Download Time-Cost

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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Time and Cost Control
Dr. Khalid Al-Gahtani
1
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.
Fall 2006,
King Saud University
Time and Cost Control
Dr. Khalid Al-Gahtani
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Fall 2006,
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Time and Cost Control
Dr. Khalid Al-Gahtani
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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
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Time and Cost Control
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Sequencing
5
Traditional A/E PDS
Owner
A/E
Sub1
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GC
Sub2
Sub3
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Dr. Khalid Al-Gahtani
Sub4
6
Professional Construction Management
Owner
A/E
WP1
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CM
WP2
WP3
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Dr. Khalid Al-Gahtani
WP4
WP4
7
Developing WPs
•
Develop WBS
– Identify WPs
•
Draw a WPs Network
WP3
WP1
WP4
WP6
WP2
WP5
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King Saud University
Time and Cost Control
Dr. Khalid Al-Gahtani
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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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King Saud University
Time and Cost Control
Dr. Khalid Al-Gahtani
9
Developing WPs
•
Bid a WP at the most short time so as to
stimulate competition (Keep away
uncertainty)
WP1
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WP2
Time and Cost Control
Dr. Khalid Al-Gahtani
WP3
WP4
10
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
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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.
Fall 2006,
King Saud University
Time and Cost Control
Dr. Khalid Al-Gahtani
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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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Time and Cost Control
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Type of performance
BCWP
BCWS
ACWP
Fast & Low
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BCWS
15
Type of performance
ACWP
BCWP
BCWS
Fast & High
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Type
of performance
Fast & Low
BCWS
BCWP
ACWP
Slow & Low
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High
TypeFast
of&performance
BCWS
ACWP
BCWP
Slow & High
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Cost Index
Cost 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
ACWP  BCWP
=
,
BCWP
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King Saud University
Time and Cost Control
Dr. Khalid Al-Gahtani
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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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King Saud University
Time and Cost Control
Dr. Khalid Al-Gahtani
20
Budgeted Cost At Completion (BAC)
= Total ofCost/Time
Quantities  UnitAt
price
Estimated
Completion
Planned
BudgetedTime
CostAtAtCompletion
Completion(TAC)
(BAC)
= Total of Quantities
Productivity
Quantities ÷ Planned
Unit price
Estimated
CostAtAtCompletion
Completion(TAC)
(EAC)
Planned Time
ACWP
BAC Productivity
=
Total
of
Quantities
÷
Planned
ToDate
=
 BAC =
BCWP
CPI
ToDate
ToDate
Estimated Cost At Completion (EAC)
More accurate estimate can be reached by using these formulas:
To Date Variance
Time
ACWPToDate
BAC
 BAC
=
Estimated=Cost At Completion
(EAC)
CPI ToDate
ToDate
BCWP

BCWP
ToDate
= 
 1 - BCWP
Time ToDate
(BAC
To Date )
= ACWP

ToDateToDate
To Date
Variance
Time
 BCWS

CPI ThisPeriod
 BCWP
Fall 2006,
Time andCost
Control
Estimated
Time
At
Completion
(ETAC)
ToDate
=

 1  Time

King Saud University

Dr. Khalid Al-Gahtani ToDate
21
Fall 2006,
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Time and Cost Control
Dr. Khalid Al-Gahtani
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Project Example
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Time and Cost Control
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Project Example
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Time and Cost Control
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Project Example
ENGINEERING SUBTASKS STATUS AT END OF MONTH 3
(thousands of dollars)
Task
System design
Subcontract specs
Material tests
Specs review
Drafting
Fabrication/assembly support
Fabrication/assembly process
Test support
Engineering release and review
Total
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Status
Completed
Started
Completed
Started
Started
Completed
Started
Started
Not Started
Time and Cost Control
Dr. Khalid Al-Gahtani
BCWS
$131.0
132.0
22.0
22.0
97.0
29.0
100.0
21.0
BCWP
$131.0
82.0
22.0
15.0
59.0
29.0
63.0
21.0
ACWP
$144.0
84.0
22.5
15.5
59.0
36.0
67.0
21.0
$554.0
$422.0
$449.0
25
Project Example
Figure 5-9 Status summary of engineering subtasks in progress and estimate to complete.
Task
Subcontract specs
Specs review
Drafting
Fabrication/assembly process
Test support
BCWS BCWP ACWP
Status
$132
$82
$84 Behind schedule and over cost
22
15
15.5 Behind schedule and over cost
97
59
59
Behind schedule but within cost
100
63
67
Behind schedule and over cost
21
21
21
On schedule and within cost
449
Estimated to complete:
 765 =$812 K
442
Summary: Engineering work is behind schedule and a cost overrun is occurring
Fall 2006,
King Saud University
Time and Cost Control
Dr. Khalid Al-Gahtani
26