range of user devices and evaluate the potential improvements in efficiency of the existing transportation network. These devices will provide end-users with area and route-specific advisories on the highway operating conditions in the Twin Cities Metropolitan Area.

7.2.18 MINNESOTA GUIDESTAR - GENESIS
Genesis is an advanced traveler information system that uses Personal Communications Devices (PCDs) to distribute information. Timely delivery means gathering the data in real-time and distributing the data to travelers when they need it, where they need it, and how they need it. Genesis is an element in the Minnesota Guidestar ITS program. With transit and traffic data, Genesis is able to provide the urban traveler with current data relevant to a chosen trip mode and route. The Genesis PCD is portable and transit information is fully accessible to the user.

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7.2.19 DENVER HOGBACK MULTIMODAL TRANSFER CENTER
This project will provide a multimodal transfer center on I-70 near the western edge of the metro area for travelers bound for the rural recreational areas west of Denver, as well as downtown Denver. Electronic methods will be used to provide real-time information to a kiosk for the traveler’s use.

7.2.20 DIRECT
Driver Information Radio Experimenting with Communication Technology (Direct) is an operational field test that deploys and evaluates several alternative low-cost methods of communicating advisory information to motorists. These include use of the Radio Data System (RDS), FM subcarrier, automatic highway advisory radio, low-power highway advisory radio, and cellular phones. The Michigan Intelligent Transportation Systems (MITS) Center collects traffic information from various sources, fuse the information, and provide traffic advisory updates to travelers on an exception basis. For more information on commuter response to real-time traveler information, see http:// www.itsonline.com/c_resp.html.

7.2.21 TRAFFIC ASSIST
Traffic Assist is a private company providing real-time traffic information to users. Users call the system via telephone, and receive routing instructions over the phone. There are several maps: one of them is the Los Angeles, CA, grid. Origin and destination locations are identified through numbers on the map. The system asks users to input the origin and destination of their intended travel. For example, if users wish to travel from LAX to Katella Ave. (off the 55 freeway), they select the corresponding numbers from the map. Number “2504” corresponds with LAX, and “1642” corresponds to Katella Ave. at the 55 freeway. After they key in those numbers, the system provides a set of directions that indicates the shortest time route at the time of the call. For example, the recorded voice might tell users to travel east on Century Blvd., south on the 405 San Diego freeway, east on the 105 Glen Anderson freeway, etc. The traveler is then informed of the total distance in miles and the estimated time en-route. Traffic Assist can also send information to a pager or a PDA (portable digital assistant). They receive loop sensor data from just the freeway grid, and use historical profiles for arterial data. For more information, see: http://www.itsonline.com/tassist.html

7.2.22 TRAVTEK
The INFORM project implemented in Long Island, New York, demonstrated that drivers will divert to less congested routes if presented with reliable and credible traffic congestion information. The project showed that 5 to 10 percent of freeway traffic can be diverted to appropriate off-ramps when neces7-24

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sary, saving an estimated 300,000 vehicle-hours of travel; the ramp metering system has increased morning peak-period speeds by 3 to 8 percent. To determine the usefulness of advanced in-vehicle navigation and information systems for drivers, Orlando launched the TravTek (Travel Technology) project. The test involved approximately 100 vehicles—mostly rental cars—equipped with electronic guidance systems. Some 4,000 drivers, the vast majority tourists, participated in the trial. The in-vehicle systems, loaded with databases, featured a navigation map showing all roads in a five-county, 1,200-square-mile area, as well as an American Automobile Association (AAA) Florida TourBook and Orlando tourist information on hotels, restaurants, attractions, and special events. Touch-screens allowed drivers to do everything from search for Italian restaurants to map the route from Orlando’s airport to their hotels. Once a specific destination was selected, the system automatically calculated the best and fastest route to that destination, factoring in real-time traffic conditions. On-screen maps displayed easy-to-follow, turn-by-turn driving directions for the prescribed route, along with the calculated distance and estimated travel time to the specified destination. Verbal instructions were also available to drivers, as were cellular phones for emergency help or additional information. Built-in magnetic compasses, satellite technology, and sensors in the wheels (to measure distance traveled) kept vehicles on their established courses. Thanks to the system’s extreme ease of use, novices operated it fully after just a brief orientation. Orlando has compared results from the TravTek trial to those of control tests in which drivers usedstandard printed road maps to find their way. Overall, the city found, TravTek reduced travel time by 19 percent—and helped drivers have fewer accidents. The hugely successful TravTek project, fully operational for one year ending March 1993 in Orlando, Florida, showed that drivers were receptive to (and enthusiastic about) in-vehicle, dynamic route-guidance devices. System use analysis showed that drivers using route suggestions provided by the system shortened travel times by up to 20 percent. Many users reported an easy transition to (and eventual reliance on) finding destinations electronically, without using paper maps. The TravTek experience has influenced private-sector development decisions, including marketing of in-vehicle devices now available as both new-car sales options and after-market installations.

7.2.23 TRAILMASTER
Trailmaster’s advanced traveler information system provides accurate and timely information to motorists in the Phoenix area and throughout Arizona. Several local television stations use footage from cameras along the freeway during their traffic reports to show real-time traffic conditions, and travelers can call a toll-free number to get updates on road closures, construction, and weather information statewide. In addition, Trailmaster features an Internet Web site (www.azfms.com) that averages more than 23,000 hits a day. A map of the freeway system provides average traffic speeds and alerts travelers to areas of heavy congestion. Users can also click on a specific camera location to see a still-frame photo of the area’s freeway conditions that is automatically updated every five minutes (ITS World, Jan/Feb 1997).

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7.2.24 NEW YORK TRAVELER INFORMATION SYSTEM
New York City Transit (NYCT) is testing whether a traveler information system that provides real-time transit information can increase ridership. Real-time transit information will be generated from a GPS-based Automatic Vehicle Location (AVL) system. Under another project, NYCT is installing an AVL system on approximately 200 crosstown and uptown buses assigned to midtown Manhattan. NYCT is disseminating real-time transit information through four different kinds of traveler-information-systems devices. First, NYCT is installing 50 interactive kiosks at major bus stop transfer points and tourist locations. Second, NYCT is mounting 100 video monitors at major bus stops and storefront windows (e.g., banks, department stores, etc.). To comply with Americans with Disabilities Act (ADA) requirements, these monitors can also provide voice announcements. Third, NYCT is installing 100 electronic signs at major bus stops. Finally, NYCT is equipping 50 vehicles with message displays/interactive stations and annunciators for the visually challenged. Negotiations for the traveler information system are complete; however, final negotiations for the AVL and communications systems are still being conducted. These systems will be installed within two to three years. Until these systems are installed, the traveler information system cannot be deployed (September 1996).

7.2.25 TRANSMIT
TRANSMIT will provide a testbed for the application of Automatic Vehicle Identification to advanced traffic-management operations, from point-to-point journey time calculations and incident detection, through the origin-destination and traffic volume measurement. It is also enhancing the trafficmanagement tool to provide traveler information. Currently, traveler information services in the New York, New Jersey, Connecticut region operate independently of TRANSMIT. The ability to communicate with motorists is limited by the information capacity of the DMSs and directional insensitivity of the HAR. It is very difficult to tailor the information provided by these devices to the needs of the individual motorist. The integration of HAR and DMSs into the central computer system with the invehicle devices will enhance the traffic-management and traveler-information capabilities of the system. This will allow the system to automatically activate displays and information broadcasts based on detected traffic conditions. The New York Wide-area Information Network System (NYWINS) will provide travelers with travel time from TRANSMIT, as well as incident and construction information from the TRANSCOM Operations Information Center and potential other traffic-management systems. TRANSMIT will use AVI transponders to provide two-way communication. Based on the data measurements, TRANSMIT will send specific information regarding traffic conditions back to vehicles equipped with transponders (K.R. Marshall and Brian Cronin, October/November 1996). Etak and Metro Networks will develop the first nationwide real-time traveler information system. The system will transmit a variety of traffic and traveler information as it occurs to numerous products and services, including mobile PCS, video kiosks, message watches, cable TV, and other devices. Realtime traffic information will be available beginning with 10 metropolitan areas in 1997 (New York, Los Angeles, Chicago, San Francisco, Detroit, Atlanta, Seattle, Houston, and two others), an additional 20 in 1998 and 20 more in 1999, covering the major metropolitan areas throughout the country. The service will feature real-time reports that inform travelers of regional traffic incidents, traffic speeds, road conditions and construction, special events, weather conditions, etc.
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Using FM subcarrier broadcasts and other distribution media, traffic information will be sent to a variety of wireless products and services, including vehicle navigation systems, portable notebook PCS, palmtop computers, pagers, and cellular phones. It will also be available for fixed devices, including home and office computers, via the Internet and cable TV, interactive TV, and electronic kiosks (The Urban Transportation Monitor, January 31, 1997).

7.2.26 TRAFFICONLINE
TrafficOnline, which provides customized, route-specific and point-to-point real-time information, is available in the Chicago metropolitan area, Atlanta, Boston, Detroit, Houston, Los Angeles, Minneapolis/St. Paul, New York, Orange County, Phoenix, San Diego, and Seattle. TrafficOnline provides significant advantages over existing Web page-based real-time traffic information services. It can be customized to a user’s specific interests, thus providing more detailed information more efficiently, as only volume data is sent over the Internet. The shareware provides the ability to obtain travel time and other customized information. It provides customized, route-specific, and point-to-point real-time traffic information, including average speed, travel time, incidents, and construction information. In addition, a clickable real-time congestion map of major city highways, automatic warning of abnormal route travel times, and automatic update of real-time traffic information is available (The Urban Transportation Monitor, November 22, 1996). Three southern California Area Traffic Reports are provided as a free Internet public service developed jointly by Maxwell Technologies Information Systems Division and Caltrans. The information service was designed to provide a graphical, real-time freeway traffic information tool to assist southern California commuters in navigating the freeway systems every day, 24 hours a day via the Internet. Since these real-time, graphical traffic maps of southern California’s freeway conditions first appeared live on the Internet, they have become one of the most popular Internet sites for Southland motorists. They are visited day in and day out by thousands of southern Californians who are interested in checking freeway traffic conditions for their commutes to and from work, sporting events, sales calls, concerts, business meetings, airports, train stations, etc. This information technology continues to garner strong technical accolades as an example of how useful public services can be when provided over the Internet. Freeway speeds are available for San Diego, Los Angeles, and Orange Counties. Incident reports, construction closures, and flow rates are available for San Diego County. General road conditions for the entire State are also available (www.scubed.com/caltrans/about.html www.scubed.com/caltrans/about.html).

7.2.27 FAST-TRAC
With more than $70 million committed, the Faster and Safer Travel through Traffic Routing and Advanced Control (Fast-Trac) system is the largest operational test of intelligent transportation systems in the world. The program integrates advanced traffic management with advanced traveler information systems. At the core of traffic management is the Sydney Coordinated Adaptive Traffic System (SCATS), which operates traffic signals in real time and adjusts them automatically to reflect changes in traffic flow,
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incidents, and accidents. Video sensors enhance the data-gathering capabilities of the computer-based traffic-signal control system. (Oakland County chose video sensors over more conventional inductive loops for several reasons. For starters, the video devices can be installed on any surface and—important for Michigan—in any kind of weather. Also, one video camera can survey several traffic lanes at a time. Loop detectors, on the other hand, must be installed within roadways—tearing up pavement and restricting work to mild weather—and only one to a lane.) At the traffic operations center, monitors display the overall traffic “picture,” including signal operations, information from video detectors, and congestion levels. Maintaining its own database of information, the system eliminates the need for traditional traffic-count studies and makes data instantly available for economic forecasts and other planning. Fast-Trac has been successful on several fronts. At the World Cup soccer matches held in Detroit’s Silverdome—and since then, at major concerts and other special events—tests showed that the traffic-management system eased traffic flow and reduced the need for police to manually direct traffic. Overall, the program is responsible for a 19-percent increase in rush-hour travel speed and a significant decrease in accidents. Studies suggest that Fast-Trac could potentially reduce the average number of vehicle stops by one-third, decreasing the incidence of rear-end collisions and slashing carbon monoxide emissions to the environment by 12 percent. Already, instituting a “leading” left-turn signal at intersections has reduced the number and severity of left-hand and head-on accidents; eventually, pedestrian priority signals at school crossings will minimize risks to children’s safety. By making optimal use of its existing roadways, Oakland County is taking the fast track to a healthier community. The jurisdiction is saving money, attracting residents and businesses, and preserving its woodlands and lakes for future generations to enjoy.

7.3 EVOLVING TECHNOLOGIES
Call Box and Commercial Telephone
Call boxes are often installed along freeways to provide motorists a means of calling for assistance. They are also used for incident detection to inform the operating agency of the incident and its nature. Call boxes now have become multitasking, used not only for motorist aid but also for the acquisition and transmission of traffic data and weather and environmental data. Other capabilities include: full duplex voice capability; the ability to transmit and receive digital data; and detection and processing of real-time traffic information.

Internet
Using the Internet to disseminate real-time traffic information is a new application of the technology. The Internet world-wide computer network is a cost-efficient means of disseminating traffic information to the public. Access to the Internet is available to any personal computer user with an Internet connection. Dial-up connections can be obtained for home use by local Internet providers for a

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minimal monthly fee. Dissemination of real-time traveler information (textual, graphical, and/or photographs) via the Internet is being accomplished by many public agencies across the country. Such traveler information includes graphical representations of freeway networks depicting real-time speeds (color-coded), real-time snapshots showing existing traffic conditions taken from CCTVs, realtime weather conditions, incident locations, scheduled construction and maintenance roadway closures, and transit schedules.

Intranet
The Intranet is very accessible in most large companies that already are connected electronically via a Local Area Network (LAN). A LAN links dozens or even hundreds of desktop computers in an internal network so employees can communicate with one another, share information, and access common databases. The Intranet, using LAN infrastructure already in place and employing the same standards and protocols as its more famous cousin, the Internet, is the internal version of the World Wide Web. But, whereas the Internet comprises an open network of Web sites that anyone with a computer is free to access and download, the Intranet is a network turned inward, protected from the outside world by an electronic firewall. Intranets are used for a variety of corporate purposes. Their Web sites contain corporate databases, announcements (electronic bulletin boards), manuals, company policies and procedures, directories, schedules, and internal correspondence. The use of Intranets is limited only by the needs and imagination of their corporate sponsors. One of the more inventive uses of the Intranet is the communication of real-time traffic information. An example of Intranet use is found in the Fast-Trac TV system deployed at the vast Chrysler Technology Center in Auburn Hills, Michigan. The data from the Fast-Trac system is transmitted to a traffic operations center where a central computer automatically adjusts traffic signals throughout the network to optimize traffic flow and minimize delays at intersections. The data also provides a foundation for a traveler information system. The traffic operations center’s computer generates color-coded maps, known as Fast-Trac TV, that depict in real time the state of congestion on Oakland County’s streets and alerts motorists of traffic bottlenecks and major highway incidents. Initially, TOC’s traffic surveillance capability was limited to Oakland County’s arterial road network. Recently, the TOC has been linked to Michigan DOT’s freeway surveillance system (MITS) which covers 32 miles of central Detroit’s freeway network and will eventually be expanded to monitor an additional 150 miles of freeways in the Detroit metropolitan area. Today, Fast-Trac TV is the only system in the nation that depicts traffic conditions on a combined arterial-freeway network. Realizing the potential value of this information to commuters, the Traffic Improvement Association of Oakland County (TIA), representing local employers and other business community interests, brokered an arrangement between the Road Commission and Chrysler Corporation to provide FastTrac TV to the 10,000 employees at the Chrysler Technology Center (CTC) in Auburn Hills. The signal is transmitted by a modem to the Tech Center and then, using specially developed software, converted and disseminated over CTC’s cable network to more than 500 TV monitors located throughout the giant CTC facility. Maps are updated continuously, providing departing employees with up-to-the-minute reports on traffic conditions throughout the region and allowing them to determine the best route home—or postpone their time of departure in case of a major incident.

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The computer-generated congestion maps are supplemented by text messages alerting home-bound employees to major incidents, road closures, construction detours, and hazardous road conditions. Eventually, this information will also be accessible through employees’ desktop computers, and may include an icon that automatically alerts users of unusual traffic conditions along their customary itinerary, which has been preprogrammed into their individual computers. Eventually, Fast-Trac TV will be expanded to neighboring facilities in the Oakland Technology Center and is expected to reach an estimated 40,000 employees (Kenneth Orski, www.itsonline.com/ko_int.html).

Leased Cable Television (CATV)
Through public/private partnerships between transportation agencies and local cable companies, CATV has been used to broadcast live video from freeway surveillance cameras to trip planners. Prior to starting their trips, potential motorists can view real-time traffic conditions on their cable TV at home. They then can make decisions as to what route to take, what mode of transportation to take, or whether or not they should delay their departure.

Kiosks
The kiosk is a combination video monitor/computer mounted in a stand-alone cabinet that allows travelers to interact and retrieve requested information via touch screens or mouse. Various applications of kiosks include: • • • • • • Real-time displays of the freeway conditions map. Access to commuter transportation services. Routing and itinerary services. Carpool ridematching. Customized mass transit directions, including fares, times, route numbers and connections. Up-to-the-minute travel information including details of traffic bottlenecks and airline delays.

SOURCES: • • • TRANSMIT: From AVI to ATMS, October/November 1996, by K.R. Marshall and Brian Cronin, TollTrans. Traveler Information Systems, June 1996, ww.fta.dot.gov/library/technology/APTS/iti/ project9.htm#TRAVELER. TravTek, Test Driving the Future, October 1995, video prepared for FHWA by SAIC.

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•

Development of Human Factors Guidelines for Advanced Traveler Information Systems and Commercial Vehicle Operations: ATIS and CVO Development Objectives and Performance Requirements, September 1995, Report FHWA-RD-95-109, Prepared for FHWA by Batelle Memorial Institute, Columbus, Ohio. Minnesota Guidestar project Travlink, April 1994, Paper presented at 1994 ITS America Annual Meeting. An Evaluation of the SmartTraveler ATIS Operational Test, April 1994, Paper presented at the 1994 ITS America Annual Meeting. Toward a TravInfo Architecture, April 1994, Paper presented at the 1994 ITS America Annual Meeting. Genesis: Project Design and Pilot Test, April 1994, Paper presented at the 1994 ITS America Annual Meeting.

• • • •

Return to Table of Contents

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CHAPTER 8

Integration of Systems

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8-2

Integration of Systems

Individual metropolitan intelligent transportation infrastructure elements are usually independently developed by a variety of agencies within a metropolitan area. However, the movement of goods and people occurs on the total transportation system within an area. In order to manage the entire transportation system within a metropolitan area in a coordinated fashion, individual elements are usually integrated. Therefore, integration is considered a key aspect of the metropolitan intelligent transportation infrastructure deployment. It is important to note that the metropolitan intelligent transportation infrastructure demands are unique for different areas. Each community should implement only the appropriate intelligent transportation infrastructure element(s) that match its particular needs. It is not effective to simply copy a successful system from one community to another and expect it to work. Many metropolitan areas and communities already have several intelligent transportation infrastructure elements in place. The importance and benefits will be realized fully by linking them in areas that do not have integrated systems. This integration will maximize the value of investments and service to the traveler. In addition, buying smarter is the key when the existing technologies and equipment need to be replaced or upgraded. The steps toward attaining integration include identification of the data that need to be transferred (including the timeliness of the data transfer), the establishment of methods for transferring data between systems, and the use of the data by the receiving systems. Integration of systems consists of data transfer and control. Data transfer is the physical exchange of data from one system to another, where the recipient system can use the data to structure its response to changing travel conditions more efficiently. Data sharing can occur among computer systems, operators, designers, and the public. Control is the processing and use of the data that have been transferred. Both data transfer and control can be measured by varying levels of sophistication in the systems constructed to handle them. For example, lane closures on a freeway due to either planned (construction) or unplanned (incidents) events may cause traffic to divert to alternate arterial routes. This diversion may be directed by the provision of traveler information or may naturally occur as travelers avoid standing queues on the freeway. In an integrated system, traffic data on the freeway are transferred from the freeway-management system to the traffic-signal control system. If these systems are embodied in a comprehensive Traffic-Management Center, the transfer is automatic. In systems where they are physically separate, communications techniques must be used, sometimes with operator intervention. Regardless of the method to communicate, the transfer must be made as close as possible to real-time, so as to be useful. After the data are transferred, a decision of how to use the data must be made (the control function). This can range from implementing pre-determined signal-timing plans based on the severity of freeway conditions (e.g., low speeds over varying distances) to dynamically determining what the appropriate response should be through predictive models.

8.1 FREEWAY-MANAGEMENT SYSTEMS
Information collected by the freeway-management system can also be used by other metropolitan intelligent transportation infrastructure systems. Relevant information can be made available to support incident-management and emergency-management services, traffic-signal control, and
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regional multimodal traveler information. Information links to incident-management and emergencymanagement services may be used to transfer data concerning the location, severity, and duration of incidents on the freeway system. Traffic data measuring the demand and performance of the freeway system can be linked to the traffic-signal control system to coordinate the operation of the surface street system with the freeway system. Freeway traffic data can be linked to a regional multimodal traveler information center to provide travelers with information concerning the performance of the freeway system. A link to provide relevant information to transit management may also be included.

8.2 TRAFFIC-SIGNAL CONTROL
Traffic-signal control data on arterial travel speeds and conditions may be shared with the freewaymanagement, incident-management, and transit-management systems. The traffic-signal control system may also provide data to the regional multimodal traveler information system. Traffic-signal control may incorporate peripheral techniques/technologies not essential to the task of traffic control per se, which may enhance overall traffic-management capabilities in the area. These techniques/ technologies may include closed-circuit television surveillance; motorist information systems (e.g., DMSs); a database management system to support analysis and development of management strategies; a data exchange with other traffic-management systems including freeway management and incident management. Offline simulation may be included to project near-term traffic trends for selection of signal-timing strategies to optimize throughput.

8.3 INCIDENT MANAGEMENT
Incident management relies on traffic data provided by the freeway-management system as well as the traffic-signal control system (surface arterial system) to detect and verify incidents. In addition, the system continues to monitor traffic conditions during the entire duration of an incident and to implement various control strategies to mitigate its impact. The freeway-management strategies may be coordinated with the traffic-signal control system to provide a balance of demand and capacity during congested periods. Incident location, severity, and duration data are shared with the emergency-management services to develop an appropriate incident response and to monitor the progress of incident clearance. Travelers may be provided with information concerning the incident location, duration, and severity, as well as incident clearance activities through the traveler information devices operated by the freeway-management and regional multimodal traveler information systems. Incident data may also be relayed to the transit-management system so that transit vehicles can adjust their routing. The incident-management system is frequently located with the freeway-management system, and both may be part of a single freeway-management center.

8.4 ELECTRONIC TOLL COLLECTION
Roadside readers mounted at various points along the freeway and arterial roadway system can be used to detect the presence and passage of vehicles equipped with toll tags to provide data to calculate roadway performance. These probe data can be used by the freeway-management and traffic8-4

Integration of Systems

signal control systems to measure roadway conditions. Electronic toll collection can also be integrated with electronic fare payment through the use of a common fare media as a “smart” card.

8.5 TRANSIT AND EMERGENCY MANAGEMENT SYSTEMS
Information links from the transit and emergency-management systems to freeway management and traffic-signal control can provide for priority treatment of transit and emergency vehicles to improve on-time performance. Transit management can also provide freeway management and traffic-signal control with probe information for highway travel time determination. Transit location and schedule data as well as data on real-time schedule adherence can be transferred to the regional multimodal traveler information system, to distribute traveler information concerning transit service performance. In addition, there may be coordination with the traffic-signal control system for signal preemption and with the incident-management system for improved route guidance. Signal priority provides capability to preempt traffic signals on an emergency vehicle’s route so that the emergency vehicle is nearly always presented with a green signal. It includes the capability to warn drivers of affected vehicles that an emergency vehicle is approaching. Links with 911 and/or Federal/State or local emergencymanagement centers would be beneficial. These linkages would be especially helpful during inclement weather and potential evacuation situations.

8.6 REGIONAL MULTIMODAL TRAVELER INFORMATION SYSTEMS
As with other elements of the metropolitan intelligent transportation infrastructure, integration is essential to the deployment of an effective regional multimodal traveler information system. It is the aggregation of data from many sources, and the presentation of these data integrated in a common, easily assimilated format, that makes regional multimodal traveler information such a valuable element in influencing mode selection, route selection, and travel-time scheduling. Regional multimodal traveler information relies upon the other elements and technologies to provide current travel conditions in a metropolitan area. It receives incident, traffic, and transit data from the other elements.

8.7 CASE STUDIES
8.7.1 SMART CORRIDOR
The Smart Corridor project, in Los Angeles, is located along 12.3 miles of the Santa Monica freeway corridor. The objectives of the Smart Corridor are to provide congestion relief, reduce accidents, reduce fuel consumption, and improve air quality. This will be accomplished using advanced technologies to advise travelers of current traffic conditions and alternate routes (using strategies such as highway advisory radio, dynamic message signs, kiosks, teletext, etc.), improving emergency response, and providing coordinated interagency traffic management. The freeway systems will be operated by the State of California (Caltrans) and the arterial streets by the city of Los Angeles, with coordination provided via voice communications and electronic data sharing. The coordination and
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shared responsibility of the city and State transportation agencies will enable them to allocate their resources better, provide expanded coverage of the surface transportation system, and enable the control and management of the freeway and arterial systems to be a unified effort. The heart of the project is a scenario/rules-based expert system that offers reactive guidance to freeway and arterial control. The Smart Corridor software is not a replacement for existing traffic control and information systems, but an umbrella system that incorporates new and existing systems into a single coordinated management system that can be accessed by any agency operator.

8.7.2 PENNSYLVANIA I-476
The I-476 project in Pennsylvania incorporates a system architecture that utilizes several intelligent transportation infrastructure elements communicating over a variety of communication technologies. The system allows expansion and growth for accommodating future elements and other technologies to be integrated. It includes: CCTV, ramp metering, incident detection, advanced vehicle detection, and a test-bed for evaluating the performance of overhead-mounted vehicle detectors. Operations will utilize a range of communication technologies to link field elements and the existing Traffic Control Center, including leased T-1, dial-up and Type 3002 telephone lines, fiber optics, and spread spectrum radio (Ramesh Gangisetty and Karl Ziemer, August/September 1996).

8.7.3 ARIZONA DOT TRAFFIC INTERCHANGE MANAGEMENT SYSTEM
The purpose of the Arizona Department of Transportation (ADOT) Traffic Interchange Management System (TIMS) is to facilitate coordination among the ADOT Trailmaster Freeway-Management System and city and county Traffic-Management Centers (TMCs), which will assist in reducing motorist delays. The TIMS provides the means for ADOT operators and city of Phoenix TMC operators to exchange and coordinate timing plan information and changes. The TIMS software at the ADOT TOC acts as a server for this information exchange, communicating with a client computer located at a city traffic-management site. This client computer runs the Remote Freeway-Management System User Interface, configured with only the options necessary for TIMS functionality. At the TOC, the TIMS automatically detects a freeway-management system timing plan change and informs the appropriate city traffic control centers. The TIMS also provides the city control center with suggestions to indicate which city timing patterns should be used to achieve a desired or optimum traffic progression. The data that specifies which cities are affected by an ADOT traffic interchange and the suggestions will be maintained in the ADOT Freeway-Management System database at the TOC and consist of predefined sets of timing patterns designed to synchronize freeway-management systems and city signals. The suggestion of timing-pattern change to the city TMC will be informational only. Any actual change in a city timing plan will be at the discretion of city traffic-management personnel. In the future, functionality will be developed to fully automate timing-pattern changes. When changes in a city timing pattern are implemented at the city traffic-control center, the city can inform the ADOT operators at the TOC of the change through the TIMS. The TIMS will provide the ADOT operators
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with suggestions of which freeway-management system timing patterns need to be used to achieve the desired traffic progression (http://www.azfms.com/About/System/tims.html).

8.7.4 MARYLAND CHESAPEAKE HIGHWAY ADVISORIES ROUTING TRAFFIC (CHART)
Maryland’s Chesapeake Highway Advisories Routing Traffic (CHART), established in 1989, includes four major elements: 1. Surveillance; 2. Incident Response; 3. Traveler’s Information; and 4. Traffic Management. The CHART system is an integrated traffic-management system that includes incident management, traffic control, and traveler information for freeways and surface streets throughout the State of Maryland. It interfaces with several external systems such as the Econolite system that controls intersections throughout the State; the Montgomery County Signal System, providing information on surface streets in Montgomery County as well as sharing information about incidents; the DMS system, the traveler advisory radio system maintained by the State Highway Administration and Montgomery County; CCTV systems currently maintained by Montgomery County and the State-run tunnels; and a winter storm advisory system available from the State of Maryland Geographical Information System (GIS). CHART uses electronic equipment to detect traffic incidents, inform motorists of highway conditions, and provide assistance during traffic incidents. A discussion of this equipment follows.

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Closed-Circuit Television (CCTV) - The CCTVs are used for verification of traffic conditions detected by CHART devices including overhead traffic detectors, #77 cellular phone calls (to report disabled vehicles), and Emergency Traffic Patrols (ETPs) /Emergency Response Units (ERUs). Bi-directional Traffic Detectors - These detectors monitor average speed across a given section of highway and notify state operations center operators when average speed falls below a preset threshold. The detectors enhance the operator’s ability to quickly evaluate traffic incidents and dispatch appropriate resources. Dynamic Message Signs (DMS) Traveler Advisory Radio (TAR) - TAR station frequencies include: 530 AM along the I-70 corridor from Baltimore to Cumberland; 1290 AM along the Capital Beltway and I-270 in the Washington metropolitan area; 1610 AM along the Baltimore Beltway, I-95 and I-83 in the Baltimore metropolitan area, as well as along U.S. 50 from Annapolis to Ocean City; and 1040 AM at the BWI Airport.

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Emergency Traffic Patrols - ETPs are tow trucks that carry equipment to perform minor vehicle repairs and clear vehicles or debris from the roadway. ETPs are staffed by State Highway Administration (SHA) maintenance personnel and operate during peak travel hours on major Maryland highways, including I-95, I-495 and I-695. Emergency Response Units - ERUs are vans that carry equipment to perform minor repairs, and provide a higher level of service, including the establishment of proper traffic control and assistance in coordination of emergency activities upon arrival at an incident scene. ERUs also relay information to SHA’s TOCs regarding lane closures and backups. ERUs are staffed by trained and certified CHART personnel and operate weekdays from 5 a.m. to 9 p.m. in the Baltimore and Washington areas. Road Pavement Sensors - Road pavement sensors use the latest computer technology to record road surface temperatures, information about snow, ice and winter chemicals on the roads, and whether a road is wet or dry. Information collected by road sensors is sent via telephone lines to a remote processing unit and then to a central computer at the emergency operations center. The data is helpful in determining when and where to send plows and de-icing equipment. (http:// www.inform.umd.edu/UMS+State/MD_Resources/MDOT/sha/chart/chart.htm)

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8.7.5 SILICON VALLEY SMART CORRIDOR
Oakland, CA, is implementing the Silicon Valley Smart Corridor in northern California. The project will coordinate freeway and selected surface-street traffic operations along 15 miles of the I-880/Route 17 corridor. The California Department of Transportation, the cities of San Jose, Milpitas, Santa Clara, and Campbell, the town of Los Gatos, and Santa Clara county will all be able to monitor and control the system as peers. The system will allow real-time data exchange and control such as adjustment of traffic signals, electronic signs, and other devices to respond to traffic volume changes and incidents. Each agency will have its own real-time status display map of the corridor to provide a common frame of reference for all traffic management. The system will also offer information to travelers, including a link to TravInfo, the San Francisco Bay Area’s regional traveler information system (http://www.itsworld.com/techno.htm).

8.8 STANDARDS
The National Transportation Communications for ITS Protocol (NTCIP) will support integration of ITS technologies through the use of a standard communications protocol. Vendors can produce hardware and software products that will be able to effectively communicate with other NTCIP compliant devices in the system. SOURCES:

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Interstate-476: Networking for the Future, August/September 1996, by Ramesh Gangisetty and Karl Ziemer, COMtrans. An Integrated Intelligent Transportation Infrastructure for Your Area, January 1996, US DOT Publication No. FHWA-JPO-96-005, prepared by FHWA and FTA.

Return to Table of Contents

Funding

CHAPTER

Funding

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Funding

Implementation of an ITS program for a region requires extensive funding to achieve the needs of most regions. Funding is required to initially implement the system as well as to operate, maintain, and upgrade the system as technology and system needs evolve. In defining potential funding sources, key guidelines for success are to be creative, innovative, and flexible. The funding process for ITS can be approached in at least two ways. If viewing ITS as an integrated element of many other transportation strategies, ITS funding would be approached as a part of funding an entire package of improvements to address specific problems. For example, ITS funding could be included as part of the funding of a major corridor capacity-expansion project or HOV laneaddition project. In this case, ITS is likely a small part of the total funding package. Altematively, ITS can be treated as a separate set of actions with separate funding. In this case, ITS is often viewed to be in competition for funding against other projects, and obtaining funding tends to become part of an advocacy process. The allocation of funding at the State and metopolitan level often involves a process of advocacy. The extent to which agencies and individuals become advocates of ITS funding is a local decision. The traditional funding sources, discussed below, are available to assist with the funding of ITS programs. The traditional funding sources include: • • • • • • Federal-aid National Highway System funds. Surfact Transportation Program (STP) funds. Congestion Mitigation and Air Quality (CMAQ) funds. State and local sources. Operational tests. Defense conversion funds.

These funds are available through the traditional methods of allocation, application, and obligation. Procedures in each State may vary regarding how funds may flow down to the metropolitan and local level. Some areas have made major commitments to allocate a significant portion of certain funding pools to ITS. For example, the Houston region’s new TRANSTAR system was funded largely through the commitment of CMAQ funds. Other areas have drawn funds from multiple sources over a long period of time, building and operating in increments as the funds became available. Appendix L describes some of the multifaceted funding approaches to ITS that have been taken in southern Califomia. The successful development and implementation of the metropolitan intelligent transportation infrastructure elements will largely depend upon the availability of funds to cover the costs of such systems. Following are the various funding sources made available through ISTEA. In addition to these funding sources, other funding opportunities exist at the local, State, and Federal level, as well as privatesector contributions. Some of these are: • At the Local level: Local sales tax, motor vehicle registration fee tax, transit-related funds, tollroad funds, privatization.
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At the State level: State gas tax, State ITS research funds, petroleum violation escrow account, State transit funds.

9.1 ISTEA
The 45,000-mile interstate system, Federal project, has become part of the 155,000-mile National Highway System. The primary, secondary, and urban system designations, previously used, have been dropped. The Federal legislation has shifted responsibility for many transportation decisions to States and local governments. It has consolidated categories into new programs and has increased State and local officials’ ability to fund projects that help their communities. It gives States and local governments greater flexibility in how they use Federal funds. This results in getting projects underway faster and has led transportation agencies to tap into new sources of funding. It provides States and local governments with more flexibility and greater freedom to pursue their own vision.

9.1.1 FLEXIBLE FUNDING
The new programs established under ISTEA allow Federal highway and transit funding for flexible use with some restrictions. These programs represent a clear departure from the way Federal financial resources have been administered in the past, with State and local transportation agencies gaining much more control over how and where Federal funds are spent. Because flexible funds have fewer use restrictions, planners are not limited to developing transportation solutions based on what type (highway or transit) of funding is available. They, instead, can orient their transportation plans and programs toward the evaluation of a wide range of alternatives (e.g., demand management, bicycle, pedestrian facilities) that best achieve local goals. Similarly, instead of letting funding requirements drive project investment decisions, officials can determine investment priorities based on their ability to meet not only these local goals for the delivery of transportation services, but broader social and environmental objectives, such as those included among ISTEA’s planning factors. Funding flexibility means that for many multimodal projects, local and State planners have discretion in choosing how funds are to be administered. Several Federal Highway Administration (FHWA) programs may provide for transit-related projects without funds being administered by the Federal Transit Administration (FTA). Certain projects on the National Highway System may receive flexible funds from transit capital operating assistance if certain conditions are met: the use of these funds for highway purposes is approved by the metropolitan planning organization after appropriate notice and opportunity for comment and appeal are provided to affected transit providers; the funds are not needed for capital transit investments required by the Americans with Disabilities Act of 1990; and State and local funds used to match Urbanized Area Formula funds made available for highway purposes are also eligible to fund either highway or transit projects. ISTEA provides flexibility for Federal funds to be spent on linking different modes of transportation. The transfer of funds from one mode of transportation to another demonstrates an innovative, cooperative approach to meeting investment needs identified by a transportation planning process, regardless of mode. As an example, transferring transit capital to highway capital funds and subsequently

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trading these highway funds for transit operating assistance in a certain community demonstrates funding flexibility and interagency cooperation for the benefit of the communities, as well as all modes transit projects at the discretion of State and local agencies. All programs under ISTEA are considered flexible funding programs. For example, projects eligible for activities such as construction and rehabilitation of roads and bridges, public transportation capital improvements, car pooling projects, bicycle and pedestrian facilities, highway and transit research transit safety improvements, and capital and operating costs for traffic-management and control projects. This provides for wide flexibility in ISTEA funding. (MPOs), now decide which projects to fund and build. The local role in transportation decision making has increased as MPOs have been given more power. ultimately sends to States to “reimburse” them for projects costs is controlled through the annual limitation on obligations, part of the Federal budget process. This is an upper limit on the amount of redistributed obligation authority. FTA programs, however, are appropriated budget authority programs. Funds must be appropriated each year through the Federal budget process. The amounts annually for various FTA programs. It is this flexibility of fund transfer between the two Federal agencies, then that make it possible for certain public transportation projects and programs to be The Federal Highway Administration delivers several new programs established by ISTEA that provide State and local transportation planners and decisionmakers with the flexibility to fund transportation authorized Federal-aid programs for highways and transit for a period of six years at a total funding level of $151 billion. Funding provided for major programs is as follows. SIX-YEAR FUNDING (Billions) National Highway System Interstate construction/substitution $ 8,160 $17,000 Surface Transportation Program Bridge Program $16,100

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Congestion Mitigation/Air Quality Program Intelligent transportation systems $ $ Congress demonstration projects Other highway $18,830 $31,500 0.66 1.8

National Highway System
In November, 1995, President Clinton signed into law the National Highway System Act of 1995. The purpose of the National Highway System is to provide an interconnected system of principal roadways that serve major population centers, international border crossings, ports, airports, public transportation facilities, and other transportation facilities; meet national defense requirements; and serve interstate and interregional travel. The National Highway System includes the entire interstate system, plus most primary urban and rural highways (including toll facilities) that provide motor vehicle access between such highways and a major port, airport, public transportation facility, and other intermodal transportation facility. It consists of approximately 155,000 miles of major roads. Eligible highway and transit projects under the National Highway System program include: • • • • • Construction and rehabilitation of roads and bridges. Fringe and corridor parking facilities. Bridge and pedestrian facilities. Carpool and vanpool projects. Public transportation facilities in a National Highway System corridor.

ISTEA authorized funding for the National Highway System at $21 billion over six years. a. Funding Each State may unconditionally transfer up to 20 percent of its interstate maintenance apportionment to the Surface Transportation Program or the National Highway System. Up to half of the money may be shifted to Surface Transportation Program highway and transit. Fifty percent of a State’s National Highway System apportionment may be transferred to the Surface Transportation Program. If a State certifies that its apportionment is in excess of its maintenance needs, it may, upon approval by the U.S. Secretary of Transportation, transfer this excess to the Surface Transportation Program or the National Highway System. Funds transferred to the Surface Transportation Program may be used
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Funding

anywhere within the State. One hundred percent of a state’s National Highway System apportionment may be transferred to the Surface Transportation Program with the approval of the U.S. Secretary of Transportation. b. ITS Under the National Highway System, up to two years of start-up funding can be provided for the operations of traffic-management and control systems. Operational improvements include projects to the National Highway System, as well as non-National Highway System highways in a National Highway System corridor. The National Highway System, therefore, provides a major opportunity for ITS funding on principal arterials and corridor systems.

Surface Transportation Program
The Surface Transportation Program provides for the most flexibility of ISTEA’s programs and has the bulk of the non-interstate funds. Surface Transportation Program funds may be used for several highway and transit capital and planning activities, including the following. CAPITAL Construction/rehabilitation of roads and bridges Public transportation capital improvements Car/vanpool projects Fringe and corridor parking facilities Bicycle and pedestrian facilities PLANNING Surface transportation activities Development of ISTEA management systems Wetland mitigation Highway and transit research and development Environmental analysis

Other eligible projects under the Surface Transportation Program include highway and transit safety improvements, capital and operating costs for traffic management and control projects, and most transportation control measures. a. Funding States must use 10 percent of their Surface Transportation program allocations for highway safety construction projects (e.g., hazard elimination, rail-highway crossing improvements, intersection safety improvements, minor highway alignment improvements, guardrail and other protective device installations). States must use 10 percent of their Surface Transportation Program allocations for transportation enhancement projects (e.g., pedestrian and bicycle facilities, acquisition of scenic easements and scenic or historic sites, scenic or historic highway programs, landscaping and other scenic beautifi9-7

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cation, historic preservation, control and removal of outdoor advertising, archaeological planning and research, and mitigation of water pollution due to highway runoff). Whether used for highway or transit projects, 50 percent of each State’s Surface Transportation Program allocation must be divided according to relative share of population between each of the areas of greater than 200,000 population and all other areas of the State. The remaining 30 percent of the Surface Transportation Program allocation can be used in any area of the State. Up to 40 percent of bridge program funds may be transferred by States to the Surface Transportation system or the National Highway System for purposes consistent with either program. b. ITS ITS and traffic management projects are not eligible under the 10 percent set-aside for highway safety construction projects and for transportation enhancement projects. While Surface Transportation Program funding for FTA projects requires a local match of at least 20 percent, traffic projects require only 11.5 percent local matching funds. While there is obvious application of Surface Transportation Program funding to capital expenditure for ITS and traffic-management projects, its application to operations and maintenance is not so well defined. There is a provision at the Federal level making such expenditures eligible. However, current local guidelines are that local agencies provide funding for operations and maintenance. Such guidelines need to be modified, given the new ITS technologies to be supported and the increased budget limitations on even routine operations and maintenance.

Congestion Mitigation/Air Quality Program
The Congestion Mitigation and Air Quality improvement (CMAQ) program provides additional funding for air quality nonattainment areas (areas where the air quality is worse than the ozone or carbon monoxide standards) to implement transportation projects that will contribute to an area’s compliance with the Clean Air Act. This program is intended to help improve air quality through traffic congestion mitigation projects. Nonattainment areas are found in both urban and rural regions. Projects that reduce travelers’ reliance on single-occupancy automobiles can benefit from CMAQ funds. These projects include a wide variety of transit-related projects, such as park-and-ride facilities, high-occupancy vehicle facilities, bus-dedicated lanes, vanpooling and carpooling operations. Additional activities under the CMAQ program include: transit system capital expansion and improvements intended to increase ridership; travel demand management strategies; traffic flow improvement (e.g., incident-management initiatives, ramp metering, signal-timing improvements); pedestrian and bicycle facilities; and automobile inspection and maintenance programs. CMAQ funds are apportioned to States based on population in nonattainment areas and the severity of its air quality problems states that are in attainment of air quality standards receive 0.5 percent of the national program, which may be used for any project or program under the Surface Transportation Program.

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Funding

a. ITS Traditionally, ITS and traffic-management programs have been viewed as effective in reducting fuel consumption and pollution, although their effect has not been determined. The Federal share for most eligible activities is 80 percent or 90 percent if used for certain activities on the interstate system. Some activities, including traffic-control signalization and certain transit-related ITS elements may be eligible for 100 percent funding. Because of the broad array of projects eligible under CMAQ, use of these funds for ITS will have to compete with numerous alternative funding requests. It is important, therefore, to establish ITS strategies as an effective use of funds early in the CMAQ program lifecycle. The air quality benefits to be derived from ITS should be demonstrated in the early years of the program.

Intelligent Transportation Systems
The $600 million authorized for ITS in the ISTEA does not replace but is in addition to the $140 million provided for ITS in the 1992 Transportation Appropriations Act. This results in a total ITS program of $800 million. The applicable Federal share is 80 percent. The program was designed to promote the use of advanced technologies in multimodal transportation. While the use of advanced technologies in transportation has been ongoing for many years, the creation of the ITS program has accelerated the pace of innovation and integration of technologies into the transportation system. ITS consists of advanced computers, electronics, and communication technologies used to increase the effectiveness of the entire surface transportation system. The coordination of ITS projects with other transportation programs is vital to optimizing the benefit of those programs and to the success of ITS. The ITS Corridors Program funds (approximately $500 million) are not to be used to create infrastructure but are targeted at ITS planning, early deployment, and operational tests. The FHWA, which administers these funds and directs them to individual projects, has identified four priority corridors in ozone nonattainment areas to receive funds under the Corridors program. The early deployment program allows for the development and design of initial projects. Under the ITS planning and research program, $27 million of funding is available each year. However, these funds are competitive on a national basis, due to the earmarking of much of this money for specific projects and project types. A certain portion of funding for any given year will be used to support previously funded projects.

Safety
ISTEA provides $1.8 billion for the National Highway Traffic Safety Administration (NHTSA) and Motor Carrier Safety Assistance programs. There is no separate safety construction program. Ten percent of the Surface Transportation Program funds are set aside for safety.

Transit
In addition to the significant increases in funding for transit programs and projects, the Federal share for transit projects rises to 80 percent, the same as highway projects. Formula programs now make up 76 percent of the total transit program. Discretionary funds are divided 40 percent for rail modernization, 40 percent for new fixed guideway systems and extensions, and 20 percent for buses and

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related equipment. Operating assistance continues at a 50 percent Federal share. Capital funds can be used for highway purposes in large urban areas if all the requirements of the Americans with Disabilities Act are met, the MPOs approve, and State and local matching dollars are intermodal. a. Funding Sixty percent of the funding for transit programs comes from the transit account of the Highway Trust Fund. A transit planning and research program has been established and is funded at 3 percent of the total transit program funds. A National Cooperative Transit Research Board and a National Institute have been established and are modeled after their highway counterparts.

9.2 NEXTEA
The National Economic Crossroads Transportation Efficiency Act (NEXTEA) program, which President Clinton has officially unveiled, is a $175 billion program of which ITS would get $1.3 billion (i.e., $196 million annually for the first three years and $230 million annually for the last three years). This represents an 11-percent increase over the 1991 ISTEA, which expires in 1997. Core infrastructure programs retained: Interstate Maintenance (IM), National Highway System (NHS), Surface Transportation Program, Bridge Program, and Federal Lands Highway Program. NEXTEA mandates higher funding levels for all except the Bridge Program (which takes a small cut, because it is the narrowest program and bridges are eligible under the other major programs). Eligibility of most core infrastructure programs are expanded, to provide greater flexibility and greater intermodal scope. The biggest eligibility changes are in the Surface Transportation Program (STP), which encompasses railroad as well as highways and transit capital. To increase efficiency of NHS, NHS eligibility is expanded to include passenger terminals and freight-transfer facilities that are on or adjacent to the NHS. Transferability between IM, NHS, and Bridge Programs is largely retained, but with some conditions to ensure good decision making. STP substate distribution requirements are retained and strengthened, to ensure that metropolitan areas and rural areas are protected. The Federal Lands Highway Program is increased to $525 million/year, and restructured to contain these four elements: 1) Indian Reservation Roads, 2) Park Roads and Parkways, 3) Forest Highways, and 4) Public Lands Highways The environmental programs retained include: Congestion Mitigation Air Quality (CMAQ), Transportation Enhancements (TE), Scenic Byways, and Recreational Trails. CMAQ and TE funding is increased by more than 25 percent. The safety programs have been strengthened by NEXTEA. The Surface Transportation Program’s (STP) 10 percent safety set-aside is replaced with two new programs: (a.) Flexible Highway Infrastructure Safety Program, at $500 million, which can be used for rail grade crossings and elimination of highway safety hazards, and (b.) Integrated Safety Fund, which The major programs as they relate to ITS of the Administration’s March 1997 proposal for NEXTEA is summarrized below:

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Funding

INTERSTATE MAINTENANCE PROGRAM INTERSTA
Year Authorization 1997(ISTEA) $2,914M 1998 $4,480M 1999 $4,405M 2000 $4,392M 2001 $4,419M 2002 $4,419M 2003 $4,419M

PROGRAM PURPOSE Although the Interstate System is part of the National Highway System, it retains its separate identity because of the significance of this highway network to the nationwide movement of people and goods, and the resulting impact on the economy. The Interstate Maintenance (IM) Program provides criteria and funding for preserving this important element of the infrastructure. FUNDING/FORMULA Continues the apportionment formula in current law -- 55% on Interstate System lane miles, 45% on vehicle miles traveled on the Interstate System. Every State guaranteed a minimum of 1/2% of total IM funds apportioned annually. Continues 90% Federal share. ELIGIBILITY Continues to include the reconstruction of bridges, interchanges, and overcrossings along existing Interstate routes, including the acquisition of right-of-way where necessary. Construction of new travel lanes other than High Occupancy Vehicle or auxiliary lanes (such as truck climbing lanes) is not eligible. Expands to include (1) the reconstruction of Interstate highways and (2) infrastructure-based ITS capital improvements to the extent that they improve the performance of the Interstate. TRANSFERABILITY Continues flexibility of States to transfer IM funds (up to 100% of their apportionment) that are in excess of needs for Interstate pavement and bridges to the NHS or STP apportionments. Provides that all such transfers be conditional upon acceptance by the Secretary of the State’s certification of adequate maintenance of its Interstate pavement and bridges in accordance with condition criteria developed by the Secretary. (ISTEA allows unconditional transfers up to 20% of the IM apportionment.) This requirement is separate from the broader annual maintenance certification discussed below. KEY ISSUES Strengthens requirement that States maintain highway infrastructure by requiring States to annually certify that they are maintaining all (including Interstate) Federal-aid projects in accordance with the purposes for which each project was constructed. Focusing on the infrastructure as a whole,

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NEXTEA eliminates special requirements just for Interstate (i.e., guidelines, annual Interstate maintenance certification, separate Interstate preventive maintenance eligibility standard). See separate fact sheet on Toll Roads, Bridges, and Tunnels for changes in toll provisions affecting Interstate highways.

NATIONAL HIGHWAY SYSTEM NATIONAL HIGHWA
Year Authorization 1997(ISTEA) $3,600M 1998 $4,466M 1999 $4,391M 2000 $4,378M 2001 $4,405M 2002 $4,405M 2003 $4,405M

PROGRAM PURPOSE To provide funds for improvement of routes on the National Highway System (NHS). Under current law, funds may be used for certain transit capital improvements and improvements to non-NHS highways. NEXTEA would expand eligibility to other modes (see below). FUNDING/FORMULA Establishes a new apportionment formula: 75% based on contributions to the Highway Account of the Highway Trust Fund (HA/HTF) as a percent of total HA/HTF contributions by all States; 15% based on contributions to HA/HTF attributable to commercial vehicles as a percent of total contributions by all States; and 10% based on State’s public road mileage as a percent of total public road mileage in all States; each State receives ½% minimum apportionment. Retains the basic Federal share at 80% with allowable increase to 90 percent for projects on the Interstate System, including HOV or auxiliary lanes, but excluding any other added lanes. Retains takedown for I-4R Discretionary Program, at a funding level of $45 million/year for 19982003 (reduced from the current level of $65M); also retains takedown for Territories (see below). ELIGIBILITY Designates the connections to major intermodal terminals submitted by the Secretary on May 24, 1996, as part of the NHS. Expands the list of eligible activities to include: 1) Publicly owned intercity passenger rail capital projects (including Amtrak) under the same criteria that currently apply to transit and non-NHS highway projects. 2) Natural habitat mitigation. 3) Publicly owned intracity or intercity passenger rail or bus terminals (including Amtrak) and publicly owned intermodal surface freight transfer facilities (see definition below), other than airports and
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seaports, where the terminals and facilities are located at or adjacent to the NHS or connections to the NHS. Intermodal surface freight transfer facilities include any access road, parking or staging area, ramp, loading or unloading area, rail yard, track, interest in land, publicly owned rail access line to a seaport, and publicly owned access road to a seaport, if they are used to effect the transfer of freight. Clarifies eligibility of Intelligent Transportation System (ITS) capital operations and maintenance, and defines operational improvements (already an eligible activity) to expressly include the installation, operation, or maintenance of public infrastructure to support ITS, as well as improvements designated by the Secretary that enhance roadway safety and mobility during adverse weather. Retains 1% takedown for Territories. Expands eligibility, only in the Territories, to encompass STPeligible projects and capital improvements to airports and water ports. TRANSFERABILITY Continues existing transferability -- up to 50% of NHS funds may be transferred to STP at State discretion; transfers to STP in excess of 50% must be approved by the Secretary.

SURFACE TRANSPORTATION PROGRAM SURFACE TRANSPORTA
Year Authorization 1997(ISTEA) $4,097M 1998 $5,874M 1999 $5,785M 2000 $5,723M 2001 $5,728M 2002 $5,684M 2003 $6,192M

PROGRAM PURPOSE The Surface Transportation Program (STP) provides a flexible source of funds to be used on any surface transportation infrastructure project (except local streets and roads not now eligible), regardless of mode. FUNDING/FORMULA Establishes a new apportionment formula: 70% based on contributions to the Highway Account of the Highway Trust Fund (HA/HTF) as a percent of total HA/HTF contributions by all States, and 30% based on the State’s population as a percent of total population in all States (latest available annual data). Eliminates 10% set-aside from STP funds for safety construction, which will become a stand-alone program. Retains 10% transportation enhancements set-aside; codifies requirement that enhancement projects must have a direct link to surface transportation. Retains State sub-allocations.
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Extends the provision requiring States to make available obligation authority to urbanized areas over 200,000 population, but in two 3-year increments rather than one 6-year period as in ISTEA. Adds the requirement that the State, affected MPO, and Secretary ensure compliance with this provision. Specifies that the State and affected MPOs ensure fair and equitable treatment of central cities over 200,000 population in the allocation of these attributable funds. Retains the special rule for areas of less than 5,000 population. ELIGIBILITY Expands the list of eligible activities to include: 1) Publicly owned rail safety infrastructure improvements and non-infrastructure highway safety improvements. 2) Natural habitat mitigation. 3) Publicly or privately owned vehicles and facilities that are used to provide intercity passenger service by bus or rail (including Amtrak). 4) Publicly owned intercity passenger and freight rail infrastructure (including Amtrak). Clarifies the eligibility of Intelligent Transportation System (ITS) capital operations and maintenance, and defines operational improvements (already an eligible activity) to expressly include the installation, operation, or maintenance of public infrastructure to support ITS, as well as improvements designated by the Secretary that enhance roadway safety and mobility during adverse weather. Clarifies current law to assure that modifications of existing public sidewalks (regardless of whether the sidewalk is on a Federal-aid highway right-of-way), to comply with the requirements of the Americans with Disabilities Act, are eligible under STP . KEY ISSUE: STREAMLINING See fact sheet on Program Streamlining for important changes in program delivery and project oversight that affect the STP .

CONGESTION MITIGATION AND AIR QUALITY IMPROVEMENT PROGRAM MITIGATION
Year Authorization 1997(ISTEA) $1,029M 1998 $1,300M 1999 $1,300M 2000 $1,300M 2001 $1,300M 2002 $1,300M 2003 $1,300M

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Funding

PROGRAM PURPOSE The Congestion Mitigation and Air Quality Improvement Program (CMAQ) funds transportation programs and improvement projects that will assist air quality nonattainment and maintenance areas to reduce transportation emissions. FUNDING/FORMULA Retains basic structure of the apportionment formula, distributing funds on the basis of population and the severity of pollution, but makes certain changes in formula details. Modifies the current apportionment formula to include maintenance areas, i.e., areas redesignated to attainment, and particulate matter nonattainment areas. Eliminates: The freeze on the apportionment factors imposed under the NHS Designation Act. The provision for California, New York, and Texas which apportions funds to these States based on total population rather than nonattainment area populations. Retains ½% minimum apportionment to each State. Retains Federal share of project cost at 80%. ELIGIBILITY Expands to include scrappage of pre-1980 vehicles and extreme cold start programs. Expands the use of funds to designated nonattainment areas under the newly proposed air quality standards, provided the State has submitted to the Environmental Protection Agency a State Implementation Plan including the new nonattainment areas. Currently, funds may be used only in nonattainment and maintenance areas that meet the classifications under the 1990 Clean Air Act Amendments. Reinstates a three-year limit on the use of funds for operating assistance on traffic management and control projects. Limits Federal share for signalization and carpooling to standard 80%. TRANSFERABILITY Targets funding at maintenance areas if there are no nonattainment areas within a State, but relieves this requirement if the State can demonstrate adequate funding for transportation-related maintenance plan activities.

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Advanced Transportation Management Technologies

KEY ISSUES Levels the playing field by allowing CMAQ proposals to compete for funding equally. Operating assistance is limited to three years for all projects, and all projects are funded at the same 80% Federal share. Modifies resource allocation by more fairly apportioning funds on the basis of need and expanding the formula to include other transportation-related pollutants such as carbon monoxide and particulate matter. Addresses continuing needs by providing greater focus and funding to maintenance areas. Ensures that no State will lose CMAQ funding as a result of the inclusion of any area in the CMAQ apportionment formula designated under the newly proposed air quality standards.

MAJOR CAPITAL INVESTMENTS PROGRAM (5309) CAPITAL
Year Authorization 1997(ISTEA) $760M 1998 $800M 1999 $950M 2000 $1,000M 2001 $1,000M 2002 $1,000M 2003 $1,027M

PROGRAM PURPOSE The Major Capital Investments Program would provide transit capital assistance for new fixed guideway systems and extensions to existing fixed guideway systems. FUNDING/FORMULA Continues funding from the Mass Transit Account of the Highway Trust Fund. Continues the discretionary nature of the program in current law, limited to new starts under a newly titled Major Capital Investments Program. Projects must still compete for funding using specific criteria to justify the major investment involved. Ends discretionary grants for bus and bus related capital projects; resources moved to Urbanized Area Formula Program. Moves fixed guideway modernization formula program into Urbanized Area Formula Program. Continues 80% Federal share and the 90% Federal share for the incremental costs of vehicle related equipment needed to comply with Clean Air and Americans with Disabilities Act requirements. Removes 40%, 40%, 20% allocation formula among rail fixed guideway modernization, new fixed guideway systems and extensions, and bus and bus-related facilities since this section now covers only major capital investments.

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Funding

KEY MODIFICATIONS Restricts eligibility to capital projects for new fixed guideway systems and extensions to existing fixed guideway systems. Streamlines and consolidates program requirements and procedures such as certification of legal, financial, technical capacity, continuing control over the use of equipment and facilities, maintenance of equipment and facilities, government’s share of costs, and advance construction.

URBANIZED AREA FORMULA PROGRAM (5307)
Year Authorization 1997(ISTEA) $3,118M 1998 $3,657M 1999 $3,657M 2000 $3,657M 2001 $3,657M 2002 $3,657M 2003 $3,759M

PROGRAM PURPOSE The urbanized area formula program provides transit capital and operating assistance to urbanized areas. Under ISTEA, approximately $11.8 billion was provided to transit agencies for bus and rail vehicle replacements and facility recapitalization. FUNDING/FORMULA Continues the apportionment formula in the current law - which is based on population and population density for areas under 200,000; and on population, population density, and transit data for areas over 200,000 in population. Proposes funding completely from the Mass Transit Account of the Highway Trust Fund. Now funded from both the Mass Transit Account and the General Fund. Continues 80% Federal share and 90% Federal share for the incremental costs of vehicle related equipment needed to comply with Clean Air and Americans with Disabilities Act requirements. ELIGIBILITY Expands funding in areas under 200,000 in population to operating and capital without limit. Use for operating expenses now subject to statutory cap. Expands definition of capital to include preventive maintenance while eliminating operating assistance for areas over 200,000. Expands eligibility to include planning, the transportation cooperative research program, university transportation centers, training, research, technology transfer.

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Advanced Transportation Management Technologies

Streamlines and consolidates program requirements and procedures such as certification of legal, financial, technical capacity, continuing control over the use of equipment and facilities, maintenance of equipment and facilities, government’s share of costs, and advance construction. TRANSFERABILITY Continues existing flexibility by permitting funds to be used for a highway project only if local funds are eligible to finance either highway or transit projects, i.e., are flexible.

HIGHWAY SAFETY PROGRAM
Year Authorization 1997(ISTEA) $302.7M* 1998 $392.5M 1999 $392.5M 2000 $392.5M 2001 $392.5M 2002 $392.5M 2003 $402.4M

* 1997 includes NHTSA/FHWA authorizations for Section 402 (including rescissions), NHTSA Section 410 and 403, the National Driver Register, and the portion of the NHTSA program not funded by ISTEA ($88M), for comparability with later years; 1998-2003 consolidates NHTSA and FHWA Section 402 authorizations and includes the total NHTSA program. PROGRAM PURPOSE The Highway Safety Program provides funding for grants to States for non-infrastructure, safety behavior programs. The new authorization also will provide funding for the entire National Highway Traffic Safety (NHTSA) program, including motor vehicle and cost savings programs. Emphasis will be on performance based management and quantifiable results. FUNDING/FORMULA Establishes a consolidated Section 402 State formula grant program and incentive grants in the following 4 program areas: (1) Alcohol-Impaired Driving Countermeasures: provides increased authorization level for a revised and updated alcohol incentive grant program; States can qualify for basic and supplemental grants by meeting programmatic and legal criteria or new results criteria (based on the percent of fatally injured drivers with a blood alcohol count of 10 or more); funding for each basic grant: up to 15% of the State’s FY 1997 apportionment; funding for supplemental: for each criterion met (for no more than 2 years), up to 5% of the State’s Section 402 FY 1997 apportionment. (2) Occupant Protection Program: a new incentive grant program to encourage States to increase level of effort for safety belt and child safety seat use; States can qualify for basic and supplemental grants by meeting programmatic and legal criteria or results criteria (based on safety belt use rates);

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Funding

funding for each basic grant: up to 20% of the State’s FY 1997 apportionment; funding for supplemental: for each criterion met, up to 5% of the State’s Section 402 FY 1997 apportionment. (3) State Highway Safety Data and Traffic Records Improvements: a new incentive grant program to improve data to identify priorities, evaluate effectiveness, and link data; authorized for 1998-2001; first year and succeeding year grants; set dollar amounts, based on available appropriations. (4) Drugged Driving Countermeasures: a new grant program; authorization beginning in 1999; States must meet 5 out of 9 programmatic and legal criteria; funding for grants: up to 20% of the State’s Section 402 FY 1997 apportionment. Increases the 402 apportionment amount to Native American populations by one-quarter percent and broadens the coverage of Indian tribes by a new definition, “Indian Country,” which counts Indians living in areas off reservations. Otherwise, Section 402 State formula remains the same (75% based on population ) and 25% based on public roadway mileage).

FLEXIBLE HIGHWAY INFRASTRUCTURE SAFETY PROGRAM AND INTEGRATED HIGHWA INTEGRATED SAFETY FUND
Year Infrastructure Sfty. Integ. Safety Fund 1997(ISTEA) * ... 1998 $500M $50M 1999 $525M $50M 2000 $550M $50M 2001 $550M $50M 2002 $550M $50M 2003 $575M $50M

* Over the life of ISTEA, an average of $445 million was set aside from STP for safety construction.

Infrastructure Safety Program
PROGRAM PURPOSE The Infrastructure Safety Program provides funds to eliminate hazards on public roadways other than the Interstate, and to improve the safety of rail/highway grade crossings. It replaces the STP safety set-aside. FUNDING/ FORMULA Rail/highway grade crossing -- Funded at $165M/year: 25% on number of crashes at public grade crossings, 25% on number of fatalities at public grade crossings, 25% on number of public grade crossings, and 25% on number of public crossings with passive warning devices. Hazard elimination -- Balance of the Highway Infrastructure Safety authorization: 75% on population, 25% on public road mileage; 1/2% minimum. These funds can be used for grade crossing improvements if the State decides the crossing constitutes a hazard; no transfer is necessary.
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Advanced Transportation Management Technologies

Continues 90% Federal share. ELIGIBILITY Continues Hazard Elimination eligibility, which includes all public roads except Interstate. Expands grade crossing eligibility to include all public grade crossings and certain private crossings where sufficient public benefit has been identified. Adds trespassing and enforcement. TRANSFERABILITY Allows flexing from grade crossing to hazard elimination to the extent that a State reduces the number of grade crossing crashes. Broadens flexing from hazard elimination: If State has integrated safety planning process, may flex into non-infrastructure highway safety investments (402 and motor carrier safety). KEY ISSUES Revamps grade crossing funding formula to target safety problems and risks. Ties ability to flex (from grade crossing to hazard elimination) to safety improvements. Opens door for funding of non-infrastructure highway safety programs.

Integrated Safety Fund
Integrated Safety Fund is a new incentive grant designed to foster integrated safety planning. For States that have integrated safety planning (specific criteria to be developed in rulemaking), provides additional funds that can be used for any highway or traffic safety purpose within the Section 402 behavioral program, the Highway Infrastructure Safety Program, and the motor carrier safety program. For qualifying States, the formula for distribution will be 75% on population, 25% on public road mileage; award not to exceed 50% of the State’s FY 1997 Section 402 apportionment.

TRANSPORTATION ENHANCEMENTS TRANSPORTA
PROGRAM PURPOSE Transportation enhancements (TE) are transportation-related activities that are designed to strengthen the cultural, aesthetic, and environmental aspects of the Nation’s intermodal transportation system. The TE funds are intended for nontraditional community-oriented projects and features that go beyond standard transportation mitigation. A TE project may stand alone as a separate project or may be a distinct part of a larger transportation project, whether existing or proposed. Examples of

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Funding

allowable projects include the renovation and reopening of a historic railroad station as an intermodal facility and development of a pedestrian and bicycle trail along an abandoned railway. FUNDING/FORMULA Continues to be funded as a 10% set-aside from each State’s Surface Transportation Program funds. Increases funding for Transportation Enhancements by more than 30% over ISTEA levels. ELIGIBILITY Maintains the existing list of eligible transportation enhancement activities, i.e., the ten specific project activities listed in ISTEA. Codifies the requirement that transportation enhancement activities must have a direct link to surface transportation.

VALUE PRICING PILOT PROGRAM
Year Authorization 1997(ISTEA) * 1998 $14M 1999 $14M 2000 $14M 2001 $14M 2002 $14M 2003 $14M

* ISTEA authorized $25 million in FY 1997 for the Congestion Pricing Pilot Program, but the NHS Act redirected these funds to other uses. PROGRAM PURPOSE The objective of the Value Pricing Pilot Program (formerly the Congestion Pricing Pilot Program) is to encourage implementation and evaluation of value pricing demonstration projects in order to provide congestion relief and related air quality and energy conservation benefits. FUNDING Increases the Federal share on projects under this program to 100% (from 80%). Removes funding caps for individual pilot programs. Continues to allow authorized funds to be available for three years after the year in which they are authorized. Reverts any unobligated allocations to the States and unallocated balances remaining with the Secretary at the end of the four-year period to the Surface Transportation Program. Continues three-year project funding limitation which begins once the project has actually been implemented, not in the pre-project stage.
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Advanced Transportation Management Technologies

ELIGIBILITY Continues to include singular or collective pricing of roads, highways, freeways, arterials, and streets for the purpose of reducing traffic congestion. Singular facility pricing may involve a bridge, tunnel, highway arterial, freeway, or intersection. Collective pricing may take place in a corridor or involve a core area or region-wide application. Pricing may be proposed on new facilities, currently untolled facilities, or on existing toll facilities. Charges may involve both peak-period surcharges and off-peak discounts. Continues to include pre-project activities, such as the development of public involvement programs, activities designed to overcome institutional barriers to implementing congestion pricing, and funding for automated vehicle identification or tolling equipment and other capital and operational costs for pricing applications. Increases the number of pilot programs eligible for funding to 15, where each program may cover one or more specific value pricing projects within the area. Removes the three-program cap on the number of pilot projects which may allow tolls on the Interstate. Permits value pricing projects to include single-occupant vehicle use on HOV lanes, if drivers pay a fee. KEY ISSUES Expands to allow toll revenues collected through pilot projects to be used for any surface transportation purpose. Expands to require, at the project level, the consideration of the impact on low income drivers and the development of possible mitigation measures.

FORMULAS
PURPOSE Apportionment formulas are the basis for distributing most program funds to the States. NEXTEA proposes a transition to formula factors that relate well to the objectives of the basic program elements. Equity adjustments are provided to ensure an orderly transition to this sounder, more logical basis for apportionment of Federal funds. FORMULAS National Highway System (NHS): 75% according to a State’s contributions to the Highway Account (NHS) of the Highway Trust Fund (HA/HTF)as a percent of total HA/HTF contributions by all States; 15% according to a State’s Commercial Vehicle Contributions (CVC) to the HA/HTF as a % of total CVC

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Funding

by all States; 10% according to a State’s public road mileage as a percent of total public road mileage within all States; ½% minimum; use the latest available data. Surface Transportation Program (STP): 70% according to a State’s contributions to the HA/HTF as a (STP) percent of total HA/HTF contributions by all States; 30% according to a State’s total population as a percent of total population within all States; ½ % minimum; use latest available data. Retain Current Formula for Interstate Maintenance (IM) (i.e., 55% Interstate lane miles; 45% Interstate vehicle miles traveled; ½% minimum). Retain Current Formula for Highway Bridge Replacement and Rehabilitation Program (HBRRP) (i.e., 100% of the relative share of costs to repair deficient bridges; 1/4% minimum; 10% maximum). Special Note on Interstate Reimbursement Program: The Administration is proposing reauthorization Program: of the Interstate Reimbursement Program at $1 billion annually, or a total $6 billion over the reauthorization period. State shares for this program are based on each State’s original cost of constructing routes which later became part of the Interstate System. Other Revised Formulas: Apportionment formulas for Congestion Mitigation and Air Quality ImFormulas provement (CMAQ) and Highway Infrastructure Safety are revised (see individual fact sheets). EQUITY ADJUSTMENTS NEXTEA equity adjustments provide for an orderly transition from current law formula factors to alternative formula factors that relate well to program purpose and goals, but in a fashion which will not abruptly alter any State’s apportionment dollars from one year to the next. NEXTEA discretionary allocations (Public Lands Discretionary, Bridge Discretionary, Scenic Byways, etc.) are not calculated in the base for these equity adjustments. Following are the formulas for the three proposed equity adjustments: Minimum Allocation (MA): Each State receives apportionments of at least 90% of its percent contri(MA): butions to the HA/HTF.** 90 Percent of Apportionments: Each State receives apportionments of at least 90% of its prior year’s Apportionments dollar apportionments throughout NEXTEA years. Special Provision for Alaska: Alaska will receive 90% of its FY 1997 apportionments in FY 1998 (like all other States), and 100% of its prior year’s dollar apportionments thereafter (unlike all other States), throughout all years of NEXTEA.** **Combined funding for the MA and 90 Percent of Apportionments equity adjustments is capped at ** $790M for FY 1998, $674M for FY 1999, $583M for FY 2000, $528M for FY 2001, and $508M for FY 2002-2003. State Percentage Guarantee: Each State’s share of NEXTEA annual apportionment dollars received Guarantee: must equal at least 95% of its average ISTEA (FY 1992-97) percent apportionments throughout all NEXTEA years. In order to accomplish this, adjustments are made within the STP apportionments. Special Provision for Massachusetts: In calculating each State’s average ISTEA % apportionments,

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Advanced Transportation Management Technologies

Massachusetts’ annual Interstate Completion funds, which were significantly higher than all other States under ISTEA, shall be capped at the level of the next highest State.

STATE INFRASTRUCTURE BANK PROGRAM STA
Year Authorization 1997 $150M* 1998 $150M 1999 $150M 2000 $150M 2001 $150M 2002 $150M 2003 $150M

* FY 1997 DOT Appropriations Act provided $150 million from the General Fund. PROGRAM PURPOSE The State Infrastructure Bank (SIB) program provides States with a new capability for financing infrastructure investment to complement the Federal-aid program. Originally limited to ten States, a new SIB program will offer all States ready to implement a SIB the opportunity to provide financial assistance to Title 23-eligible highway, transit, and railway projects. The SIB program is designed to give States the potential to increase the efficiency of their transportation investments and significantly leverage Federal resources by allowing them greater flexibility in the use of their Federal funds to attract non-Federal public and private investment. FUNDING Continues requirement that States must keep separate accounts for highway and transit. $150 million/year in Federal seed money for capitalization grants will be awarded on a discretionary basis among States with SIBs, to be deposited into either the highway or transit account of the SIB. States can further capitalize their SIB with up to 10% of funds from the following categories: 1) For the highway SIB account -- National Highway System, Surface Transportation Program, Interstate Maintenance, Highway Bridge Replacement and Rehabilitation Program, Interstate Reimbursement, and equity adjustment programs. 2) For the transit SIB account -- urbanized and non-urbanized area formula programs and the major capital investment program. These funds will be disbursed at a flat 20%/year outlay rate over five years. SIBs offer a menu of loan and credit enhancement assistance (e.g., direct loans, interest rate subsidies, lines of credit, and loan guarantees). As loans are repaid, the SIB funds are replenished and thus become available to provide financial assistance to additional transportation projects.

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Funding

ELIGIBILITY SIB-assisted projects eligible for highway account assistance have been expanded to include all projects eligible under Title 23. SIB-assisted projects eligible for transit account assistance must be Title 49 capital transit investment projects.

THE TRANSPORTATION INFRASTRUCTURE CREDIT ENHANCEMENT PROGRAM
Year Authorization 1997(ISTEA) ... 1998 $100M 1999 $100M 2000 $100M 2001 $100M 2002 $100M 2003 $100M

PROGRAM PURPOSE The new Transportation Infrastructure Credit Enhancement Program will provide $100 million/year in grants to assist in the funding of nationally-significant transportation projects that otherwise might be delayed or not constructed at all because of their size and uncertainty over timing of revenues. The goal is to encourage the development of large, capital-intensive infrastructure facilities through public-private partnerships consisting of a State or local government and one or more private sector firms involved in the design, construction or operation of the facility. It will encourage more private sector and non-Federal participation, and build on the public’s willingness to pay user fees to receive the benefits and services of transportation infrastructure sooner than would be possible under traditional funding techniques. REVENUE STABILIZATION FUNDS Grants under this program (limited to 20% of project costs), together with any supplemental contributions by States and other entities, will comprise a Revenue Stabilization Fund for each project, to be used to secure external debt financing, or to be drawn upon if needed to pay debt service costs in the event project revenues are insufficient. These debts will not be considered “Federally guaranteed” under the Internal Revenue Code, thus allowing the program to be used in connection with either taxable or tax-exempt bond issues. ELIGIBILITY Any publicly-owned project that is eligible for Federal assistance through regular surface transportation programs under title 23 or title 49 would be eligible for the Federal Credit Enhancement Program. This includes new facilities as well as renovation or expansion of existing highway facilities, mass transit facilities and vehicles, intercity passenger rail facilities and vehicles (including Amtrak), publicly owned freight rail facilities, and various publicly owned intermodal facilities.

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Advanced Transportation Management Technologies

PROJECT SELECTION The Secretary, in consultation with the Secretary of the Treasury, will determine a project’s eligibility, then select among potential candidates based on both quantitative and qualitative factors. In order to be considered, a project must first meet the following criteria: (1) Cost at least $100 million or 50% of a State’s annual Federal-aid apportionments, whichever is less. (2) Be supported, at least in part, by user charges or other dedicated revenue sources. (3) Be included in a State’s transportation plan and program. (4) Be “nationally significant” -- resulting in major economic benefits through more efficient and costeffective movement of people and goods. (5) Be unable to obtain financing on reasonable terms from other sources. Qualified projects meeting the initial threshold eligibility criteria would then be evaluated and selected based on the extent to which they leverage private capital, their overall credit worthiness, and other program goals.

TOLL ROADS, BRIDGES, AND TUNNELS
PROGRAM PURPOSE To provide States with greater flexibility and financing options, a change is proposed in Federal toll law to permit States to levy tolls on Interstate highways under the same conditions as tolls are now permitted on all other Federal-aid highways, bridges, and tunnels. ELIGIBILITY Continues the current eligibility of Federal-aid highway funding for five broad categories of toll activities: 1) Initial construction of toll highways, bridges, or tunnels 2) 4R work on existing toll facilities 3) Reconstruction or replacement of free bridges or tunnels and conversion to toll 4) Reconstruction of free highways and conversion to toll 5) Preliminary feasibility studies for toll construction activities

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Funding

Expands the eligibility of Federal-aid highway funding for toll activities by eliminating the current exclusion of Interstate routes, which occurred under numbers 1 and 4 above. The initial construction of Interstate toll roads and the reconstruction of existing toll-free Interstate routes and conversion to toll would now be eligible for Federal-aid highway funding. FEDERAL SHARE Continues the current Federal share for eligible toll activities at 80%. TOLL AGREEMENT Continues to require a toll agreement for Federal-aid funded toll projects documenting acceptable uses of toll revenues. Toll revenues in excess of those needed to adequately maintain the tolled facility can be used for any surface transportation project. State and Local Funding for Toll Highways (New Flexibility for Interstates) Title 23, Section 301, requires that all highways constructed with Federal-aid highway funding under Title 23 remain free from tolls, except as provided in Section 129. Therefore, public highways that had not utilized Federal funding under Title 23 could be converted to toll by the responsible highway authority with no Federal involvement. Under ISTEA, Federal-aid funds could not be used for construction and conversion of existing toll-free Interstate routes to toll nor for construction of new toll Interstate highways. Also, existing-toll free Interstate routes constructed under Title 23 could not be reconstructed and converted to toll using State or local funds. With the proposed modification as noted above under Eligibility, Interstate routes could be reconstructed and converted to toll, or new toll Interstate highways could be constructed with either Federal-aid highway or other funding sources, as long as the appropriate toll agreement is executed. PILOT PROGRAM Eliminates the pilot program for toll facilities, currently under Section 129(d), which has accomplished its intended purpose.

METROPOLITAN PLANNING METROPOLITAN
PROGRAM PURPOSE The metropolitan planning process establishes a cooperative, continuous, and comprehensive framework for making transportation investment decisions in metropolitan areas and is administered jointly by FHWA and FTA. CONTINUING PROVISIONS Responsibility of local officials, in cooperation with the State and transit operators, for determining the best mix of transportation investments to meet metropolitan transportation needs.
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Advanced Transportation Management Technologies

Federal reliance on the metropolitan planning process, established in the early 1960s and strengthened under ISTEA, as the primary mechanism for making State and local transportation decisions on the use of Federal funds in metropolitan areas. Emphasis on tailoring the planning process to fit the complexity of problems. Responsibility of Metropolitan Planning Organizations for adopting the plan. A 20-year planning perspective, air quality consistency, fiscal constraint, and public involvement established under ISTEA. Emphasis on fiscal constraint and public involvement in the development of three-year Transportation Improvement Programs (TIP). Emphasis on alternatives to capacity additions through the Single Occupant Vehicle project limit in larger metropolitan areas which are nonattainment areas for air quality. Relationship of transportation planning and air quality boundaries in effect on September 30, 1996. Requires a Congestion Management System in larger metropolitan areas. Requires major transportation mode operators be included in the membership of large MPOs if redesignated. DOT certification of the planning process in larger metropolitan areas. Funding currently in place for metropolitan transportation planning. KEY MODIFICATIONS Simplifies planning factors by focusing on seven broad issues to be considered in the planning process (same as for statewide planning). Modifies the general objectives of the planning process to include operations and management of the transportation system. Encourages comprehensive planning through coordination with other planning activities such as housing, land use, etc. Adds freight shippers to list of stakeholders to be given opportunity to comment on plans and TIPs. Reduces population threshold for designating and redesignating an MPO from 75% of affected population, including the central city, to 51% of the affected population, including the central city. Modifies provision for designating multiple MPOs in urbanized areas, adding a requirement for MPO and DOT Secretary concurrence.

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Funding

Adds a requirement for MPO, State, and transit agencies to cooperate in the development of financial estimates that support plan and TIP development. Enhances coordination requirement for air quality and transportation plans by extending it from Transportation Control Measures to the entire air quality and transportation plan process. Includes particulate matter nonattainment boundary as a consideration in establishing metropolitan planning area boundaries. Clarifies the distinction between project selection and TIP development (project selection means implementation from a cooperatively developed TIP). Modifies sanctions for not being certified. Current penalty is withholding 20% of STP funds; this is revised to allow the Secretary to withhold all or part of Title 23 or Title 49 funds.

STATEWIDE PLANNING STA
PROGRAM PURPOSE The statewide planning process establishes a cooperative, continuous, and comprehensive framework for making transportation investment decisions throughout the State and is administered jointly by FHWA and FTA. CONTINUING PROVISIONS Federal reliance on the statewide transportation planning process, established under ISTEA, as the primary mechanism for cooperative decision making throughout the State (the planning process is conducted cooperatively with local officials). Need to coordinate statewide planning with metropolitan planning and to provide opportunity for public involvement throughout the planning process. Emphasis on fiscal constraint and public involvement in the development of a three-year Statewide Transportation Improvement Program (STIP). Emphasis on tailoring the planning process to fit the complexity of problems. Emphasis on involving and considering the concerns of Tribal governments in planning. Funding currently in place for statewide transportation planning. KEY MODIFICATIONS Simplifies planning factors by focusing on seven broad issues to be considered in the planning process (same as for metropolitan planning).

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Advanced Transportation Management Technologies

Adds provision that the concerns of rural officials with jurisdiction over transportation are to be considered in making transportation decisions in both the plan and the STIP . Adds a provision that the Secretary, prior to approving the STIP (at least every two years), must determine if the planning process producing the STIP is consistent with the statewide and metropolitan planning requirements. Clarifies the distinction between project selection and TIP development (project selection means implementation from a cooperatively developed TIP).

Clarifies language that metropolitan area projects in the STIP are to be the same as in the approved TIP . Encourages comprehensive planning through coordination with other planning activities in areas such as housing and land use. Modifies the general objectives of the planning process to include operations and management of the transportation system. Clarifies the focus on a 20-year planning horizon for the transportation plan. Strengthens language concerning the intermodal nature of the State transportation system as an integral part of the Nation’s intermodal system. Adds particulate matter to the list of pollutants for nonattainment consideration. Adds freight shippers to list of stakeholders that must be afforded an opportunity to comment on the plan and STIP . Adds a provision that only regionally significant Federal lands projects need to be individually identified in the STIP .

INTERMODAL TRANSPORTATION R&D PROGRAM INTERMODAL TRANSPORTA
Year Authorization 1997(ISTEA) ... 1998 $10 M 1999 $15M 2000 $20M 2001 $25M 2002 $30M 2003 $35M

PROGRAM PURPOSE To conduct long-term, higher-risk, inter/multi-modal research that will continue the steady advances in transportation technology necessary to meet the demands of the 21st century. Focused by strategic planning and assessment studies, these technologies later become the basis for partnership initiatives to bring about implementation.

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Funding

PROGRAM STRUCTURE AND FUNDING RSPA will manage a program of “enabling research” that focuses on five long-term research areas: 1) Human performance and behavior 2) Advanced materials 3) Computer, information, and communications systems 4) Energy and environment 5) Sensing and measurement 6) Tools for transportation modeling and design KEY PROVISIONS Recognizes that innovations in transportation generally result from application of disciplines not specific to transportation. Continual research in these areas is necessary, but the long-term nature and diffuse benefits of such research may be insufficient to motivate private investment. Augments R&D conducted to address specific concerns of modal administrations with research focused on broader national needs. Provides for conduct of research that: 1) Supports long-term national transportation goals. 2) Offers benefits too widely spread for any potential sponsor to capture returns on its investment. 3) Presents a risk too great relative to needed investment for any potential sponsor tobear alone. 4) Offers benefits too far in future to meet private investment criteria. Facilitates departmental leverage of transportation-related research conducted by other Federal agencies and academia.

STRATEGIC PLANNING FOR RESEARCH & TECHNOLOGY STRATEGIC TECHNOLOGY
PROGRAM PURPOSE The strategic planning process provides the Secretary with a corporate mechanism for determining national transportation R&T priorities, coordinating Federal transportation R&T activities and measuring the impact of such R&T investments on the performance of the national transportation system.
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Advanced Transportation Management Technologies

PROGRAM STRUCTURE AND FUNDING RSPA’s FY 98 request for program funding includes resources to support the Secretary in implementing the strategic planning process. KEY PROVISIONS Provides the Secretary with greater flexibility in structuring a research and development oversight process which should prove useful to States and local governments in developing and carrying out their own R&T initiatives. Directs the Secretary to establish a strategic planning process for research and technology which considers the need to: 1) Coordinate transportation planning at all government levels 2) Ensure compatibility of standards-setting with concept of seamless transportation 3) Encourage innovation 4) Facilitate partnerships 5) Identify core research to meet long-term needs 6) Ensure the nation’s global competitiveness 7) Measure impact of investments on system performance Authorizes the Secretary to consult with other Federal entities involved in transportation research and to make appropriate use of the capabilities resident in Federal laboratories. Authorizes the Secretary to adopt procedures to validate the scientific and technical assumptions underlying DOT’s R&T plans. Gives Secretary broad discretion in implementation, including use of an interagency executive council or a board of science advisors. Recognizes the need to foster cooperation in research and technology planning among government, academia and industry in addressing the nation’s transportation goals.

FHWA RESEARCH AND TECHNOLOGY
PROGRAM PURPOSE The Research and Technology Program researches, develops, and deploys transportation innovations and technologies through laboratories, test and evaluation, training, technology demonstrations, and public and private partnerships.
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PROGRAM STRUCTURE AND FUNDING Restructures Research and Technology Program to focus on four key areas, listed below. Part of the program receives separate authorizations (all with contract authority) in NEXTEA, while other elements of the program are funded from the FHWA’s general operating expenses. (See the FHWA Research and Technology Funding fact sheet for details on the 1998 funding levels.) 1) Initiates a National Technology Deployment Initiatives Program to expand the adoption of innovative technologies by the surface transportation community in seven goal areas. This replaces the current Applied Research and Technology Program. Funding levels are $56 million per year for fiscal years 1998-2000, then $84 million for years 2001-2003. A significant portion of these funds is planned to be allocated to States to fund deployment of innovative technology. 2) Initiates a Professional Capacity Building and Technology Partnerships Program that brings together technology transfer programs and activities, including education and training efforts, that focus on equipping people to use new technology. Existing programs that are encompassed under this program are the Local Transportation Assistance Program ($12 million/yr), the National Highway Institute ($8 million/yr for 1998-2000 and $14 million/yr for 2001-2003), Eisenhower Transportation Fellowship Program ($2 million/yr), and Technology Partnership Support (formerly SHRP Implementation) ($11 million/yr). 3) Continues the Long-Term Pavement Performance Program to test, evaluate and collect data on various types of pavements ($15 million/yr for 1998-2003) and initiates an Advanced Research Program to address longer-term, higher-risk research ($10 million/yr for 1998-2000 and $20 million/yr for 2001-2003). 4) Continues the State Planning and Research Program. Funding continues to come from a 2% setaside of a State’s apportionments of most Federal-aid program funds. ELIGIBILITY Continues authority of the Secretary to engage in research, development, and technology transfer activities with respect to motor carrier transportation and all phases of highway planning and development. Continues authority of the Secretary to carry out the research and technology program independently or through cooperative agreements, grants, and contracts. Initiates the inclusion of the private sector and the international community as sources of products for technical innovation and as recipients of training and technology transfer activities. Continues authority of the Secretary to undertake and continue, on a cost-shared basis, collaborative research and development with non-Federal entities for the purposes of encouraging innovative solutions to highway problems and stimulating the marketing of new technology by private industry.

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FHWA RESEARCH AND TECHNOLOGY FUNDING
(Dollars in Millions)
FY 1997 FY 1998

FEDERAL-AID PROGRAM (CONTRACT AUTHORITY): )
ITS/ITI Incentive Deployment $0.000 FHWA Research and Technology Programs: Intelligent Transportation Systems $113.000 1 University Transportation Centers 6.000 1 University Research Institutes 6.250 Local Transportation Assistance Program [6.000] 2 Tech. Partnership Support (formerly SHRP Implementation) [14.000] 2 Long-Term Pavement Performance [6.000] Eisenhower Transportation Fellowship Program [2.000] 2 National Tech. Deployment Initiatives (formerly App.Res.& Tech.)[41.000]2 Seismic Research and Development Program [2.000] 2 National Highway Institute 0.000 Advanced Research 0.000 Subtotal $125.250 $100.000 $96.000 6.000 6.000 12.000 11.000 215.000 2.000 56.000 0.000 8.000 10.000 $222.000

LIMITATION ON GENERAL OPERATING EXPENSES (LGOE):
Research Programs: Highway Research and Development $67.124 Sustainable Transportation Initiative -- Research & Pilot Program0.000 Intelligent Transportation Systems 120.358 Technology Assessment and Deployment 13.811 Local Technical Assistance Program 2.827 National Highway Institute 4.269 Rehabilitation of Turner Fairbank Highway Research Center 0.500 Research and Development Technical Support 0.000 Global Position Systems Oversight 0.000 National Advanced Driver Simulator 0.000 $69.653 4.250 54.000 14.800 0.000 0.000 2.000 10.000 2.100 12.250

3 1 2 3

$208.889 $169.053 Total, Research and Technology Programs $405.139 $491.053 Administered by the U.S. DOT’s Research and Special Programs Administration. In FY 1997, these programs, totaling $71 million, were funded from the administrative takedown.The R&T total listed for FY 1997 includes $125.250 million for R&T contract authority programs, $71 million for R&T programs funded from the administrative takedown, and $208.889 million from LGOE funds.

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INTELLIGENT TRANSPORTATION SYSTEMS TRANSPORTA
PROGRAM PURPOSE ISTEA launched a program of research, testing, and technology transfer of intelligent transportation systems (ITS) aimed at solving congestion and safety problems, improving operating efficiencies in transit and commercial vehicles, and reducing the environmental impact of growing travel demand. NEXTEA continues this research, testing, and technology transfer program, and also launches the integrated, intermodal deployment of proven technologies that are technically feasible and highly cost-effective. The result will be a 21st Century national system, using common standards and common architecture. ITS RESEARCH, TESTING, AND TECHNOLOGY TRANSFER (See FHWA Research and Technology Funding fact sheet) Continues 80% Federal share; funding match requirement can be waived for innovative research activities. Will focus on the demonstration and evaluation of fully integrated intelligent vehicle systems. INTELLIGENT TRANSPORTATION INFRASTRUCTURE DEPLOYMENT INCENTIVES PROGRAM Funded at $100M/year for 1998-2003. Provides funding to State and local applicants to support integration (not components) of metropolitan area travel management intelligent infrastructure, intelligent infrastructure elements in rural areas, and Commercial Vehicle Information Systems and Networks (CVISN) deployment within States and at border crossings. These funds are a sweetener to encourage integrated deployment, as well as innovative financing and public/private partnerships. Limits Federal share to 80%; not to exceed 50% from Deployment Incentive funds; remaining 30% of Federal share may be funded from other FAH and transit apportionments. Establishes annual award funding limitations as follows: 1) $15 million per metropolitan area 2) $2 million per rural project 3) $5 million per CVISN project 4) $35 million within any State Establishes funding priorities as follows: 1) At least 25% for implementation of CVISN and international border crossing improvements.
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2) At least 10% for other deployment outside metropolitan areas. Replaces the IVHS Corridors Program; currently designated Priority Corridors are eligible for funding. OTHER KEY PROVISIONS Requires the Secretary to develop a National Architecture and supporting standards and protocols to promote interoperability among ITS technologies implemented throughout the States. Use of approved standards and protocols is required as a prerequisite for use of Federal-aid funds to implement ITS technology and services. Requires the Secretary to take necessary actions to secure a permanent spectrum allocation for Dedicated Short Range Communications. Makes explicit the authority of States and local entities to use specified core infrastructure programs, highway and transit, for ITS implementation, modernization, and operations and maintenance activities. Requires life-cycle cost analyses when Federal funds are to be used to reimburse operations and maintenance costs and the estimated initial cost of the project to public authorities exceeds $3,000,000. Mandates updating the ITS National Program Plan. Expands technical assistance to include training and building of professional capabilities. Directs the Secretary to develop guidance and technical assistance on appropriate procurement methods for ITS technology and services.

PROGRAM STREAMLINING
PURPOSE A variety of statutory changes are proposed to eliminate or simplify Federal requirements and to allow greater flexibility to States, MPOs, and local governments. PROGRAM DELIVERY Establishes annual program-wide approval for STP projects, rather than the current quarterly projectby-project certification and notification. Removes a restriction that applies Federal share to each progress payment to the State and allows a variable Federal share on progress payments.

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Removes a restriction that prohibited reimbursement of certain indirect costs to the States, thereby making Federal-aid highway funding more compatible with grants from FTA and other Federal agencies. Removes 15% limitation on project Construction Engineering charges, thereby allowing reimbursement of actual costs for CE. Permits merger of PS&E approval and Project Agreement execution and provides for obligation of Federal share on a project when the Project Agreement is executed. Restores provision to allow reobligation in the current fiscal year of Federal funds released from prior year obligations. PROJECT OVERSIGHT Expands flexibility to States and FHWA to mutually determine the appropriate level and extent of State and FHWA oversight on NHS projects. Provides that FHWA’s oversight responsibilities shall not be greater than they are under Certification Acceptance and ISTEA, unless the State and FHWA mutually decide otherwise. Provides that State must assume Title 23 oversight responsibilities on non-NHS projects. (FHWA would retain oversight responsibility for non-Title 23 requirements, e.g., NEPA, on all projects.) Provides for development of a financial plan for any project with an estimated cost of $1 billion or more. PROCEEDS FROM SALE OR LEASE OF REAL PROPERTY Retains provisions allowing States to use net proceeds generated by sale or use of property for purposes eligible under Title 23. (I.e., States don’t have to turn these revenues in to the Federal government). Expands application to cover all proceeds generated from sale or lease of property acquired with Federal funds, instead of just airspace income. REAL PROPERTY ACQUISITION AND CORRIDOR PRESERVATION Affirms that early acquisition of property in support of preservation considerations is appropriate public policy. Rescinds the Federal Right-of-Way Revolving Fund by ending new obligations and setting time limits for repayment of old obligations. Retains potential for retroactive Federal funding of early right-of-way acquisition as an option. Allows a State to receive credit to State matching share for value of State and locally owned property incorporated in a federally funded project.
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9.3 PRIVATE FUNDING POTENTIAL
A new and much-needed source of funds is based on the potential for public/private partnerships. The private role is increasing in this arena. It is one in which the private entity may provide ITS services and/or system elements; however, instead of direct reimbursement from the public agency, some or all of the private entity’s costs for these funtions are recouped by selling ITS-based services to other private entities (i.e., collecting a user fee or deriving revenue from advertising) or by receiving a nonmonetary consideration for these services from the public agency. This offers advantages both in public cost reduction and in capitalizing on the private-sector’s market orientation. Several examples of this latter concept of public-private partnerships are being developed in the United States, including:

• •

Marketing and sales of in-vehicle and portable devices to provide real-time traveler information and routing. The government agency providing access to the highway right-of-way to a private communications firm, in return for which the private entity installs and maintains a communications network (e.g., conduit, cable, and electronics) for the government agency’s ITS network. The private communications firm recoups the cost of the communications system by sizing it to provide telecommunications services to other users (e.g., other private entities) and charging for the service. Collection, marketing, and sales of real-time traveler information and traveler services information.

•

Developing sustainable public-private partnerships is proving difficult. Private-sector involvement is driven by the profit motive, and the potential profitability of certain ITS applications remains a major question in the eyes of potential private-sector players. There is also general mistrust by public agencies of the profit motive, and a distrust by the private sector of the stability of decisions that would be made in the public realm. Instability increases risk. Successful partnerships with the private sector will likely be initiated by private-sector players who understand the market. However, additional exposure of the private sector to ITS is important and may generate other joint projects. Areas or regions desiring strong, solid ITS programs must define and encourage the relationship between the public and private sectors, along with their respective responsibilities. Arranging joint meetings, conducting conferences on ITS, soliciting private input on typically public transportation issues, encouraging public/private cooperation, implementing legislation encouraging these relationships, becoming visible in private-group concems (without harm to public conflict-of-interest issues), developing a cooperative atmosphere/business climate, and openly promoting the ITS advantages to the private sector represent steps that need to be taken by the public side to encourage private participation. Some basic principles of developing public/private partnerships follow. • Assist the private sector in areas of ITS that make good business ventures. While private companies may be “good citizens” in participating in ITS projects for a period of time, long-term commitment to ITS projects need to be justified, ultimately, by whether the company can make a profit be

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•

from that activity. It is critical that public agencies understand this a an essential element of a succesful private venture Structure projects to be self-monitoring. The private entity should have reason other than government regulation and enforcement to make certain that the project succeeds. There should be a built-in motivation for customer service that leads to additional profits. If the only force that holds the project together is the threat of government retribution, the project is likely to fail in the long run, and relationships will quickly turn adversarial. Be willing to take calculated risks. The private sector operates within an atmosphere of risk on a daily basis. From the government perspective, much of the risk will take place wither the perception of the public of “deals struck” with the private sector, or in the failure of the private sector to deliver on services traditionally provided by the government. These risks need to be addressed in the structure of the arrangements made for a particular ITS project. Be willing to alter the traditional rules by which State, MPO, and local governments operate. Legislative changes may be necessary to enable certain private sponsored ITS projects to occur. Provide an atmosphere of stability. Private partners are usually unwilling to move forward on projects where the public partner’s decisions are unreliable. Unfortunately, there is only so much that staff can do to create this atmosphere. Political change introduces sometimes dramatic shifts in thinking concerning public decisions. Long-term commitments need to be locked in to engender the confidence of the private partner(s). Devise mechanisms that will protect both parties while not squelching the opportunity itself. This is where a balance needs to be achieved between willingness to take risks and building in necessary protections. Because government agencies have not traditionally negotiated in these areas with the private sector, experts with experience dealing with the private sector may need to be retained to guide the government agency through the process. Be willing to give up turf where there is a legitimate area for privatization. Leave room for competition. If there are profits to be made, and if there are ways to allow for multiple providers, the customer is best served by creating a competitive environment. The extent to which this is possible will depend on the specific nature of the ITS activity.

•

•

• •

•

• •

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9.4 INNOVATIVE FINANCING
Through the innovative finance provisions contained in the Intermodal Surface Transportation Efficiency Act (ISTEA), the Test and Evaluation (TE) 045 program, and the National Highway System (NHS) Designation Act, the Federal Highway Administration (FHWA) has been reshaping the Federal-aid program’s matching share requirements. Traditional grant-based pay-as-you-go financing has given way to more innovative techniques aimed at enhancing transportation investment and accelerating project implementation. Some of these innovative finance tools are now available to states as part of the regular Federal-aid program. Some are still experimental. Four of the available matching share tools are flexible match, soft match, tapered match, and shared resources.

Flexible Match
The NHS Designation Act amended 23 U.S.C. 323 to allow states to apply the value of third party donated funds, material, or services toward their share of project costs. This flexible match provision increases a state’s ability to fund its transportation programs by: 1) accelerating certain projects that receive donated resources; 2) allowing states to reallocate funds that otherwise would have been used to meet Federal-aid matching requirements; and 3) promoting public-private partnerships by providing incentives to seek private donations. Third parties as defined by the NHS Designation Act include private companies, organizations, and individuals; Federal, state, and local government agencies are excluded by this definition. The Maryland Department of Transportation (DOT) is one agency currently using flexible match to help finance the reconstruction and widening of a one-mile segment of MD 355. The route serves a rapidly expanding area of Montgomery County in the Washington, DC metropolitan area. The project involves expansion of MD 355 by one lane in each direction. Maryland DOT is crediting $8 million in private funds toward its matching share of project costs.

Soft Match
Section 1044 of ISTEA permits states to earn credits on toll revenue expenditures. These toll credits can then be applied toward the non-Federal matching share of current Federal-aid projects. The soft match provision of ISTEA increases the flexibility of state transportation finance programs by allowing states to use toll revenues when other state highway funds are not available to meet non-Federal share matching requirements. The soft match provision of ISTEA requires states receiving toll credits to pass a “maintenance of effort” (MOE) test. The MOE test established under ISTEA requires a state to demonstrate “a continuing commitment to non-Federal transportation investment” by showing that its previous year’s expenditures on transportation improvements are equal to or exceed the average of its previous three years’ expenditures. Under TE-045, the MOE test is relaxed to allow for a more prospective view. The New Jersey DOT, for example, is using a soft match to help finance the construction of a southbound viaduct over the Waverly Yards in Newark. The recent reconstruction of the northbound viaduct
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has left the southbound viaduct demolished and the highway operating at 50 percent capacity. New Jersey DOT is expediting construction by applying $15 million in toll credits toward its share of the project costs.

Tapered Match
Tapered match allows states to vary the required matching ratio over the life of a project. With this tool, states can delay the use of their own funds while using Federal funds to bring projects through the critical early phases of construction. Although tapered match has been tested under the TE-045 experimental program, it is not available through the regular Federal-aid program. The Washington State DOT is using a tapered match to help finance the construction of high occupancy vehicle lanes on SR 520 located northeast of Seattle. The project is necessary to accommodate the region’s rapidly expanding traffic volumes and to enhance safety on the Evergreen Point Bridge. Tapering the Federal share will allow Washington State DOT to begin construction on the project a year earlier, while achieving better cash flow management.

Shared Resources
Shared resources are private donations of communications technology (principally fiber optic communications) granted in exchange for access to public rights-of-way. The use of shared resources is an invaluable tool for states seeking to build a technological backbone for Intelligent Transportation Systems (ITS). In addition to obtaining increased access to telecommunications technology, states can credit the value of the private donations toward their matching share of project costs associated with the deployment of ITS projects utilizing the donated technologies. The shared resources concept has been limited to selected experimental projects, and has not been recognized as part of the regular Federal-aid program. In some states, shared resource arrangements may be prohibited by state law. The Missouri DOT has entered into an agreement with Digital Teleport, Inc., which will provide the DOT with access to a 210-mile, $23 million fiber optic network to be located near St. Louis. In return, Digital Teleport has been granted exclusive access to the public rights-of-way necessary for completing the project. In addition, FHWA has recognized the value of the donation and is allowing Missouri DOT to receive credit toward its matching share on ITS deployment projects in the St. Louis area.

9.4.1 PROVISIONS OF THE NATIONAL HIGHWAY SYSTEM
Changes to Advanced Construction
The U.S. Department of Transportation (U.S. DOT) can approve an application for advance construction for reimbursement after the final year of an authorization period provided the project is on the State’s transportation improvement program (STIP). The STIP is fiscally constrained under section 135(f) of Title 23. This change also provides greater flexibility to States to engage in advance construction using their anticipated apportionments.
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Debt Instruments for Reimbursements as Construction Expenses
States can be reimbursed with Federal-aid funds for bond principal, interest costs, issuance costs, and insurance on Title 23 projects. To date, Federal-aid funds have been limited to bond retirement costs on certain categories of projects and interest costs were only eligible on some interstate projects.

Federal Share on Toll Projects
This provision sets the Federal share for toll projects on highways, tunnels, and bridges at a maximum of 80 percent of eligible costs. Up until now, the Federal share for toll projects has varied from 50 to 80 percent, based on activity and system designation.

ISTEA Loan Provisions
States can loan Federal-aid funds to toll and non-toll projects with dedicated revenue streams. Interest rates on loans may be at or below market rates. A loan is not required to be subordinated to any other debt financing. Loan repayments can be used for various credit enhancements. A loan can be made for any phase of a project including engineering and right-of-way work.

Matching Credit
This provision allows private funds, materials, or assets to be donated to a specific Federal-aid project and permits the State to apply the value to the State’s matching share. To date, States could only receive credit for State and local funds or for donations of private property incorporated into a Federal project.

9.4.2 INNOVATIVE OPTIONS
Partial Conversion of Advance Construction
Previously, if a State chose to convert an advance construction project to regular Federal-aid project funding, the State had to obligate the full Federal share of the project costs. This can be a major “drawdown” of the State’s annual Federal obligation ceiling. Partial conversion of advance construction is a strategy which allows a State to obligate funds and receive reimbursement for only part of its funding of an advance construction project in a given year. In conjunction with legislative changes proposed for advance construction flexibility, this change will make using Federal funds more compatible with State financing needs. This change was implemented through Federal regulatory change on July 19, 1995.

ISTEA Section 1044 Investment Toll Credits
ISTEA Section 1044 permits a State to use certain toll revenue expenditures as a credit toward the non-Federal matching share of all programs authorized by Title 23 and ISTEA. This “investment credit” concept allows the Federal share to be increased up to 100 percent to the extent credits are available. States which meet or exceed the ISTEA Maintenance of Effort (MOE) test can earn credits for toll road expenditures. The idea behind the MOE test is for States to show they are keeping up their commitment to non-Federal transportation spending. States may now more easily earn these
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credits under an expanded Maintenance of Effort test, which includes a prospective interpretation. This change was implemented through guidance memorandum on April 3, 1995.

9.4.3 STATE INFRASTRUCTURE BANKS (SIBS)
Meeting today’s transportation infrastructure needs requires new flexibility and multiple financing strategies. In response to these needs, the State Infrastructure Bank (SIB) Pilot Program was approved by Congress in the National Highway System Designation Act of 1995. The initial legislation allowed U.S. DOT to approve ten state SIBs. Those States were Arizona, California, Florida, Missouri, Ohio, Oklahoma, Oregon, South Carolina, Texas, and Virginia. Recent legislation, passed in September 1996, will allow U.S. DOT to approve SIBs for additional qualified states. SIBs will offer a variety of forms of financial assistance, support different types of projects at various stages of project development, and test different ways of capitalizing and operating their SIBs. On March 1, 1997, the Secretary of the U.S. Department of Transportation reported to Congress on the SIB Pilot Program. The program goal is to understand how SIBs can leverage Federal dollars to increase transportation infrastructure investments as ISTEA reauthorization legislation moves forward. By giving state and local officials new flexibility, SIBs will enable the development of vital construction projects that would otherwise be delayed or financially infeasible.

Capitalizing the SIB
A SIB begins with an initial infusion of Federal and a matching non-Federal contribution. States can deposit up to 10 percent of most of their FY 1996 and FY 1997 Federal-aid highway apportionment into their SIB highway accounts. States can also deposit up to 10 percent of Federal transit funds (sections 3, 9 and 18 funds) for FY 1996 and FY 1997 into their SIB transit accounts for capital projects. Each state will match Federal capitalization funds with 20 percent of the total deposit (or at their usual matching ratio).

Types of SIB Assistance
An SIB has myriad of financial support alternatives to assist a public or private project sponsor during all project stages. The spectrum of financial assistance a SIB may provide ranges from loans to credit enhancements. Other forms of assistance may include interest subsidies, letters of credit, capital reserves for bond financing, construction loans, and purchase and lease agreements for highway and transit projects. An example of how SIB assistance might work is what Missouri plans to do. Funds will be held in the SIB to cover debt service reserve requirements as part of a future bond issuance for Highway 179. In this case, the funds are only used on an as needed basis. Unlike traditional transportation funding, a SIB can provide assistance throughout all stages of transportation projects to a multitude of project sponsors. In addition, SIB assistance can be for any

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amount or percentage of the project, also unlike the traditional transportation funding which has fixed percent contributions. The initial use of Federal funds may be from separate accounts for eligible Title 23 and transit capital projects. As the funds are repaid, the SIB can provide financial assistance to transportation projects following state procedures.

Recent Legislation
Congress passed legislation in September, 1996 that enables U.S. DOT to designate additional qualified states to participate in the SIB pilot program. Previously, the program was limited to ten states. Congress also approved an additional $150 million to be distributed to the initial ten SIBs and any additional states designated for the program for capitalization. These funds cannot be distributed for 6 months, until additional states have been approved. The funds will be available to both highway and transit accounts of the SIB.

States’ Planned Projects
As the states move from proposing projects to funding projects the number and type of projects may change. These projects are only under consideration and the specifics around the amount, type of assistance and repayment source may still need to be determined. The Pilot Program will provide an opportunity to review how well an SIB could assist a variety of projects and increase transportation infrastructure investment.

Credit Enhancement
Missouri is considering supporting the construction of Highway 179 in Jefferson City and Cole County. For this project, the SIB might provide either the county or city with debt service reserves for debt issuance. This means the SIB would hold funds as collateral for the bond issuance.

Low Interest Loans
Oklahoma proposes to provide low interest loans to local governments to improve safety at rail and grade crossings, a part of Title 23 construction. The local government might use a sales tax to repay the loan.

Construction Loans
In September, Ohio provided a $10 million preconstruction loan to the Butler County Transportation Improvement District for right-of way acquisition for a series of realignment, widening, and interchange projects for State Route 129. The loan would be repaid from toll-backed bonds issued at the start of construction. Ohio expects to have completed financing agreements for two additional projects in September.

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Administrative Details
Under the Pilot Program, SIBs are expected to evolve considerably as the states develop their cooperative agreements with U.S. DOT, broaden the types of assistance that they can provide, establish SIB administration, and identify projects that will receive SIB assistance. The types of financial assistance that can be provided and to whom are determined by the enabling legislation each state has or expects to have in the near future. The lessons learned from applying diverse forms of assistance to a wide range of projects will be invaluable as the SIB Pilot Program progresses and ISTEA Reauthorization moves forward.

9.4.4 INNOVATIVE FINANCE GUIDANCE - NATIONAL HIGHWAY SYSTEM PROVISIONS
Section 313(b) replaced 23 U.S.C. 129(a)(7), relating to eligibility of State loans for Federal-aid reimbursement. The previous provision established the eligibility of State loans for construction of toll facilities for Federal-aid reimbursement. The NHS Act amendment expanded eligibility of loans to include State loans to non-toll facilities with a dedicated revenue source for Federal-aid reimbursement. Further, the States were given greater flexibility in determining the interest rates for loans and given the authority to use loan repayments for additional credit enhancement activities. The ISTEA amended Section 129 to allow Federal participation in a State loan to a toll project. This provision was implemented by memoranda from FHWA Headquarters dated March 12, 1992, and May 14, 1993. Section 313 of the NHS Act amended the loan provisions of Section 129(a)(7). The purpose of this guidance is to consolidate in one document, information on the loan provisions of Section 129(a)(7) contained in the two previous memoranda, modified as appropriate to implement the NHS Act amendments. The following provides implementing guidance on the Section 129(a)(7) loan provisions.

Eligibility
Section 129(a)(7)(A) allows the State to make loans to a public or private entity that is constructing, or proposing to construct, a toll project that is eligible for Federal-aid funding or a non-toll highway project with a revenue source specifically dedicated to support the project. The State may request authorization of a project for the purpose of making a loan to the public or private entity. The amount loaned by the State is considered an eligible Federal-aid project cost. There are no Federal requirements that apply to how a State selects a public or private entity to be a recipient of a State loan. This selection process, including creation of public/private partnerships, is governed by State law. Further, it is the State’s responsibility to ensure that the loan recipient has used the loan for the purposes specified.

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Dedicated Revenue Source - Non-Toll Projects
A specifically dedicated revenue source is a revenue source that the loan recipient or other appropriate entity pledges for repayment of the loan. Revenue sources can include, but are not limited to, excise taxes, sales taxes, real property taxes, motor vehicle taxes, incremental property taxes, or other beneficiary fees. (However, there are criteria that limit use of airport revenues as a dedicated revenue source, and any proposal to use airport revenues must receive FHWA Headquarters’ concurrence prior to authorization of the loan.) The pledge for repayment may involve all or only a portion of a revenue source or a combination of various revenue sources. In requesting authorization of Federal-aid funding for a loan to a project with a dedicated revenue source, the State will identify the dedicated revenue source(s) and provide written assurance that a pledge has been secured regarding use of the revenue sources(s) for repayment of the loan.

Authorization
If a project meets the test for eligibility, a loan can be made at any time. The loan may be for any amount, provided the maximum Federal share of the total eligible project cost is not exceeded. Total eligible project cost is limited to the costs of engineering, right-of-way acquisition, and physical construction remaining to be accomplished at the time the FHWA authorizes the loan to be made. In other words, a loan can be initiated on an active, eligible project, but the amount cannot include the cost of work done prior to the loan authorization. A loan project can be authorized under the advance construction provisions of 23 U.S.C. 115 that apply to the type of Federal-aid funds being used. Federal-aid funds for loans may be authorized in increments. Federal-aid funds are obligated in conjunction with each incremental authorization. The State is considered to have incurred a cost at the time the loan, or any portion of it, is made. Federal funds will be made available to the State at the time the loan is made.

Federal Share/Non-Federal Share
The Federal share for a loan project under Section 129(a)(7) is established by Section 129(a)(5). Accordingly, the Federal share is 80 percent and may not be adjusted in accordance with a sliding scale under 23 U.S.C. 120. The non-Federal share may be provided by the public or private entity receiving the loan.

Compliance with Federal Laws
The State must ensure that the project is carried out in accordance with Title 23 and other applicable Federal laws, including any environmental and right-of-way provisions included in Federal law. The only exception, discussed under “Other Issues,” concerns procurement of consultants or contractors by a private entity or toll authority. The initial toll or non-toll project for which a State has requested Federal payment for a loan is viewed as a Federal-aid project subject to the same basic requirements and FHWA oversight responsibilities which are being followed for comparable non-loan Federal-aid projects.
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Subordination of Debt
At a State’s option, the amount of any loan eligible for Federal reimbursement under Section 129(a)(7) may be subordinated to any other debt financing for the project.

Repayment/Terms of Loan
Loans must be repaid to the State. The repayment must begin within 5 years after the project is completed and opened to traffic and must be completed within 30 years after the date Federal funds are authorized for the loan or first increment of the loan. Interest on the loan is at or below market rates, as determined by the State, to make the project which is receiving the loan feasible.

Subsequent Use of Repaid Amounts
The State may use repaid amounts for: • • Any project eligible under Title 23, or The purchase of insurance or for use as a capital reserve for other forms of credit enhancement for project debt in order to improve credit market access or to lower interest rates for projects eligible under Title 23.

No Federal requirements attach to activities advanced with funds repaid to the State.

Other Issues
Loan guarantees are not an eligible activity under the Section 129(a)(7) loan program. However, a reimbursable Section 129(a)(7) loan could well act as credit enhancement where a public or private entity is seeking market financing for a project. Federal funds can participate in the construction of a toll facility or a non-toll facility with a dedicated revenue source either through a direct commitment of funds to the project (a regular Federal-aid construction project) or through a loan(s) to the public or private entity building the project. A State could also choose to use its Federal-aid funds to finance a portion of a project as a regular Federal-aid project and use a reimbursable loan for another portion of that project. If Federal funding involves a regular Federal-aid project, the consultants or contractors used on the Federal-aid project must be selected under the Brooks Act or Title 23 competitive bidding procedures, respectively. However, if the Federal-aid funding is only via a Section 129(a)(7) loan project to a private entity or toll authority, that entity is allowed to select the consultant or contractors in whatever manner it sees fit as long as the selection process follows State laws and procedures. The Automated Traffic Surveillance and Control (ATSAC) system in Los Angeles, for example, used nontraditional funding sources that included Federal and State gasoline taxes, as well as city fees on development projects that generate increased traffic flow and therefore increase the city’s traffic control costs. Additional funding was secured through innovative bartering arrangements. CalTrans, the State transportation authority, financed two segments in return for the city’s help in managing traffic diversions to accommodate freeway resurfacing projects. Private developers and independently
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funded public institutions like the University of California at Los Angeles financed other segments of the system in exchange for traffic mitigation credits needed to obtain environmental permits for construction projects. These financial innovations have raised the nearly $130 million spent to date. The Allocation and Decisionmaking Process for Regular Federal Funding Surface Transportation Program (STP) and Congestion Management and Air Quality (CMAQ) funds are the most regularly used funds available to local agencies for implementing ITS projects. Some states and MPOs suballocate these funds to jurisdictions within the urban area while others require all types of projects to compete for funding regardless of jurisdictional split. Another model is to allocate funds to specific programs based on goals and then to have projects compete within the program. While local governments rely on STP and CMAQ funds for ITS projects, States can use Interstate and National Highway System (NHS) funding for ITS projects. The concern of local officials interviewed was for the equitable allocation of the total federal funding pot to the area and in particular to the central city. The ability of the M.O. or the sponsoring ITS agency to blend funding from the various sources creates the best chance for success for an areawide ITS program. The section on pending Federal legislation raises some important issues on the future of federal funding for ITS. The ITS program is somewhat unique in that the FHWA has been authorized approximately $660 million for ITS programs and the federal government has the responsibility for allocating these funds rather than the states. This issue is also discussed further in the federal legislation section, but those interviewed were unanimous in agreeing that the availability of special federal funding has greatly enhanced the success of ITS programs. The availability of these funds for early deployment studies, priority corridors, operational tests and model deployment activities were seen as important factors in the success of ITS programs. The converse should be addressed also. The success of the ITS programs in some areas has attracted further ITS special funding, while those areas struggling to implement an ITS program have not been as successful. This issue will be discussed in the federal reauthorization process but the Task Force might want to discuss this issue as well. The participants in the four priority corridor areas were particularly enthusiastic on the usefulness of the program and funding to create technology platforms to implement the ITI. In fact the primary conclusion of the U.S. DOT policy review of the priority corridors program was the success of the program in regional institution building.

State and Local Funding Sources
Almost all states have a trust fund for highways and in some cases for other modes of transportation. The existence of state funding over and above that required for matching federal funding was viewed as a factor influencing the success of implementing the ITI. Houston and Los Angeles and to some degree New York have state pots of funds available to increase mobility. The availability of state funding also has some issues. Some Transportation Trust Funds are highly leveraged through the use of bonds. Certain types of projects, (e.g., small operational improvements, equipment with a short useful life and operations and maintenance costs) are usually not eligible for bonding. Some of the ITS projects fall into these categories. Also some states have constitutional or legislative restrictions on the use of state funds on non-state jurisdictional highways or for narrowly defined highway purposes. The structure of state funding in each area needs to be reviewed as part of the ITI implementation process.

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Appendix L presents a case study of ITS funding approach in Orange County, California.

9.5 CASE STUDIES ON FINANCING PROJECTS
A public/private partnership success has been claimed for financing the $694 million E-470 in Colorado. The combined efforts of the E-470 Public Highway Authority and Morrison Knudsen enabled the entire sum to be secured through a combination of VRF bonds, senior current coupons, deferred interest, government loans and contractor investment. The segments of the road under this agreement will be opened gradually between mid-1998 and mid 1999 (TollTrans, Oct/Nov 1996). A 1990s incentive to change the funding source for the road from traditional fuel tax and public finance to toll collections has helped Dallas construct the George Bush Turnpike. A TXDOT loan to the Texas Turnpike Authority, partial conversion of advance construction (to tap Federal-aid funds) and local right-of-way contributions have made the $463 million required for the project (TollTrans, Oct/ Nov 1996). In Irvine, California, a three-pronged approach was instituted to financing the ITS infrastructure development and operating and maintenance requirements. They have established a mutually beneficial relationship with their developers whereby they can choose to pay a $70,000 per intersection fee for a 5 percent capacity credit. They can also construct their adopted standards for communication infrastructure (fiber optics) as they build projects throughout the city. The ATMS fee is not a requirement, rather an option that developers may exercise in lieu of traditional mitigation measures. They have also being very successful in securing outside funding grants because of their long standing philosophy of investing in shelf-ready projects. They have a significant capital grants program as well as participation in important research projects (Arya Rohani, August/September 1996) The Dallas-Forth Worth Texas Region have used CMAQ, STP and NHS funding for advanced trans, portation management capital improvements. In addition, they have obtained other funding to support current operational investments from maintenance funds while future retrofit and upgrading investments are funded by Rehabilitation 10B funds. Local governments can also receive a majority of funding from different sources depending on their geographical location. Such categories include city bond funds, operating funds from their cities budget, county funds, state funds, turnpike authority funds, and transit Local Assistance Program/Congestion Management System funds (Dana Rocha and Chris Klaus, October/November 1996)

State Infrastructure Bank (SIB)
More states have been invited to participate in the State Infrastructure Bank (SIB) pilot program. An SIB serves as an umbrella under which a variety of innovative finance techniques can be implemented. The SIB could offer a range of loans and credit options, such as low-interest loans, loan guarantees, or loan requiring repayment of interest-only in early years and delayed repayments of the loan’s principal. Through a revolving fund, states could lend money to public or private sponsors of transportation projects. Project-based or general revenues (such as tolls or dedicated taxes) could be used to repay loans with interest, and the repayments could replenish the fund so that new loans could be supported. Also, states could use federal capital as a reserve or a collateral against which to borrow
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additional funds, usually by issuing bonds. Arizona, Florida, Ohio, Oklahoma, Oregon, South Carolina, Texas, Virginia, California and Missouri were selected to participate in the pilot program, initially, and more states will be have recently been invited to participate. Presently, participating states estimate that SIBs will fund between 10 and 50 percent of transportation projects (The Urban transportation Monitor, November 22, 1996).

State of Maryland
Maryland is engaged in a shared resource project to install 75 miles of fiber optics in its right-of-way. The agreement involves MCI and Teleport Communications Group (TCG). Operation began on September 4, 1995 on a portion of the project (College Park to downtown Baltimore segment). Maryland is allowing MCI access to 75 miles of right-of-way for 40 years (with options for renewal), in which MCI may lay as many conduits as feasible and desired and pull fiber as needed afterward. In return, MCI is giving Maryland 24 “dark fibers” for state use and acting as the lead contractor in building the system and providing routine maintenance. MCI has installed two conduits in the Baltimore-Washington Corridor segment of I-95, one for itself and one for Maryland, with no excess capacity. TCG, which entered the arrangement as a subcontractor to MCI, will pay MCI to install and maintain fiber for TCG’s use in the privately held conduits. In return for access, TCG is providing the state with equipment necessary to light the original 24 dark fibers plus an additional 24 unlit fibers for public sector use. Each of the three partners retains ownership of the fiber dedicated to its use. As the party responsible for construction and maintenance, however, only MCI will physically access the system. Maryland set up this shared resource project strictly as a procurement, purchasing telecommunications capacity with right-of-way access. The state also disaggregated its fiber-optics backbone geographically. Bidders could invest only in right-of-way routes of specific interest to them. The right-of-way for this agreement is part of the I-95 corridor that runs between Washington, D.C., and New York City, an area in which telecommunications redundancy can be valuable. Railroad and other utility rights-of-way are competitive options in the corridor. The telecommunications capacity gained by the public sector as part of this shared resource arrangement will be used for a broad array of public agency needs; that is, it is not restricted to transportation needs. Coordination of public agency communications needs, under the auspices of the Department of General Services (DGS), preceded this shared resource project. The DGS began coordinating and purchasing telecommunications state-wide in the mid-1980s, when each agency was found to be contracting separately for inter-LATA services. At the time that the shared resource approach was introduced, self-supply through a statewide network was already under consideration. The Request For Proposals (RFP) published by the DGS listed a number of technical requirements in exchange for private sector access to the right-of-way, including fiber, manhole access, and equipment. The bid received was less than fully compliant with these requests. For example, the state had requested equipment to light the fiber and local communications switching connections as well as free maintenance; the bidder offered dark fiber and maintenance. The DGS, however, has the ability to negotiate post-bid revisions and was able to conclude a more favorable arrangement with MCI. TCG did not respond to the initial RFP but was incorporated later in the arrangement.

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Although the rights granted to MCI and TCG are technically not exclusive, the private partners have “practical exclusivity” because the state does not want repeated construction projects in the right-of-way. Maryland will probably allow only one company to put in fiber and oversee maintenance. Additional partners would have been accepted if they had responded to the RFP with an acceptable bid. This limited window of opportunity was defined by Maryland for both practical and safety reasons. The state does not want to create problems with traffic congestion and accidents from additional construction. The shared resource arrangement provides for relocation cost sharing. That is, the state will pay for the necessary duct for the fiber-optics cables if and when relocation of the duct is required by construction or reconstruction of the roadway. MCI will relocate and provide ancillary equipment to reestablish the network connectivity to operate at “pre-move” performance levels. Potential contractors had requested that the state commit not to require relocation for at least five years from the contract date. Although the state did not expect to move facilities within that term, it would not commit contractually to refrain from doing so. It is unclear if MCI will be responsible for relocation if the state installs an ITS application. The state’s liability is limited to repair of any facilities that it damages; it is not liable for consequential damages. MCI has indemnified the state for any dissemination of information pertaining to the contract and for any negligent performance of its services under the contract. According to the interviewees, this was a significant issue in the negotiation of the contract. Because MCI is a major long-distance contractor, potential liability costs for “consequential” damages could run into millions of dollars.

Ohio Turnpike Commission
During the 1980s the Ohio Turnpike Commission entered into a number of licensing agreements for installation of telecommunications facilities in the Turnpike right-of-way, the most recent in the late 1980s. These agreements use a standard license form and are expressly non-exclusive; licenses extend for a 25-year period. Most of the current applications are for cellular uses; of the four or five licensing agreements for fiber optics, two covered the entire length of the Turnpike. Litel has 200 miles of fiber and MCI less than 75 miles of fiber along the Turnpike; other firms have also been granted licenses. Of the five cases studied, only the Ohio Turnpike Commission receives a fixed per-mile fee for the use of its right-of-way. In return for allowing access, the Commission receives a license fee of $1,600 per mile of installed fiber, as well as rights to use the fiber optics for Turnpike purposes at low or no cost. At present, the Commission uses relatively little of the capacity available. Valuation of the right-of-way was determined with information from market studies conducted prior to the 1980s. The Ohio Turnpike agreement requires relocation, alteration, or protection of the telecommunications facility, at the licensees’ sole expense, in order to avoid interference with the operation, reconstruction, improvement, or widening of the Turnpike. From a strictly legal drafting perspective, the agreement contains excellent, broadly drafted indemnities. The licensees are required to maintain specified levels of insurance and to hold the Turnpike Commission harmless from losses, costs, claims, damages, and expenses arising out of or related to any claims as a result of the agreement. The Commission
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has the right to defense by its own counsel and to control any claims made against it. The agreement also requires licensees to indemnify the Commission for bodily injury and property damage, to the extent of the licensees’ negligence. The Commission is only liable to the extent that damage to its system is caused by its own “gross” negligence.

State of Missouri
In 1994, Missouri entered into a contract with Digital Teleport, Inc. (DTI) for the installation of a statewide backbone system of more than 1,300 miles of fiber optics. More than 300 miles have been installed and activated, and an additional 100 miles of conduit have been installed. The principal areas already constructed are within the City of St. Louis and between St. Louis, Columbia, and Jefferson City. In return for allowing access to the right-of-way, Missouri receives six lighted fibers for state highway use as well as DTI maintenance of the system. Missouri’s arrangement offers two strong advantages. It gives exclusivity to one telecommunications firm, although that firm can lease access to other telecommunications firms on its lines, and is doing so. And there is limited or no serious competition from alternative right-of-way locations, such as railroads, in the areas of greatest interest to the bidders; i.e., within the St. Louis Standard Metropolitan Area (SMA). Missouri law allows utilities to exist in highway rights-of-way so long as they do not interfere with the roadway; however, the state has historically restricted utility access on the freeways to outer roadways or limited utility corridors, where access is contingent on meeting state permit requirements. Missouri’s agreement with DTI grants an exclusive easement for 40 years within highway air space outside the standard utility corridor. The DTI facility was defined by the state as a “state highway facility,” so it is permitted under the contract to be located in places other utilities are not located. “Exclusive” in this context applies only to other fiber-optics cable systems or communications systems. Missouri, like Maryland, set up its shared resource project strictly as a procurement, purchasing telecommunications capacity with right-of-way access. DTI’s exclusive access is considered a procurement contract awarded to a single contractor in a competitive process, rather than a special privilege, which might be subject to legal challenge. Missouri’s RFP specified requirements for a basic statewide fiber-optics system, with the winner to be that bidder offering the most attractive package for transportation telecommunications infrastructure and service over and above the minimum requirements. Compensation was specified as access to highway right-of-way for the winner’s own telecommunications system in the same corridors as the state system. Although DTI can also locate within the standard utility corridor, the exclusivity provision does not apply to that portion of the right-of-way. The provision permits other firm’s fiber-optics cables to cross DTI’s easement at an approximate right angle, but only upon mutual agreement of the Missouri Highway and Transportation Commission (MHTC) and DTI regarding the location. Nothing in the agreement limits the Commission’s authority to install its own fiber-optics cable for highway purposes within MHTC air space. The state is to bear the cost of relocating. MHTC may either acquire additional right-of-way for the fiber-optics cable corridor in some fashion acceptable to DTI or remove and relocate other utilities at its own expense, so that DTI may place its system in the utility corridor if necessary.
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DTI assumes responsibility for all warranties and liabilities for service and performance, and maintains insurance for bodily injury and property damage, product, and completed operation (with underground property damage endorsement, commercial automobile insurance, and worker’s compensation insurance). Holders of sub-easements from DTI must maintain the same level of insurance. MHTC is not responsible for any liability incurred by DTI. DTI is responsible for all injury or damage for its negligent acts or omissions and “saves harmless” MHTC for any expense or liability deriving from such acts or omissions, whether on its part or on the part of its subcontractors or agents. MHTC is liable for actual repair costs if its personnel, contractors, or subcontractors damage or destroy any part of the fiber system or equipment installed by DTI, but it is not liable for lost revenues or other incidental or consequential damages sustained by DTI.

Bay Area Rapid Transit
In this three-party agreement concluded in 1995, San Francisco Bay Area Rapid Transit (BART) procured a new fiber-optics system for use in operating its rail transit facilities. In addition to installing approximately $45 million worth of capital improvements procured by BART for its own system, MFS Network Technologies (MFS) will invest $3 million to install additional conduit throughout the BART system. MFS will then rent that conduit space to any carrier that wishes to pull its own fiber. BART will receive 91 percent of the rental returns, and MFS will receive the remaining 9 percent. BART anticipates that these revenues will cover all but $2 million of the cost—including operations, maintenance, and interest on debt—for its train control and communication system over the 15-year period; they may cover even more. BART had investigated developing its own fiber system but determined that ownership of fiber or conduit might trigger its regulation as a public utility, which it preferred to avoid. This prompted BART to search for a joint development partner. BART’s right-of-way gains value from the fact that it is a closed system and generally well protected from intrusion. Railroads are the main competition for right-of-way lessees; Southern Pacific, for example, owns substantial right-of-way leased to telecommunications carriers. A particularly valuable portion of BART right-of-way runs through the BART tunnel under the San Francisco Bay. Although there are two other ways for telecommunications firms to cross the Bay, they pose greater risk: running cable across the Bay floor runs the risk of disruption from shipping or natural events, and capacity for stringing fiber along the Bay Bridge is limited due to weight considerations. The BART agreement also involves the California DOT (Caltrans) as a “silent” partner. Of the 100 miles of right-of-way included in BART’s current and planned extensions, 25 miles are actually owned by Caltrans, which conceded control but not ownership to BART. Thus, Caltrans is also a lessor and, for the airspace lease it negotiated with BART, will receive a portion of the revenues generated from MFS conduit leases after BART has fully paid for its telecommunications system. BART divides its revenues by facility segment and will pay Caltrans 25 percent of the revenues it receives from conduit leases on those segments of right-of-way shared with Caltrans (which are considered relatively lower value for telecommunications use). This cash compensation goes into the state highway account to be used for highway improvements throughout the state as allocated by the California Transportation
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Commission; this format has already been established by Caltrans, which raises about $12 million per year from other airspace leasing. Caltrans also receives in-kind compensation—four of BART’s 48 strands of fiber-optics along the full 100 miles of the BART system, with access at 15 strategic locations. In fact, this in-kind compensation was the dominant attraction for Caltrans. Caltrans has estimated that this in-kind benefit is equivalent to $8-12 million in avoided costs for independent construction of Caltrans infrastructure or $960,000 per year in lease costs for comparable fiber. Caltrans’ lease of air space to BART appears to be exclusive for the conduit system. BART’s license to MFS does not provide exclusivity; however, as long as the conduit system between two adjacent BART stations has unoccupied capacity and MFS is not in default under the agreement, BART has agreed that it will not grant any other provider a license to install a communications system between such points. After system capacity has been reached this exception will cease, even if space later becomes vacant; however, BART must give MFS right of first refusal if BART wants to add conduit capacity. BART is obligated to designate a new route for the conduit if it must be relocated, and all relocation costs not paid for by a third party are to be paid by BART. MFS indemnifies BART for everything resulting from MFS’s performance under the Agreement, regardless of the negligence of BART or whether liability without fault is sought to be imposed on BART, except where the damage results from negligent or willful misconduct by a “BART Indemnitee” and was not contributed to by any omission of MFS. MFS is not obligated to indemnify BART for BART’s own negligence or willful misconduct. Both BART and MFS waived consequential, incidental, speculative, and indirect damages, lost profits, and the like. The agreement includes the form of license to be used by MFS in marketing excess capacity to third-party customers, the “User Agreement.” Interestingly, it requires the user to insure MFS, exculpate MFS from liability for service interruptions, and indemnify MFS.

City of Leesburg, Florida
The City of Leesburg’s Communications Utility and its private partners, Knight Enterprises and Alternative Communications Networks (ACN), developed a new fiber-optics system within the City. Leesburg is providing funding for construction and right-of-way access on above-ground utility poles; ACN is designing and constructing the network and leasing the capacity to private or public customers under a five-year contract with the City. The City owns only the dark fiber on its right-of-way, which it can also use for communications among its own buildings. Customers own the fiber from the right-of-way line to their own facilities, pay ACN a fee for access to the City-owned backbone, and can either use their own equipment or pay ACN for use of ACN equipment to light the fiber. Approximately 10 miles of fiber have been installed, and plans are under way for an additional 30 miles of fiber. Leesburg is investing its own capital in the project and will receive cash compensation based on lease payments (i.e., revenue sharing) in addition to fiber-optics capacity. The initial cash revenues will be used to repay capital and, thereafter, revenues will be split evenly between the City and its telecommunications partner. Funds will be deposited into a separate utility fund for communications to pay

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maintenance and miscellaneous costs. At the end of the year, any funds remaining in the account will be transferred to the general account. Leesburg will also use revenues from its telecommunications system to obtain fiber-optics interconnections for government services. The City’s agreement with ACN requires that if other entities express interest in the City’s cables, ACN must coordinate the connection and the equipment used for those connections. ACN can bill those other entities for time and materials spent in the evaluation. Further, since the City is sharing revenues from ACN’s marketing of the network, it prohibited ACN from competing with the City’s cables. Essentially, there are two levels of private sector exclusivity in the Leesburg arrangement: (1) the number of private sector partners involved in the shared resource agreement, and (2) the number of telecommunications service providers gaining access to the fiber-optics infrastructure. ACN is the exclusive marketing partner for City-owned cable built under the ACN-Leesburg arrangement. The City can allow additional vendors to operate within the service area under other agreements, and the “Leesburg Telecommunications Systems Permit Ordinance” appears to contemplate open access to multiple vendors. Exclusive access to the City-owned telecommunications capacity is not granted to telecommunications service providers. The Leesburg-ACN agreement also has a unique reverse-exclusivity provision. Within the service area, ACN may not offer certain services on cables other than those provided by the City without permission from the City. Relocation is not explicitly addressed in the agreement, probably because of the short (five-year) duration of the contract. SOURCES:

• •

Full Speed ITS in Irvine, August/September 1996, by Arya Rohani, Traffic Technology International. Planning for the People: The MPO’s Role in ITS for the Dallas-Fort Worth Texas Region, October/ November 1996, by Dana Rocha and Chris Klaus, Traffic Technology International.

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