Presentation on theme: "CONSTRUCTION SCHEDULING & COST CONTROL By PROF. LIAQAT ALI QURESHI UET TAXILA."— Presentation transcript:
CONSTRUCTION SCHEDULING & COST CONTROL By PROF. LIAQAT ALI QURESHI UET TAXILA
Planning & Scheduling Planning: Process of choosing the method and order of work Scheduling: Process of determining the interrelationship of associated timings of operations.
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
Use of Dummy Activity
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, Projects 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) Activity CodeOperationDependenceEst. Dur. (Days) ENAEarthworks, north abutment-5 ESAEarthworks, south abutmentENA4 CONNConstruction, north abutmentENA14 CONSConstruction, south abutmentESA, CONN12 COMNCompaction, north abutmentCONN2 CIMSCompaction, south abutmentCONS, COMN2 RNBRoad, north of bridgeCOMN2 RSBRoad, south of bridgeRNB,COMS2 PBPrefabricate bridge deck-18 TDTransport deck to sitePB2 EBErect bridge deckTD, CONN, CONS, COMN 3 LBSLay bridge surfaceEB, RNB, RSB2 ICBInstall crash barriers etc.EB1 LLandscapeRNB, RSB1
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.
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
1- 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 1. 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. 2. Historical Information 3. Scope Statement: Contains the project justification and the project objectives.
Inputs to Resource Planning 4. Resource Pool Description: Knowledge of what resources are potentially available. 5. 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 1. 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.
Tools and Techniques for Cost Estimating 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 (a) Influencing the factors which create changes to the cost baseline to ensure that changes are beneficial. (b) Determining that the cost baseline has changed (c) Managing the actual changes when and as they occur
Cost Control 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.
Inputs to Cost Control 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.
Tools and Techniques for Cost Control 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 1 – 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)Plant costs 3)Site overheads i.e. site facilities, access roads and office etc 4)Cost of tendering including bonds, insurance, etc. 5)Material costs. 6)Head office overheads proportioned over all current projects.
OBJECTS OF COST CONTROL 2 – 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: 1) According to units of production 2) According to line items; e.g., labour, material, equipment, overheads, – Provides feedback data on actual project performance to future project planning