PDM (Precedence Diagramming Method) is a technique for planning and scheduling projects using a diagram that shows the logical relationships between activities. It involves identifying activities, determining their logical sequence and duration, and calculating the earliest and latest start and finish times. The critical path in a PDM shows the longest sequence of activities to complete the project with zero float. Managing critical path activities is important for finishing the project in the shortest time.

1. PRECEDENCE DIAGRAM
METHOD - PDM
PHAN CAO TAI
Joint Master Program
National Taiwan University
National University of Civil Engineering

2. What is PDM?

3. A SCHEDULE
MODEL
What is PDM ?
TECHNIQUE

4. What is PDM ?
ACTIVITY
ACTIVITY
i j
ADM
PDM
Logical
relationship
Logical
relationship

5. Why?

6. Why Do We Need To Learn PDM?
1. Available on almost all commercial
microcomputer-base on PMS.
2. Around 30% of contracting organization in
Europe are using PDM
3. This technique is more versatile as
compared to the other network planning.

7. Why Do We Need To Learn PDM?
4. Availability of lag has made this technique
more adaptable to the planner’s needs.
5. This tool can guide managers in making
critical decisions such as to deploy
resources based on priority.
6. Can assist the client in determining the
duration for extension of time.

8. ADVANTAGES & DISADVANTAGES
Fewer
Activities
Complicates
Manual
Calculations

9. ADVANTAGES & DISADVANTAGES
Activity A Activity B
Activity C Activity D
Activity E

10. Logical Relationship
FS • Finish to
Start
SS • Start to
Start
FF • Finish to
Finish
SF • Start to
Finish

11. Logical Relationship
Activity A Activity B
Finish to Start
F S

12. Logical Relationship
Activity A
Start to Start
SS
Activity B

13. Logical Relationship
Activity A
Fnish to Fnish
FF
Activity B

14. Logical Relationship
Activity A Activity B
Start to Finish
SF

15. LS – Lastest
Start Time
EF - Earliest
Finish Time
ES - Earliest
Start Time
CF – Critical
Path
TF – Total
Float
LF – Lastest
Finish Time
Precedence Diagram’s Notation

16. Total Float (TF) is the amount
of time an activity can be
delayed without delaying
project end date.
Precedence Diagram’s Notation

17.  How to calculate Float?
 Float = LS – ES or LF - EF
Precedence Diagram’s Notation
Activity A
ES EF
LS LF
FORWARD PASS
BACKWARD PASS

18.  Critical Path (CF) is the longest
duration path in a network diagram.
 And is the shortest time to complete
project
 It helps to determine the focus for
project management efforts.
 CF activities have Zero Float
Precedence Diagram’s Notation

19. Schedule Model
TF=0 TF=0
TF=0TF=0