Engineering Project Management
Edited by Foxit Reader
Copyright(C) by Foxit Corporation,2005-2009
For Evaluation Only.
Eng. Imad Zreid
Precedence Diagram Method (PDM)
Example 1
Activity
A
B
C
D
E
Preceded by
ــــــ
A
A
C
B,D
Duration
4
3
2
5
2
1- Forward Pass ( calculating Earliest Start and Earliest Finish)
2- Backward Pass ( calculating Latest Start and Latest Finish)
1
Engineering Project Management
Edited by Foxit Reader
Copyright(C) by Foxit Corporation,2005-2009
For Evaluation Only.
Eng. Imad Zreid
3- Float calculation ( calculating Total Float and Free Float)
Activity Total Float (TF) = Activity LS –Activity ES = Activity LF –Activity EF
Free Float (FF) = min. ES of Activity’s successors – Activity EF
Activity A
TF = LS- ES = 0 – 0 = 0
FFi = ESj – Efi = 4 – 4 = 0
Activity B
TF = LS- ES = 8 – 4 = 4
FFi = ESj – Efi = 11 – 7 = 4
Activity C
TF = LS- ES = 4 – 4 = 0
FFi = ESj – Efi = 6 – 6 = 0
Similarly you can calculate floats for the other activities.
Example 2
Draw PDM , complete the table ,and determine the critical Path
Activity
Preceded
by
A
B
C
D
E
F
G
H
ــــــ
A
A
ــــــ
B,C
D
E,D
G
START
Duration
ES
LS
FINISH
EF
LF
FF
TF
3
2
5
3
12
5
18
0
3
2
Engineering Project Management
Solution
3
Edited by Foxit Reader
Copyright(C) by Foxit Corporation,2005-2009
For Evaluation Only.
Eng. Imad Zreid
Engineering Project Management
Edited by Foxit Reader
Copyright(C) by Foxit Corporation,2005-2009
For Evaluation Only.
Eng. Imad Zreid
Exercise 1
Draw PDM and calculate activities times and floats. Determine the critical path.
Activity
A
B
C
D
E
F
Preceded by
ــــــ
ــــــ
A,B
A,B
A,B
C,D,E
Duration
8
4
3
8
5
5
Ans. Project duration = 21 day, critical Path : A-D-F
Exercise 2
Draw PDM and calculate activities times and floats. Determine the critical path.
Activity
A
B
C
D
E
F
G
H
I
J
K
Preceded by
ــــــ
ــــــ
A
A
B
E
E
C,D,F
H,G
H
I,G
Duratio
n
3
2
4
5
3
6
4
5
7
2
5
Ans. Project duration = 28 day, critical Path : B-E-F-H-I-K
4
0
