Construction Sequence Analysis for Optimum Cost and Duration

This article provides an analysis of the construction sequence for optimum cost and duration. It includes a network diagram, evaluation of cost and time schedule, and project crashing. The least time and least cost of the project is 18 days and 255500 cost respectively.

CONSTRUCTION
SEQUENCE

Analysis of network on the basis of normal duration for activities
On looking at the network diagram above, the following path for completing the construction
project has been obtained.
A – E – F –D = 6 + 6 + 7 + 6 = 25 weeks
Cost = 12000 + 36000 + 10000 + 18000 = 76000
Indirect cost = 25 * 2300 = 57500
Total cost = 133500
A – E – I – C – D = 6 + 6 + 2 + 3 + 6 = 23 weeks
Cost = 12000 + 36000 + 20000 + 18000 + 18000 = 104000
Indirect cost = 23 * 2300 = 52900
Total cost = 156900
A – B – C – D = 6 + 8 + 3 + 6 = 23 weeks
Cost = 12000 + 24000 + 18000 + 18000 = 72000
Indirect cost = 23 * 2300 = 52900
Total cost = 124900
A – G – H – D = 6 + 5 + 8 + 6 = 25 weeks
Cost = 12000 + 20000 + 40000 + 18000 = 90000
Indirect cost = 25 * 2300 = 57500
Total cost = 147500
The cost and time schedule evaluated above indicates that the optimum cost and optimum time
of the project is 124900 and 23 weeks respectively.
However, as there are two critical paths due to having similar duration on two paths through
which project could be accomplished, therefore, the project crashing will be done as follows:

Activity Normal
duration
Crash
duration
Normal
cost
Crash
cost
Time to
be
crashed
Activity
crashing
cost
Crash
cost
per
week
A 6 4 12000 20000 2 8000 4000
B 8 4 24000 48000 4 24000 6000
C 3 2 18000 20000 1 2000 2000
D 6 4 18000 24000 2 6000 3000
E 6 4 36000 54000 2 18000 9000
F 7 6 10000 50000 1 40000 40000
G 5 3 20000 30000 2 10000 5000
H 8 6 40000 50000 2 10000 5000
I 2 2 20000 20000 0 0 0
Project crashing
Days Activity
crashed
Incremental
cost of
crashing
Cumulative
crashing
cost
Indirect cost Normal
direct
cost
Total cost
25 - - - 25 * 2300 = 57500 198000 255500
24 D 3000 3000 24 * 2300 = 55200 198000 256200
23 D 3000 6000 23 * 2300 = 52900 198000 256900
22 A 4000 10000 22 * 2300 = 50600 198000 258600
21 A 4000 14000 21 * 2300 = 48300 198000 260300
20 E,G 14000 28000 20 * 2300 = 46000 198000 272000
19 E,G 14000 42000 19 * 2300 = 43700 198000 283700
18 F,C,H 47000 89000 18 * 2300 = 41400 198000 328400

Working notes:
Paths Duration Round
1
Round
2
Round
3
Round
4
Round
5
Round
6
Round
7
A – E – F –D 25 24 23 22 21 20 19 18
A – E – I – C –
D
23 22 21 20 19 18 17 16
A – B – C – D 23 22 21 20 19 19 19 18
A – G – H – D 25 24 23 22 21 20 19 18
From the above analysis, it has been identified that optimum cost and duration is 255500
and 25 days respectively. This is because while completing project within the duration of 25
days, there will be least cost incurred for the project. Also, the maximum crashing of the project
gives us the earliest duration within which the project could be accomplished that is, 18 days.
Accordingly, the least time and least cost of the project is 18 days and 255500 cost respectively.