3 project management project crashing

7/28/2019 3 Project Management Project Crashing

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33 CHAPTER THREE

ProjectProjectManagement:Management:

Project CrashingProject Crashing

ProjectProjectManagement:Management:

Project CrashingProject Crashing

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A project that your company has undertaken has the followingactivities, which are listed below:

ActivityPreceding

ActivityNormal time

(weeks)Normal cost

($)Crash time

(weeks)Crash cost

($)

ABC

DEFGHJ

--

A

CB, CD, E

FE, G

H

465

8108953

400060004000

300015006000200060003000

25-

47-7--

60006500

-

78003600

-6000

--

The normal costs shown for each activity are the costs to complete eachactivity by working under normal conditions. The crash time represents theshortest time in which the activity can be completed given the use of costlymethods of completion. Assume that it is possible to reduce the normal timeto crash time in steps of one week and that the extra cost will be proportionalto the time saved. In addition, there is a site cost of $1,500 per week.

Problem


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1.1. Compute the crash cost per time period.Compute the crash cost per time period.

Crash costCrash costper periodper period ==

(Crash cost(Crash cost Normal cost)Normal cost)

(Normal time(Normal time Crash time)Crash time)

ActAct AA BB CC DD EE FF GG HH JJ

CCCC 10001000 500500 -- 12001200 700700 -- 20002000 -- --

MaxMax 22 11 -- 44 33 -- 22 -- --

2.2. Using normal activity times, find the criticalUsing normal activity times, find the criticalpath and identify the critical activities.path and identify the critical activities.

Determine the minimum cost of undertaking this

project and state its associated time of completion

3 4

A

4

40

B

6

60

Start

0

00

C

5

94D

8

179

E

10

199 F

8

2719 G

9

3627

H

5

4136J

3

4441

44414136

36272719199

19119440

93

Critical path:

A-C-E-F-G-H-J

Project Duration = 44 weeks

Total cost = $35,500+(44x1500)=$101,500

Network Diagram


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Network Diagram - Crashing

A1000

2

4

40

B5001

6

60

Start

0

00

C--5

94D

12004

8

179

E7003

10

199F--8

2719G

20002

9

3627

H--5

4136J--3

4441

44414136

36272719199

19119440

93

OBJECTIVE minimize totalcost

One critical path min. crashcost per week on this criticalpath $700 (activity E) thencrash activity E by 2 weekswhy 2 weeks?

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A1000

2

4

40

B5001

6

60

Start

0

00

C--5

94D

12004

8

179

E7001

8

179 F--8

2517 G20002

9

3425

H--5

3934J--3

4239

42393934

34252517179

1799440

93

Duration: 42

New Total Cost =101500+(700x2) (2x1500) =$99,900

Now two critical paths:ACDFGHJ & ACEFGHJ min.crash cost per week for both

paths$1000 (activity A) thencrash activity A by 2 weeks.


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A1000

0

2

20

B5001

6

60

Start

0

00

C--5

72D

12004

8

157

E7001

8

157F--8

2315G

20002

9

3223

H--5

3732J--3

4037

40373732

32232315157

1577220

71

Duration: 40

New Total Cost =99,900+(1000x2) (2x1500) =$98,900

Two critical paths:ACDFGHJ &ACEFGHJSTOPsince min.crash cost per week for both

paths ($1200+$700) (D & E)greater than $1500site cost.

3 project management project crashing

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