Steps in Construction Scheduling

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Steps in Construction Scheduling Planning & Scheduling

Planning: Process of choosing the method and order of work Scheduling: Process of determining the interrelationship of associated timings of operations. Advertisements

Steps in Construction Scheduling

      

Splitting of the project into work activities Determining logic relationships/interrelationships between activities. Construction of Network Diagrams. Assigning durations to work activities. CPM Calculations resulting in start times, finish times and float calculations of activities. Marking of critical Path Construction of Bar Charts / Time phased diagrams.

Activity

 

An element of work performed during the course of a project. Or

 An amount of work that can be identified so that we know what it involves and can recognize, when it starts and finishes. An activity normally has an expected duration, an expected cost, and expected resource requirements

Network Diagrams

  

Any schematic display of the logical relationship of project activities. Always drawn from left to right to reflect project chronology. Usually a combination of arrows and nodes.

Mainly of two types:

1. Arrow Diagram 2. Node Diagram / Precedence Diagram Arrow Diagrams

     

Activities shown by Arrows. Relationship between activities shown by nodes / events. Length of arrows does not obey any scale. Start-to-finish relationships. Dummies. Numbering of nodes / events. Milestones

Activity Durations



  

Activity duration is forecasted by any of the several means, including: 1. Check Past Records. 2. Check Standards and / or cost guides, if available. 3. Ask the workers, who will do it 4. make an educated guess Any time units may be allotted to activity durations like days, hours, weeks, months, shifts, etc. In CPM, a single duration is forecasted for an activity. In PERT (Program Evaluation & Review Techniques), 3 durations are forecasted for an activity and mean taken by weighted average method. Then, Project’s Duration or any Event Completion Time is calculated by probability distribution.

CPM Calculations



Calculates the following for each activity

EST = Earliest Starting Time

EFT = Earliest Finishing Time LST = Latest Starting Time LFT = Latest Finishing Time TF = Total Float FF = Free Float   

Total Float is Maximum time for which an activity can be delayed without delaying the project. Free Float is maximum time for which an activity cane be delayed without delaying the start of proceeding activity. Total Float = Free Float + Interfering Float

Critical Path

   

The path (or paths) in the network diagram, from start to finish, on which all the activities have zero total and free floats, is called Critical Path. It is the longest path (or paths) from start to finish in a net work diagram. It gives minimum normal time to complete a project. It is usually marked by double lined arrows in a network diagram.

SINGLE SPAN BRIDGE PROJECT (ACTIVITY DESCRIPTION)

Node Diagrams

   

Activities shown by Nodes, relationship between Activities shown by arrows or links. Easier to construct. Generally no need of dummies. Instead dummies used only to give single start or finish. CPM Calculations similar to Arrow diagrams.

Bar Chart

     

Gives Pictorial Representation of Activities. Activities begin at EST and show their EFT, FF, TF, Durations, etc. Arrows at the relative ends to show dependency. Status Line Concept Unable to show complete interdependency between Activities. Time-scaled Network Diagrams show complete interdependency between Activities.

Construction Project Quality Management What is Quality?

   

FEDEX - “Performance to the standard expected by the customer” General Services Administration - “Meeting the customer’s need the first time and every time” BOEING - “Providing customers with products and services that consistently meet their needs and expectations. US Department of Defense - “Doing the right thing right the first time, always striving for improvement, and always satisfying the customer”.

Quality can be defined in terms of the agent. Who is the judge of quality? Advertisements

Quality involves meeting or exceeding customer expectations. Quality applies to products, services, people, processes, and environments. Quality is an ever-changing state (i.e., what is considered quality today may not be good enough to be considered quality tomorrow). Quality is a dynamic state associated with products, services, people, processes and environments that meets or exceeds expectations.

The Total Quality Approach

Total quality is an approach to doing business that attempts to maximize the competitiveness of an organization through the continual improvement of the quality of its products, services, people, processes and environments.

Characteristics of the Total Quality:

          

Strategically based Customer focus (internal and external) Obsession with quality Scientific approach to decision making and problem solving Long-term commitment Teamwork Continual process improvement Education and training Freedom through control Unity of purpose Employee involvement and empowerment

Two Views of Quality

Elements of Total Quality Strategically Based

 

Comprehensive strategic plan with following elements: vision, mission, broad objectives and following activities Provides sustainable competitive advantage in the marketplace.

Customer Focus

  

“Customer is the driver”. External customers: define the quality of the product or service delivered. Internal customers: define the quality of people, processes, and environment associated with the products or services.

Obsession with Quality

 

All personnel at all levels approach all aspects of the job from the perspective of “How can we do this better?”. “Good enough” is never good enough.

Scientific Approach

 

Hard data are used in establishing benchmarks, monitoring performance, and making improvements. Decision making and problem solving is based on scientific principals.

Long-term Commitment



Quality improvement is NOT another management innovation but a whole NEW way of doing business that requires an entirely new corporate culture.

Teamwork



Internal competitiveness vs. External competitiveness

Continual Process Improvement



Continually improve systems (environments) where products are developed and services are delivered by people.

Education and Training

 

Best way to improve people on a continual basis. Train hardworking people “How to work smart?”

Freedom through Control

 

Involving and empowering employees to simultaneously bring more minds to bear on the decision-making process and increase the ownership employees feel about decisions that are made. Well-planned and carried-out controls (not loss of management control).

The Deming Cycle

    

Conduct consumer research and use it in planning the product (PLAN). Produce the product (DO). Check the product to make sure it was produced in attendance with the plan (CHECK). Market the product (ACT). Analyze how the product is received in the market in terms of quality, cost and other criteria (ANALYZE)

Deming’s Fourteen Points

1. Create constancy of purpose toward the improvement of products and services in order to become competitive, stay in business, and provide jobs. Adopt the new philosophy. Management must learn that it is a new economic age and awaken to the challenge, learn their responsibilities, and take on leadership for change. 2. Stop depending on inspection to achieve quality. Build in quality from the start. Stop awarding contracts on the basis of low bids. 3. Improve continuously and forever the system of production and service, to improve quality and productivity, and thus constantly reduce costs. Institute training on the job. 4. Institute leadership. The purpose of leadership should be to help people and technology work better. 5. Drive out fear so that everyone may work effectively. 6. Break down barriers between departments so that people can work as a team. Eliminate slogans, exhortations, and targets for the workforce. They create adversarial relationships. 7. Eliminate quotas and management by objectives. Substitute leadership. Remove barriers that rob employees of their pride of workmanship. Institute a vigorous program of education and self-improvement. Make the transformation everyone's job and put everyone to work on it. 8. Lack of constancy of purpose to plan products and services that have a market sufficient to keep the company in business and provide jobs. 9. Emphasis on short-term profits; short-term thinking that is driven by a fear of

unfriendly takeover attempts and pressure from bankers and shareholders to produce dividends. 10. Personal review systems for managers and management by objectives without providing methods or resources to accomplish objectives. Performance evaluations, merit ratings, and annual appraisals are all part of this disease. 11. Job hopping by managers. 12. Using only visible data and information in decision making with little or no consideration given to what is not known or cannot be known. 13. Excessive medical costs. 14. Excessive costs of liability driven up by lawyers that work on contingency fees. Juran’s Contributions

1. Build awareness of both the need for improvement and opportunities for improvement. 2. Set goals for improvement. 3. Organize to meet the goals that have been set. 4. Provide training. 5. Implement projects aimed at solving problems. 6. Report progress. 7. Give recognition. 8. Communicate results. 9. Keep score. 10. Maintain momentum by building improvement into the company's regular systems. Juran’s Contributions Quality Planning

1. 2. 3. 4.

Determine who the customers are: Identify customers’ needs. Develop products with features that respond to customer needs. Develop systems and processes that allow the organization to produce these features. 5. Deploy the plans to operational levels.

Quality Control

1. Assess actual quality performance. 2. Compare performance with goals. 3. Act on differences between performance and goals. Quality Improvement

1. Develop the infrastructure necessary to make annual quality improvements. 2. Identify specific areas in need of improvement, and implement improvement projects. 3. Establish a project team with responsibility for completing each improvement project. 4. Provide teams with what they need to be able to diagnose problems to determine root causes, develop situations, and establish control that will maintain gains made. Crosby’s Contributions Crosby’s Quality Vaccine Ingredients

1. Determination. 2. Education. 3. Implementation. Total Quality Efforts Succeed

     

The successful organizations avoid these errors: Senior management delegation and poor leadership. Team mania. Deployment process. Taking a narrow, dogmatic approach. Confusion about the differences among education, awareness, inspiration, and skill building

Six Sigma Concept

     

Identify the product characteristics wanted by the customers. Classify the characteristics in terms of their criticality. Determine if the classified characteristics are controlled by part and/or process. Determine the maximum allowable tolerance for each classified characteristic. Determine the process variation for each classified characteristic. Change the design of the product, process, or both to achieve a Six Sigma processes performance.

Six Sigma Concept What is Six Sigma?

Six Sigma is an extension of total quality management which has the aim of taking process and product quality to levels where all customer requirements are met. How is Six Sigma Achieved?

 

By improving process performance. Or, Without improving the process at all if the specifications describing acceptable product can be loosened enough to correspond to the original process’s ± 6 sigma points

. The Future of Quality Management

        

Demanding global customers. Shifting customer expectations. Opposing economic pressures. New approaches to management. A total commitment to continually increasing value for customers, investors, and employees. A firm understanding that quality is defined by customers, not the company. A commitment to leading people with a bias for continuous improvement and communication. A recognition that sustained growth requires the simultaneous achievement of four objectives all the time, forever: (a) customer satisfaction, (b) cost leaderships, (c) effective human resources, and (d) integration with the supplier base. A commitment to fundamental improvement through knowledge, skills, problem solving and teamwork.

Cost Control Cost Management Techniques Project Control

   

Cost control Cash Flow Analysis Schedule Control Material Management

Cost Control

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Possible corrective actions could include:      

Adding additional trade workers or crews Adding or removing equipment Working overtime Bringing in additional subcontractors

Making the job more efficient Eliminating factors that cause subcontractors to interfere with each other

Productivity

Let R = Production rate Where: T is total time, Q is the total quantity to be installed The total cost is determined by the equation: Ct = Ch T Where Ct = total cost and Ch = cost per hour, or Ct = Ch (Q/R) Cash Flow Analysis

Front Loaded Cost Curve

COST MANAGEMENT

 

Includes processes required to ensure that the project is completed within the approved budget. Processes involved are:

1. Resource Planning 2. Cost Estimating 3. Cost Budgeting 4. Cost Control Resource Planning

Involves determining what physical resources (people, equipment, materials etc) and what quantities of each should be used to perform project activities. Inputs to Resource Planning



Work Breakdown Structure: 

 

A deliverable-oriented grouping of project elements that organizes and defines the total scope of the project. It Identifies the project elements that will need resources.

Historical Information Scope Statement:



Contains the project justification and the project objectives.

Resource Pool Description:



Knowledge of what resources are potentially available.

Organizational Policies:



The policies of the performing organization regarding staffing and the rental or purchase of supplies and equipment.

Tools and Techniques to Resource Planning

1. Expert Judgment 2. Alternative identifications: 

To adopt different approaches for the same problem.

Outputs from Resource Planning

Resource Requirements: 

Description of what types of resources are required and in what quantities for each element of the work break down structure.

Cost Estimating

 

Developing an approximation (estimates) of the costs of the resources needed to complete project activities. Includes identifying and considering various costing alternatives.

Cost Estimating and Pricing

 

Cost Estimating involves developing an assessment of the likely quantitative result-how much will it cost the performing organization to provide the product or service involved. Pricing is a business decision-how much will the performing organization charge for the product or service

Inputs to Cost Estimating

      

Work Breakdown Structure Resource Requirement Resource Rates:

 scheduled or non-scheduled Activity Duration Estimates Historical Information Chart of Accounts: Describes the coding structure used by the performing organization to report financial information in its general ledger.

Tools and Techniques for Cost Estimating

Analogous Estimating / Top-down Estimating: 

Using the actual cost of a previous, similar project as the basis for estimating the cost of the current project. It is less costly but less accurate. (Rough-cost Estimate)

Parametric Modeling:



Using project characteristics (parameters) in a mathematical model to predict project costs.

Bottom-up Estimating: 

Estimating the cost of individual work items, then summarizing or rolling up the individual estimates to get a project title. (Detailed Estimate)

Computerized Tools: 

Use of computerized tools such as project management software and spreadsheets to assist with cost estimating.

Outputs from Cost Estimating

  

Cost Estimates Supporting Details like Scope of work, Calculation sheet, Assumptions made, Possible range of results, etc. Cost Management Plan describing how cost variances will be managed.

Cost Budgeting

Allocation of overall cost estimates to individual work items in order to establish a cost baseline for measuring project performances. Inputs to Cost Budgeting

  

Cost Estimates Work Breakdown Structure Project Schedule

Tools and Techniques for Cost Budgeting

Tools and Techniques for developing project Cost Estimates are used to develop budgets for work items as well Outputs from Cost Budgeting

Cost Baseline

A time-phased budget that will be used to measure and monitor cost performance on the project. It is developed by summing estimated costs by period and is usually displayed in the form of an S- curve.

Cost Control

Cost Control is concerned with 1. Influencing the factors which create changes to the cost baseline to ensure that changes are beneficial. 2. Determining that the cost baseline has changed 3. Managing the actual changes when and as they occur

Cost Control includes:    

Monitoring cost performances to detect variances from plan. Ensuring that all appropriate changes are recorded accurately in the cost baseline Preventing incorrect, inappropriate, or unauthorized changes from being included in the cost baseline. Informing appropriate stakeholders of authorized changes.

Inputs to Cost Control

  

Cost Baseline Performance Reports



Provide information about cost performance such as which budgets have been met and which have not. It also alerts the project team to issues which may cause Problems in the future. Change Requests



These may occur in many forms-oral or written, direct or indirect, externally or internally initiated, and legally

mandated or optional. These may require increasing the budget or may allow decreasing it.

Tools and Techniques for Cost Control

Cost Change Control System 

It defines the procedures by which the cost baseline may be changed. It includes the paperwork, tracking systems, and approval levels necessary for authorizing changes.

Performance Measurement 

It helps to assess the magnitude of any variations which do occur.

Additional Planning

Perspective changes may require new or revised cost estimates or analysis of alternate approaches. Computerized Tools Outputs from Cost Control

    

Revised Cost Estimates Budget Updates Corrective Action Estimate at Completion

 It is a forecast of total project costs based on project performance. Lessons Learned

OBJECTS OF COST CONTROL



To have a knowledge of the profit and loss of the project throughout the duration of the project.

PROJECT PROFITS

1. Client payments. 2. Sale of surplus or scrap material and plant 3. Payments for plants or labor by others, where, this plant or labor is , from time to time not required for the project. PROJECT LOSSES

1. Labor and site office costs 2. 3. 4. 5. 6.

Plant costs Site overheads i.e. site facilities, access roads and office etc Cost of tendering including bonds, insurance, etc. Material costs. Head office overheads proportioned over all current projects.

To have a comparison between the actual project performance and that conceived in the original project plan. 

Comparison is basically done according to the following bases:

 

According to units of production According to line items; e.g., labour, material, equipment, overheads, ---

Provides feedback data on actual project performance to future project planning.

Resource Levelling Allocation Management Techniques RESOURCES

   

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Means to complete project activities are called RESOURCES. Examples are People, Machinery, Material, Capital, Time, etc. Peak demands of resources over short periods is undesirable. Resources may be limited or unlimited in nature from project to project.

Resource Utilization Factor



The degree to which a resource may be used is measured in terms of a Resource Utilization Factor.

Mathematically, Usable Resources x Days Used x 100 R.U.F. (%) = Usable Resources x Days available. Resource Profile



Plot of daily Resource requirements versus time is called

  

Resource Profile Resource-use Graph Histogram

Resource Allocation

To assign required resources to work activities such that available resources are not exceeded. Resource Leveling

 

Smoothening of a resource demand is called Resource leveling. Resource leveling is an attempt to assign resources to project activities in a manner that will improve productivity and efficiency.

Ideal Condition

Early-start and Late-start Histograms

Ideal Level Histogram

Practical & Target Histogram

Objects of Resource Leveling

   

Fixed Crew Size Learning Curve Start-up Problems Completion Congestion

Techniques for Resource Leveling



Sum of Resources Square method

 

Burgess Leveling Procedure Wiest Leveling Procedure

Limited Resource Allocation

  

Where resources e.g., plant, labour, materials (or capitals) are restricted, the activities have to be rescheduled to satisfy this form of constraint. T his will imply scheduling those activities that use such resources, in a sequential or serial fashion. And this might create the situation where activities overrun their allowable float. If resource limitations are known at the outset, for example, only one site crane is available, then the original network plan for the project can include this constraint. In certain cases, it may be possible to hire additional plant to cover peak requirements; in this case no rescheduling of the activities is called for

Algorithm

1. Calculate initial early start (ES) and late start (LS) time for each activity in the project, and set time now equal to1, i.e., T = 1 2. Determine the initial eligible activity set (EAS), i.e., those activities with all predecessor activities scheduled. 3. From among the members of the current EAS, determine the ordered scheduling set (OSS) of activities i.e., activities with ES < T, ordered according to LS with smallest values first and within this characteristic, according to least activity duration first. 4. Consider the activities in OSS in the order listed and schedule those activities for which sufficient resources are available for the duration of the activity. As activities are scheduled, update the level of resources available, and update the members of EAS. 5. Have all activities been scheduled, i.e., is EAS empty set ? If Yes STOP If No Set T new = T old + 1, and compute new ES times for the updated EAS. 6. Go to step 3 and continue. EXAMPLE

Reschedule the Project given in Figure keeping in view the limitation of Resources L to be 8 per day and M to be 6 per day.

Let T = 1 EAS : A B C (E F) ES : 1 1 1

LS : 6 1 7 OSS : B A C Schedule B to days 1-2 Remove B from EAS Add F to EAS Let T = 2 EAS : A C E F ES : 2 2 3 3 LS : 6 7 4 3 OSS : A C No Activity can be scheduled on T = 2 Let T = 3 EAS : A C E F (I D) ES : 3 3 3 3 LS : 6 7 4 3 OSS : F E A C Schedule F to days 3-10 Remove F from EAS Schedule E to days 3-7 Remove E from EAS. Schedule A to days 3-4 Remove A from EAS EAS Add I & D to EAS Let T = 4 EAS : C I D ES : 4 8 5 LS : 7 9 8 OSS : C No Activity can be scheduled on T = 4 Let T = 5 EAS : C I D ( G ) ES : 5 8 5 LS : 7 9 8

OSS : C D Schedule C to day 5 Remove C from EAS Add G to EAS Let T = 6 EAS : I D G ES : 8 6 6 LS : 9 8 8 OSS : G D No Activity can be scheduled on T = 6 Note: G and D have same LS. These are ordered on less duration first.

Project Control Schedule Control Value Engineering Project Control

   

Cost control Cash Flow Analysis Schedule Control Material Management

Cost Control

Advertisements Possible corrective actions could include:     Schedule Control

Adding additional trade workers or crews Adding or removing equipment Working overtime Bringing in additional subcontractors

 

Critical path - By definition, activities on the critical path will delay the entire project if they are delayed Physical progress can be compared with the financial progress to determine if the project is:

 

on schedule or late over budget or under budget

Materials Management

Ensure that materials are delivered in a timely manner to the site in the quantity and quality required. When materials arrive they are:   

Counted Inspected if necessary, Tested

Must determine the latest order date accounting for the: 

  

shop drawing

  

Preparation submission and approval time

lead time required for fabrication shipping Too many materials stored on the site can lead to problem of:

  

space allocation weather damage theft

Construction Related Design

Temporary structures such as:      

Scaffolding Forms Temporary bridges Shoring Cofferdams Rigging must be designed by the contractor

Risk Management

Risks are inherent in construction  

      

Industry is moving toward allocating risks to the party most able to control the specific risk Managing risks means:

  

minimizing risks insuring against risks

and sharing risks Construction risks - inability of a subcontractor to perform Economic risks - cost escalation Political/public risks - disapproval of the required project permits Physical risks - subsurface conditions Contractual and legal risks - risks assigned by contract over which the contractor has no control Design risks - a project design that is not constructible Worker injured or kille

 

A job accident that injures the publi A construction vehicle is involved in an accident off the project

Risks are best assumed by the party with the ability to best control the risk The best way to manage risks is to avoid them, but the construction industry is characterized by risks!    

Contractors manage risks by purchasing insurance Examining the contract language addressing changed conditions… Contractor safety programs Subcontracting is also a form of risk management –require performance and payment bonds

Value Engineering (VE)

  

Function analysis or value analysis Main objective to reduce project cost, without reducing the quality of the structure VE exists because contractors know better ways to build projects, and owners are willing to pay for that knowledge!!

Policies of Management of Construction Projects Policies of Management



Factors contractors consider in deciding whether or not to bid a particular project include:

 

Advertisement s 

Location of the work Factors Contractors Consider

  

Identity of the owner Availability of key company personnel Experience in the type of work solicited

Factors Contractors Consider

 

Whether or not there is financing for the project Size of the project.

Bid Preparation

Bid preparation is expensive! In preparing a bid, contractors must consider the costs of:    

Equipment Labor Materials Subcontractors

Consider the costs of:  

Job and company overhead, contingency, and profit Should also consider the number of competitor bidders and the bidding history of those competitors on similar projects

Award Phase

 

Owner provides:

 Builder’s Risk insurance Successful bidder must provide:     

Payment and performance bonds Workers compensation insurance Liability insurance List of subcontractors Detailed project schedule

Notice to Proceed

Contractor cannot begin the work until the Notice to Proceed is received – so Use the time between bid opening and contract award for detailed pre-project planning. Pre-project planning

Planning how the work will proceed and in what sequence     

Construction procedures Type of equipment to be used Job access Location of the field office and storage areas Final selection of subcontractors and suppliers

Pre-project planning

  

Cash flow analysis should be completed to determine if the company needs to borrow money Detailed project schedule is prepared Work break down (WBS) and pay schedule are planned

Construction Phase

Size of the contractor’s on-site project management organization is a function of the size and complexity of the project.

The 5 Golden Rules of Project Management Rule 1: Time Management is Critical

To deliver your project on time, you need to manage time carefully. To do this, make sure every task is listed in a Project Plan and that they are scheduled to occur precisely when they need to. Advertisements

Every week, update your plan with the time spent completing tasks and identify whether each task is ahead or behind schedule. Track the % complete of each task and if it's behind schedule, then get it back on track by assigning more resource or reducing the scope of the task. Don't let tasks slip. Be vigilant. You can use Primavera Project Planner Software or MS Project management software

Rule 2: Track Costs and Manage Finances

Every element of your project incurs a cost. You need to identify all of the planned costs upfront and get them approved by your manager. Then record every expense as it occurs - including people, equipment and materials. Check that your actual expenditure does not exceed your planned expenditure. And if it does, then you need to cut back. If you're running over budget, tell your Project Sponsor early.

Rule 3: Ensure Quality Targets are Set

You need to specify upfront exactly what it is that the project will deliver (i.e. the "deliverables" ). Then set targets for the quality of these deliverables. Get your quality targets agreed by your customer. Then every week, review the quality of each deliverable produced by the project. If it's not up to standard, fix it immediately. Never wait until the end of the project before fixing up quality issues.

Rule 4: Control Scope at the Micro Level

Your scope is defined as "the set of deliverables that need to be produced by the project". So make sure that you know what your scope is, try not to let anyone change it. Check every week that your team is working on "just" the set of deliverables agreed, and nothing more. Check that every deliverable being produced exactly matches the specification you've defined for it. Note: An increase in the scope of your project will make it harder to deliver.

Rule 5: Resolve Issues Early

If issues arise during the project, then resolve them early. Pounce on every issue before it delays your project. Record it formally and then track it until it's resolved. Unresolved issues lead to delays which lead to project failure. Stay safe – resolve issues early

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