Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
1
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.
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
2
Example
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
3
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.
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
4
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
5
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
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
6
Traditional A/E PDS
Owner
A/E GC
Sub1 Sub2 Sub3 Sub4
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
7
Professional Construction Management
Owner
CM
WP1 WP2 WP3 WP4 WP4
A/E
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
8
Developing WPs
• Develop WBS – Identify WPs
• Draw a WPs Network
WP1
WP2
WP3
WP4
WP5
WP6
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
9
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
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
10
Developing WPs• Bid a WP at the most short time so as to
stimulate competition (Keep away uncertainty)
WP1 WP2 WP3 WP4
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
11
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
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
12
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
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
13
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.
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
14
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.
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
15
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
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
16
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
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
17
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
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
18
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
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
19
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 ,
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
20
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
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
21
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
BCWP
ACWP BAC = ToDateCPI
BAC
To Date Variance Time
= ToDateToDate
ToDate Time1BCWS
BCWP
Budgeted 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
More accurate estimate can be reached by using these formulas:
Estimated Cost At Completion (EAC)
= ThisPeriod
DateToToDate CPI
)BCWP-(BACACWP
Estimated Time At Completion (ETAC)
= ThisPeriod
ToDateThisPeriodToDate BCWP
)BCWP-(BACTime Time
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
22
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
23
Project Example
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
24
Project Example
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
25
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
Spring 2008, King Saud University
Time and Cost ControlDr. Khalid Al-Gahtani
26
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: 765442
449 =$812 K
Summary: Engineering work is behind schedule and a cost overrun is occurring
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