Time cost-control

Spring 2008, King Saud University

Time and Cost ControlDr. Khalid Al-Gahtani

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Updating Construction Schedules• Procedure:

– Change the duration of all completed activities to zeros.

– Identify all activities on which work is currently proceeding as live activities.

– Put early start time of live activities equals the update time and their durations equal the remaining duration given by the update report.

– Change durations of future activities as given in the update report.

– Carry out network analysis in the normal way and prepare a new activity schedule.



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Example



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Example• The position of the activities at the end of the fifth

week is as follows:– Activities B, C, D and E have been completed.– Activity F is ready to start at beginning of week 6.– Remaining duration of activity H is 4 weeks.– Remaining duration of activity I is 3 weeks.– Activity G will not start until end of week 7.– Volume of work in activity L has been increased by 33%

approximately.– Activity J has been omitted.– It is decided to shorten activity K by 2 weeks.

• Construct the updated schedule indicating the critical path and showing new activities times.



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Work Breakdown Structure • WBS divides the project into recognizable systems (work

packages, WP’s or Bid Packages) that responsible assignable work units, and for which accountability can be expected/assigned.

Project

Work Packages

Activities Sequencing



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Traditional A/E PDS

Owner

A/E GC

Sub1 Sub2 Sub3 Sub4



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Professional Construction Management

Owner

CM

WP1 WP2 WP3 WP4 WP4

A/E



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Developing WPs

• Develop WBS – Identify WPs

• Draw a WPs Network

WP1

WP2

WP3

WP4

WP5

WP6



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Developing WPs• Each WP must have

– One Performing Agency (PA) such as Subcontractor

– One Responsible Agency (RA) such owner’s Project Engineers

• Interconnection between Packages should be district and clear to facilitate coordination

WP1 WP2

WP3



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Developing WPs• Bid a WP at the most short time so as to

stimulate competition (Keep away uncertainty)

WP1 WP2 WP3 WP4



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Cost Coding System

• Cost Central level = Lowest level at which functional responsibility for individual WBS element exit. – XXX XXX XXX XXX

• An example:– 0534.02220.21.A.00.cf34



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MASTERFORMAT system TABLE 1 Major Divisions in the Uniform Construction Index

0 Conditions of the contract 1 General requirements 2 Site work 3 Concrete 4 Masonry 5 Metals 6 Wood and plastics 7 Thermal and moisture prevention 8 Doors and windows

9 Finishes 10 Specialties 11 Equipment 12 Furnishings 13 Special construction 14 Conveying system 15 Mechanical 16 Electrical



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Cost Coding System• Advantages of coding systems are:

– Provide a numbering system to replace verbal descriptions of items.

– These codes reduce the length or complexity of the information to be recorded.

– aids consistency in definitions and categories between projects and among the various parties involved in a project.

– aid in the retrieval of historical records of cost, productivity and duration on particular activities.

– electronic data storage and retrieval operations are much more efficient with standard coding systems.



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Project Cost Control • Budgeted Cost of Work Scheduled (BCWS) is the

budgeted amount of cost of the work scheduled to be accomplished in a given time period (including support and allocated overhead).

• Budgeted Cost of Work Performed (BCWP) is the budgeted amount of cost for the work completed in a given time period, including support effort and allocated overhead. (This is sometimes referred to as “earned value of work accomplished”.)

• Actual Cost of Work Performed (ACWP) is the amount reported as actually expended in completing the particular work accomplished within a given time period.



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Type of performance BCWP

BCWS

ACWP

Fast & Low

ACWP

BCWP

BCWS

Fast & High

B CW S

B CW P

A CW P

S low & Low

BCWS

BCWP

S low & High

ACWP



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BCWS

ACWP

Fast & Low

ACWP

BCWP

BCWS

Fast & High

B CW S

B CW P

A CW P

S low & Low

BCWS

BCWP

S low & High

ACWP



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BCWS

ACWP

Fast & Low

ACWP

BCWP

BCWS

Fast & High

B CW S

B CW P

A CW P

S low & Low

BCWS

BCWP

S low & High

ACWP



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BCWS

ACWP

Fast & Low

ACWP

BCWP

BCWS

Fast & High

B CW S

B CW P

A CW P

S low & Low

BCWS

BCWP

S low & High

ACWP



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Cost IndexCost Variance = BCWP ACWP +ve Under Budget Cost Variance 0 Within Budget - ve Over Budget Cost Performance Index = BCWP/ACWP > 1 Under Budget CPI = 1 Within Budget < 1 Over Budget % cost overrun/underrun

= BCWP

BCWPACWP ,



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Schedule Index

Schedule/Performance Variance=BCWP-BCWS. +ve Ahead Schedule Sch./per. Variance 0 On Schedule -ve Behind Schedule Schedule Performance Index = BCWP/ BCWS. >1 Ahead Schedule SPI =1 On Schedule <1 Behind Schedule



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Estimated Cost/Time At CompletionBudgeted Cost At Completion (BAC)

= Total of Quantities Unit price

Planned Time At Completion (TAC)

= Total of Quantities ÷ Planned Productivity

Estimated Cost At Completion (EAC)

= ToDate

ToDate

BCWPACWP BAC =

ToDateCPIBAC

To Date Variance Time

= ToDateToDate

ToDate Time1BCWSBCWP

Budgeted Cost At Completion (BAC)

= Total of Quantities Unit price

Planned Time At Completion (TAC)

= Total of Quantities ÷ Planned Productivity


= ToDate

ToDate

BCWPACWP BAC =

ToDateCPIBAC

To Date Variance Time

= ToDateToDate

ToDate Time1BCWSBCWP

More accurate estimate can be reached by using these formulas:


= ThisPeriod

DateToToDate CPI

)BCWP-(BACACWP

Estimated Time At Completion (ETAC)

= ThisPeriod

ToDateThisPeriodToDate BCWP

)BCWP-(BACTime Time



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Project Example



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Project Example



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ENGINEERING SUBTASKS STATUS AT END OF MONTH 3 (thousands of dollars)

Task Status BCWS BCWP ACWP System design Completed $131.0 $131.0 $144.0 Subcontract specs Started 132.0 82.0 84.0 Material tests Completed 22.0 22.0 22.5 Specs review Started 22.0 15.0 15.5 Drafting Started 97.0 59.0 59.0 Fabrication/assembly support Completed 29.0 29.0 36.0 Fabrication/assembly process Started 100.0 63.0 67.0 Test support Started 21.0 21.0 21.0 Engineering release and review Not Started

Total $554.0 $422.0 $449.0

Project Example



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Project ExampleFigure 5-9 Status summary of engineering subtasks in progress and estimate to complete.

Task BCWS BCWP ACWP Status Subcontract specs $132 $82 $84 Behind schedule and over cost Specs review 22 15 15.5 Behind schedule and over cost Drafting 97 59 59 Behind schedule but within cost Fabrication/assembly process 100 63 67 Behind schedule and over cost Test support 21 21 21 On schedule and within cost

Estimated to complete: 765442449 =$812 K

Summary: Engineering work is behind schedule and a cost overrun is occurring

Documents

Time cost-control