Pert and Cpm2

8/13/2019 Pert and Cpm2

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17-2 Project Management

Developed in 1950sCPM by DuPont forchemical plantsPERT by U.S. Navy forPolaris missile

maintenance


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The Network Diagram

Network (precedence)diagram

Activity-on-arrow (AOA)

Activity-on-node (AON) Activities

Events

Slack is the amount of timean activity can be delayedwithout delaying the project

maintenance


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The Network Diagram (contd)Path

Sequence of activities that leads from thestarting node to the finishing node

Critical pathThe longest path; determines expected projectduration

Critical activities Activities on the critical path

Slack Allowable slippage for path; the difference thelength of path and the length of critical path


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Project Network Activity on Arrow

1

2

3

4

5 6

Locatefacilities

Order furniture

Furnituresetup

Interview Hire andtrain

Remodel

Movein

AOA


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Project Network Activity on Node

1

2

3

5

6

Locatefacilities

Order furniture

Furnituresetup

Interview

Remodel Movein

4

Hire andtrain

7S

AON


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Time Estimates

DeterministicTime estimates that are fairly certain

Probabilistic

Estimates of times that allow for variation


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1

2

3

4

5 6

8 weeks

6 weeks

3 weeks

4 weeks 9 weeks

11 weeks

1 week

Movein

Deterministictime estimates


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Routs to reach from 1 to 6

1) 1-2-4-5-6 (16weeks )

2) 1-2-5-6 ( 20 weeks )

3) 1-3-5-6 ( 14 weeks )


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1

2

3

4

5 6

8 weeks

6 weeks

3 weeks

4 weeks 9 weeks

11 weeks

1 week

Movein

Deterministictime estimates


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Example 1 Solution

Path Length(weeks)

Slack

1-2-3-4-5-61-2-5-61-3-5-6

182014

206

Critical Path


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Network activitiesES: early start (As soon as you can start the activity)EF: early finish (As soon you can finish the activity)LS: late start ( For back calculations)LF: late finish ( For back calculations)

Used to determineExpected project duration

Slack timeCritical path

Computing Algorithm


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Computing ES, EF, LF, LSSlack (LS-ES)

Activity duration ES EF LF LS LS-ES1-2 8 0 8 8 0 0

1-3 4 0 4 10 6 62-4 6 8 14 16 10 22-5 11 8 19 19 8 0

3-5 9 4 13 19 10 64-5 3 14 17 19 16 25-6 1 19 20 20 19 0

17 15 P j M


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CPM

EXAMPLES OF CRITICALPATH METHOD

17 16 P j M


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Picnic program


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17 18 P j t M g t

Without precedence


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Picnic program Activities Time in min

A PREPARE TEA 20

B PREPARE FRUITS 5

C PREPARE SANDWICHES 10

D PREPARE BASKET 10E DRESS UP 15

F COLECT BLANKETS 5

G PREPARE SUIT CASE 20

H LOAD CAR 10

I GET GAS 10

J GET SPARES 15

K DRIVE 30

Without precedence

17 19 Project Management

HOW TO ARRANGE IT


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3

10

2

4

8

5

6

9

1

7

HOW TO ARRANGE IT



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Picnic program

Activities Time in min

A 1,3 PREPARE TEA 20

B 1,2 PREPARE FRUITS 5

C 2,3 PREPARE SANDWICHES 10D 3,4 PREPARE BASKET 10

E 4,6 DRESS UP 15

F 4,5 COLECT BLANKETS 5

G 5,6 PREPARE SUIT CASE 20H 6,7 LOAD CAR 10

I 7,8 GET GAS 10

J 8,9 GET SPARES 15

K 9,10 DRIVE 30



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NODE DIAGRAM

` A D E H I J K20 10 15 10 10 15 30

5B 10 C 5 F 20 G

MAX TIME = 120 MIN.

1 3 6 9 108

52

74



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NODE DIAGRAM

CRITICAL PATH 1-3-4-5-6-7-8-9-10

1 3 6 9 108

52

74



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CPM

EXAMPLE CONSTRUCTIONOF A ROOM

http://www.animationlibrary.com/a-l/?n=image.php3&image_id=8434


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ACIVITIES TIME IN DAYS

A 1-3 FOUNDATION 2

B 1-2 BRICKS COLLECTION 1

C 2-3 CEMENT COLLECTION 1

D 3-4 FIRST DPC 3

E 4-6 CURING 2

F 4-5 BRICKS COLLECTION 1

G 5-6 CEMENT COLLECTION 1

H 6-7 2 ND DPC 2

I 7-9 CURING 2

J 7-8 BRICKS COLLECTION 1

K 8-9 CEMENT COLLECTION 1

L 9-11 WALLS 5

M 10-11 EARTH FILLING 1

N 11-13 ROOF 21

O 11-12 DOOR AND WINDOW 5

P 12-16 SERVICES 15

Q 13-14 PLASTERS 2

R 14-16 FLOORS 15

S 14-15 WHITE WASH 2


Optimization MSc

maintenance


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NODE DIAGRAM

1

10

43

1552

1696 7 11

8

13 14

12

Optimization MScmaintenance



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j g



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j g

FIND OUT THE CRITICAL PATH



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j g

PERT

Program

Evaluation andReviewTechnique

http://www.animationlibrary.com/a-l/?n=image.php3&image_id=12345


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j g

Probabilistic Time Estimates

Optimistic timeTime required under optimal conditions

Pessimistic time

Time required under worst conditions

Most likely time

Most probable length of time that will be required



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Probabilistic Estimates

Activity

start

Optimistic

time

Most likely

time (mode)

Pessimistic

time

to tptm te



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Expected Time

te =to + 4tm +tp

6

te = expected timeto = optimistic timetm

= most likely timetp = pessimistic time



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Variance

2 = (tp to)2

36

2 = varianceto = optimistic time

tp = pessimistic time



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Example

3-4-5d

3-5-7e

5-7-9f

2-4-6b

4-6-8h

Optimistictime Most likelytime Pessimistictime



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Path Probabilities

Z = Specified time Path mean

Path standard deviation

Z indicates how many standard deviationsof the path distribution the specified time

is beyond the expected path duration.



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17

Weeks

Weeks

Weeks

Weeks

10.0

16.0

13.5

1.00

1.00

a-b-c

d-e-f

g-h-i


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Advantages of PERT

Forces managers to organize

Provides graphic display of activities

IdentifiesCritical activities

Slack activities 1

2

3

4

5 6


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Pert and Cpm2

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