GIS in Construction Management

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GEOGRAPHIC INFORMATION SYSTEMS IN CONSTRUCTION MANAGEMENT
A thesis submitted in fulfillment of the requirements for the award of the degree of

DOCTOR OF PHILOSOPHY
in

CIVIL ENGINEERING
by

Vijay Kumar Bansal
(Reg. No. 2K05-NITK-Ph.D 1049 ‘C’)

to the

Department of Civil Engineering National Institute of Technology Kurukshetra, Kurukshetra, India-136119
Sep. 2008

Dedicated to the memory of my late grandparents

Certificate
This is to certifu that thesisentitled..Geographic Information Systems in Construction Management,,beingsubmined Mr. Vijay by Kumar Bansal Registration Number.2K05-NITK-Ph.D 1049 ,C' ,,, to the Department of Civil Engineering, National Institute of Technology Kurukshetra, Kurukshetra, India for theaward degree of of Doctorof Philosophy civil Engineering the bonafide in is research work carried by himunder supervision. thesis reached standards out my This has the of fulfilling the requirements regulations and relatedto the awardof Doctor of Philosophy thisinstitute. of Theworkpresented thisthesis in have been not submitted partor full to in anyother university institute theaward or for ofanyother degree diploma. or

professor Assistant Department Civil Engineering of NationalInstitute Technology of Kurukshetra, Kurukshetra, India-l 36I 19

@r. Maheshpat)

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Acknowledgements
Dr. Pal,for his priceless I would first like to thankmy supervisor, Mahesh guidance and patienceover the last severalyears before and after Ph.D. were registration. knowledge, His support, adviceandkindheartedness invaluable for the completion this thesis. of During my Ph.D.,he taughtme the way to be a good researcher. additionto this, I am also thankful to him for many other In opportunitiesthat he has made available for me. ATcGIS 9 (a Geographic Information Systems software developed by Environmental Science and throughthe financialsupport Research Institute)usedin this studywas arranged Govemment India underFIST Of from Department Science Technology, of and in and other (Fund for Improvement S&T infrastructure universities of scheme IIT thanksaredueto Prof.KoshyVarghese, highereducational institute). Special of in Madras, his criticalcomments improvingthepresentation this thesis. for gratitude chairman, of to Department my I would like to express sincere friendshipand help. for Civil Engineering all colleagues their warmhearted and of Ms. Shruti Kamara(B.Tech.secondyear studentin the Department Civil her mentionfor devoting time in proof readingthe Engineering) deserves special manuscnDt. I could not thank enoughmy parents(Sh. Chand S. Bansal and Smt. Bohari Devi), brother (Ajay) and sisters (Savita and Sarita) for their gratitude Finally, my deepest unconditionallove, supportand encouragement. goes to my belovedwife (Shelly) for her devotionand sacrificeon this long journey. Sheprovedto be a strongand determined face this reality of life, to love. thanksfor her steadfast

(Vijay Kumar Bansal)

IV

Geographic Information Systems in Construction Management

Abstract: Critical Path Method (CPM) schedule is widely used to represent the project schedule, in which different activities are related to one or more components of a project. To visualise construction sequence of the project, planner uses two-dimensional (2D) drawings and mentally associates the components of drawings with related activities in the schedule. Since, there is no dynamic linkage between the schedule and drawings in commercially available scheduling tools, therefore, its interpretation varies with individuals that makes it difficult to understand, communicate and discuss whether problems exist or not. Such limitations in the CPM schedule forced researchers to use 4D construction management that results by the combining 3D capability of Computer Aided Design (CAD) with schedule generated in Primavera or Microsoft Project. Despite of lot of researches in 4D CAD technologies, their use is not very common in Architecture, Engineering and Construction (AEC) industry. This study provides an alternative to the existing CAD based 4D construction management system by combining 3D capability of GIS with schedule generated in GIS itself, in which both 3D model and schedule can be manipulated on a single platform. The scheduling in GIS allows easier understanding of a project schedule as well as helps to detect the problems in it. It allows planner to understand the construction schedule quickly as well as help to visualise the buildable schedule on a computer screen. Construction projects are defined by several spatial (drawings) and nonspatial (schedule, material type and quantity, safety and quality control recommendations, etc.) documents that are maintained separately in different forms by project team members. The overlaps and lacks of consistency among these documents often lead to the construction errors. In this work efficient 4D construction management is achieved by using a single repository within GIS for

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both spatial and non-spatial documents. The database management capabilities of GIS are used to maintain the construction resource data. To extend the use of a GIS based 4D construction management approach for different phases of a construction project, GIS based procedure for quantity takeoffs, cost estimate and direct sunlight visualisation are also developed and integrated with it. Several programmes are developed within GIS to extract necessary dimensions from building model to generate the accurate bill of quantities and cost estimate. The sun’s position fluctuates with diurnal and annual cycle of a year, therefore, to preview the effect of sun lighting in an architectural 3D space over time, designer is allowed to navigate in a 5D space (three dimensions of space and two of time). KEYWORDS: GIS; Construction management; Schedule review; Construction animation; GIS-based cost estimate; CPM; 4D CAD.

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Table of Contents
Title Page............................................................................................…............... i Certificate...................................................................................…............…..... iii Acknowledgements...................................................................…........................iv Abstract......................................................................................................……... v List of Figures…………………………………………………………………...xi List of Tables…...……………….………………………..…………………….xv

CHAPTER 1: Introduction...........….......................................... 1-25
1.1 Background............................................……………………………...1 1.2 Current State of GIS Applications in Construction Industry…………3 1.2.1 Database Management……………………………………...4 1.2.2 Quantity Takeoffs and Construction Cost Estimate………...5 1.2.3 Site Layout for Construction Materials……………………..7 1.2.4 Real-Time Schedule Monitoring System…………………...7 1.2.5 E-Commerce Applications in Construction………………...9 1.2.6 Route-Planning…………………………………………….10 1.2.7 Construction Site Layout………………………………..…12 1.2.8 Visualisation……………………………………………….12 1.2.9 GIS in Construction Progress Control……………………..13 1.3 Problem Diagnosis and Approach Toward Solution………………...14 1.3.1 Difficulties in Detecting Problems through CPM Schedule14 1.3.2 Linking Schedule and CAD Systems (4D CAD)……….…14 1.3.3 Problems Associated with 4D CAD……………………….15 1.3.4 Different Tools for Different Tasks: Interoperability Problems…………………………………………………………15 1.3.5 A Move Toward nD Modelling…………………………....16 1.3.6 Problem Formulation…………………………………...…17 1.3.7 Approach toward Solution…………………………...……20 1.4 Research Objective………………………………………………..…21 1.5 Thesis Organisation……………………………………………...….23 vii

CHAPTER 2: Geographic Information Systems.................... 26-44
2.1 Introduction………………………………………………………….26 2.1.1 Data Models in GIS………………………………………..27 2.1.2 GIS Software………………………………………………29 2.1.3 ESRI Shapefile………………………………………….…30 2.1.4 ArcGIS Format for representing 3D Objects…………...…31 2.2 Data Interoperability……………………………………………...…33 2.3 GIS Based Spatial Operations……………………………………….33 2.3.1 Grouping of Features………………………………………34 2.3.2 Extrusion…………………………………………………..34 2.3.3 Merging of Themes Together……………………………...35 2.3.4 Subtract Feature…………………………………………...36 2.3.5 Hot-Linking……………………………………………..…36 2.4 GIS Based Non-Spatial Operations…………………………………37 2.4.1 Joins and Link…………………………………………..…37 2.4.2 Length, Perimeter and Area Calculation……………….…39 2.5 Non-Spatial Data in Present Work………………………………….39 2.6 Generating 2.5D View Using 2D Themes……………………….….41 2.7 GIS Versus CAD……………………………………………………42

CHAPTER 3: Critical Path Method Programming........…... 45-59
3.1 Background……………………………………………………….…45 3.2 Structures and Element of Network…………………………………46 3.2.1 Forward and Backward Pass Rules……………………..…48 3.3 Tool Implementation…………………………………………..……48 3.3.1 Forward Pass Calculations………………………..………49 3.3.2 Backward Pass Calculations………………………………51 3.4 Functions and Usage of Developed Tool……………………………53 3.4.1 CPM Calculation……………………………………...…...53 3.4.2 Single Calendar Dates……………………………………..55 3.4.3 Bar Chart…………………………………………..………55 3.4.4 Updating……………………………………………...……56

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3.4.5 Resource Requirements……………………………………56 3.4.6 Data Integration……………………………………………57 3.4.7 Quality and Safety…………………………………………57 3.5 Advantages of Scheduling in GIS……………………………...……57

CHAPTER 4: Schedule Evaluation and Visualisation………60-72
4.1 Background………………………………………………………….60 4.2 Case Study……………………………………………….…………..61 4.3 Evaluation and Visualisation of Schedule…………………………...62 4.4 Degree of Details in the 4D Model………………………………….68 4.5 Advantages of Scheduling in GIS……………………………...……69

CHAPTER 5: 3D Animation Based Schedule Review………73-88
5.1 Introduction……………………………………………………….…73 5.2 Animation of Construction Process…………………………………75 5.2.1 Three-Dimensional Modelling in GIS………………….…75 5.2.1.1 Building Interior Modelling…………………..…75 5.2.1.2 Landscaping Around the Building………………76 5.2.2 Information Database Module……………………………..77 5.2.3 Identifications of Components Corresponding to Activitie.77 5.2.4 Association of Components and CPM Schedule………….78 5.2.5 Animation of Construction Process……………………….80 5.2.6 Timing Properties in Animation…………………………...81 5.3 Animation Based Schedule Review…………………………………82 5.3.1 Complexity Capturing of CPM Schedule………...……….82 5.3.2 Logical Errors and Schedule Correction……………..……84 5.3.3 Missing Activities………………………………………....86 5.3.4 Spatial Queries………………………………………...…..87 5.4 Benefits of GIS Based Animations………………………………….87

CHAPTER 6: Quantity Takeoffs and Cost Estimation…89-103
6.1 Background……………………………………………………….…89 6.2 Cost Estimation…………………………………...…………………90

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6.3 Generation of Spatial Data…………………………….…………….92 6.4 GIS-Based Quantity Takeoffs Procedure……………………………97 6.5 Cost Analysis…………………………………………………..……99 6.5.1 Generating Bill of Material……………………………..100 6.5.2 Labours and Equipments Cost…………………….……101 6.6 2.5D Visualisation……………………………………………...…102

CHAPTER 7: Direct Sunlight Visualisation……………..104-110
7.1 Introduction………………………………………………………...104 7.2 Tool Implementation……………………………………………...105 7.2.1 Overview of Methodology…………………………….....107 7.3 Navigable Animations……………………………………………...108

CHAPTER 8: Conclusion and Future Studies……………111-117
8.1 Introduction…………...…………………………………………...111 8.2 Contributions to the Body of Knowledge………………………….113 8.3 Conclusion…………………………………………………………114 8.4 Suggestions for Future Studies……………………………………116

Reference.................................................…….......................................... 118-126 Publications from this work ................………………..............................…. 127 Vita ........................................................................................................……... 128

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List of Figures
Fig. 1.1. GIS-Based quantity takeoffs algorithm (adapted from Cheng and Yang 2001)……………..………………………………………………………6 Fig. 1.2. System structure for functional modules (adapted from Cheng and Chen 2002)……………………………………………………………………...8 Fig. 1.3. Business model of COME (adapted from Li et al. 2003)……………...11 Fig. 1.4. Linking of spatial and non-spatial information, 4D scheduling and spatial analysis planned to be carried out in GIS environment……….…22

Fig. 2.1. Geometry of different type of multipatch parts (adapted from ESRI 1998)…………………………………………………………………….32 Fig. 2.2. Grouping of selected features of a theme, which removes boundaries between adjacent polygon. Non-adjacent polygon features are combined together to form a multipart polygon feature…………………………....34 Fig. 2.3. (a) Feature of a 2D theme, (b) 2D feature at a suitable orientation, (c) feature in the space at elevation value equal to its base height, (d) feature is extruded upward by value equal to its height……………………………35 Fig. 2.4. (a) Three 2D themes, (b) merging themes together pieces the features from three themes together to a single theme, (c) different features in the space at elevation value equal to their base height, (d) all features are extruded upward by value equal to their height……………………………36 Fig. 2.5. Functionality subtract feature is used to calculate net area by subtracting one feature from other… …………………………………………….….37 Fig. 2.6. Relationships between the two tables connected through a field named Activity_ID utilised in the present study………………………………...38 Fig. 2.7. Screenshot of resource database maintained in GIS environment to facilitate construction planning………………………………………….40

Fig. 3.1. Network used for programme demonstration……………………….…49

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Fig. 3.2. Tabular output of CPM calculations from the developed scheduling tool in ArcGIS environment………………………………………………….53 Fig. 3.3. Multi input dialog box used to prompt the user to add information for CPM calculation in ArcGIS……………………………………………...54 Fig. 3.4. Date-wise output of CPM basic scheduling computations…………….55 Fig. 3.5. Chart of the developed scheduling tool, (a) bar chart, (b) resource requirement chart…………………………………………………….….56 Fig. 3.6. Screenshot showing how quality control recommendations get highlighted for a project activity……………………………………...…58

Fig. 4.1. Floor plan consists of different data layers in ArcGIS in which few layers are kept invisible/transparent to make appearance

understandable…………………………………………………………...62 Fig. 4.2. Architecture for linking a 3D model of building with the construction schedule n ArcView……………………………………………………..63 Fig. 4.3. Procedure for evaluation and visualisation of the construction schedule………………………………………………………………….65 Fig. 4.4. (a) Three 3D themes, (b) merging themes together pieces the features from three themes together to a single theme…………………………...67 Fig. 4.5. Comparison on the same date between the schedules, (a) without sufficient degree of details, (b) corrected with sufficient degree of details………………………………...………………………………….69 Fig. 4.6. 3D view of the sample building in which roof slab is set transparent to provide the internal details………………………………………………71

Fig. 5.1. 3D model of the proposed building placed in its surroundings in a navigable 3D display in ArcGIS…………………………………………77 Fig. 5.2. (a) View from outside to inside through a window in a navigable 3D environment (window glasses were kept transparent), (b) screenshot

while flying inside a 3D model in ArcGIS………………………...…….78 Fig. 5.3. Relationships between components of a 3D model and CPM schedule connected through field named Activity_ID………………..……………79 Fig. 5.4. Interactive Animation manager to move keyframes in each animation track………………………………………………………………………………80 xii

Fig. 5.5. Animation based construction schedule review and correction process…………………………………………………………………...82 Fig. 5.6. Complexity capturing of the CPM schedule, (a) screenshot of animation without sufficient degree of details, (b) corrected with sufficient degree of details……………………………………………………………………84 Fig. 5.7. (a) A small part of brickwork above main gate appeared floating in air, (b) support appeared after appearance of brickwork above main gate, (c) part of brickwork above main gate was isolated from rest…………...…86

Fig. 6.1. Architectural drawing of hexagonal building used to demonstrate the GIS based cost estimation procedure (adapted from Dutta 1998)………93 Fig. 6.2. Data theme of architectural drawing used for quantity takeoffs in ArcView environment…………………………………………………....94 Fig. 6.3. A flow diagram to generate bill of quantities in ArcView………….…98 Fig. 6.4. Bill of quantities for various items of work represented by different data themes in ArcView……………………………………………….……..100 Fig. 6.5. Flow diagram to generate bill of material for different items of the work represented by data themes………………………………………….....102 Fig. 6.6. Screenshot containing two documents of ArcView used to show perspective views (3D Scene documents) and 2D data themes (view document)…………………………………………………………..…..103

Fig. 7.1. Rotation of data layers of a building at suitable angle to give proper orientation……………………………………………………………...108 Fig. 7.2. The navigable 3D views of a building with long side parallel to the E-W at different times (15-May 2005, latitude 290N59’ and longitude 760E51’)………………………………………………….…………….109 Fig. 7.3. The navigable 3D views of a building with long side parallel to the E-W (10 A.M., latitude 290N59’ and longitude 760E51’), (a) south-facing walls attain the most solar heat gain during the winter (15-December 2005), and (b) least in the summer (15-May 2005)…………………………..……110 Fig. 7.4. The navigable 3D views of a building depict that horizontal surfaces receive more solar heat in the summer than in winter (10 A.M., latitude

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290N59’ and longitude 760E51), (a) 15-January 2005, (b) 15-March 2005, (c) 15-May 2005………………………………………………………..110

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List of Tables
Tab. 1.1. Comparison of the non-integrated system versus GPS and GIS integrated system (adapted from Li et. al. 2005)……………………….9

Tab. 2.1. List and description of GIS based spatial operation used in this work……………………………………………………………………41

Tab. 6.1. List of different items of the work, calculated by constructing the one or more data themes for each item with geographic element polygon and line……………………………………………….…………………….95 Tab. 6.2. List of the geographic elements used to construct the different data theme……………………………………………………..……………96

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Chapter

1

Introduction
1.1 Background
Construction industry is essentially a service industry where management revolves around the close follow up of laid down procedures. It is quite complex and highly individualistic in character. The companies/contractors are generally assumed to take the responsibilities of completing the project in a specified time, cost and quality. In doing so, they accept legal, financial and managerial obligations. Therefore, efficient construction project management becomes an important aspect of any construction work. The use of computers in planning, monitoring and controlling projects is well recognised. Advancements in the information technology have opened new ways for research and developments in Architecture, Engineering and Construction industry (AEC). Information Technology (IT) has been widely regarded as a key enabler for performance improvement in the AEC industry from last decades. A construction project contains information in several spatial (drawings and blueprints) and non-spatial (schedule, cost estimate, specifications, etc.) forms that are maintained separately by various project members with the help of different commercially available tools. The persons working in AEC industry have to go through this information, which sometimes do not agree with each other. The overlaps and lack of consistency in information may often lead to the construction errors, which results in miscommunications that are expensive and time-consuming in nature.

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The softwares for various disciplines (architecture, construction, structural and civil engineering) are being used to maintain and analyse information throughout the lifecycle of a project. The drafting group generally uses AutoCAD, planner uses Primavera and Microsoft Project whereas construction and operations group use blueprints or printed-paper, etc. Integrating their output is a major problem in their use in construction industry. Further, the information flow between various groups working in a project is not through well-defined standards and procedures, which results in inefficient process characterised by data redundancy, redundant processes and poor data quality. Poor and inefficient sharing of construction information among owners, engineers, contractors and public has always affected the AEC industry. Even after the technological developments within last few decades, routine field activities are performed manually and delivered weeks/months later (Ogunlana et al.1996). This lack of communication and data sharing has a direct impact on claims, public relations, project cost, etc. If both, spatial and non-spatial information are maintained in a single environment and changes are made to these documents at one place only, drawings, schedule, cost estimate and specifications of a construction project will be consistent to each other. This change may significantly reduce the communication problems that often slow down the project and increase the cost. The main idea of this study is to use a single repository for both construction spatial and non-spatial information by deploying a tool that is not generally available within AEC industry. Geographical Information Systems (GIS) are among the fields of research where computers are of great assistance. With the availability of personal computers, GIS is being used in many areas by a wide range of specialists to solve different problems. Its use has also proliferated within the AEC industry in recent years. GIS is a computer-based tool used extensively to solve various construction engineering problems involving the use of both spatial and nonspatial information (ESRI 2005) and has supplemented the already existing abilities and knowledge in construction industry. It is a tool for creating, managing, analysing and visualising all types of geographic information. This

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fact is illustrated by increasing numbers of articles/papers finding their way into conference proceedings and construction journals (Miles and Ho 1999). The use of GIS in AEC industry has already been reported for various purposes such as database management, information integration, complex visualisation, site layout, construction planning, etc. (Cheng and Chang 2001, Cheng and O’Connor 1996, Cheng and Yang 2001, Li et al. 2005, Varghese and O’Connor 1995, Zhong et al. 2004). Most of the works reported so far have used GIS in combination with different softwares to meet various project requirements like scheduling, data managements, construction simulation, etc. The use of GIS has been successful in improving the construction planning and design efficiency by integrating spatial and non-spatial information in a single environment.

1.2 Current State of GIS Applications in Construction Industry
Successful implementation of GIS has been reported in many fields of civil engineering such as transportation, water resources, facilities management, urban planning, construction, E-business, landslides, etc. (ESRI 2005, Jat et al. 2008, Gómez and Kavzoglu 2005, Saha et al. 2005). The creation and management of construction information, integration of various information, visualisation, E-commerce and cost estimation are some of the major benefits of using GIS in construction industry. This section provides a summary of the work on the different applications of GIS technology in construction industry. GIS is one of the fast emerging technologies whose complete potential to the AEC industry has not been realised (Cheng and Yang 2001). Most of the reported works in this area suggest that GIS can benefit the AEC industry in several areas where most of the commercially available construction management tools are lacking. Oloufa et al. (1994) utilised GIS to create a database to store descriptive soil data pertaining to boreholes and linked this data to the corresponding geographic locations of boreholes to generate a sub-surface profile. Cheng and O’Connor (1996) developed an automated site layout system called ArcSite that assists a designer in identifying suitable areas to locate temporary facilities. Cheng and Yang (2001) developed a GIS based tool called 3

MaterialPlan to support construction managers in identifying suitable locations to locate materials at construction site. Cheng and Chen (2002) developed an automated schedule monitoring system called ArcShed for precast building construction that integrates barcodes and GIS for monitoring construction progress on real time basis. The web based GIS proposed by Li et al. (2003) provides the solution for buyers to compare cost of transportation of construction materials when suppliers are located in different areas. Expert GIS was used for automating the tedious route-planning tasks for large vehicles within the construction site (Cheng and Chang 2001, Varghese and O’Connor 1995). The GIS based visual simulation methodology was used to graphically simulate the complex construction process (Zhong et al. 2004). As traditional scheduling and progress control techniques such as bar charts and Critical Path Method (CPM) fail to provide information pertaining to the spatial aspects of the construction project. Poku and Arditi (2006) supplemented the non-spatial scheduling techniques by developing a GIS based spatial system to represent construction progress that is synchronised with the construction schedule. The design generated in AutoCAD was plugged with the construction schedule generated using primavera in a GIS package. Following sections present a detailed discussion about the applications of GIS, in the context of construction industry. 1.2.1 Database Management The information required for planning and design in construction industry is stored in form of drawings, specifications and bar charts. During the planning process, planner has to repetitively reorganise and interpret the information collected from various resources. Thus, making this process quite tedious and prone to errors (Cheng and Yang 2001). GIS can improve construction planning and design efficiency by integrating locational and thematic information in a single environment. Its capability to store large database may be utilised to maintain construction data in digital form. The construction database available in digital form can provide a wide range of information to construction industry with a mechanism for rapid retrieval and manipulation capabilities. Use of GIS also satisfies the need of spatial and descriptive information required in different construction processes (Jeljeli et al. 1993, Oloufa et al. 1992).

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The prototype system developed by Sun and Hasell (2002) suggests the suitability of automated acquisition and storage of data to support project management. They suggested that instant spatial data capture provides fast and accurate visual information about on site progress. Sun and Hasell (2002) also suggested that integration of spatial database with project management functions provides a powerful and effective management control system. The integrated project data can be visualised by instantly colour-coding the spatial display based on the non-spatial attributes in a GIS environment. The construction site investigation is an important step for estimating and planning new projects. Oloufa et al. (1994) suggested the use of GIS based methodology to develop a database for foundation analysis, design, construction planning, and design-construction integration. The surface and sub-surface conditions influence construction methods and choice of equipments that affect cost and scheduling of a project. Study by Oloufa et al. (1994) used a database to store descriptive soil data in GIS environment that was linked to corresponding locations of boreholes. A graphical user interface was used to facilitate input, query and output data. Camp and Brown (1993) suggested the use of database management capabilities of GIS to develop a procedure for generating sub-surface profiles from well-log data. The well-log database was constructed from a series of borehole and GIS based procedure was used to create a Three Dimensional (3D) sub-surface environment. 1.2.2 Quantity Takeoffs and Construction Cost Estimate Cheng and Yang (2001) suggested an approach for quantity takeoffs and cost estimates using Map/Info GIS. For quantity takeoffs process and cost estimation, architectural drawing was divided into different layers (Fig. 1.1). These layers were classified according to basic design components in an architectural design. The data layers used for quantity takeoffs includes columns, beams, interior and exterior walls and slabs. The beam layers were further classified into main-beam and sub-beam. In GIS based quantity takeoffs, area and perimeter were used as the basic parameters. Therefore, data layers were 5

created as polygons in AutoCAD and transferred to Map/Info in form of geometric coverage. The data required for each layer for cost estimation consists of locational and thematic information. Locational information includes spatial feature parameters such as coordinate, area, perimeter and spatial relationship, which were derived from the coverage itself. Thematic information includes identification (ID) code, beam number, floor number, etc. Locational and thematic information were integrated by using one-to-one, one-to-many, and many-to-many relationships by using Open Database Connectivity (ODBC). Spatial operation coverage overlay was used to find geometric dimensions of graphical features. To complete quantity takeoffs calculation, parameters such as depth of beam and slab, floor height, area of door and window, etc. have to be entered by the user. Fig. 1.1 shows an overview of algorithm for GIS based cost estimation developed by Cheng and Yang (2001). The Structured Query Language (SQL) was used to retrieve data for cost estimation from related attribute tables and an aggregated tabulation of quantities for different working activities was obtained.

Fig. 1.1: GIS-Based quantity takeoffs algorithm (adapted from Cheng and Yang 2001). 6

1.2.3 Site Layout for Construction Materials The MaterialPlan, a GIS based tool developed by Cheng and Yang (2001) integrates GIS based cost estimates with material layout planning. The system uses rules of thumb and experience to decide the size of material storage areas and placement of materials. It assists the planner in quantity takeoffs as well as in material layout design. MaterialPlan integrates cost estimates with construction schedule to generate dynamic materials requirements. The system is designed to pass on information dynamically to site for material planning. Based on information regarding quantities and locations of materials required in a project, proposed methodology identifies suitable site to store construction materials. 1.2.4 Real-Time Schedule Monitoring System Cheng and Chen (2002) developed an automated schedule monitoring system to control erection process for precast building construction by using GIS. ArcSched, a GIS based system that assists construction managers to control and monitor lifting process of precast components, was developed. A case study was taken where structural elements were prefabricated in a manufacturing plant and transported to construction site for installation. Erection of prefabricated structural components was considered a major critical activity for precast building construction. The schedule for prefabrication and transport of structural elements to site is developed based on installation schedule. The study suggested that use of GIS improves real time schedule monitoring system, construction process and efficiency. ArcSched improves schedule control efficiency by integrating spatial and thematic information into a single GIS environment. The proposed system has three major modules: I. Precast component information management module, developed in Visual Basic. Management of erection schedule database is directly related to this module.

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II.

Erection schedule planning and control module used, MS-Project to create and control the scheduling plan.

III.

GIS display and query module used, to store, retrieve, manipulate and analyse spatial data (Fig. 1.2). The barcode system combined with wireless radio technology was used to

collect and transmit the job site data to control centre automatically. Construction integration was achieved by applying automated barcode identification system in three phases (design, manufacturing and erection) of the precast construction life cycle. Through the application of barcode system, data integrity and consistency between different phases were ensured (Cheng and Chen 2002).

Fig. 1.2: System structure for functional modules (adapted from Cheng and Chen 2002). The work reported by Li et al. (2005) integrated Global Position System (GPS) and GIS technologies to reduce construction waste. A prototype was developed using automatic data capture, barcode for construction Material and onsite Equipment Management (M&E) and integrated GPS and GIS technology to M&E based on the Wide Area Network (WAN). Barcode system was first extended to an enterprise-wide construction by integrating it with traditional construction project management system. The system was developed in such a way that managers from headquarters and construction sites get real-time information to control cargos on road to sites, so as to reduce waste generation on

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sites. Site managers used accurate arrival time of construction M&E to deal with limitations of M&E storage on site and to finish construction project in time with minimum generation of wastes. A comparison of systems (Tab. 1.1) suggests that GPS and GIS integrated solution improved construction efficiency by increasing effective working hour of construction equipments, thus, reducing construction duration and cost of workforce. The initial investment in hardware and softwares was justified by the fact that company can utilise the developed system in different construction projects at later stages also.

Parameters Hardware cost Software cost Equipment utility Construction duration Workforce cost Construction waste

Non-integrated system $2500 $1200 3100 h. 210 days $400,000 $8500

Integrated system $8000 $6000 3600 h. 195 days $360,000 $2000

Variations 220% (Increase) 400% (Increase) 16% (Increase) 7% (Decrease) 10% (Decrease) 77% (Decrease)

Tab. 1.1: Comparison of the non-integrated system versus GPS and GIS integrated system (adapted from Li et. al. 2005)

1.2.5 E-Commerce Applications in Construction The collaboration in AEC industry is essential to generate and exchange project information as well as timely sharing of updated information for successful project completion. Web technology has made it much easier for industry practitioners to collect project information in a central repository and share it over the internet regardless of their physical locations. Construction material trading involves: buyers, suppliers and agents as three major players. Agents help buyers and suppliers to complete transactions. The buyers and suppliers are required in all trading activities while agents exist only in certain trading situations. The links among them may be organised in three ways: (1) buyers and suppliers form direct connections, (2) buyers and suppliers form connections through agents, and (3) buyers and suppliers form connections through electronic markets.

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Li et al. (2003) presented an internet-based GIS model for e-commerce business based on the type (3) trading situation. The e-commerce system, called COME (construction materials exchange) can be used for on-line order and offline delivery of different construction materials (Fig. 1.3). The electronic market in type (3) provides platform for suppliers to provide online information about their products. Buyers can easily search and compare products of different suppliers through online system and contact the suppliers directly. If required, buyers can also invite agents to undertake certain tasks required in order to complete a transaction. Thus, type (3) has the most flexibility and functionality to support all trading situations encountered in construction material trading and do not support bargaining and bidding trading situations. The study by Li et al. (2003) also identified the limitations of traditional construction material procurement method and suggested that e-commerce may help to solve these problems. In all kind of business activities transportation cost is involved, consequently, cost of transportation is a critical consideration in ecommerce. Thus, internet-based GIS provide an ideal solution to manage costs of transportation and market analysis in overall e-commercial activities (Li et al. 2003). The costs of transporting construction materials are not only dependent on the distance but involve some other variables, such as the locations of local distributors also that can reduce shipping cost by combining shipment to various buyers in the same area. 1.2.6 Route-Planning The conventional approach of route planning requires information to be stored in various forms, planners have to repeatedly retrieve such information from different sources. Thus, significant portion of efforts are wasted for information retrieval and integration. This makes the planning process time consuming and prone to errors. Varghese and O’Connor (1995) developed a GIS based system to integrate information required for route planning. They successfully demonstrated the use of an expert GIS for automating the tedious and repetitive route-planning tasks for large vehicles within the construction site. Access planning is an important consideration in the development of an effective project-execution plan, as the conventional planning tool does not provide this 10

facility. Varghese and O’Connor (1995) used GIS and expert system where expert system attempts to model human reasoning process through a set of predetermined rules and GIS provide the data display capabilities to the system.

Fig. 1.3: Business model of COME (adapted from Li et al. 2003) In most of the tunnelling projects for electrical supply system, sites are often in close contact with existing public utility lines and structures. In urban areas, obstacles such as existing public utility lines, railways, canals and roads may influence the route significantly as there may be only a limited number of feasible crossing points. Selection of a suitable route to avoid existing obstacles not only reduces the risk of damaging existing utilities, but also minimises the project cost and duration required. The study by Cheng and Chang (2001) discusses the development of a GIS based system to automate the process of routing and design of an underground power supply system by integrating and organising ill-structured construction information. The RoutePlan, a GIS based tool developed by Cheng and Chang (2001) consists of specific knowledge and databases obtained from expert’s experience for route planning and automating design. Factors affecting the optimal route selection were identified, and Arc/Info database containing the existing utility layers and associated feature attribute tables were developed. In the proposed system, surface and underground utilities are represented in several layers. The tool integrates GIS with the database management system for potential route analysis and determination of the optimal route. The optimal paths for routing is determined using the network analysis of 11

Arc/Info GIS tool. The conflict points between the basic coverage and the selected route are identified and a reallocation schedule is determined through database queries and spatial operations. 1.2.7 Construction Site Layout The conventional approach of laying out Temporary Facility (TFs) involves designing site layout using sketches, templates and Two Dimensional (2D) physical model. The resulting layout through this process is based on the incomplete information stored in different form. Such visual representations of TFs do not yield adequate and descriptive results (Cheng and O’Connor 1994). To layout TFs, project manager has to continuously extract information from various resources and draw it on the paper. As TFs should be located close to their supporting activities to reduce the time for travel, Cheng and O’Connor (1996) explored the use of GIS and developed an automated site layout system ArcSite using GIS for layouts of TFs. ArcSite consists of GIS integrated with DBMS, it integrates the information required to find suitable locations for TFs and perform series of complicated spatial operations and database queries to identify the optimal site layout. 1.2.8 Visualisation The 2D GIS have widely been used in the construction industry for site layouts, route planning, road network analysis, etc. The 3D GIS is similar to 2D GIS, with a change that attributes are associated with 3D objects (Bradshaw 2007, Zlatanova et al. 2002). A realistic 3D visualisation may be useful for security and emergency planning (Smith and Friedman 2004). Ford (2004) describes how ‘true’ 3D features can be stored and visualised in ArcGIS. He suggested the use of multipatch for 3D petroleum dataset. GIS allows importing information from numerous packages into a standard commercial data store, which in turn allows 3D features to be visualised and queried in two or three dimensions. Ekberg (2007) suggested a need of further exploration of 3D editing capabilities of GIS because they are not comparable with Computer Aided Design (CAD) systems.

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The construction process simulation is proved to be an effective tool for planning and improving the performance of a construction process in many of successful case studies. However, simulation tools lack the capabilities to represent explicit geographic information in the simulated construction process. Zhong et al. (2004) suggested that GIS could be utilised to overcome this limitation. They suggested to use3D spatial data that have physical dimensions to represent elements in 3D GIS. By considering time as an attribute, GIS can be used to depict simulated operations dynamically in a 3D environment. A tool called GIS-based visual simulation system (GVSS) developed by Zhong et al. (2004) offers powerful planning, visualising and querying capabilities as well as facilitate the detection of logical errors in simulation models. An optimum scheme was selected after simulating three potential construction schemes. Other parameters such as efficiencies of equipment, monthly intensity of concrete construction and annual concrete construction volume was obtained through tables and charts. This process of visualisation was found helpful in detecting performance inconsistencies and obtain insight into simulated construction operations. 1.2.9 GIS in Construction Progress Control Traditional scheduling and progress control techniques such as bar charts and CPM fail to provide information pertaining to spatial aspects of a construction project. Poku and Arditi (2006) developed a GIS based system to represent construction progress not only in terms of a CPM schedule but also in terms of construction graphics synchronised with the schedule. The architectural drawings were created in AutoCAD whereas the construction schedule was generated using project management software primavera. The design and schedule information (including percent complete information) were plugged into a GIS. After updating the system, a CPM-generated bar chart alongside a 3D rendering of the progress of project can be produced. The system helps to effectively communicate the schedule/progress information to the parties involved in the project.

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1.3 Problem Diagnosis and Approach toward Solution 1.3.1 Difficulties in Detecting Problems through CPM Schedule A construction project is a set of tasks or activities related to the achievement of some planed objective. The large construction, civil engineering and building firms use CPM regularly for their contracts because it gives a clearer picture of complete execution programme. The different activities of the project execution schedule are related to one or more components of facility under construction. The CPM schedule provides non-spatial information; therefore, to have spatial aspects of a project, construction planner uses 2D drawings generated by the CAD systems (Cherneff et al. 1991). To visualise the

construction sequence the project planner mentally associates the components of drawings with the related activities present in the schedule as there is no dynamic linkage between the CPM schedule and its spatial aspects in commercially available scheduling tools (Koo and Fischer 2000). Thus, interpretation of the CPM schedule without any link between its activities and the spatial components is difficult because a construction project may contain hundreds of activities. This makes schedule difficult to check for its completeness (Whyte et al. 2000) as well as to find whether problems exist in the schedule or not (Fischer and Kunz 1995). Also, interpretation of CPM schedule may vary with the experience of persons involved due to the difficulty in mentally linking each element in a 2D drawing with the corresponding activities of the schedule. 1.3.2 Linking Schedule and CAD Systems (4D CAD) The construction industry has acknowledged that its current scheduling and progress reporting practices require substantial improvements in terms of quality and efficiency (Retik 1999). This creates a gap in effective communication among different project participants. The limitations of CPM schedule forced the researchers to combine it with a 3D CAD model that leads to the development of a 4D CAD. The 4D CAD allows a planner to visualise the construction process in a way, as it would actually be built. Koo and Fischer (2000) suggested that a 4D model increases the comprehensibility of the project schedule and allows users to detect potential problems such as scheduling 14

conflicts prior to the execution. They have suggested that the planner using 4D simulation is likely to allocate resources more effectively. The use of 4D CAD also assists the planner to avoid schedule conflicts, examine constraints and evaluate alternative construction methods (Akinci et al. 2002a, b). 1.3.3 Problems Associated with 4D CAD Despite of a lot of research in 4D CAD technologies, their use is not very common in construction industry. These tools are somewhat difficult to use and the visualisation provided by them is not easy to customise (Issa et al. 2003). Existing CAD systems are unable to aggregate and distribute the information between spatial and non-spatial databases and so far there is no standard procedure for using 4D CAD technologies in construction. The 4D CAD tools are based on object-oriented concepts and are used primarily for planning, design phase analysis, and appraisal type of analysis (Poku and Arditi 2006). Most of these tools have an ad-hoc modelling approach that makes it difficult to update and maintain these systems. Furthermore, 4D CAD models have a single level of detail, which hinders the collaboration among general contractors and subcontractors. Moreover, these models generally do not support computer based quantity takeoffs, construction cost and safety analysis (Poku and Arditi 2006). Therefore, the research in the field of sharing and manipulating data on a common platform is still required for the wide spread use of existing 4D CAD tools. 1.3.4 Different Tools for Different Tasks: Interoperability Problems In construction industry 4D CAD tools are generally used as schedule visualisation tools that lack in the analysis like quantity takeoffs, cost estimation, spatial analysis, energy simulations, etc. The software from various disciplines other then 4D CAD are being used to maintain and analyse different aspects of building design, scheduling, operation, health and comfort, energy efficiency performance, etc. The planners use CPM or 4D CAD, drafting group generally uses AutoCAD whereas construction and operations group use blueprints or printed-paper, etc. Different software have their own languages/formats which make it difficult to send, receive, share and use the information provided by 15

them. Architecture, engineering, construction, owner and operator face challenges because of different information formats used to represent spatial and non-spatial information which are difficult to bridge together. Lack of interoperability is a major obstacle that limits the workflow usability due to difficulty in acquiring information from building geometries, coordinates, climate location, thermal zones, etc. This lack of communication and data sharing has a direct impact on public relations and project cost. A study by United States’ National Institute of Standards and Technology (NIST) in 2004 found that in 2002, the annual cost associated with inadequate interoperability among Computer Aided Design (CAD), engineering and software systems in the United States was $15.8 billion that is about 30% of overall cost (Reichardt 2008). 1.3.5 A Move Toward nD Modelling An nD modelling is an extension of the building information model made by incorporating all the design information required at each stage of the lifecycle of a building facility (Lee et al. 2003). Thus, a Building Information Model (BIM) is a computer model database of building design information (Graphisoft 2003). Traditional 4D CAD software creates views as a series of lines and planes and stores information in multiple files while BIM creates a single database capable of generating multiple and consistent 3D views of a model. This visualisation is a common attribute in many of the AEC design packages, such as 3D Studio, ArchiCAD, CommonPoint, Navisworks, etc. The fundamental information needed in BIM is captured in digital models at the time design objects are created. The idea behind BIM is a single repository where every item is described only once. This is an approach to documentation in which all project data may be stored in one and only one location, therefore, every user of the repository may be certain that what they are seeing is exactly the same information that every other project participant sees (Autodesk 2003). BIM has an important role in creating and coordinating objects as a source of intelligent information about a building. The advantages that are offered by BIM to the building industry provide strong premises to overcome the fragmented nature of the industry that was missing in the existing 4D CAD systems.

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However, BIM does not necessarily ensure bi-directional connectivity among all manifestations of a model. In some BIM systems, information is extracted, rather than linked. Modifications made to these extracted documents are not reflected in the model and it must be separately updated (Graphisoft 2003). Traditional approaches to share project information via file exchange using formats such as .dxf, .dwf, .dwg and .pdf do not transfer the appropriate levels of object intelligence from one model to another. A pragmatic and achievable basis for information sharing between these different models is essential to achieve the urgent need for better interoperability between disciplines and software applications across the industry. The nD modelling still needs application level integration for spatial analysis to support various project requirements. For example, GIS application can import CAD data format or directly connects CAD layers in its applications. However this integration could not solve building and geospatial information integration problems because this method relies on either CAD or GIS application but cannot be used to tightly integrate the whole range of data (Aouad et al 2007). Therefore nD modelling requires spatial analysis capabilities those are already available in GIS. 1.3.6 Problem Formulation The nD modelling itself lacks spatial features like evaluation of a new building location for the compliance with constraints like existing water and waste water systems availability and capacity, drainage problems, flooding of building site, entrance of security and emergency vehicle from different access routes to a building location (Smith and Friedman 2004). Even after the development of BIM, AEC industry is still looking to bring the capabilities from different environments such as editing and 3D visualisation from CAD systems, spatial analysis from GIS systems and ability to manage large data sets from DBMS together. This convergence has major impact on professionals involved in AEC industry (Rowlinson and Yates 2003). Bringing together the diverse information on a single platform is necessary to analyse, model, understand and deal with the complex and critical issues such as analysing efficiency, evaluating costs and benefits ratios, etc. Such analysis is not possible in 4D CAD systems, 17

therefore, use of GIS is a fast emerging field being utilised to meet various engineering project requirements but its complete potential to the construction industry has not been realised yet. Keeping the importance of GIS in view, Poku and Arditi (2006) linked AutoCAD and Primavera in GIS. The major limitation of study is the manual transfer of information from Primavera and AutoCAD to ArcView, which is a problem in its practical/field application. Only few of the tools/commands offered in AutoCAD are recognised in ArcView. Therefore, users are restricted to use only those tools/commands of AutoCAD to generate the 2D layers. The 2D layers representing project activities were created in AutoCAD and converted into 3D by writing mathematical expressions in ArcView that is not scaleable. Various layers created for sub-activities of an activity were merged into one and linked with the corresponding activity defined earlier in the schedule. Thus, the sub-activities that belong to an activity located at different positions in the space were joined together to one. According to various researches in the fields of 4D technologies, such activities (merged sub-activities) appear on the computer screen abruptly (Koo and Fischer 2000) and sometime could not represent the correct construction sequence. Integrating a 3D building model developed in GIS with project management tools such as Primavera and Microsoft Project is tedious and timeconsuming process. This integration may be difficult because it require coding within different programming environments. As the construction progresses, CPM calculation need to be updated frequently and scheduling computations are carried out many times on the modified data. Therefore, in schedule evaluation and updating process, 4D model need to be disconnected so that required updating/correction may be carried out in separate environments. This problem can be solved if both components of a 4D construction management are created, evaluated and updated on a single platform. Koo and Fischer (2000) suggested that 4D construction management in AEC industry requires a tool that can manipulate the project schedule and 3D components in a single environment. If both, spatial and non-spatial information are maintained in a single environment and changes are made to these documents 18

at one place only, drawings, schedule, cost estimate and specifications of a construction project will be consistent to each other. This change may significantly reduce the communication problems that often slow down the project and increase the project cost. Further this approach also needs the spatial analysis features like those available in GIS in which nD modelling is also lacking. To extend the use of 4D tools to different stages of a construction project their linking with construction cost was recognised as one of the most important area (Heesom and Mahdjoubi 2004). Therefore, a need to links GIS based 4D construction management tool with GIS based cost estimation methodology. As discussed in section 1.2.2, Cheng and Yang (2001) explored the capabilities of GIS for cost estimation in combination with AutoCAD to compute quantity takeoffs. Methodology suggested by Cheng and Yang (2001) could not replace the CAD systems from GIS based cost estimation procedure. The user communicates with the components of the system through a custom interface developed using VBA (visual basic application) and MapBasic that is difficult to modify for different application. To generate Bill of Material (BOM) Map/Info along with Microsoft Access was used. The Open Database Connectivity (ODBC) was used to write/read the information to/from the associated spatial and nonspatial database. However, few of the commercially available GIS tools like ArcView/ArcGIS developed by Environmental Systems and Research Institute (ESRI), have linkage between the spatial and attribute data, therefore, there is no ODBC requirement. Further, their study uses Microsoft Access for database management, therefore, there is still potential of use of GIS based cost estimation methodology that utilise the database management capabilities of GIS and can replace the CAD and Microsoft Access. The location of a building and its orientation provide the opportunities to reduce its energy consumption. A well-planned and optimally oriented building relates well to its site as well as climate and maximises the opportunities for passive solar heating during winter and solar heat gain avoidance during summer. The visualisation tools may help the designers to understand and recognise the solar heating problems of building during the early conceptual design stage. The

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sun angles’ variations with diurnal and annual cycles need to be considered due to the change in the sun’s position with time. The sun’s lighting phenomenon occurs in 3D, in addition, the sun’s position fluctuates with time (diurnal and annual cycle of a year). Therefore, to preview the effect of direct sun lighting in an architectural 3D space over time, designers must navigate in a 5D space that consists of the three dimensions of space and two dimensions of time (Bund and Do 2005). 1.3.7 Approach toward Solution One of the limitations with 4D CAD and BIM tools are that they are not geospatial in nature, whereas in GIS, objects are associated and perceived together with their surroundings and environment. However, the level of sophistication, particularly in 3D modeling is superior in CAD and BIM tools but GIS, on the other hand, has its own strengths such as complex geospatial analysis tools which are not available in 4D CAD and BIM. Thus the need of an information system that combines precise geometric models referenced to the earth, with support for temporal evolution, project management and execution. As data interoperability among CAD/BIM and GIS is still a problem and no web standards are available for CAD and BIM data. Thus present study plans to explore the potential of a GIS to store and manipulate different types of information required by AEC industry in a single environment. Building (floor level detail), 4D scheduling and geospatial information together support neighbourhood planning, improve delivery of services, assure adequate safety and security procedures, plan line of sight communications, optimise way finding, support transportation and logistics and improve customer awareness about their access to retail services (Smith and Friedman 2004). Beginning with this idea, a project contractor and organisation create, store and share information about a construction project, construction site and surrounding geography. GIS, which combines CAD like editing, database management and spatial analysis system, seems to have the potential to solve this problem. The use of GIS has already been explored in construction industry for spatial analysis and various other construction project requirements. Despite of 20

the several applications of GIS, construction industry still depends on tools other than GIS for 4D scheduling, as integrating GIS with project management tools such as Primavera Project Planner (P3) and Microsoft Project is tedious and time-consuming process. Keeping this limitation in view in this work tends to explore the potential of GIS to handle CPM basic scheduling computations and links the schedule with a 3D model in the same environment to develop a 4D scheduling tool. This work plans to expand the GIS based methodology for 4D scheduling that can be used in combination with quantity takeoffs, cost estimate and direct sunlight visualisation in GIS itself. Therefore, if the planner wants to visualise the direct sunlight on a building in 5D space, the 3D model developed for 4D scheduling and quantity estimation can be utilised.

1.4 Research Objective
In a construction project, if both, spatial and non-spatial information are maintained in a single environment, changes can be made to the information at one place. This idea may significantly reduce the communication problems, which often slow down projects and increases the construction cost. Researches reported so far in this area are limited. Therefore, efforts to use GIS in AEC industry have not embraced the issues associated with its implementation in industry practices. Several GIS based tools are suggested in the literature and their applicability has been demonstrated with case studies. However, the value of these tools with industry practice is still doubtful and their implementations on the real life project in industry are rare. The main objective of this study is to explore the capabilities of existing GIS tools to generate the project schedule in GIS itself and combining it with 3D capabilities in order to manipulate both 3D model and schedule on a single platform. The efficient data management, data retrieval and analysis may be achieved if the construction resource data is maintained on the same platform. Therefore, database management capabilities of GIS are used to maintain the construction resource data in GIS (Fig. 1.4). To extend the use of a GIS based 4D management approach for different phases of a construction project, quantity 21

takeoffs, cost estimate and direct sunlight visualisation may also be integrated with the 4D system developed within GIS.

Many more Quality control Specifications

Construction non-spatial information in GIS

Safety measures Cost estimate CPM scheduling

GIS
Many more Route planning Sunlight visualisation Modeling topography 3D Modeling 2D Drawings
Spatial Information in Non-spatial Information in

Spatial information in GIS

4D visualisation in GIS

FIG. 1.4: Linking of spatial and non-spatial information, 4D scheduling and spatia analysis planned to be carried out in GIS environment.

This study aims to supplement the capabilities of exiting GIS software and can not be considered as a replacement of the already available commercial tools such as Revit, ArchiCAD, CommonPoint and Navisworks etc. Keeping all

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these aspects in mind, following objectives were planned to be achieved in this study: I. To explore the capabilities/functionality of GIS (ArcGIS 9 and ArcView 3.2 in this work) to maintain construction resource information, 3D visualisation, linking spatial and non-spatial information, quantity takeoffs, cost estimation and sunlight visualisation. II. To supplement the capabilities of exiting GIS software by developing a methodology for CPM basic forward and backward passes calculation. The methodology would also consider problems of frequently updating of the construction project network. III. To link activities of the CPM schedule with corresponding 3D components of a building model for visualising the buildability of project schedule on the computer screen. IV. To investigate the potential of GIS in creating navigable 3D animation of construction project activities for construction schedule review and corrections. V. To explore the usefulness of a GIS based methodology for quantity takeoffs in construction management and to design a procedure for construction cost estimation using the construction resource data maintained in GIS. VI. To supplement the capabilities of GIS by developing a methodology for direct sunlight visualisation on a 3D building model.

1.5 Thesis Organisation
This thesis constitutes a collection of 8 chapters, each chapter is presented in such a way to make it a distinct piece of work contributing to overall research literature. Chapter 1 presents a brief background of GIS applications in construction industry. The current state of GIS applications in AEC industry is discussed in a separate section of this chapter. Keeping research literature into account the research area for this work is identified and objectives of the proposed work are defined. 23

Chapter 2 presents the summary of different spatial and non-spatial operation available in ArcGIS 9 and ArcView3.2 used in this work. This chapter also provides a brief introduction of ArcGIS 9. Variety of interoperability modes including file conversion, entity translation and direct read/write are listed in this chapter. At the end, comparison between the GIS and CAD systems is also provided. Chapter 3 addresses an approach to enhance the capabilities of GIS for CPM basic scheduling computations. According to the capabilities of software and the information required in handling scheduling calculation, functions of ArcView 3.2 and ArcGIS 9 are enhanced and explained in this chapter in detail. The advantages of tabular approach of scheduling in GIS are also described at the end. Chapter 4 emphasizes on the use of GIS to develop a 4D system that facilitate the manipulation of 3D model and CPM schedule in a single GIS environment. This chapter provides a detailed procedure to evaluate and visualise the construction schedule within a GIS environment. At last, advantages of GIS as a scheduling tool are also described. Chapter 5 describes the development of a GIS based navigable 3D animation of construction activities for construction schedule visualisation and review. The dynamic linkage between project activities and corresponding 3D components was utilised to facilitate the detection of missing activities and logical errors in the schedule sequence. Chapter 6 discusses an approach for cost estimation within GIS itself and demonstrates the significance of GIS based system for quantity takeoffs. Procedures to find the bill of quantities on the basis of dimensions of the drawing and cost of construction are also described. Chapter 7 presents an approach to develop a methodology in GIS for direct sunlight visualisation on the buildings in 5D system. The ArcView 3.2 is used for the calculation of azimuth and altitude angles of sun by writing programme whereas ArcGIS 9 is used to develop a navigable animation. 24

Chapter 8 summarises all the findings and discusses the contribution of this thesis to the existing literatures. Few recommendations for future studies are also discussed.

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Chapter

2

Geographic Information Systems
2.1 Introduction
Information system is a system used to achieve the specific objectives of collecting, storing, analysing and presenting the information in a systematic manner (Lo and Yeung 2002). An information system consists of several interrelated components such as combination of data, technical and human resources. Individual information system can be operated independently and sometimes can be linked with other information systems through standard communication protocols (Lo and Yeung 2002). Geographic Information Systems (GIS) is a special class of information system dealing with the data related to the earth’s features, surface and recourses including human activities related to them. Depending upon the nature of the data that an information system processes, they can be classified as spatial and nonspatial information systems. Non-spatial information systems are used to process the data that are not referenced to any position in the geographic space, whereas spatial information systems are used to process the data that are described in terms of locations on earth surface. Every information system dealing with spatial data cannot be considered as GIS. CAD systems are the example to deal with spatial data but are not considered to be GIS. GIS is a special class of information system that can be divided into four components involving a computer system, GIS software, human expert and data (Clark 2001). Since the late 1960s computers have been used to store and process geographic information, but it has been considered to be a difficult, expensive, and proprietary task for number of years. The inventions of graphical user

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interface, affordable hardware and software have widened the range of computer applications to store and manipulate various types of data. These factors have brought the GIS to mainstream practitioners who efficiently capture, store, manipulate, analyse and display all forms of geographically referenced information in a user friendly and flexible manner. Activities of GIS may be grouped into spatial data input, attribute data management, data display, data exploration, data analysis and modelling (Lo and Yeung 2002). GIS can handle both spatial and attribute data, whereas spatial data relates to the geometry of features, while attribute data stored in tabular form describes the characteristics of different features (Chang 2002). Data used in GIS are available in many formats, including satellite and aircraft imagery, Digital Elevation Model (DEMs), road infrastructure, communications infrastructure, building locations and footprints, land type and use, water bodies, streams, population densities, etc. GIS capture, store and manage spatially referenced data as points, lines, polygons (vector data model), and as continuous fields (raster data model). For example, in GIS land parcels will be represented as polygons, whereas streets are represented as centrelines and wells as points. The query languages and user interfaces in GIS tools permit rapid modification of parameter values (i.e., attribute data assigned to spatial entities or fields). The convenient and quick updating of modelling parameters is a major benefit of GIS over other type of information system. The visualisation of data using the graphic features of GIS may assist in verifying data and information pertaining to a model and its application. The GIS also facilitate the construction of DEMs, and derive slope and aspect from DEMs (Lo and Yeung 2002). Keeping in view the use of GIS in present work this chapter discuss about the GIS software and the functionality used in this study. 2.1.1 Data Models in GIS GIS uses raster and vector spatial data model to represent spatial features. Raster data is defined as a tessellation of a plane into regular cells, where each cell represents a value of some quantity at a given location. In other words, raster data model uses a grid to represent the spatial variation of a feature. Each cell of a grid has value that corresponds to characteristic of spatial feature at that location.

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The whole dataset represents field of given quantity varying across the space. Spatial position of each cell is implicit in the ordering of pixels. The cells are usually square-shaped, but in principle they can be of any uniform shape that completely covers plane without any gap. Raster data plays important role in remote sensing applications and other systems where the entities are continuous in the space (Clark 2001). Vector data model uses points and their x, y-coordinate to construct spatial features (points, lines or polygons), features are treated as discrete objects in the space. Vector model contains individual objects (features), which usually represent real-world phenomena. The spatial components of each object are composed of points, lines or polygons. Only the co-ordinates of special points (end points of lines, corners of polygons, etc.) are stored in the dataset whereas co-ordinate information for the locations without any object is not stored. This representation of features makes it more compact than the raster data. Each attribute value is similar to the value of a pixel in raster data model. An object may possess many attributes, allowing a user to perform various queries on attribute data. The choice of the data model is based on the type of problem, properties of data, capabilities of computer software, hardware and the experience of personnel. As most of the spatial information of a construction project lies in CAD drawings, therefore, the focus of this work will be on vector dataset. The data model used in the present work stores spatial and attribute information in separate files and links them by using feature ID. Both spatial and non-spatial information (attribute) are synchronised so that both can be quarried, analysed and displayed. Spatial data is related to the geometry of features and may be of different types such as: satellite images, scanned map of city or streets. It is used either for visualisation, spatial queries or for analysis. The attribute data that describe the characteristics of different features in a layer are maintained in tabular form. This data is stored in a DBMS and treated in same way as in other information systems. Each row of a table represents a feature, while each column represents the characteristics of a feature. The intersection of a column and row shows a value of particular characteristic of a feature (Chang 2002). Each feature of a spatial data has associated attributes,

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which are stored in the dBASE file. Attributes may have various data types (strings, integers, floating point numbers, etc.) according to dBASE file specification. 2.1.2 GIS Software ArcGIS Desktop 9.0 and ArcView 3.2 developed by Environmental Systems Research Institute run on standard desktop computer are used in the present work. They are used to create, import, edit, query, map and analyse geographic information. ArcGIS Desktop consists of: ArcReader, ArcView, ArcEditor and ArcInfo. ArcReader allows viewing, exploring and printing of spatial information. ArcView is full-featured GIS software for visualising, managing, creating, querying, and analysing spatial information. ArcView’s functionality are accessible via an easy-to-use interface that is customisable and extensible through programming. ArcEditor includes all the functionality of ArcView in addition to editing tools and contains extensive set of tools for simple data cleanup and input as well as for sophisticated design. ArcInfo is a complete and extensible GIS tool, it includes all functionality of ArcView and ArcEditor as well as having advanced geoprocessing and data conversion capabilities. ArcInfo provides all functionality for creating and managing an intelligent GIS system (ESRI 2005). Optional extensions such as Spatial Analyst, 3D Analyst, ArcGIS Data Interoperability, Network Analyst, Survey Analyst, etc. allow performing additional tasks with ArcGIS. ArcGIS Spatial Analyst provides a comprehensive set of grid based spatial modelling and analysis tools to ArcGIS Desktop. ArcGIS 3D Analyst allows visualising and analysing surface data and allows viewing a surface from multiple viewpoints, querying and determining what is visible from a chosen location on a surface. It also has the ability to incorporate a variety of 3D objects created in other programs. ArcGIS Data Interoperability eliminates barriers for data sharing by providing state-of-the-art direct data access, transformation and export capabilities (ESRI 2005). It allows ArcGIS Desktop users to easily use and distribute data in many formats including CAD and GIS as well as many other raster and vector formats (ESRI 2003). ArcGIS Network Analyst allows creating and managing sophisticated network datasets and

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generating routing solutions. Network Analyst is a powerful extension for routing and network-based spatial analysis (e.g., location analysis, drive-time analysis and spatial interaction modelling). ArcGIS Survey Analyst is an extension that allows managing survey data in a geodatabase and display survey measurements and observations on a map. Surveyors can easily incorporate their measurements and calculations into GIS databases to serve as a control framework for various applications. Like ArcGIS 9.0, ArcView 3.2 developed by ESRI is also used in this work to perform various tasks. ArcView also runs on standard desktop computers in windows environment. ArcView is a collection of different documents that provide different menu/command structure to perform various operations. Each document type has its own set of menus, buttons and tools. The Project Window document in ArcView is used to store and organise spatial and non-spatial (tables, charts or scripts) information. It may be considered as a table of contents for different documents in ArcView. View is an interactive document used to display, explore, query and analyse spatial information in ArcView. Table document facilitates the working with non-spatial information in tabular form. Attributes are stored separately from spatial information in database files. Chart document is a visual representation of data in a table, especially attributes of a theme features. The document Layout is a map that displays views, charts, tables and graphics. Script document is the component of ArcView that contains Avenue programming language GUI. In addition to various documents, ArcView also contains different extensions such as Spatial Analyst, 3D Analyst, Network Analyst, CAD Reader, Geoprocessing, etc. to perform specific tasks. 2.1.3 ESRI Shapefile The shapefile is a spatial data format used in this work was developed by ESRI in early 1990s. The shapefile format does not support topological relations between the objects. The dataset in shapefile format consists of at least a main file (theme.shp) where actual data is stored, an index file (theme.shx) and a database (theme.dbf) for feature attributes (ESRI 1998). The attributes are stored as a table in dBASE format. The index file contains offsets of each feature in the main data file, thus, allowing random access to data. The dataset may also

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accommodate additional files, which contain information about the data (e.g. coordinate system information). 2.1.4 ArcGIS Format for representing 3D Objects ArcGIS represents 3D features in its 3D Analyst extension where objects may be displayed in 2.5D or in true 3D. ArcGIS stores 2.5D surfaces in the form of raster, Triangulated Irregular Network (TIN) and DEMs and all surface locations have only one elevation (a single z value for each x, y-coordinate). True 3D surfaces are solid model surfaces handled in ArcGIS through multipatch features (ArcGIS 2004). The multipatch is a type of geometry composed of planar 3D rings and triangles, used in combination to construct objects that occupy discrete areas or volumes in 3D space. Multipatches may be used to construct geometric objects, like sphere, cube and building (Fig. 2.1). Multipatch consists of geometries such as triangle strips, triangle fans and rings. Triangle strips and fans are sequences of connected triangles, where a strip always connects to the last vertex (0, 1, 2, 3, 4, ….n) and fans always connects to the first vertex in the sequence (0, 1, 0, 2, 0, 3, 0, 4, ….0, n). Triangle strips or fans are specifications of how to ‘fold’ an object, drawn on a 2D surface, to accomplish a 3D object (ESRI 1998). Ring describes the boundary of a surface and can be divided into four groups: ring (unknown), first ring, inner ring and outer ring (ESRI 1998). Ring (unknown) defines a surface of unspecified type and may only be followed by a first ring or other ring typed parts. First ring is the first in a sequence of rings that defines a surface of unspecified type and used when the innerness or outerness of a surface is unknown. The inner ring in a sequence of rings defines a hole in a surface whereas the outer ring defines the surface that has holes. Multipatches are stored in ArcGIS as shapefiles in the same manner as point, line and polygon data. It contains attributes and its different faces may contain texture information, such as a digital photograph of the front of a building. Thus, allowing the creation of photo-realistic 3D views. ArcGIS renders 3D models as features in a multipatch feature class (ESRI 1998). Displaying multipatch data is same as displaying other geometry types. Although multipatch exists in ArcGIS as a data type but there is no possibility to create/edit multipatch features within ESRI products interactively. This is possible only through

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programming with ArcObjects or through a standalone application such as SketchUp (Ford 2004). ArcScene provides the ability to create and view 3D objects without any editing capability. ArcMap can be used for editing in the 2D (x, y) plane whereas ArcScene provides a function for converting features to 3D. Polygon created as polygonZ feature (ESRI 1998) is just a surface, not a true 3D object. Extruding polygons up to a roof height may create a multipatch feature, which is a true 3D object, however, ArcMap does not provide any functionality for editing multipatch features but allows editing of polygonZ features. Just like polygons can be extruded upward, polygonZ features can also be extruded to create flat roof buildings.

Fig. 2.1: Geometry of different type of multipatch parts (adapted from ESRI 1998).

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2.2 Data Interoperability
ArcGIS has number of tools for spatial analysis, which provides an ability to assemble intelligent datasets and perform advanced editing work with and between vector and raster data. These tools can be used to create derivative information, construct static and dynamic models, calculate spatial statistics and perform a wide variety of domain-specific functions and analytical assessments (Kennedy 2006). ArcGIS also includes an improved bi-directional CAD-GIS translator that can transfer data from CAD system to GIS and vice-versa to facilitate data sharing. ArcGIS offers variety of interoperability modes including file conversion, entity translation and direct read/write of files. The Data Interoperability extension provides additional functionality to read a variety of CAD data formats without conversion, including the latest versions of DWG, DXF and DNG files. ArcGIS also symbolises the data as defined in CAD file (ESRI 2005). ArcGIS can export selected GIS features (points, lines, polygons and annotation) directly to CAD systems. Data Interoperability extension directly read/write or translate more than 70 different spatial data formats including GML, XML, Autodesk® DWG/DXF™, MicroStation Design DGN, MapInfo® NID/MIF and TAB, Oracle® Spatial, Intergraph GeoMedia® Warehouse, etc. ArcGIS also has the ability to import variety of popular 3D model formats including SketchUp (.skp), 3D Studio (.3ds), OpenFlight (.flt) and VRML (.wrl) as full 3D objects (ESRI 2005).

2.3 GIS Based Spatial Operations
In present work, vector data models (non-topological) that utilise simple graphical objects such as point, line, polygon and multipatch to represent geometric spatial features are used. Each point, line, polygon or multipatch theme in spatial database is stored as a shapefile. In spatial database, features classes are logically organised as themes/layers, where each theme is allowed to have only one type of graphical element (point, line, polygon or multipatch). ArcGIS used to create spatial data in this work has CAD like tool/commands for modelling. In

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addition, ArcGIS also contains tools to handle editing session of geographical applications (ArcGIS 2004). The functions such as delete, move, cut, and paste available in ArcGIS may be applied to one or more selected features point, line and polygon. For reshaping lines and polygons, vertex edit tool may be used. The spatial functionality of ArcGIS/ArcView used in this study are discussed in the following sections: 2.3.1 Grouping of Features The merge in ArcGIS and union features in ArcView groups the features of a theme into one feature. These tools combine different features by removing boundaries or nodes between adjacent polygons or lines as well as join nonadjacent features to create a single feature. For example Fig. 2.2 contains five walls, which are dissolved into one, and three non-adjacent polygons are merged to create a single multipart polygon feature.

Fig. 2.2: Grouping of selected features of a theme, which removes boundaries between adjacent polygons. Non-adjacent polygon features are combined together to form a multipart polygon feature.

2.3.2 Extrusion The 2D theme does not have base height and feature height information. To display 3D perspective view, a 2D theme must be assigned base height and feature height from the fields of its own attribute table. Base height is the elevation value for the features of a theme in 3D space. The extrusion function in ArcView/ArcGIS changes a point into vertical line, lines into vertical walls and polygons into 3D blocks. Fig. 2.3(a) shows a 2D theme whereas Fig. 2.3(b) shows theme at required orientation, 2.3(c) shows the feature of a theme in space

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at elevation value equals to its base height, and is extruded upward to make it 3D by a value equal to its feature height as shown in Fig. 2.3(d).

Height Rotation Base height

(a)

(b)

(c)

(d)

Fig. 2.3: (a) Feature of a 2D theme, (b) 2D feature at a suitable orientation, (c) feature in the space at elevation value equal to its base height, (d) feature is extruded upward by value equal to its height.

2.3.3 Merging of Themes Together Merging is used to create a new theme by piecing together two or more themes of same geometry type (e.g. points, lines or polygons). The merging themes together tool of GeoProcessing extension available in ArcView is used to merge the themes. This tool combines features of two or more input themes to generate a single output theme. The output theme encloses the fields from one of the input themes. If the remaining input themes have same fields, then all cells in the output theme’s attribute table will get populated. If any of the remaining input themes have additional fields, they will not be included in the attribute table of the output theme (ArcView GIS 3.2 1996). Fig. 2.4(a) shows three 2D input themes. In Fig. 2.4(b), three themes are merged to one using tool merging themes together. Fig.2.4(c) shows different features of theme in a space at the elevation value equal to their base height whereas Fig. 2.4(d) displays all features extruded upwards by a value equal to their feature height.

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2.3.4 Subtract Feature The functionality subtract feature of ArcGIS/ArcView is used to calculate net area by subtracting one feature from other. This function is used in GIS based cost estimates and discussed in more detail in chapter 6. In Fig. 2.5, a feature depicting doors is subtracted for another feature depicting brickwork in superstructure. The resulting feature is used to calculate the net area of brickwork in superstructure.

(c)
Merging Assigning base height Extrusion

(a)

(b) (d)

Fig. 2.4: (a) Three 2D themes, (b) merging themes together pieces the features from three themes together to a single theme, (c) different features in the space at elevation value equal to their base height, (d) all features are extruded upward by value equal to their height.

2.3.5 Hot-Linking GIS can be used to store and retrieve as-built construction photographs. At various stages of construction, photographs taken with a digital camera, can be stored and retrieved using hot-linking capabilities of ArcGIS. This allows user to access a time series of photographs, which can be used to resolve disputes pertaining to quality of work and the location of individual elements of construction (ArcGIS 2004).

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Subtract feature

Fig. 2.5: Functionality subtract feature is used to calculate net area by subtracting one feature from other.

2.4 GIS Based Non-Spatial Operations
The non-spatial information in GIS defines the characteristics of spatial features and stored in a table called the feature attribute table. Each row of the table represents a feature whereas each column represents its characteristic. Sometimes all attributes are not stored in a feature attribute table, which makes it difficult to use and update. An alternative approach to manage attribute information is to store it in separate tables called database tables. The database management system may then be used to manage these database tables. In the present work, all construction resources information is maintained in such tables. Database table is also used to generate the construction schedule in GIS. The non-spatial functionality of GIS, used in this study are discussed in the following section: 2.4.1 Joins and Link Three types of relationships i.e. one-to-one, one-to-many and many-to-one are used to join/link different tables together. To explain these relationships, one needs to define source (from) and destination (to) tables. For example, if the purpose is to add data from database table to the estimate table, then estimate table is the destination table and database table is source table. Fig. 2.6 provides a diagram showing various relationships betweens two tables. One-to-one relationship means that one and only one record in the destination table is related

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to one and only one record in the source table. The one-to-many relationship means that one record in the destination table may be related to more than one record in the source table. In many-to-one relationship two or more records in the destination table may be related to one record in the source table (Chang 2002).

Field Activity_ID, common between two tables, used to establish the connection between corresponding records in tables

Destination

Source

Destination

Source

Destination

Source

1 2 3 4 5

1 2 3 4 5
One-to-one

1 1 4 4 4

1 2 3 4 5
Many-to-one

1 2 3 4 5

2 2 4 4 4
One-to-many

Fig. 2.6: Relationships between the two tables connected through a field named Activity ID utilised in the present study.

The Join function of ArcGIS/ArcView is used to establish one-to-one or many-to-one relationship between the destination table and the source table. Two tables are joined on the basis of a field called Activity_ID, which is available in both the tables. The name of field does not need to be the same in both tables, but the data type (number-to-number or string-to-string) must be the same. After joining, the contents of the destination table change to include the joined attribute from the source table, whereas the source table remains unchanged. The function Link in ArcGIS and Relate in ArcView establishes one-tomany relationship between the destination table and the source table. Unlike joining tables, Link/Relate defines the relationship between two tables, rather than appending the attributes of the source table to that of destination table. After Link/Relate is established, selecting a record in the destination table will automatically select the record or records related to it in the source table.

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2.4.2 Length, Perimeter and Area Calculation The word layer is a collection of features drawn on a view and has an associated legend that defines the symbolisation of features in ArcGIS. Instead of layer, the word theme is used in ArcView. In ArcView, feature attribute tables are used to store attributes and shape information of various features in a theme. If the table is feature attribute table of a line or polygon theme and has fields length, perimeter and area. ArcView calculates the values of length, perimeter and area based on the shape using expressions (Tab. 2.1). For example to calculate length, the expression will be like [Shape].ReturnLength in ArcView 3.2. A sample script available in ArcView is another way to calculate the area and perimeter for polygon theme. The script processes lists of active themes to calculate area and perimeter. Script adds the field area and perimeter to the feature attribute table of theme if these fields do not exist in a table. In case these fields are already available in feature attribute tables, their values will be recalculated.

2.5 Non-Spatial Data in Present Work
The methodology proposed in this work stores construction information related to materials, workers, and equipments data in three different tables for various possible tasks involved in the construction project (Fig. 2.7). Storing, maintaining and updating resource data are at the core of this work. Additional information can also be incorporated to all tables to ensure expansion and updating of database at later stages. Options are designed in a way that only selected users such as owner or a system developer can update it. Material table in the database contain different fields named as: key; units; cement; sand; course aggregate; bricks; lime; impervious material; steel; stone; wood frame; wood shutter and quantity. Material table can be connected to other tables by a field key, where key represent attributes in a table whose value can uniquely identify a record (row) in that table. If field key is common between two tables, it can be used to establish the connection between the corresponding records in the tables (Fig. 2.6). Field activities contain different possible items of construction work. Each record of table contains amount of different material required for a task in

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the corresponding field (column). If intersection of a record and field in the table has zero entry, it indicates that the item corresponding to that row does not need any material in the corresponding field. To avoid fraction, all entries in different fields of material of the material table are not for single work unit. The field quantity in the table contains amount of work for which the values are entered in the respective row. To obtain the materials needed for single work unit of the items, one needs to divide all entries of corresponding row by values of the field quantity.

Fig. 2.7: Screenshot of resource database maintained in GIS environment to facilitate construction planning.

Labour table contains fields: key; activities; mason; helper; T&P; blacksmith; carpenter; water-man; scaffolding; shuttering and quantity. Each row of this table contains number of different class of workers required for a task in the corresponding fields. The number of different class of workers is calculated by dividing the man-hour required to perform work by the working hours in a day. The entries in this table can be converted into cost by multiplying entries by the appropriate labours’ rate per day. Similarly equipment table contain fields: key; activities, quantities and fields for different equipments such as excavator,

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vibrator, mixture, truck, crane, welding set, etc. Each field contains the rate of the equipment for the amount of the work entered in the field quantity. Safety Recommendation table has two fields: key and safety recommendation. Quality Recommendation table also has two fields i.e. key and quality control recommendation.

Operation/ tool Length calculation by script/ command

Descriptions Add a column to the attribute table containing length values

Changes in attribute table Length

Graphical illustrations

Perimeter calculation by script/ Command

Add a column to the attribute table containing perimeter values Add a column to the attribute table containing area values

Perimeter

Area calculation by script/ command

Area

Subtracting the features by Subtract Feature Combines features with union tool

Calculate net area by subtracting one feature from other Removes boundaries of adjacent polygon features Changes points to vertical lines, lines into vertical walls, polygons into 3D blocks Base Height

Extruding the features of a layer with Extrusion

Tab. 2.1: List and description of GIS based spatial operations used.

2.6 Generating 2.5D View Using 2D Themes
The 2D themes generated in AutoCAD/ArcGIS may be utilised to generate 2.5D perspective view. The attributes required to generate a 2.5D view from 2D

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theme include base height and feature height values. Two fields (called base and height) need to be added to feature attribute table of a 2D theme that maintains the base height and feature height information respectively. The extrusion functionality (discussed in section 2.3.2) may be used to change the form of a feature from points into vertical lines, lines into vertical walls and polygons into 3D blocks. 3D Scene Viewer control-bar of ArcGIS facilitates the understanding of 3D model through zooming, pan, fly forward or backward, navigation, etc. Fig. 6.6 in chapter 6 shows the 3D views of a hexagonal building generated form 2D theme.

2.7 GIS versus CAD
In AEC industry, CAD systems are generally used to create 2D/3D drawings of buildings and objects. CAD systems provide geometric descriptions of various entities of a drawing. The geometric entities in most of the CAD systems cannot describe their meaning, therefore, their interpretation varies from person to person. Further, CAD drawings cannot be used for calculations of length of a line, area of a region bounded by lines as well as the volume of objects. CAD drawings are simply the lines on a sheet of paper/screen and their interpretation varies from observer to observer. CAD offers very little spatial analysis tools but provide a rich set of tools for creating digital drawings in comparison to GIS. Editing and visualisation of 3D information in CAD have a long history. The design of CAD systems have partly been focussed on developing good 3D editing tools and effective 3D visualisation that has not been a major issue in the development of GIS. CAD systems typically organise information in three ways: as layers of graphics in a drawing, as a collection of drawings on a sheet and as drawing sheets in a set of sheets (ESRI 2003). While, GIS organise information with feature type (point, line, polygon or multipatch). Features in GIS are symbolised and organised into thematic layers. The main difference between the two systems is that CAD systems was originally designed for modelling in local coordinate system, e.g. buildings, industrial parts, machine tools, etc. whereas GIS was designed to represent reality

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in a geographic coordinate system in order to replace traditional paper maps. Another difference between CAD and GIS is the way they store the spatial information. The CAD supports a variety of primitives like cone, sphere, cylinder and freeform shapes to handle complex constructions, while, GIS supports points, lines, polygons and multipatch. Recent research suggests a trend in bringing both CAD and GIS systems together (Oosterom et al. 2006). In addition to the capabilities that associate attributes with different features in GIS, features geometry with in GIS also maintains their topology (spatial relationship among different features). Therefore, GIS has the ability to provide and maintain both feature’s meaning (component knows it is a wall) and topological meaning (wall knows it crosses floor I). In this way, GIS provides an added level of intelligence over the existing CAD systems. In GIS, the geometry defines where the shape of a 3D object is located in space and topology describes the spatial relationships with others objects in space. Topology is a complement to the geometry and often considered to be the foundation for most of the GIS based spatial operations (Ekberg 2007). The main difference that distinguishes two systems lies in the way they represent entities in space; how they tie these entities to a spatial reference; how they organise information; how they store information in a computer and their capacity to perform spatial analysis. CAD systems use a Cartesian coordinate system to reference geometry to a local origin (0, 0, 0) and do not typically reference the geometry to a location on the surface of the earth. In comparison, GIS systems use a Geodetic Reference System, either in the form of geodetic coordinates (longitude and latitude) or a specific map projection with geodetically referenced coordinates. Most of GIS systems can georeference local coordinates in a CAD drawing to geodetic coordinates on surface of the earth. While integrating CAD and GIS systems, main difficulty is the difference between the data types and file formats supported by the two systems. Thus, making it difficult to exchange data between them without any data loss. GIS does not support all primitives that CAD supports, therefore, loss of geometry may occur during an export from CAD to GIS (ArcGIS 2004). An object represented with various primitives in CAD, must be represented with lines and

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polygons in GIS. Similarly, object imported from GIS to CAD may lose semantic information since CAD systems are not well equipped in dealing with semantic information (Kelsey 2007, Oosterom et al. 2006).

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Chapter

3

Critical Path Method Programming
3.1 Background
Primavera and Microsoft Project are most widely used softwares to represent the non-spatial schedule of a construction project. In spite of their widespread use, these softwares lack in the spatial aspect of a construction project. In order to visualise a construction sequence, planner uses 2D drawings and associates their components with the related activities present in the schedule. As there is no dynamic linkage between activities of the schedule and the corresponding components of a 2D drawing, it is difficult to understand and communicate the construction sequence. Thus, lack of linkage makes it difficult to check the schedule for its completeness and creates problems in identifying missing activities or logical errors in the schedule that may pose a serious problem for the successful completion of a project (Chau et al. 2003, Koo and Fischer 2000). Above limitation of schedule generated in Primavera and Microsoft Project forced researchers to combine it with 3D CAD model that leads to the development of a 4D CAD system (McKinney and Fischer 1998). Despite the suggested advantages of 4D CAD models, these are not very popular in construction industry. 4D technologies are difficult to customise and unable to distribute the information between spatial and non-spatial databases (Issa et al. 2003). The 4D tools are commonly used for planning and design phases of a project, therefore, further research is required in the field of sharing and manipulating construction data on a common platform for the widespread use of exiting 4D tools (Poku and Arditi 2006). As 4D CAD tools do not provide a platform to manipulate both schedule and 3D model in a single environment.

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Koo and Fischer (2000) suggested the requirement of a 4D tool that can manipulate schedule and 3D components in a single platform. The potential of GIS for 3D modelling has been explored in earlier studies (Poku and Arditi 2006, Smith and Friedman 2004) but so far no study has explored the capability of GIS to generate the construction schedule. Keeping this in mind, this chapter explores the uses of GIS for CPM scheduling. A major advantage of developing a scheduling tool in GIS will be the manipulation of both 3D model and CPM schedule in a single environment.

3.2 Structures and Element of Network
Poku and Arditi (2006) used AutoCAD and Primavera to generate construction design and schedule respectively that were later linked in ArcView. A major limitation of their study is that, if resulting 4D model does not provide actual construction sequence, schedule generated in Primavera cannot be corrected in ArcView. As CPM schedule needs frequent revisions, it is to be linked/unlinked many times from the components of 3D model to correct the construction sequence. Thus, making it a time consuming process. To solve these problems, this study proposes to use in-house programmes developed for CPM scheduling within ArcView and ArcGIS environment. Section 3.3 discusses a tabular programming approach that has been tested and used with both ArcView and ArcGIS in different programming environments (Avenue in ArcView and Visual Basic for Applications in ArcGIS). The working of CPM starts by identifying all activities (portions of a project consume time and resources and have well defined beginning and ending) involved in the project. Activities are designated as i-j (beginning and ending points of an activity), i.e., an activity with predecessor event i and successor event j. Once activities constituting the project are defined their technological dependencies are shown explicitly in the form of a network diagram. Network diagram shows the inter-relationships of various activities involved in the project. A network diagram is constructed with two basic elements: arrow (activity) and node (event). Identifications of different activities of the project and their relationships are known as planning phase that requires a thorough analysis of the project. The next step is to add time estimate to each activity in the network

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diagram. The process of the time estimation and network refinement are closely related and usually done at the same time. The following assumptions are made in the development of tabular approach for CPM calculations: I. Before an activity begins, all activities preceding it must be completed. II. III. The network must be free of loops. No duplication of event numbers is allowed.

Initial draft of the project network is developed and first project event (with no predecessor activities) is numbered as 1. If there are more then one initial project event, then they should be numbered consequently in any order. Next step is to delete all activities from the initial event(s) and search for events in the new network that are now initial events. Number these events as 2, 3……k in any order. Repeat this procedure until the terminal project event is numbered (Moder et al. 1983). The following nomenclature is used to describe various scheduling computations: TN = To Node

FN = From Node
Dij

= Estimate of mean duration for an activity (i-j) = Earliest occurrence time for the event i = Latest allowable occurrence time for the event i

Ei Li

EST = Earliest start time for an activity (i-j)
EFT = Earliest finish time for an activity (i-j) LST LFT TF FF
= Latest allowable start time for an activity (i-j) = Latest allowable finish time for an activity (i-j) = Total float time for an activity (i-j) = Free float time for an activity (i-j)

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IntF

= Interfering float time for an activity (i-j)

3.2.1 Forward and Backward Pass Rules To compute the EST and EFT for each activity of the project, the forward pass calculations are started by assuming that initial project event occur at time zero (Moder et al. 1983, O’Brien 1971) and initial event is denoted by 1 (i.e. E1 = 0). All activities are assumed to start as soon as possible, ESTi-j = Maximum of EFT’s of activities immediately preceding activity

i-j, i.e., all activities ending at node i
EFTi-j = ESTi-j +Di-j

(3.1) (3.2)

LFT for the terminal event‘t’ of the project is set equal to its EFT, computed in the forward pass calculation. LFTi-j = This is the minimum of LST’s of activities directly following activity

i-j
LSTi-j = LFTi-j - Di-j Three types of floats defined as below are used in the calculations: Total float ( TFi-j ) = LSTi-j - ESTi-j = LFTi-j - EFTi-j Free float (FFi-j ) = Ej - EFTi-j Interfering float (InF) = TFi-j- FFi-j

(3.3) (3.4)

(3.5) (3.6) (3.7)

In CPM analysis values of EST, LST, EFT, LFT, TF, FF and IntF are documented for every activity and their criticality is decided on the basis of total float.

3.3 Tool Implementation
To represent a network in tabular form, four columns were used. First column represents the ‘activity’; second column represents ‘from node’; third column represents ‘to node’ of an activity while fourth column represents corresponding activity ‘duration’. A sample network demonstrating the proposed procedure is shown in Fig. 3.1, while all calculations are provided in Fig. 3.2.

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Each row of a table in Fig. 3.2 corresponds to an activity of a sample network. For example, in first row label ‘1-2’ gives the description of activity 1-2. The entries 1, and 2 in columns 3 and 4 respectively give from and to nodes of an activity 1-2. The entry of 1 in column 5 is the estimated duration of an activity 1-

2.

4 2

1

5 1

1 1 2 3 3 3 4 6 2 2 7

Fig. 3.1: Network used for programme demonstration.

3.3.1 Forward Pass Calculations For forward pass calculations, programme uses four columns to represent the network and equations 3.1 and 3.2 were used to compute EST and EFT of different activities. The scheduling calculations carried out for forward pass are as: Activity 1-2 Assume EST1-2 = 0 Enter the EST1-2 = 0 at the intersection of column 6 and the row corresponding to activity 1-2. Activity 2-4 For activity 2-4, from node is 2 (represented in column 3) Note the entries (values) in column 4 (to node column) having To Node (TN) = 2. There is one entry corresponding to TN = 2, because only one activity i.e. 1-2 in the network precedes event 2. Calculate EST2-4 as:

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EST1-2 + D1-2 = 0 + 1 = 1, where D1-2 is the value in column 5 and EST1-2 is the value in column 6 respectively corresponding to an activity 1-2. EST2-4 = 1 Enter the value of EST2-4 at the intersection of column 6 and row corresponding to activity 2-4. Activity 2-3 For activity 2-3, from node is 2 (represented in column 3) Note the entries in column 4 (to node column) having TN = 2. EST2-3 = EST1-2 + D1-2 = 0 + 1 = 1 Activity 3-4 For activity 3-4, from node is 3 (represented in column 3) Note the entries in column 4 (to node column) having TN = 3. EST3-4 = EST2-3 + D2-3 = 1 + 3 = 4 Activity 4-5 For activity 4-5, from node is 4 (represented in column 3) Note the entries in column 4 (to node column) having TN = 4. This is the case having more than one entry for same TN value. In this case the value of

EST2-4 + D2-4 = 1 + 2 = 3 and EST3-4 + D3-4 = 4 + 2 = 6 are calculated. Finally, maximum of these two values will be taken as EST4-5. Activity 3-6 For activity 3-6, from node is 3 (represented in column 3) Note the entries in column 4 (to node column) having TN = 3. EST3-6 = EST2-3 + D2-3 = 1 + 3 = 4 Activity 5-6

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For activity 5-6, from node is 5 (represented in column 3) Note the entries in column 4 (to node column) having TN = 5. EST5-6 = EST4-5 + D4-5 = 6 + 1 = 7 Activity 5-7 For activity 5-7, from node is 5 (represented in column 3) Note the entries in column 4 (to node column) having TN = 5. EST5-7= EST4-5 + D4-5 = 6 + 1 = 7 Activity 6-7 For activity 6-7, from node is 6 (represented in column 3) Note the entries in column 4 (to node column) having TN = 6. EST6-7 = Max (EST3-6 + D3-6 = 8, EST5-6 + D5-6 = 9) = 9. 3.3.2 Backward Pass Calculations Compute LFT and LST according to the equation 3.3 and 3.4 respectively. LFT for the project terminal event‘t’ is set equal to its EFT computed in the forward pass calculation. Activity 6-7 LFT6-7 = 12 (LFT of project terminal event is set equal to its EFT computed in the forward pass calculation for the sample network) Enter the LFT6-7 = 12 at the intersection of column 9 and row corresponding to an activity 6-7. Activity 5-7 LFT5-7 = 12 Activity 5-6 For activity 5-6, to node is 6 (represented in column 4)

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Note the entries in column 3 (from node column) having From Node (FN) = 6. There is only one entry, in this case, LFT5-6 = LFT6-7 – D6-7 = 12 - 3 = 9 Activity 3-6 For activity 3-6, to node is 6 (represented in column 4) Note the entries in column 3 (from node column) having FN = 6. LFT3-6 = LFT6-7 – D6-7 = 12 - 3 = 9 Activity 4-5 For activity 4-5, to node is 5 (represented in column 4) Note the entries in column 3 (from node column) having FN = 5, this is the case having more then one entry for same FN value. In this case the value of LFT5-6 - D5-6 = 9 - 2 = 7 and LFT5-7 – D5-7 = 12 1 = 11 are calculated. Finally, LFT4-5 will be the minimum of (LFT5-6 - D5-6 = 7, LFT5-7 – D5-7 = 11) i.e. 7 Activity 3-4 For activity 3-4, to node is 4 (represented in column 4) Note the entries in column 3 (from node column) having FN = 4. LFT3-4 = LFT4-5 – D4-5 = 7 - 1 = 6 Activity 2-3 For activity 2-3, to node is 3 (represented in column 4) Note the entries in column 3 (from node column) having FN = 3, In this case the value of LFT3-4 – D3-4 = 6 - 2 = 4 and LFT3-6 – D3-6 = 9 - 4 = 5 are calculated. Finally, LFT2-3 will be the minimum of (LFT3-4 – D3-4 = 4, LFT3-6 – D3-6 = 5) i.e. 4 Activity 2-4

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For activity 2-4 to node is 4 (represented in column 4) Note the entries in column 3 (from node column) having FN = 4. LFT2-4 = LFT4-5 – D4-5 = 7 - 1 = 6 Activity 1-2 For activity 1-2, to node is 2 (represented in column 4) Note the entries in column 3 (from node column) having FN = 2, in this case the value of LFT2-4 – D2-4 = 6 - 2 = 4 and LFT2-3 – D2-3 = 4 - 3 = 1 are calculated. LFT1-2 will be the minimum of (LFT2-4 – D2-4 = 4, LFT2-3 – D2-3 = 1) = 1.

Fig. 3.2: Tabular output of CPM calculations from the developed scheduling tool in ArcGIS environment.

3.4 Functions and Usage of Developed Tool
To handle the scheduling calculation within ArcView/ArcGIS, seven functions as discussed below were developed by writing programmes for different computations: 3.4.1 CPM Calculation This function creates an empty table with fixed number of column. The number of rows depends upon the number of activities in a network. A multi

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input dialog box (Fig. 3.3) allows user to input information into output table. The label activity description in multi input dialog box is designed for activity description. The from node is for predecessor event number of an activity whereas to node is for successor event number. The activity duration is designed to enter the activity time estimate in the programme. The label activity_ID is used to establish the connection with corresponding components (discussed in chapter 4). The programme is designed in a way to enter data related to an activity into a row of output table itself. Dummy activities are entered into the table as other activities but having zero time estimates. Activities may be entered in a random order. The programme is designed to display the user about calculated project duration through a message box. The output table (Fig. 3.2) provide values of different times, floats and criticality of network activities.

Fig. 3.3: Multi input dialog box used to prompt the user to add information for CPM calculation in ArcGIS.

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3.4.2 Single Calendar Dates This function has single calendar date option (7-day weeks, 6-day weeks, and 5-day weeks), which provides output in the form of day and date (e.g. Monday 18 July, 2005). This function required following inputs: I. II. III. Starting date for first event of a network. Units of activity duration. Output table from CPM Calculation function. This function generates a new table providing date-wise schedule (Fig. 3.4). The table contains same number of fields and data as in the input table except four fields for earliest/finish start/finish times. The programme allows displaying these fields in form of calendar dates.

Fig. 3.4: Date-wise output of CPM basic scheduling computations.

3.4.3 Bar Chart In bar chart, activities are listed in order of construction priorities on the left-hand side, while the time scale is plotted horizontally. The inbuilt functionality of ArcView/ArcGIS is used to develop the bar chart. Fig 3.5(a) shows the schedule of sample network as bar chart. The main advantage of a bar chart in GIS is that when a bar on bar chart is clicked, a window displaying the

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scheduling information related to that particular activity appears on the screen. Bar chart is dynamically linked with the schedule so as to reflect the updates.

(a) (b) Fig. 3.5: Chart of the developed scheduling tool, (a) bar chart, (b) resource requirement chart.

3.4.4 Updating This function accepts the changes in estimated duration of the activities already available in the network. Thus, to update a project, entire network need not to be inputted again. The output table from CPM Calculation function can be directly edited in ArcView/ArcGIS. The deletion and addition of new activities is also possible while using this function. While updating, only affected inputs are altered directly in the table obtained from CPM Calculation function. The i and j numbers may or may not be changed in the situation where deletion and addition of a new activity take place. Care should be taken so that no errors or gaps are created in a network during this process. After incorporating all changes, function

update is clicked to compute update.
3.4.5 Resource Requirements The multi input dialog box (Fig. 3.3) also allows adding resource required for each activity. Label R-1 is designed for resource type first, and R-2 is for resource type second and so on. The programme itself enters data related to an

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activity into the output table. This function generates different types of resource requirements as per the earliest/latest time of the schedule (Fig. 3.5(b)). 3.4.6 Data Integration The database management capabilities of GIS are also utilised to maintain and update construction resource database to facilitate project planning (section 2.5). The non-spatial information (like material type and quantity, labour requirements, safety and quality control recommendations etc.) corresponding to different activities in the schedule can be extracted from the database maintained in GIS and can be linked with respective activities present in the schedule. 3.4.7 Quality and Safety To access quality control recommendations available in construction

quality table, programme calls inbuilt function link or relate of ArcView and ArcGIS respectively. This function links CPM schedule and construction quality
tables using a field key. When two tables are linked to one another, both tables remains unchanged. Selecting an activity (row) in the CPM schedule table will automatically highlight the records related to it in construction quality table, while selecting a record in the construction quality table does not select the corresponding activity in CPM schedule table (Fig. 3.6). Therefore, to access the

quality control recommendations about any activity from a database, user needs
to click on a row in the CPM schedule table. Same approach may be used to extract and link the construction safety information with the activities in the CPM schedule.

3.5 Advantages of Scheduling in GIS
Multiple Initial and Terminal Events: The programme permits multiple initial and terminal events in the construction project networks. Event Numbering: The events need not to be numbered in ascending order, that is, each successor event number need not to be larger then the predecessor event number. Programme permits random numbering of events, provided no two nodes or activities receive identical number.

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Unique Pair: Any two events may be directly connected by more than one activity. The requirement of a unique pair of i and j number for each activities is not required. Shorting the Output: The project activities can easily be stored/listed in variety of useful ways, such as shorting in ascending/descending order on any field in the output table.

Fig. 3.6: Screenshot showing how quality control recommendations get highlighted for a project activity.

Statistical Calculation: Calculations like sum, count, mean, maximum,
minimum, range, variance and standard deviation of a particular field in an output table can also be done in the suggested GIS based approach. Database connection is also possible by using the SQL connection feature of GIS to retrieve records from other databases. Other Advantages: The proposed tool has the benefit of visual presentation of schedule, which is a major shortcoming of most of the traditional

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construction management software. Thus, integrating project schedule and 3D components within GIS allows visual understanding of the construction process and discussed in detail in chapter 4.

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Chapter

4

Schedule Visualisation and Evaluation
4.1 Background
In most of the construction projects, CPM networks and bar charts are widely used to represent the schedule. Different activities of CPM network are related to one or more components of the project under consideration. The CPM schedule provides the non-spatial information which lacks in the spatial aspects of construction activities. Therefore, to have the spatial aspects of the project, construction planner uses 2D drawings and associates the components of drawings with the related activities present in the schedule (Cherneff et al. 1991, Koo and Fischer 2000). A construction project may contain hundreds of activities, thus, interpreting the schedule without any link of its activities with the spatial components is a difficult task. This makes it difficult to check the CPM schedule for its completeness. The interpretation of the non-spatial CPM schedule may also vary with the experience of persons involved due to the difficulty in mentally linking each element in 2D drawing with the corresponding activities of the CPM schedule (Koo and Fischer 2000). The construction industry has acknowledged that its current scheduling and progress reporting practices require substantial improvements in terms of quality and efficiency (Retik and Shapira 1999, Whyte et al. 2000). The limitations of CPM schedule forced the researchers to combine construction schedule with 3D CAD models leading to the development of 4D CAD models. The 4D CAD allows a planner to visualise the construction process in a way, as it would actually be built. Koo and Fischer (2000) suggested that 4D model increases the comprehensibility of the project schedule and allows users to detect potential problems such as scheduling conflicts prior to the construction. They

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suggested that the planner using 4D simulation is likely to allocate resources more effectively. The use of 4D CAD also assists the planner to avoid schedule conflicts, examine constraints and evaluate alternative construction methods (Akinci et al. 2002a, b, Koo and Fischer 2000). In spite of the continuing research in 4D CAD technologies, these systems are still unable to aggregate and distribute the information between spatial and non-spatial databases and so far there is no standard procedure to use 4D CAD technologies. The 4D CAD tools are based on object-oriented concepts and used primarily for planning, design phase analysis, and appraisal type of analysis (Poku and Arditi 2006). Most of these tools have an ad-hoc modelling approach that makes it difficult to update and maintain these systems. Furthermore, 4D CAD models have a single level of detail, which hinders the collaboration among general contractors and subcontractors. Moreover, many of these models do not support computer based cost and safety analysis (Poku and Arditi 2006). Keeping in view the above-mentioned limitations of 4D CAD systems, this chapter explores the potential of GIS for 4D construction management in which manipulations of both schedule and 3D components are made possible on a single environment. Several in-house programmes are developed for this purpose. All programmes used in this chapter are written in Avenue and the methodology is developed in ArcView 3.2 whereas ArcGIS 9 is used for the generation of 3D components only. Chapter 5 discusses the use of ArcGIS for 4D construction management system in more details.

4.2 Case Study
Being in the research stage, the proposed methodology is implemented on a single-storied residential house (Fig. 4.1 and Fig. 4.2). The 2D drawing of the building consists of three living rooms, a single lobby, bathroom, toilet and kitchen. Stairs are located in front of the main entrance of the building and are not covered with the roof (with a possibility to add more stories in future). The entire work was divided into four parts to manage the project effectively. The first part involved substructure, i.e., activities related to trench excavation for foundation, foundation concrete, foundation brickwork, backfilling and damp 61

proofing course. The second part involved the superstructure, i.e., activities related to exterior walls, interior partition, erection of door and window frames and flooring, whereas third part involved activities pertaining to roof slab and parapet wall construction. Electrical fitting, wooden and plumbing works were included in the fourth part of the construction. Chapter 6 discusses a approach to develop 3D components corresponding to activities in the construction schedule in more detail. For further detail about the 3D modelling of building readers are referred to the studies by Ekberg (2007), Smith and Friedman (2004), Zlatanova et al. (2002).

Fig. 4.1: Floor plan consists of different data layers in ArcGIS in which few layers are kept invisible/transparent to make appearance understandable.

4.3 Evaluation and Visualisation of Schedule
Fig. 4.3 represents a detailed procedure to evaluate and visualise the construction schedule within ArcView. Various steps involved to evaluate and visualise the construction schedule within ArcView are discussed below:

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Step 1: Construction Schedule- Schedule is a timetable for execution of various project activities and acts as a roadmap for successful implementation of the methodology. This step involves in identification of all possible activities of the project and recognition of their inter-relationships to arrange all in a proper sequence. The construction project is decomposed into different activities and the time duration for each is estimated. Programme written for CPM calculations receives the identified activities, their inter-relationships and durations through a dialogue box and computes the project duration. The output table provides

start/finish times, floats and criticality of each activity of the project. The calendar dates (or timescale) that provide the quick overview of start and completion dates of individual activities may also be generated. The components corresponding to each activity of the project are linked with CPM schedule using either earliest start time or latest start time.

Construction schedule, generated by programming CPM algorithm in ArcView Linking activities in schedule with respective 3D components with help of script written in ArcView GIS

2D view of different data themes constructed in ArcGIS to develop 3D model

3D components linked with construction schedule in ArcView

Fig. 4.2: Architecture for linking a 3D model of building with the construction schedule n ArcView.

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Step 2: 3D components- - Spatial information of different activities available in the schedule are maintained in the data themes/layer, which form the basis of GIS based visualisation. In GIS based visualisation, it is not necessary to have 3D components corresponding to each activity in the schedule. For example, in the schedule of the sample building, activities like clearing and levelling of construction site, marking of the site and curing of the concrete do not have related 3D components. However, corresponding to each 3D component, there should be an activity in the CPM schedule. The number of themes created corresponding to each activity (representing its spatial aspects) will depend on the degree of detail to be provided in the resulting 4D model. For example in Fig. 4.4, brickwork can be shown with three sub-activities in different themes by providing different start/finish times for each. Another possibility is to merge the sub-activities represented by three different themes to make a single theme (a single 3D component). The number of themes to be created for each activity may also depend on the shape, openings and thickness at different levels of the height. For example, in the sample building, one theme will be enough to represent the concreting in foundation. As thickness of brickwork in foundation wall changes twice across the height, therefore, two different themes representing these changes in height are created and merged into one. Similarly five different themes for brickwork in superstructure are created at different levels of height to consider openings in different walls. The themes corresponding to the activities in the schedule may be reviewed by viewing them in 2D/3D. All components are linked with the schedule only if they comply with the requirement otherwise they are reshaped. Sometimes different themes may be merged together (or split) depending on the activities defined in the CPM schedule generated in step 1. For example, in Fig. 4.4, brickwork is shown in three different themes, if the entire brickwork is included in a single activity of the CPM schedule, three themes may be merged into a single theme. The components in a theme that belong to same activity but are located at different positions in the 3D space may also be grouped together. For example, the lintels over the doors and windows are not adjacent to each other but can be grouped into a single component.

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After creating the spatial aspect corresponding to activities in the CPM schedule, spatial information are reviewed by viewing the resulting 3D components. If it complies with the requirement, next step is followed otherwise components are edited.

Construct 3D components in ArcGIS corresponding to the activities in the schedule. START List all possible activities of the construction project.

Review by viewing the constructed 3D components related to the activities.

Yes
Do components comply with actual construction desired?

Identify the interrelationships and develop the schedule in ArcView environment.

No
Re-construct 3D components as per the requirements.

Associate activities in the schedule to corresponding 3D components within ArcView and view the developed model.

Yes
Schedule Require change in logic only. 3D + Schedule Resources Information Safety/quality Recommendations Cost Estimate

No

Does the model complies with actual construction sequence and not requires any change in number of activities and logic.

No

Yes

Fig. 4.3. Procedure for evaluation and visualisation of the construction schedule.

Step 3: Linking activities with corresponding 3D components- Linking activities with 3D components implies, connecting spatial aspects generated in step 2 with the corresponding activities of the CPM schedule obtained in step 1. The linkage between a component and an activity of the CPM schedule may not always be one-to-one (one component corresponding to an activity of the

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schedule). However, relationships like many-to-one may exist in which many components correspond to an activity in the schedule (Fig. 4.2). In such a relationship, components are merged together and linked with the corresponding activity thereafter. The one-to-many linking is also possible if there is a single component corresponding to many activities (Fig. 2.6). Linking involves adding a field called Activity_ID to the CPM schedule and the attribute table of each component. This can be achieved by adding it manually or by using a programme. The field Activity_ID that is common between the two tables (i.e. CPM schedule and feature attribute tables of each component) is used to establish connections between the components and the corresponding activities. All entries in the field Activity_ID are to be entered manually and should be unique in both the tables. Thus, the attribute required to associate the components with the corresponding activities in the schedule are the entries in the field Activity_ID. A programme is used to associate activities in the schedule to the corresponding 3D components. Programme also informs the user about those activities in the schedule that do not have corresponding 3D components and also provides a list of 3D components without corresponding activities in the schedule. After the association of activities in the schedule to the corresponding 3D components, resulting 4D model can be viewed for its correctness. Step 4: Schedule evaluation- This step involves evaluating the schedule to verify the construction sequence. A programme that generates the lists of all the dates (i.e. starting times) of construction schedule is added to ArcView. By clicking on a date in the list, activities that are planned to be in operation on and before that date will be graphically visible in 3D on the computer screen. The schedule for different dates can also be evaluated by visualising it in 3D by having a series of images to depict the state of the construction on a particular date. This step may be a time consuming process but provides the opportunity to explore the alternate construction sequences also. The system is designed to communicate the house construction according to the schedule on the computer screen. If construction sequence complies with the desired output and does not require any change in the number of activities and 66

logics, the CPM schedule will be accepted and no alteration is allowed afterwards (Fig. 4.3). This step suggests the usefulness of GIS based approach in identifying and correcting the problems in the schedule.

Merge themes together

(a)

(b)

Fig. 4.4: (a) Three 3D themes, (b) merging themes together pieces the features from three themes together to a single theme.

Step 5: Schedule corrections- The proposed approach displays at what time components are to be built and where they will be in the space. This facilitates the understanding of a 3D model and topological relationship between different components in many ways like zooming, pan, fly forward or backward, etc. After analysing the model, if it does not comply with the required construction sequence and needs some changes in the logic (interrelationship among the activities), the CPM schedule is changed again as per the requirements. All activities that are not in the sequence need to be rearranged in the CPM schedule. All relationships among the activities in the CPM network that constitute a physical impossibility or can cause major disruption or delay at construction site need to be corrected at this stage. After implementation of the desired changes, the schedule is again associated with the related components for evaluation and sequence verification. It is finally accepted if no change in the logic and number of activities is required. If the numbers of activities in the schedule need addition/deletion or if some

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editing is required in the corresponding components, the entire procedure is repeated again.

4.4 Degree of Details in the 4D Model
In order to have a sequential visualisation, the schedule should have a sufficient degree of detail for its activities. By implementing the proposed methodology in the construction of a residential house, incompleteness of the original schedule was detected and corrections were made. It was found that if some of the activities in the schedule are with limited detail, the developed model does not communicate the construction process in a desired sequential manner even if the schedule is correct. For example, in screenshot shown in Fig. 4.5(a), activity brickwork in superstructure appears after the doorframes erection. By that time no window frame was fixed on the place. Thus, the brickwork shown in Fig. 4.5(a) should not appear complete unless all the door and window frames are fixed. Similarly lintels over the door and window should also appear before the complete appearance of brickwork. Therefore, the current level of detail for this activity is not sufficient to describe the sequence correctly. The brickwork that appears on a computer screen at a time, as represented in Fig. 4.5(a), lack in the degree of details. The schedule should have activities to properly represent the hierarchy of work breakdown. Some activities of the schedule may encompass a set of subactivities that represent each activity in more detail, thus, helping to understand the logics in a much better way. To discuss this issue in detail, the activity brickwork in superstructure (Fig. 4.5(a)) is divided into five sub-activities at different levels of height and each sub-activity is treated as the main activity. Fig. 4.5(b) represents the sequence of the construction in a desired manner. In Fig 4.5(b), the door frames are shown erected before the start of brickwork (for load bearing walls) and the brickwork is shown up to the sill level. Subsequently, the window frames appear erected and brickwork appears extended up to the lintel level. The lintels and rest of brickwork appear afterwards.

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(a)

(b)

Fig. 4.5: Comparison on the same date between the schedules, (a) without sufficient degree of details, (b) corrected with sufficient degree of details.

4.5 Advantages of Scheduling in GIS
The GIS based approach suggested in this chapter eliminates the limitation of maintaining and editing the spatial and non-spatial data on different platform. As most of the developed 4D CAD technologies do not have the project management capabilities and are used primarily for planning and design phases of the project. The GIS based methodology suggested in this chapter can be used at different stages of project and allows the user to utilise its database management capability to maintain and update the construction database. A major limitation of the study by Poku and Arditi (2006) was the manual transfer of the information from Primavera and AutoCAD to ArcView. The proposed methodology utilises the drafting capabilities of GIS itself and the methodology is designed in a way to utilise the drawing generated in AutoCAD also. The major advantage of using the editing capabilities of GIS is that, if during the schedule evaluation stage, constructed 3D components do not comply with the desired construction, editing can be done in GIS itself. The proposed methodology can also read the schedule generated in Primavera but if the resulting 4D model does not comply with the actual construction sequence, the

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schedule generated in Primavera cannot be corrected in GIS (Poku and Arditi 2006). The proposed methodology may also overcome the following shortcomings of the construction schedule generated by commercially available tools likes Primavera and Microsoft Project: Omission of Activities: It is quite difficult to determine whether the schedule is complete or not by just viewing the CPM network. Further, availability of a large number of activities in the network makes it difficult to confirm that all components of the project have related activities. To ensure this, the proposed methodology uses a programme to prepare the list of activities in the schedule without spatial information. This programme also lists down all components that do not have scheduling information. In addition to this, a visual check of the schedule is also possible by viewing it graphically in 3D, which may help in preventing omission of any activity. Construction Sequence Visualisation and Evaluation: Activities with mutual dependencies may be located in different parts of the schedule. Multiple participants individually conceptualise the sequence in their minds by associating activities with the corresponding components in the drawings. This interpretation may vary according to the level of experience, knowledge, and individual perspective of the participants and may cause inconsistency. These

inconsistencies in the interpretation may lead to the miscommunication among the project participants. The proposed approach uses GIS itself to display which component is to be built at ‘what time’ and ‘where’ in the space. This is achieved by using a programme to prepare the list of dates from construction schedule. The components that are scheduled or planned to be in operation on and before a date will graphically be displayed in a 3D space by clicking on a particular date in the list. Thus, allowing a check of the schedule for each date. The proposed approach also facilitates the understanding of a 3D model and topological relationship among different components in many ways (like zooming, pan, fly forward or backward, navigation, etc). Fig. 4.6 shows a 3D view of the example building in which roof slab is set transparent to display the internal details more clearly. Any component may be set transparent to make visualisations of the model much

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easier. The users also have the option for rotating 3D components around the x, y, or z-axis to observe the developed 3D models from any direction and angle.

Fig. 4.6: 3D view of the sample building in which roof slab is set transparent to provide the internal details.

Spatial and Non-Spatial Data Integration: Failure or success of a construction project depends upon the quality and timing of the information available to contractors from the database. Thus, requiring an automated system to get the desired information without delay (Hegazy and Ersahin 2001a, b). The proposed methodology allows understanding of the construction process by integrating spatial and non-spatial information together in a single environment. The nonspatial data includes construction resource data, specification for quality control and safety recommendations. When a 3D component corresponding to an activity is clicked, a window appears on the computer screen informing the user about the various times, floats and resource information of an activity by extracting it from the feature attribute table.

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Anticipating Safety Hazard: Many accidents occurring due to unforeseen human errors and hazards at construction site are the main cause of additional cost in a construction project. Most of the construction companies consider workers’ safety to be the prime objective. GIS based approach, allows the project manager to detect accident-prone areas and execute preventive measures (such as placing warning signs, restricting access, providing safety guards, etc.). This approach allows a project manager to view the time and location of different works and inform the respective workers about the possible hazards. Miscellaneous: The spatial data generated for the purpose of visualisation in GIS can also be utilised for the quantity takeoffs (discussed in more detail in chapter 6). It may be helpful to increase the productivity in quantity estimation by reducing the manual work required in quantity takeoffs. Therefore, this work also provides a link between the cost and schedule. The queries like, activities starting on the particular date and activities starting between the particular intervals of time can be made from the generated CPM schedule. The project activities can be easily stored and listed in variety of useful ways, such as sorting the schedule in ascending or descending order of any field (floats, early or late start time) in the table and selected records could be displayed in the same table by promoting them to top.

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Chapter

5

3D Animation Based Schedule Review
5.1 Introduction
With the developments in computer hardware and software, animations are playing key roles in the demonstration of complex process. Computer animations have the ability to present concepts in a form that resembles physical and real images quickly and effectively. As the construction projects are becoming more and more complicated, software with ability to convey the physical configuration of the construction project quickly and accurately are required. Animation of the construction project may allow participants to improve communication and efficiency (Songer et al. 2001a), exchange ideas as well as to interact with 3D geometry (Abeid and Arditi 2002, Songer et al. 2001b). Animated sequences of the construction project require low level of interpretation skill than conventional 2D drawings used in the industry. Animation makes it possible to move through the design objects and view the proposed facility interactively on a computer screen. Effective communication among project participants can greatly improve the construction process and productivity. Such expedited communication leads to a substantial improvement of quality and productivity in AEC industry. Different project members can work together as a team beyond their specific interests to achieve the particular objective. Computer animations are categorised as: (i) real-time and (ii) framed (frame-by-frame recorded). Real-time animation is dynamic, interactive and requires significant graphics processing power. To generate such animations in

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AEC industry, 3D models need to be created in external CAD software or within animation software itself. 3D models are then linked with a real-time animation control parameters such as camera position, perspective angles, object positions, etc. The real-time animation has the ability to provide complete and interactive control over the motion of the objects and camera positions (Yoshihiko 1994). Similar to the real-time animation, framed animation also need 3D objects. The motion of objects and camera in a key frame are saved in the script file (Yoshihiko 1994). The system renders the computer screen, which is recorded on a videotape or digital media. Once a screen is rendered and recorded, the system moves to a next frame. This process repeats until the objects and camera motions defined by the motion script file are completed. Framed animations are less effective for interactive applications such as design review and construction simulation. Chapter 4 of this study uses ArcView for linking 3D model and CPM schedule to facilitate the schedule review process. The programme written in Chapter 4 informs the user about those activities in the schedule that do not have corresponding 3D components and also provides a list of 3D components without corresponding activities in the schedule. The programme also generates a list of all the dates (i.e. starting times) in the construction schedule. By clicking on a date in the list, activities that are planned to be in operation on and before that date will be graphically visible in 3D on the computer screen. Thus, planners have a series of images to depict the state of construction on a particular date. This chapter discusses a GIS based approach to develop a navigable 3D animation of construction activities for construction schedule review and visualisation. The animation of the construction activities utilises the dynamic linkage between activities of CPM schedule and corresponding 3D components. This facilitates the detection of missing activities and logical errors in the CPM schedule. Among the existing 4D CAD technologies, many of them do not have the project management capabilities and are used mainly for planning and design phases of the project. A GIS based animation suggested in this chapter may be used as a project management tool at different stages of the projects. The visual

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representation of the construction sequence through animation in GIS environment is expected to help industry practitioners in understanding the schedule much better. 5.2 Animation of Construction Process 5.2.1 Three-Dimensional Modelling in GIS The 3D modelling of construction project in GIS (a sample building in this study) is divided in two parts: I. II. The building interior modelling depicting floor level details. The terrain around the building (landscaping), represented by digital terrain model that provides the topographical condition around the building. 5.2.1.1 Building Interior Modelling To model the building interiors, this study makes use of vector data model organised in layers. Each layer is allowed to use only one type of graphical element (point, line, polygon or multipatch) to represent the building components (ESRI 1998). The model maintains each floor level detail in different layers and store attributes separately in tables. The components corresponding to the activities in CPM schedule and used to develop the animation are generated and maintained as data layers in ArcGIS. The number of layers used to represent each activity depends on the degree of detail to be provided in the animation. The layers generated in AutoCAD can also be utilised for this purpose. The field drawings as such cannot be used, because the proposed system needs separate component corresponding to the activities as defined in the CPM schedule. Therefore, field drawings need significant modification before their utilisation. The 3D Analyst available in ArcGIS/ArcView is used to represent the features in 3D. This tool can be used to display object in 2.5D as well as in 3D. The true 3D features are handled through multipatch class of ArcGIS. The 3D component modelling required for the development of animation need more time

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in comparison to 2D and 3D drawings. Several factors influencing the time requirement for 3D modelling are: I. II. III. IV. Quality and completeness in the size of components. Skill of modellers. Level of detail needed in the animation. Type of relationship between an activity in CPM schedule and the corresponding component. 5.2.1.2 Landscaping Around the Building The modelling of landscaping around the building involves the geographical information representation of the construction site. In addition to this, it provides realism to a 3D view by placing trees, cars and light poles as multipatch graphics at key locations around the building (Smith and Friedman 2004). The 3D terrain and entity models can be rendered with realistic textures pasted on their surface to represent more fidelity. This approach stores 2.5D surfaces as raster, triangulated irregular network (TIN) and terrain data. Further, all surfaces are considered as continuous with a single z value for each x, y coordinate. Fig. 5.1 shows a 3D model of sample building along with its surroundings rendered in navigable 3D ArcGIS display on the image of the area acquired from Google Earth. The image was georeferenced in order to place the 3D model of the building at required location. After this, the building can be viewed from any location and angle in GIS environment. The rotation of a 3D model may help to get an overview of its shape with respect to the surroundings. Users may also look out of windows to have a view of landscaping around the building as well as, fly around 3D objects, look around, look outside to inside through the window (Fig. 5.2(a)), fly inside the building (Fig. 5.2(b)). The rotation speed, observation angle and zoom level can adjusted be while rotating the model. The horizontal distances (projected) between different features can be directly measured after the registration of image on a computer screen. Interoperability between geospatial data around the building and its interior may help to support construction planning in a more efficient manner. The landscape

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modelling is not discussed in detail in this chapter as it is beyond the scope of this study.

3D model of building

Fig. 5.1: 3D model of the proposed building placed in its surroundings in a navigable 3D display in ArcGIS.

5.2.2 Information Database Module The characteristics of different components of a 3D model are stored in layer attribute table of different layers corresponding to each component. The number of columns in layer attribute table will depend on the information to be maintained. As there is a dynamic linkage between attribute and corresponding feature and vice-versa in ArcView/ArcGIS, the information related to a feature gets highlighted in layer attribute table as the feature of a layer is clicked on the screen. Thus, project manager need not search design, blueprints and data reports (Paterson 1977). Another alternative is to maintain the information in database tables that are managed by a database management system in GIS. 5.2.3 Identifications of Components Corresponding to Activities To establish a link between components and corresponding activities in CPM schedule, components corresponding to different activities need to be identified. The relationship between the components and activities may not

always be one-to-one (one component corresponding to an activity of the

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schedule). However, complexity of the project may force to have relationships like many-to-one in which many components correspond to an activity in the schedule. In such relationship, components are grouped together to a single component and thereafter linked with corresponding activity (Fig. 5.3). Grouping different components combine different features by removing boundaries between adjacent polygons. Non-adjacent polygons in same layer can also be grouped to create a multipart polygon feature. The linking is also possible if there is a single component corresponding to many activities (one-to-many). Each component of a 3D model corresponds to one or more activity depending upon the type of relationship. However, it is not necessary to have a component corresponding to each activity. For example, in the schedule of the example building, activities clearing and levelling of construction site, marking of the site and curing of the concrete do not have related 3D components.

(a)

(b)

Fig. 5.2: (a) View from outside to inside through a window in a navigable 3D environment (window glasses were kept transparent), (b) screenshot while flying inside a 3D model in ArcGIS.

5.2.4 Association of Components and CPM Schedule Associating components and CPM schedule means linking 3D components with the respective activities in the CPM schedule. This association

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involves adding a field called Activity_ID to the CPM schedule and the layer attribute table of each component. The field Activity_ID is used to establish the connection between components and corresponding activity. All entries in field Activity_ID are entered manually and have to be unique. Thereafter, system uses a program to develop the animation that associates activities of schedule to the corresponding 3D components. In one-to-one linking, program links one component with an activity in the schedule whereas in many-to-one linking, program links many components with an activity. In one-to-many linking, program links one component to many activities. One-to-many relationship sometimes creates confusion because component appears in the animation according to an activity whose start time is least (Chang 2005).

Fig. 5.3. Relationships between components of a 3D model and CPM schedule connected through field named Activity_ID.

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5.2.5 Animation of Construction Process Animation of construction activities is a rapid play of a set of 3D components according to their start time. Animation sequentially retrieves 3D components according to the schedule and renders them continuously on a computer screen. As animation advances, individual components go on adding at their defined locations in a space as per the schedule. It may be played forward and backward at various speeds, system also allows navigation in 3D space. Animation can be paused any time allowing the users to observe the construction sequence clearly. The planner may also save the images to depict the state of the construction at a particular time. GIS based animation can be exported to common environment like Audio Video Interleave (.avi) or QuickTime (.mov) files. GIS also support 3D animation by importing images from external computer graphics tools, such as AutoCAD, a widely used drafting tool in the industry.
Squares indicate EST of different project activities

Squares indicate EFT of different project activities

Progress reporting bar

Number indicates project progress

EST Project start

D

TF Project duration Project finish

Fig. 5.4: Interactive Animation manager to move keyframes in each animation track.

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A program used for this purpose needs CPM schedule and 3D components as inputs and links them together to generate an animation. Fig.5.4 shows a screenshot of animation manager used to control the way an animation is played. Each horizontal bar (called track) in the animation manager corresponds to an activity/sub-activity. The program automatically generate track

corresponding to each layer in which 3D component is maintained. Each 3D component is attached with a track as 3D keyframes, therefore, a track is made up of a set of the keyframes. The animation manager can access and manipulate the properties of tracks. It also controls the dynamic changes in properties such as background colour, camera location and visibility of related components. A project contains number of activities, therefore, program is designed to add multiple tracks to an animation simultaneously. While playing multiple animation tracks simultaneously, time setting becomes an important factor. 5.2.6 Timing Properties in Animation The sequence of construction that animation depicts may be previewed by dragging progress bar along the length of track that is equal the to project duration. The program indicates activity start/finish time and path float by marking small squares on horizontal bars (tracks) as shown in Fig. 5.4. The program automatically puts five squares on a track, among them the first and last indicate starting and ending of the project. The second square indicates earliest start time (EST) whereas third depicts the Earliest Finish Time (EFT) of the respective activity. The length of bar in between second and third square represents the activity duration. The fourth square appears only on the tracks corresponding to non-critical activities. For critical activities third and fourth squares will overlap so as to indicate zero value of Total Float (TF). The length of a bar between third and fourth square indicates the availability of TF. A 3D component corresponding to each track will be visible only after the second square. The number of tracks in the animation will depend on the layers in the table of content (TOC) of ArcGIS. Therefore, before creating animation, spatial information with respect to the activities in schedule must be available in TOC. The program is designed to automatically adjust the position of squares on a track by reading data from the construction schedule table.

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5.3 Animation Based Schedule Review
Animation based construction schedule visualising, review and correction procedure is shown in the Fig. 5.5 and discussed in detail in the following sections:

INPUTS REQUIRED
Generate 3D components in ArcGIS/ AutoCAD corresponding to activities in the construction schedule START List all possible activities those have or do not have components generated in ArcGIS /AutoCAD Identify inter-relationships among activities and develop CPM schedule in ArcView/ArcGIS /Primavera/MS-Project. Examine components geometry

Do components comply with Yes desired construction? No Reconstruct/edit components as per requirements of construction

LINKING ACTIVITIES WITH COMPONENTS

Link activities of the schedule with corresponding 3D components (one-toone, one-to-many and many-to-one relationships between components and activities) and view a navigable 3D animation

Construction Resource Database

Yes
If there are only logical errors in the CPM schedule No

No

If animation depicts the desired sequence and there is no need to change number of Yes activities and logics among them

A navigable 3D animation of construction sequence

SCHEDULE REVIEW WITH ANIMATION

Fig. 5.5: Animation based construction schedule review and correction process.

5.3.1 Complexity Capturing of CPM Schedule The degree of details in an animation will depend on the detail of the schedule, therefore, a 3D model needs to be divided into the components to have

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more detailed animation. If activities include large size components, the developed animation will have low level of details. Therefore, it is better to use full work breakdown structure (WBS), which can be linked to the individual small components of a 3D model without merging/grouping. This breakdown will help in creating animation with higher level of details. More details in the construction schedule and division of a 3D model into components corresponding to different activities will need more time to develop the animation. Inspite of the increased time requirement, it will provide planners with an opportunity to explore the alternate construction sequence. Further, animation needs for various applications require different level of details. For visualisation purpose, it may not be important to have high level of details in the schedule. However, to generate animation to find various construction alternatives, higher level of detail within the schedule is necessary. The incompleteness in the original schedule was detected and corrections were made in the schedule by using the animation of the sample building used in this study. Even if the schedule is correct and activities in schedule are with limited details, the developed animation will not communicate the correct construction sequence. For example, component corresponding to activity brickwork in superstructure appeared in animation (Fig. 5.6(a)), by that time, only the doorframes were erected and no window frames were fixed. The brickwork should not be complete unless all window frames and lintels over doors and windows frames appear in animation. Therefore, the current level of details for activity brickwork in superstructure was not sufficient to describe the correct construction sequence. An activity of the schedule may encompass a set of sub-activities that may help to understand the network logics in much better way. To correct this, activity brickwork in superstructure was divided into five sub-activities at different levels of height and each sub-activity is treated as the main activity as discussed in the chapter 4. In the correct sequence, doorframes appear erected before the start of brickwork and the brickwork appears up to the sill level. Subsequently, the window frames appear erected and brickwork extends up to lintel level. The lintels and rest of brickwork appears afterward (Fig. 5.6(b)).

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(a)

(b)

Fig. 5.6. Complexity capturing of the CPM schedule, (a) screenshot of animation without sufficient degree of details, (b) corrected with sufficient degree of details.

5.3.2 Logical Errors and Schedule Correction Logical error is the missing of relationship between two or more activities or scheduled sequence among activities. This constitutes a physical impossibility that may cause major disruption and delay at the construction site. Such errors should be removed before finalising the schedule. The doubtful sequences can be checked on computer screen by dragging the progress bar backward or forward in different portions of the schedule in order to visualise the construction activities that are planned to be in operation on and before that date on the computer screen. Before finalising the schedule, missing activities insertion and activities those are not in sequence need to be rearranged properly. If some discrepancies exist in the components, which together constitute a complete 3D, the model must be corrected for that. After implementing the changes, CPM calculations are again carried out and revised schedule is linked with the components so as to generate a correct sequence in the animation. The scheduling program allows making changes in schedule table without inputting the entire network again.

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The program accepts changes in estimated duration of activities already present in the network and also allows deletion or addition of activities. The construction sequence may be adjusted by using total float of different activities. The developed animation provides an interactive way to adjust the schedule sequence by using total float. In case of a non-critical activity having total float, start/finish time can be changed interactively by dragging square representing start/finish time in the animation manager to correct the construction sequence. Dragging progress bar either in backward or forward direction along the track will immediately reflect the change. Therefore, proposed GIS based animation approach provides an interactive way to observe the effect of start/finish time change of an individual or a group of activities on the construction sequence without changing the CPM calculation table. Fig. 5.7(a) shows a screenshot where animation is paused immediately after the completion of activity brickwork in superstructure. As shown in figure, a small part of this activity above main gate appeared floating in air (without any support). The support (a part of flight-slab that acts as a lintel above main gate) appears afterwards. This constitutes a physical impossibility. The components, flight-slab for stairs, lintel over main entry gate and roofing slab were included in the schedule as a single activity reinforced cement concreting work that appeared after the completion of activity brickwork in superstructure. Fig. 5.7(b) shows a screenshot of this situation in which support appeared after the brickwork above the main gate. To correct logical errors in the schedule sequence, two small modifications were made in the schedule. First of all, activity reinforced cement concreting work was divided into two sub-activities: flight-slab with main gate lintel and roofing slab. The sub-activity flight-slab with main gate lintel was laid first followed by the roofing slab. Secondly, small part of activity brickwork in superstructure above the main gate entry that appears after the finish of subactivity flight-slab with main gate lintel, was isolated from rest of brickwork (Fig. 5.7(c)).

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Entrance Entrance

(a)

(b)

Entrance

(c) Fig. 5.7: (a) A small part of brickwork above main gate appeared floating in air, (b) support appeared after appearance of brickwork above main gate, (c) part of brickwork above main gate was isolated from rest.

5.3.3 Missing Activities If corresponding to any 3D component, scheduling information is not included in the schedule, planner will not be able to detect the completeness of the schedule by viewing it. The incompleteness of the schedule can easily be detected through animation because all components will remain visible throughout the animation period (in animation manager square representing times/float on a track corresponding to that component will be missing). By

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making all the components visible, it can be checked whether they together constitute a complete structure or not. The users may zoom into the specified zone for a closer view and rotate 3D model around the x, y, or z-axis. Thus, GIS based animation facilitates the understanding of a 3D model and topological relationship between different components, which makes it possible to apply a visual check to verify the completeness of a 3D model. 5.3.4 Spatial Queries GIS maintain spatial data in separate layers using the same geographic reference system. These layers can be superimposed spatially to support data queries and analysis. Data stored in GIS not only associates attribute with components, but allows components to maintain their topology (spatial relationship among different components) also. GIS also maintains both,

components geometry identification (component knows it is a wall) as well as their topological meaning together (wall knows it crosses floor I). The geometry in GIS provides more information over existing CAD systems. The key strength of GIS is its spatial functionality that allows operations like spatial query, measurement, transformations, etc. Spatial queries can be used to find object length, area, distance, direction/slope, etc. The transformation operations like buffering, overlay and interpolation available in GIS may also be used to change the construction dataset. The information such as space covered during the

working of a crane, if installed at the construction site can be easily depicted through spatial data queries in GIS, which is the major advantage of GIS based approach over existing 4D CAD technology.

5.4 Benefits of GIS Based Animations
The 3D animation allows the project manager to detect accident-prone areas and execute preventive measures (such as placing warning signs, restricting access, providing safety guards, etc.). By viewing time and location of the work, project manager can inform the respective workers about the possible hazards. Most of the 4D technologies do not have the project management capabilities and are used mainly for planning and design phases of the project (Heesom and

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Mahdjoubi 2004, Songer et al. 2001). GIS based animation suggested in this chapter can be used at different stages of project. During schedule review process, if components do not comply with the requirements, editing can be done in GIS environment itself. The schedule developed in Primavera and components developed in AutoCAD can also be used as input to generate the animation in ArcGIS. In addition to schedule review, ArcGIS also provides in-built module to develop fly through animation to demonstrate site condition to give an idea about topography, transportation route, etc. Even though developed animations help to understand schedule by visualising sequence but cannot be considered as a substitute for CPM. As animations rely heavily on the linking of CPM schedule with 3D models, for which CPM is a prerequisite.

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Chapter

6

Quantity Takeoffs and Cost Estimation
6.1 Background
The preparation of a complete and concise project document is a critical issue for professionals, developers and contractors working in AEC industry. Different techniques such as manual, coordinated automated or simply automated techniques are being utilised during the quantity takeoffs (Saleh 1999). An automated technique means that a computer programme is used at each stage of the design activity. A coordinated automated technique means all design activities are performed by a computerised relational database that takes advantage of other engineering data (Kerzner 2003). In practice, the manual approaches are fast becoming obsolete and systematic estimation methods are recommended as a means of resolving the struggle between manual and automated methods. For example use of an expert system and automated evaluation technique may reduce the burden of manual analysis (Saleh 1999). The use of computer programs facilitates fast decisionmaking and creative thinking by allowing the designer to quickly recall and review the issues relevant to task at hand. An automated approach linked with a CAD system would greatly speed up the design process and reduce the construction costs (Cheng and Yang 2001, Saleh 1999). The benefit associated with this type of system is that the detailed takeoff of required quantities can directly be obtained from the CAD system, thereby eliminating the need to perform a detailed manual takeoff. Within last three decades computer based techniques have changed the way estimates were being produced and will continue to change as new software are being developed. Electronic digitisers, which trace drawings and produce a picture of the item being measured, have been used in automated quantity takeoff

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process. Electronic spreadsheets have also been used as the quantity takeoffs and pricing sheets in the construction industry (Kerzner 2003). Such spreadsheets quickly perform all mathematical steps for which a quantity estimator has to spend many hours in preparing and checking the calculations. Some of the commercially available estimating softwares take quantities determined either manually, from a CAD file, or use digitisers and apply a database of unit prices to calculate total construction cost. Demands of the new economy are driving fundamental changes in the traditional project delivery methods. Current use of computer-based tools are being leveraged to meet the demands placed on the construction industry by using improved management of information and execution of tasks such as planning, scheduling, estimating and project control (Fischer and Aalami 1996, Songer et al. 2001b). The integration of different technologies is one of the greatest contemporary challenges being faced by the construction industry. One such area receiving particular attention is the integration of 3D models with schedule/cost estimating applications and databases (Songer et al. 2001a). Cheng and Yang (2001) explored the capabilities of GIS for cost estimation to improve the construction planning and design efficiency by integrating spatial and attribute information in GIS along with other software. They developed a GIS based tool (MaterialPlan), to assist the planner in quantity takeoffs and assessing materials layout design. MaterialPlan uses GIS in combination with CAD systems to compute quantity takeoff based on the dimensions of design drawings. The developed system generates Bill of Material (BOM) by using Map/Info and Microsoft Access. The user communicates with the components of the system through a custom interface developed using visual basic application and MapBasic. Open Database Connectivity (ODBC) was also used to write/read the information to/from the associated database.

6.2 Cost Estimation
Cost estimation involves in determining the quantity takeoffs and cost of various resources required for a construction project. Some of the existing

approaches for quantity takeoffs are not accurate enough to eliminate the

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possibility of errors like missing or duplicating different items of work. Thus, requiring an approach, that may be helpful in increasing the productivity of quantity estimator by reducing the manual work in determining the quantity takeoffs. This chapter discusses a GIS based cost estimation approach in order to avoid the use of other softwares. The proposed approach works by adding new programmes into GIS environment for various cost estimation operations and allows user to communicate through an interface developed within a GIS environment itself. ArcView 3.2, which utilises the dynamic linkage between the spatial and attribute data, was used for this purpose, thus, requiring no ODBC. ArcView also has the capability to handle database, thus, avoiding the use of Microsoft Access. CAD systems are also capable of generating material requirement and quantity takeoffs, which can be used to find the resources cost. However, the estimate prepared without detailed engineering data of an organisation itself are found to be less accurate (Kerzner 2003). Thus, to increase the accuracy of estimate one need a well-defined engineering data related to the organisation. Estimate produced from organisational data usually give better estimate than any published data because it includes group of tasks such as downtime, cleanup times, lunch and tea breaks, which varies from industry to industry. The study by Cheng and Yang (2001) used AutoCAD to prepare different data themes, which were transferred to GIS as the spatial data representation of architectural drawing. The methodology proposed in this study utilises the editing capabilities of ArcGIS to generate the spatial data in place of AutoCAD due to its better editing capabilities in comparison to ArcView. Thus, completely replacing the CAD systems from the GIS based cost estimation methodology and presents a more generalised cost estimation methodology in comparison to one proposed by Cheng and Yang (2001). Proposed methodology also eliminates the errors like missing or duplicating various items by visualising each component corresponding to the items of work in 2D or 3D space in ArcView 3.2 or ArcGIS 9. Programmes written in Avenue extract the necessary dimensions from drawings prepared in

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GIS to perform various calculations for quantity takeoffs. Accurate Bill of Quantities (BOQ) can be generated on the basis of dimensions of various data themes. The methodology is designed in a way to store entire construction resource data within the GIS environment. Data for various tasks related to construction materials, workers and equipments are stored in three different tables (Fig. 2.7) in GIS environment and separate tables are used for each project to generate BOQ, BOM and labour requirement.

6.3 Generation of Spatial Data
Various data themes possessing the physical dimensions that represent the architectural drawing are used as spatial data for quantity takeoffs. A single-room hexagonal building shown in Fig. 6.1 is used to explain and implement the proposed GIS based quantity takeoffs methodology. Architectural drawing of the building given in Fig. 6.1 provides the detailed plan and the cross-section of the wall through the door. The different dimensions are marked on the architectural drawing. The various items of the work required to be calculated includes: excavation in foundation; lime concrete in foundation; brick work in foundation; damp proofing course (D.P.C.); brick work in superstructure; reinforcement cement concrete work; lime concrete in terracing; flooring and plastering work. This way, nineteen different data themes as shown in Fig. 6.2, are created. Each theme corresponds to one or a part of an item whose quantity needs to be estimated. Different features in a theme are merged so as to reduce the number of rows in the attribute table. ArcView store data themes as the shapefile, whereas their heights are stored in the feature attribute tables (Fig. 6.2). The main attributes required for quantity takeoffs are length, perimeter and area of various features. Thus, all data themes are created using geographic elements: lines or polygons (Tab. 6.1). The first column in Tab. 6.1 lists various items to be worked out, while in second column different themes created to find the quantity of various items of work are listed. The number of themes created for each item of work will also depend on the shape, openings and thickness at different levels of height. The type of geographic element used to construct different themes will depend on the unit of measurement of the various items of the work. For the units ‘running meter’ and ‘square meter’ of the items,

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geographic feature line is used to create the data theme. For example, in hexagonal building, line is used to create themes to find the quantity of plastering (Tab. 6.2). For the units ‘cubic meter’ and ‘square meter’ of the items, geographic feature polygon is used to create the data theme. For “square meter” both line and polygon features can be used.

Fig. 6.1: Architectural drawing of hexagonal building used to demonstrate the GIS based cost estimation procedure (adapted from Dutta 1998).

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Base concrete (30cm)

First footing (20cm)

Second footing (20cm)

Third footing(90cm)

Wall above floor (60cm)

Wall at windows level (150cm)

Wall at lintel level (10cm)

Wall above windows/door (130cm)

13 cm thick R.C.C slab

6 cm thick projection of R.C.C slab

8 cm L.C. terrace

Floor (2.5 cm )

Plastering outside above ground (70cm)

Plastering in/out-side wall above floor (60cm)

Plastering in/out-side Plastering in/out-side wall at window level (150cm) wall above window (140cm)

Excavation work (100cm)

R.C.C. lintel (10cm)

D.P.C. (2.0 cm)

Fig. 6.2: Data theme of architectural drawing used for quantity takeoffs in ArcView environment.

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Items of work calculated Earthwork in excavation of foundation (cum). Lime concrete in foundation base (cum). Brick work in foundation in cement mortar (cum) 2 cm Damp proofing course (sqm).

Different data theme constructed

GIS element used

1. Representing excavation work upto a depth of 100cm. Polygon

1. Representing base concrete upto a thickness of 30cm.

Polygon

Representing first step of 20cm thickness. Representing second step of 20cm thickness. Representing third step of 90cm thickness. Polygon

1. Representing D.P.C (2cm).

Polygon

Representing wall between floor and sill level for a height of 60 cm. Brick work in the superstructure (cum) Representing wall between sill and lintel level for a height of 150cm. Representing wall for lintel thickness (10cm) Representing wall between lintel and roof for a height of 130cm. Reinforced cement concrete (RCC) work (cum) 8cm Lime concrete in roof terracing (cum) 2.5cm Cement concrete floors over 7.5cm lime concrete (sqm). Representing R.C.C. lintel (10cm). Representing 13 cm thick R.C.C slab. Representing 6 cm thick projection of R.C.C slab. Polygon

Polygon

1. Representing 8cm L.C terrace.

Polygon

1. Representing Floor 2.5 cm.

Polygon

1. Plastering outside the wall (between ground and floor level for a height of 70cm). 12mm Cement plastering work on walls (sqm). 2. Plastering inside/outside the wall (between floor and sill level for a height of 60 cm). Line 3. Plastering inside/outside the (between sill and lintel level for a height of 150cm). 4. Plastering inside/outside the wall (above the lintel level for a height of 140cm).

Tab. 6.1: List of different items of the work, calculated by constructing the one or more data themes for each item with geographic element polygon and line.

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One theme will be enough to estimate the quantity of earthwork in excavation and lime concrete in the foundation because both are symmetric in plan and differ in the attribute height only. Thus, this theme is stored in database by two different names (i.e. excavation and lime concrete). The foundation involves change in thickness of brick wall three times across height, thus, three different themes representing these changes in height are created for estimation of quantities. Editing the top theme representing brickwork in the foundation creates D.P.C. theme. Four different themes for brick walls of superstructure are created at different level of height so as to take care of the opening in the walls. Two themes for the estimation of the reinforced cement concrete (R.C.C.) work in slab are also prepared because of the different thickness of the slab both inside the room and the projected part of the slab lying outside the building. Three themes are created for lime concrete in terracing, flooring and R.C.C. work in the lintel respectively. Similarly, four different themes are created for the quantity estimation of plastering. These themes include: one for outside surface between the ground and floor level and three themes for inside and outside surfaces lying between the floor and the slab. Fig. 6.2 and Tab. 6.1 provide details of different themes for plastering as well as other items of the work.

GIS element used Line

Units of measurement Running-meter Square-metre Cubic-meter

Items of the works Road work, ridge beam, etc. Plastering, wood-shutter, parapet wall, etc. Excavation, brickwork, concrete work, wood-frame, stonework, etc. Flooring, damp proofing course, etc.

Polygon Square-metre

Tab. 6.2: List of the geographic elements used to construct the different data theme.

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6.4 GIS-Based Quantity Takeoffs Procedure
In order to implement the proposed methodology in GIS environment (Fig. 6.3), several programmes are written in ArcView 3.2 using Avenue as the programming language. Different steps involved in GIS based quantity takeoffs are discussed below: Step 1: Data themes-The architectural drawing is divided into different themes, called data themes as single architectural drawing is insufficient to calculate the quantity takeoffs (Fig. 6.2). These data themes form the basic for GIS based quantity takeoffs. The parameters required for quantity takeoff are area and length of different data themes. Thus, all features of data themes are created as polygons or lines in ArcGIS. Step 2: Data transfer-Data theme generated in the AutoCAD can also be utilised by the proposed methodology, therefore, this step is required if AutoCAD is used to create the data theme. CAD Reader extension available in ArcView allows working with AutoCAD (version 14.0 in this work) drawings. CAD drawings can be added to ArcView as themes and can be symbolised and queried. ArcView uses AutoCAD drawing themes like any other type of feature theme in GIS. However, to edit or modify a CAD drawing theme's features or its associated attribute table, all themes need to be converted to shapefiles in ArcView. A Shapefile is simple, non-topological format for storing geometric location and attribute information of geographic features. All themes created in AutoCAD are transferred to GIS environment using the CAD Reader extension, which automatically adds default legends in the table of contents. User may assign different legends to differentiate various themes. Step 3: Merge polygons/lines-This process is used to remove boundaries between adjacent polygons. Different polygons/lines in each theme are dissolved using dissolve functionality to form a single or multipart single polygon (GeoProcessing extension of ArcView 3.2). Fig. 6.3 shows all data theme before and after merging different features, where each data theme contains a single record, as all features in a theme are merged to form one polygon or a line.

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Data themes

Merge and transfer themes

Data themes after merging

Architectural Drawing. Create data themes Attribute tables of different data themes.

Tables with s single row after merging.

Generate a table called BOQ containing eight fields (items; key; units; height; area; perimeter; length and amount of work).

For each data theme, get its feature attribute table and join it with resource table through field key and find the units of measurement of the item represented in the theme.

If unit is “m3” then add fields area, perimeter and their values to the each records in feature attribute table.

If unit is “m2” then

If unit is “m” then add field length and its values to the each records in feature attribute table.

If data theme contains polygon features then add fields area, perimeter and their values to the each records in feature attribute table. Quantity = area * height, Add a row in BOQ for each record of feature attribute table; fill all the entries of row into the respective column by extracting values from feature attribute table, remove join. Quantity = area, Add a row in BOQ for each record of feature attribute table; fill all the entries of row into respective column by extracting values from feature attribute table, remove join.

If the data theme contains line feature then add field length, its values to the each records in feature attribute table.

Quantity = length, Add a row in BOQ for each record of feature attribute table; fill all the entries of row into respective column by extracting values from feature attribute table, remove join. Quantity = length * height, Add a row in BOQ for each record of feature attribute table; fill all entries of row into respective column by extracting values from feature table, remove join.

Bill of Quantities (BOQ)

Fig. 6.3: A flow diagram to generate bill of quantities in ArcView.

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Step 4: Append attributes-All data themes created in ArcGIS/AutoCAD are transferred to ArcView. In all feature attribute tables (generated automatically if themes are transferred from AutoCAD) of different data themes, shape is a default field to store shape information of features. Fields key, items and height are added to feature attribute table of each data theme by using a programme written for this purpose. The values in the added fields are then entered manually. Key is a common field in all tables being joined and the values in this field are entered in a way such that it should correspond to one row of the resource table having the resource information (Fig. 2.6, 2.7). The name of item of work contained by data theme is entered in field items. For items measured in ‘square meter’ and ‘cubic meter’ represented by geographic element line and polygon respectively, the values of height need to be entered in the field height. The entries in the field height will be zero if items of the work are measured in ‘running meter’ and ‘square meter’ and represented by line and polygon respectively. Step 5: BOQ- Fig. 6.3 shows a flow diagram of the programme used to generate BOQ in ArcView. The programme uses all data themes as input and generates a new table with eight fields named as key; items; units; height; area; perimeter; length; and amount of work. The Fig. 6.4 shows the BOQ that consists of nineteen records, where each record corresponds to a particular theme used to represent one or a part of the item of the work. If, by mistake, the user forgets to merge the features in a theme (step 3), the programme is designed to take care of this problem by introducing a row in BOQ corresponding to each feature of a data theme. Thus, avoiding any error in calculating the quantities of various items of work.

6.5 Cost Analysis
Costs of different items of work represented in data themes are obtained by data integration with construction resource database. Database is a collection of different tables in ArcView/ArcGIS (section 3.5) and can be connected to BOQ through a field key. Different elements required for cost estimation using quantity takeoffs are materials, labours and equipments plus contractor profit and water charges. For any work, cost may contain one, two or all of these three elements.

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All three elements of cost are calculated by joining BOQ with three resource tables. Each element is priced separately in accordance with the unit of measurement corresponding to items of work in each row of BOQ and cost of individual elements is then added together. The detailed procedure to calculate the amount of material required for each data theme is explained in the section 6.5.1. Same process is used to calculate cost of other elements. After calculating cost of three elements, contractor profit and water charges are added to get the total cost of work.

Fig. 6.4: Bill of quantities for various items of work represented by different data themes in ArcView.

6.5.1 Generating Bill of Material Fig. 6.5 shows a flow diagram used to generate BOM. The BOQ acts as an input for this and join function of ArcView is utilised to retrieve the material required for different data themes from material table. A programme is used to extract the records of material required from material table for each data theme

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and adds it to the corresponding rows of BOQ. The content of BOQ table changes whereas the material table remains unchanged. The programme then uses a dialog box to choose the name of the field in BOQ containing the quantity of work from the list. In this way, a new table called BOM is generated with different fields for each material, plus two more fields named as items and cost. From each row of BOQ, programme retrieves the amount of different materials required for work units entered in the field quantity of material table. Each value is then multiplied with corresponding amount of work and divided by the value of the field quantity before entering it into the respective fields of BOM. A dialog box is used to input the rate of different materials, which are multiplied with the corresponding amount of material and entered in the field cost. After processing, the programme generates a new table, which provides the total cost of material for different items represented by various data themes. Finally, the programme removes all data joined with BOQ in order to keep it unchanged by calling unjoin function. 6.5.2 Labours and Equipments Cost The labour requirements for different data themes may also be obtained from data integration in the same way as discussed in section 6.5.1. again BOQ acts as an input to generate the requirement of different class of labours. The function join retrieves different class of labourers for items of work represented in different data theme into labour table. A dialog box is then used to input the name of the field containing the amount of work in BOQ. The programme then generates a new table called labour requirement with fields for different classes of workers, plus two more fields called items and cost. From each row of BOQ, programme retrieves the number and different class of workers required for work units entered in the field quantity of labour table. Each value is then multiplied with corresponding amount of work and divided by a value in the field quantity before entering it into the respective fields of output table. Another dialog box allows entering the rate of different class of workers. The values of the field cost are calculated by multiplying number of individual workers with the corresponding unit rates. After processing, programme shows the total cost of different class of labourers required for various items represented by data themes. Finally, the programme removes all joined data form BOQ calling unjoin

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function, thus keeping the BOQ unchanged. A separate programme is used to calculate the required equipment cost in a similar way.

Materials table from database

Join with common field key

Input BOQ containing field amount of work involve in different data themes

Contents of the BOQ will change to include the joined attributes from Materials table.

Input the cost of different construction materials

Create new table called BOM with different fields for different materials.

For each row in BOQ, Add a row in BOM

From each row of BOQ, retrieve the amount and different materials required for work units entered in the field quantity of the material table. Multiplies each value with corresponding amount of work, then divide by value in the field quantity and enter into the respective fields of BOM. Calculate cost by multiplying individual materials amount with corresponding rates.

Bill of Materials (BOM)

Bill of labours and equipments cost is obtained on the similar way.

Calculate total cost of three elements of construction and add cost of water charges, contractor profit to generate report.

Fig. 6.5: Flow diagram to generate bill of material for different items of the work represented by data themes.

6.6 2.5D Visualisation
A procedure to generate 2.5D visualisation of building by utilising data themes used for quantity takeoffs is discussed in section 2.6. Therefore, the data themes created for quantity takeoffs can also be utilised for generating 2.5D view. Although. CAD technologies also provide visualisation capabilities, but GIS can perform different operations on attribute data synchronised with 3D

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model, which is not possible in CAD. Fig. 6.6 shows a 2.5D view of hexagonal building generated by using a procedure discussed in section 2.6.

Fig. 6.6: Screenshot containing two documents of ArcView used to show perspective views (3D Scene documents) and 2D data themes (view document).

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Chapter

7

Direct Sunlight Visualisation
7.1 Introduction
The location of a building and its orientation provide opportunities to reduce its energy consumption. A well-planned and optimally oriented building relates well to its site as well as climate and maximises the opportunities for passive solar heating during winter and avoiding solar heat gain during summer. The visualisation tools help the designer to understand and recognise solar heating problems of buildings during the early conceptual design stage. The computer tools used to simulate sunlight visualisation require numerous trials on different days of a year, time of day and at several viewpoints. Within last few decades, a large number of software/tools are developed for building energy simulations. These tools provide information about different building performance indicators such as energy use and demands, temperature, humidity, cost of energy, etc. Crawley et al. (2005) provide a detailed discussion on different modules available in the twenty most popular energy simulation tools. For sunlight visualisation, the sun angles variations with diurnal and annual cycles need to be considered due to the change in the sun’s position with time. The solar path of the sun over a year is generally represented using stereographic projections in which the sun angles are represented by an altitude angle (describes the height of the sun in the sky) and azimuth angle that informs about its direction. The variations in the sun’s path over the time are drawn on a diagram in which concentric lines represent the altitude angle whereas the radial lines represent the azimuth angle (Markus and Morris 1980). This technique is quite useful for the assessment of the sun’s path, however, such representation does not allows the user to navigate in 3D. The sun’s lighting phenomenon

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occurs in 3D, in addition, the sun’s position fluctuates with time (diurnal and annual cycle of a year). Therefore, to preview the effect of sun lighting on an architectural 3D space over time, designer must navigate in a 5D space that consists of three dimensions of space and two of time (Bund and Do 2005). This chapter explores the potential of GIS to generate navigable animations for sunlight simulation in a 5D. The ArcView 3.2 is used for the calculation of azimuth and altitude angles of the sun by writing scripts in Avenue (ArcView 3.2 1996) whereas the ArcGIS 9 is used to create a 3D model of a building and navigable animations. Researches by Kumar et al. (1997), Mardaljevic and Rylatt (2003), Ratti et al. (2005), Rylatt et al. (2001) described some of the applications of GIS in sunlight visualisation. Kumar et al. (1997) described the modelling of topographic variation on solar radiation in a GIS environment. Mardaljevic and Rylatt (2003) suggested an approach for evaluating the total annual/monthly irradiation incident on building facades in urban settings by linking it to GIS based solar energy planning system. Ratti et al. (2005) used GIS to explore the effects of urban texture on building energy consumption based on the analysis of digital elevation models of the cities whereas Rylatt et al. (2001) developed a GIS-based decision support system for solar energy planning in urban environments. The layers created for 3D visualisation and cost estimation can also be utilised for direct sunlight visualisation in GIS environment. This chapter discusses a GIS based methodology for direct sunlight visualisation on buildings. The proposed approach is not considered as a replacement of other commercially available tools but may be a useful tool for the ACE industry utilising GIS for various project requirements.

7.2 Tool Implementation
To describe the sun’s position two angles, solar altitude (β) and solar azimuth (φ) are used. Solar altitude is measured from 00 to 900 above the horizon, whereas solar azimuth is measured from 00 to 1800 from the south with positive sign eastward and negative sign westwards. The latitude, longitude, date and time

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are the parameters required for the calculation of solar altitude and azimuth angles. Initially, declination (d) and hour angle (h) are calculated by using the true solar time. A relationship to calculate declination for a particular date and used in this study is given by the following equation (Kensek et al. 1996): d = 23.45 * sin (360(284 + n) /365) (7.1)

Where d is the declination angle in degrees (positive in northern hemisphere, negative in southern hemisphere), n is the number of days since first of January (1 on January 1, and 365 on December 31). As earth does not move in a circular orbit around the sun, its orbital speed varies slightly throughout the year. Therefore, the clock time adjusted to run at a uniform rate will show slight deviations from the true solar time. Therefore, a correction known as the equation of time (e ) needs to be applied to the clock time. The equation of time is
t

an amount that has to be added to or subtracted from the uniform mean solar time to obtain true solar time. The equation of time e (units of hours) is represented
t

by following relation: e = [-104.7sin(f) + 596.2sin(2f) + 4.3sin(4f) - 429.3cos(f) - 2.0cos(2f)+19.3
t

cos(3f)] / 3600 Where, f = π / 180 [279.5 + 0.9856 n] (degree)

(7.2)

Further, the world is divided into different time zones and each zone has a reference longitude where both mean solar time and the clock times are the same. Any place on the east or west side of the reference longitude, but lying within the same time zone must have a correction of 4 minutes per degree of longitude. If a construction site lies to the west of the reference longitude, the amount has to be added to the clock time to obtain the mean solar time whereas the amount has to be subtracted if the site lies to the east (Markus and Morris 1980). The hour angle (in degrees) is calculated by using the following equation: h = 0.25*(Number of minutes from true solar time noon) (7.3)

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The variation of the hour angle is considered positive for ante meridian (a.m.) and negative for post meridian (p.m.). After calculating the declination and hour angles of sun, the altitude angle on any date for a particular time and location can be calculated by the equation: β = sin-1 [cos (d) * cos (L) * cos (h) + sin (d) * sin (L)] (7.4)

Where β is altitude angle, d is declination, L is latitude of a building site and h is hour angle. To calculate the azimuth angle following equation is used: φ = sin-1 [cos (d) * sin (h) /cos (β)] (7.5)

Where φ is the azimuth angle measured from 00 to 1800 from the south, with positive sign eastward and negative sign westwards. 7.2.1 Overview of Methodology The direct sunlight simulation over the time is a five dimensional visualisation problem, which includes three dimensions of space and two of time, therefore, the developed methodology has two major parts: developing a 3D model for easy navigation and displaying the temporal variations of sunlight on a 3D model using navigable animations. To calculate azimuth and altitude angles of the sun, developed programme needs the following inputs: I. The geographical location of a building site and reference longitude where the mean solar time and clock times are same. II. Clock time at a geographical location and date. The calculated values of azimuth and altitude angles at different date, time and location are then used to render different faces of a 3D model with colours of varied gradients depending on the amount of incident sunlight using an in-built functionality of ArcGIS. The output consists of sun light distribution displayed on a navigable 3D model of building, which may help architects to visualise direct sunlight intensity. The 3D model of a building can be rotated to give the correct orientation with respect to its surroundings (Fig. 7.1) and can be placed at a location where it is to be constructed. Unlike a 2D drawing, GIS presentation can

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be viewed from any location and angle. A navigable 3D view of the building with long side parallel to the East-West (E-W) at different times is shown in Fig. 7.2. The users have the options to rotate the model around x, y, or z-axis, zooming, pan and fly forward or backward to observe details clearly. It allows viewing the model from any direction and angle in 3D space.

Fig. 7.1: Rotation of data layers of a building at suitable angle to give proper orientation.

7.3 Navigable Animations
In present work, animations illustrate the time dependent phenomenon of sunlight in a navigable 3D space. The keyframe is the most fundamental element used for the generation of animation in the proposed methodology. A series of keyframes are assembled in an animation track and the properties such as azimuth, altitude angles and location of a viewpoint are changed repetitively for each keyframe. The designers can also change their view position to examine sunlight intensity on different faces. ArcGIS provides the facility to export animations in a windows media player that can independently be used for demonstration. Animation is an effective tool to demonstrate the variation of sunlight intensity on a building over annual and diurnal period. Fig. 7.3 shows a navigable 3D view of a building with long side parallel to the E-W (at 10 A.M., latitude 290N59’ and longitude 760E51). The south-facing wall gains majority of solar energy during winter (15-December 2005) as shown in Fig. 7.3(a), and least in summer (15-May 2005) as shown in Fig. 7.3(b). This suggests that energy efficient buildings should be oriented with longer dimensions parallel to the E-W direction as east and west facing walls and horizontal surfaces gain more heat in

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summer than winter. Fig. 7.4 shows how horizontal surface receives more heat gain in summer than in winter at the same location.

9:00 AM

12:00 AM

2:00 PM

5:00 PM

Fig. 7.2: The navigable 3D views of a building with long side parallel to the E-W at different times (15-May 2005, latitude 290N59’ and longitude 760E51’).

The optimal orientation of a building also depends on the purpose of its use. For example, to use solar energy during winter for passive solar heating, south-face glazing is desired. The sun shading is relatively easy on south-facing glasses, which helps in minimising the solar heat gain during summer whereas north-facing wall receives very less heat gain. The sun shading on east and westface glazing is quite difficult (because of low sun angles) and contributes to unwanted heat gain in buildings.

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(a)

(b)

Fig. 7.3: The navigable 3D views of a building with long side parallel to the E-W (10 A.M., latitude 290N59’ and longitude 760E51’), (a) south-facing walls attain the most solar heat gain during the winter (15-December 2005), and (b) least in the summer (15-May 2005).

(a)

(b)

(c)

Fig. 7.4: The navigable 3D views of a building depict that horizontal surfaces receive more solar heat in the summer than in winter (10 A.M., latitude 290N59’ and longitude 760E51), (a) 15January 2005, (b) 15-March 2005, (c) 15-May 2005.

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Chapter

8

Conclusion and Future Studies
8.1 Introduction
In spite of continuous growth, construction industry has acknowledged that its current scheduling and progress reporting practices require substantial improvements in quality and efficiency (Retik and Shapira 1999). 4D visualisation integrated with the various project documents is recognised as one of the most important tools to achieve this goal (Poku and Arditi 2006). The research efforts to incorporate visualisation into project scheduling and progress control have been motivated by the failure of traditional techniques such as bar charts and the CPM to provide information pertaining to the spatial aspects of a construction project (Koo and Fischer 2000). Further, a construction project is defined by several spatial and non-spatial documents that are maintained separately in different forms by different project members. The overlap and lack of consistency among such documents often lead to construction errors. The main idea to carry out this work was to move towards a single information repository for both spatial and non-spatial documents along with 4D construction management. GIS is a computer-based tool used extensively to solve various problems in civil engineering involving the use of spatial data (Miles and Ho 1999). The growing number of research papers being published in civil engineering journals and conference proceedings illustrates the fact that GIS supplement the knowledge and abilities that already exist in the AEC industry. GIS mainly focus on geographic (land-based) information and use that information as a basis for the design and assessment of civil infrastructure. Many of the earlier studies have used land-based capabilities of GIS, for example, network analysis for routing

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(Cheng and Chang 2001, Varghese and O’Connor 1995), construction site layout planning (Cheng and O’Connor 1996), sewer/water system design (Greene et al. 1999), etc. This study utilises the capabilities of GIS to maintain spatial and nonspatial data on a common platform to make the scheduling more realistic. GIS applications for 3D modelling are described in popular civil engineering literature (ESRI 2005). The linking of project activities defined in the CPM schedule with corresponding elements of a 3D model makes the project sequence easier to understand. A GIS based methodology to link a 3D model with the construction schedule to make a 4D system using several in-house programmes are proposed in this study. The methodology is designed in such a way that it provides an alternative to the existing 4D CAD tools and allows the planner to understand the buildable construction schedule quickly. The proposed methodology enables the user to detect the incompleteness and logical errors in the schedule sequence. The methodology allows storing of non-spatial information in the tables of corresponding components by extracting it from the resource database (materials, workers, equipments, etc) maintained in GIS itself. Several programmes were also developed within GIS to extract necessary dimensions from the building model to generate the accurate BOQ and cost estimate. This work also proposes a GIS based methodology for direct sunlight visualisation on a 3D building model, which may help to determine the amount of sunlight received by different faces of building by rendering them with the colour of varied gradients. Thus, demonstrating the use of GIS to visualise the solar gain through multi-dimensional data visualisation. The developed methodology allows the visualisation of sunlight in diurnal and annual cycles through navigable 3D animations, which can be useful for designers to control the natural lighting and solar gain along with project cost and schedule. Further, researches in BIM lacks the evaluation of a new building location required for compliance with environmental, site and spatial constraints. The convergence of developed 4D scheduling with spatial analysis capabilities of GIS will have a major impact on the professionals involved in AEC industry. Thus, bringing together diverse building information on a single GIS platform will be useful to analyse, model, understand and deal with critical issues. 112

The level of functionality for building analysis in 4D CAD and BIM tools are superior, particularly in 3D modelling but GIS based 4D scheduling developed in this study along with geospatial analysis tools have its own strengths where it can be perceived together with its surroundings. Because of interoperability problems between CAD/BIM and GIS this study brings 4D scheduling, quantity takeoffs, cost estimation, direct sunlight visualisation, construction resources database and geospatial analysis on a common platform.

8.2 Contributions to the Body of Knowledge
Following are the contributions of this work to the existing literature: • This study explores the potential of GIS for CPM basic scheduling. A tool for CPM forward and backward passes computations is developed in ArcView/ArcGIS environment by writing additional programmes in Avenue/Visual Basic to handle different scheduling calculations. Developed tool works well and may be of considerable benefit to the construction industry utilising GIS to handle different construction project requirements. • The proposed GIS based methodology to build a 3D model and linking it with the construction schedule works well for the sample building and can be used as an alternative to the existing 4D CAD tools. The proposed methodology also allows the planner to understand the construction schedule quickly by linking activities of the schedule with the corresponding 3D components as well as to visualise buildable schedule on the computer screen. • This study also concludes that GIS can effectively be used to maintain the construction data in tabular form that can be later integrated with the corresponding activities of the construction project. Thus, replacing the manual methods of extracting the information from the database. As most of the information is in digital format, it can easily be updated. • Suggested GIS based approach utilising the dynamic linkage between the activities in the schedule and corresponding 3D components works well in detecting the incompleteness and logical errors in the schedule sequence.

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The proposed GIS based cost estimation methodology may be quite helpful in increasing the productivity of quantity estimator by extracting the necessary dimensions from the drawings (prepared in GIS/CAD) and perform various calculations for quantity takeoffs as discussed in chapter 6. This approach also allows generating accurate BOQ on the basis of dimensions of various data themes.



The methodology suggested for direct sunlight visualisation on a 3D building model in GIS environment also works well within given limitations. The proposed approach was able to demonstrate the solar gain through multi-dimensional data visualisation using sun angle variations with diurnal and annual cycles in navigable 3D animations.

8.3 Conclusions
This study uses GIS to represent and integrate construction spatial (drawing, layouts) and non-spatial information (specifications, resources and schedule) in a single environment. The capabilities of GIS to store construction specific information in digital form and link it with corresponding activities of a project can be utilised in decision-making and planning of a construction project. Thus, various spatial operations on drawings and non-spatial operations on attributes in a single GIS environment may improve and speed up construction planning, data integrity and accuracy. A GIS based tool for CPM basic scheduling calculation for forward and backward passes was developed and tested in this work. The AEC industry using GIS to handle various project requirements can use the developed tool to handle construction project scheduling task. The developed tool successfully handles the problems of frequently updating the schedule and provides the schedule of a construction project by using single calendar date. In the developed tool, each successor event number need not be larger than the predecessor event number. The developed tool also permits random numbering of events, provided no two events receive identical numbers. Any two events may be directly connected to more than one activity.

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Proposed methodology allows integrating project schedule with corresponding spatial details in GIS environment and works well with the sample building. Most of the 4D CAD technologies do not have project management capabilities and are used mainly for planning and design phase of a project whereas the proposed tool may be used in different stages of a project. The scheduling in GIS will allow easier understanding of a project as well as helps to detect the problems in it. By integrating and displaying

specification/recommendation and construction resource information, scheduling in GIS will also promote interaction and collaboration between project team members from different fields. Developed GIS based procedures for quantity takeoffs, cost estimate and direct sunlight visualisation works well for the problem considered in the study. The developed 4D GIS tool also allows integrating safety recommendation with the critical activities, thus, making the schedule more realistic. The CPM schedules alone only convey ‘what’ is built ‘when’, whereas the CPM schedule in GIS conveys ‘what’ is being built ‘when’ and ‘where’. The study also concludes that the database developed in GIS may be used for construction cost estimations and the data layers created for 3D visualisation can be used for quantity takeoffs. Although GIS based quantity takeoffs are precise, but cost estimates work well for repetitive tasks or activities at particular geographic region only. The construction cost calculated by the methodology is based on the data in resource tables, which need to be updated on the basis of past practice. Therefore, the accuracy in cost estimation depends on the correctness of data in resource tables and dimensions of different data layers. Direct sunlight visualisation in ArcGIS provides the facility to export the animation that can be played in windows media player. ArcGIS also provides the geometry editing capabilities, so the designer can make modifications on building model’s geometry to improve and assess its performance. A major conclusion from this research is that GIS based developments not only provide construction schedule visualisation tool but may also be used as a project management tool at different stages of a project in which the schedule and

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3D components may be manipulated in a single GIS environment. The 3D GIS technologies in construction industry are not grown-up like CAD systems, thus, making it difficult for CAD users to draft in GIS environment. Also, GIS is generally not associated with AEC industry, therefore, the professionals need education and training on the use of GIS technologies. The researches reported in this area are limited, thus, there is a need to bring the research community, software developer and AEC industry together for the successful use of GIS. Although, GIS is not generally associated with construction engineering; therefore, professionals need education and training on this indispensable technology for its long-term use. The researches reported in this field are limited, thus, there is also a need to bring the research community, software developer and construction industry professionals together for the successful use of GIS in AEC industry. This work may open the new directions of research in the use of GIS in construction industry.

8.4 Suggestions for Future Studies
Despite all suggested outcomes of this work, following are few areas that can be taken up for the future studies to enhance the capability of GIS to meet various construction project requirements: • 3D GIS are not developed to the extent like drafting capabilities in CAD systems. Therefore, efficient and comprehensive 3D editing and visualisation capabilities need to be developed in GIS environment. Studies have suggested the use of multipatch feature to represent 3D object but it is a solution to few problems only. • Most of the GIS functions are 2D and if one moves from 2D to 3D, complexity of relationships increases. Also there is a requirement of new approaches, rules and representations construction at operation level (Kamat and Martinez 2001). • This study employs activity-on-node (AON) method for scheduling in which activity splitting is not considered. Future studies can be carried out to add more functionality like those available in Primavera and Microsoft Project.

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The proposed approach uses a single-user desktop, thus, there is need of a server/web based GIS for multiple participants working on the large projects. Therefore, future work may involve extending the proposed approach to server/web based GIS (Kang et al. 2007, Wu et al. 2002).



A limitation of GIS based cost estimation approach is its incapability to calculate the area of themes drawn inclined to horizontal plane (e.g. flight of stairs). Also if 3D multipatch format is used, the proposed methodology is incapable to calculate length, area and perimeter. Further research is required to develop a methodology that takes a 3D format of ArcGIS (multipatch) as the input to generate the quantity takeoffs.



The methodology for sunlight visualisation can be improved by taking into account other factors like sky condition and urban obstructions, which affects the amount of sunlight received by a building as well as adding a tool for the design of elements like shading devices for buildings in GIS environment. Future work may also involve testing the proposed approach on multi-storied buildings.

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Paper Published from This Thesis
Journals
Bansal, V.K., and Pal, M. (2009). “Construction schedule review in GIS with a navigable 3D animation of project activities.” International Journal of Project Management, Elsevier Science UK, Accepted for publication. Bansal, V.K., and Pal, M. (2009). “Extended GIS for construction engineering by adding direct sunlight visualisations on buildings.” Construction Innovation, Emerald (London), 9(4), Accepted for publication. Bansal, V.K., and Pal, M. (2008). “Generating, evaluating, and visualizing construction schedule with Geographic Information Systems.” Journal of Computing in Civil Engineering, ASCE, 22(4). 233-242. Bansal, V.K., and Pal, M. (2007). “Discussion of ‘Construction scheduling and progress control using Geographical Information Systems’ by Stephen E. Poku and David Arditi.” Journal of Computing in Civil. Engineering, ASCE, 21(6), 478-479. Bansal, V.K., and Pal, M. (2007). “Potential of Geographic Information Systems in building cost estimation and visualisation.” Automation in Construction Elsevier Science UK, 16(3), 311-322. Bansal, V.K., and Pal, M. (2006). “GIS based projects information system for construction management.” Asian Journal of Civil Engineering (Building and Housing), 7(2), 115-124. Bansal, V.K., and Pal, M. (2006). “Geographic Information Systems for construction industry: a review.” NICMAR Journal of Construction Management, 21(2), 1-12.

International Conferences
Bansal, V.K. (2008). “Construction Process Visualization: A 3D animation of project activities.” Proc. Applied Computing Conference (ACC’08), World Science and Engineering Academy and Society, 27-30 May, Istanbul (European part of Turkey), pp.152-55. Bansal, V.K. (2008). “Geographic Information Systems for construction industry: a methodology to generate 3-D view of buildings.” Proc. Map India-2008, Noida, India. Bansal, V.K. (2007). “Potential of GIS to find solutions to space related problems in construction industry” Proc. Conf. of World Academy of Science, Engineering and Technology, Vol. 26, Dec. 2007, Bangkok, Thailand, pp. 307-310. Bansal, V.K., and Pal, M. (2007). “Geographic Information Systems in evaluation and visualization of construction schedule.” Proc. Second ESRI Asia-Pacific User Conf., New Delhi, India. Bansal, V.K., and Pal, M. (2005). “GIS in construction project information system.” Proc. Map India-2005, 8th annual user conf., New Delhi, India.

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Vita
Vijay Kumar Bansal was born on the 15th of May 1976 in Mandi district of Himachal Pradesh, India. He received his Bachelor’s degree in Civil Engineering in 1999 from National Institute of Technology (NIT) Hamirpur, Himachal Pradesh (formerly known as R.E.C. Hamirpur). He earned his

Master’s degree in Building Science and Construction Management in 2000 from the Department of Civil Engineering at Indian Institute of Technology (IIT) Delhi, India. He joined Department of Civil Engineering at National Institute of Technology Kurukshetra, India as a lecturer in September 2001, where he teaches Civil Engineering. In April 2005, he enrolled in the Department of Civil Engineering at NIT Kurukshetra, India to pursue his Ph.D. degree as a part time student. His doctoral study is focused on “Geographical Information Systems in Construction Management.”

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