The document discusses Precedence Diagramming Method (PDM), which is a network modeling technique that is an extension of the traditional arrow diagramming method (ADM) that allows for more flexible relationships between activities including lags. PDM allows for four different precedence relationships between activities: finish-to-start, start-to-start, finish-to-finish, and start-to-finish. The document provides examples of how to calculate earliest and latest start and finish times for activities using forward and backward passes in a PDM network diagram.

1. CPM P3
PRECEDENCE
DIAGRAMMING METHOD
(PDM)

2. CPM P3
What is PDM?
• An extension of the traditional AON
• Network model with additional
relationships
• Introduced in 1964
• More flexible than AON; allow overlaps
• Available on almost all commercial
microcomputer-based PMS

3. CPM P3
Introduction
• Between 20-30% of contracting
organisation in Europe are using
Precedence Diagram
• This technique is more versatile as
compared to other network planning
• Determination of ES, EF, LS and LF is
similar to that of CPM except one has to
take lag into consideration

4. CPM P3
continued
• Availability of lag has made this
technique more adaptable to the
planner’s needs
• this tool can guide the managers in
making critical decisions such as to
deploy resources based on priority
• can assist the client in determining the
duration for extension of time

5. CPM P3
Precedence Diagram’s
Notation
• Earliest start time (ES)
• Earliest finish time (EF)
• Latest start time (LS)
• Latest finish time (LF)
• Duration (D)
• Total float (TF)

6. CPM P3
Advantages &
Disadvantages
• Fewer activities • Complicates manual
• No restraints calculations
• Quicker & easier • May produce
logic different dates on
• Better represents different software
the actual work flow • Updating &
managing change
can be challenging

7. CPM P3
Precedence Relationship
• Four types of precedence relationship
which includes:
– Finish to Start (FS)
– Start to Start (SS)
– Finish to Finish (FF)
– Start To Finish (SF)

8. CPM P3
Finish to Start
Activity A has to finish completely before
Activity B can start
FS
A B

9. CPM P3
Start to Start
Activity B has to start together with Activity A
SS
A B

10. CPM P3
Finish to Finish
Activity B must finish together with Activity A
FF
A B

11. CPM P3
Start to Finish
Activity B finish as soon as Activity A starts
SF
A B

12. CPM P3

13. CPM P3
Lead and Lag
• Lead is the time that • Lag is the time that
an activity precedes an activity follows or
the start or finish of is delayed from the
its successor start or finish of its
predecessor

14. CPM P3
200 250
F&R #1-7 F&R #8-21
4 days 8 days
200 FF 2
300 350
Form&Rebar
Cast #1-7 Cast #8-21
12 days
4 days 2 days
300
Casting PDM vs.
SS 4 6 days AON

15. CPM P3
300 400
FS 5
Casting Set Col. PDM
6 days 9 days
vs.
AON
300 350 400
Casting Curing Set Col.
6 days 5 days 9 days

16. CPM P3
Driving Relationship
• Forward Pass:
– One that results in latest EF time for
successor
• Backward Pass:
– One that results in the earliest LS for the
predecessor

17. CPM P3
0 100 6 FF 4
PDM
Excavation
Forward
6 days
Pass
2 200 14 FF 2
Form&Rebar
SS 2 12 days
10 300 16 21 400 30
FS 5
Casting Set Col.
SS 4 6 days 9 days

18. CPM P3
100 FF 4 PDM
Excavation
Backward
0 6 days 6
Pass
200 FF 2
Form&Rebar
SS 2
2 12 days 14
300 400
FS 5
Casting Set Col.
SS 4 10 6 days 16 21 9 days 30

19. CPM P3
0 100 6 FF 4
PDM Total
Excavation
Float
0 6 days 6
TF=0
2 200 14 FF 2
Form&Rebar
SS 2
2 12 days 14
TF=0
10 300 16 21 400 30
FS 5
Casting Set Col.
SS 4 10 6 days 16 21 9 days 30
TF=0 TF=0

20. CPM P3
0 100 6 FF 4
PDM
Excavation
The
0 6 days 6
Critical
TF=0
2 200 14 FF 2 Path
Form&Rebar
SS 2
2 12 days 14
TF=0
10 300 16 21 400 30
FS 5
Casting Set Col.
SS 4 10 6 days 16 21 9 days 30
TF=0 TF=0

21. ACTIVITY DURATION PREDECESSOR
START 0 -
A 7 START
B 5 START
C 11 A(SS+3)
D 10 START
E 9 B
F 5 A(FS-1)
G 8 A, D
H 8 C
I 4 F, H(FF-2)
J 12 E(FS+2),
G(FF+3)
K 3 E
FINISH 0 I, J, K

22. SS+3
C
11d
A ACTIVITY DURATIO PREDECE
N SSOR
7d
START 0 -
A 7 START
STAR D B 5 START
T 10d C 11 A(SS+3)
0d D 10 START
B
5d

23. SS+3
C H
11d 8d
A FS -1
F
7d 5d
START D G
0d 10d 8d
E 9 B
F 5 A(FS-1)
G 8 A, D
B E
7d 9d H 8 C

24. I 4 F, SS+3 FF-2
H(FF-2)
C H
J 12 E(FS+2) 7d 8d
G(FF+3)
K 3 E
FINISH 0 I, J, K A FS -1 I
F
7d 4d
5d
FF+3
START D G
0d 10d 8d J FINISH
12d 0d
FS+2
B E K
7d 9d 3d

25. SS+3 FF-2
C H
7d 8d
A FS -1 I
F
7d 4d
5d
FF+3
START D G
0d 10d 8d J FINISH
12d 0d
FS+2
B E K
7d 9d 3d

26. FORWARD PASS OPERATION
SS+3 3 14 22 FF-2
14
C H
11d 8d
0 7 6 11 16 20
A FS -1 I
F
7d 4d
5d
0 0 0 10 18 FF+3
10
START D G 16 28 28 28
0d 10d 8d J FINISH
12d 0d
FS+2
0 5 5 14 14 17
B E K
5d 9d 3d

27. BACKWARD PASS
SS+3 3 14 14 22 FF-2
C H
11d 8d
20 28
9 20
0 7 16 20
6 11
A FS -1 I
F
7d 4d
5d
6 13 19 24 24 28
0 0 0 10 18 FF+3
10
STA D G 16 28 28 28
RT 10d 8d J FINISH
0 0d 0 7 17 17 25 12d 0d
16 28 28 28
FS+2
0 5 5 14 14 17
B E K
5d 9d 3d
0 5 5 14 25 28

28. IDENTIFY CP
SS+3 3 6 14 14 6 22 FF-2
C H
*
11d 8d •*
9 20 20 28
0 6 16 8 20
7 6 13 11
A FS -1 I
F
7d 4d
5d
6 13 19 24 24 28
0 0 0 0 7 10 FF+3
10 7 18
STA D G 16 0 28 28 0 28
RT 10d 8d J FINISH
0 0d 0 7 17 17 25 12d 0d
16 28 28 28
FS+2
0 0 5 5 0 14 14 11 17
B E K
5d 9d 3d
0 5 5 14 25 28