Question

Use the information contained below to compress one time unit per move using the least cost method.  Reduce the schedule until you reach the crash point of the network. For each move identify what activity(ies) was crashed and the adjusted total cost.

NOTE: The correct normal project duration, critical path, and total direct cost are provided.

Initial project duration: 12              Total direct cost $1000

Page 324, Exercise 1
	Activity	Crash Cost (Slope)	Max. Crash Time	Normal Time	Normal Cost
	A	50	1	3	150
	B	100	1	3	100
	C	60	2	4	200
	D	60	2	3	200
	E	70	1	4	200
	F	0	0	1	150

D

3

B

3

                        

F

1X

A

3

B

3

            

E

4

C

4

                        

Answer 1

Normal project duration =12

Critical path =ACEF

Process of crashing

(a) The uncrashed activities cost $1000. The least cost activity is F with 0 crashing cost. Total cost = 850 Duration =11 days

Total cost =850

(b) The least cost activity to be crashed and on critical path is A which can be reduced by 1 days at a cost of 50. Duration is now 10 days. Cost =900

(b) Activity A can be reduced by one more day at a cost of 50, Duration is 9 days. Cost =950

(c) C the least cost activity is crashed for 60. Duration 8 days. cost =1010.

(d) E can be crashed for 1 day at a cost of 70. Cost is 1080 and duration is 7 days.

(e) Activity C,E,B and D are crashed for 1 week. Cost is 1080+290 =1370. Duration is 5 days.

(f) B and E can be crashed by one day each so the duration becomes 4 days at a cost of 170. Total cost is 1540.

No more crashing is possible.