2. OBJECTIVES
• Define Network Diagram
• Purpose of Network Diagram
• Method : Activity On the Node (AON)
• Identify ES, EF, LS, LF using Forward Pass
Calculation and Backward Pass calculation
• Identify Critical Path
• Identify Slack Time
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3. INTRODUCTION
• A PND is a pictorial representation of the sequence
in which the project work can be done.
• The activities and its duration are the basic building
blocks needed to construct a graphic picture of the
project
• Its provide
- the earliest time at which work can be begin on
every activity that makes up the project
- the earliest expected completion date of the project
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4. IMPORTANCE OF ND
• ND can be used for ;
i) Planning : gives a clear graphical picture of
the relationship between project activities
ii) Implementation : when updating the project
file with activity status and estimate to
completion data, the ND is then
automatically updated and can be printed or
viewed
iii) control : while updated ND will retain the
status of all activities, the best graphical
report and controlling project work will be
Gantt Chart
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5. METHODS
I) THE ACTIVITY ON THE NODE ( AON)
• Basic unit of analysis in ND is the activity
• Each activity is represented by a rectangle (
activity node)
• Arrows represent the predecessor/successor
relationship between activities
• Every activity in the project will have its own
activity node ( each rectangle)
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6. METHODS
I) THE ACTIVITY ON THE NODE ( AON)
A
B
C
D
E
F
PDM format of a project network diagram
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7. METHODS
I) THE ACTIVITY ON THE NODE ( AON)
Dependencies
- A dependency is simply a relationship that exists
between pairs of activities
- 4 types of activity dependencies
A B FS : A finishes, B start
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8. METHODS
I) THE ACTIVITY ON THE NODE ( AON)
Dependencies
FF : A finishes, B finish
A
B
A
A SS : A start, B start
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11. I) THE ACTIVITY ON THE NODE ( AON)
Forward Pass calculations
Creating an initial project network schedule
A 1
B 3
C 2
D 5
E 2
F 3
Start End
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12. EST, LST, EFT, LFT
• CPM uses the following times for an activity
EST - Early Start time is the earliest time the activity
can begin
LST - Late Start Time is the latest time the activity can begin
- still allow the project to be completed on time
EFT - Early Finish Time is the latest time the activity can end
LFT - Late Finish Time is the latest time the activity can end
- still allow the project to be completed on time
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15. CRITICAL PATH METHOD (CPM)
• An effective way to analyze complex projects
• Represent the critical set of activities to complete a project
• Help to focus on essential activities which are critical to run
the project
• Allows the project manager to concentrate on important
activities
• CP is the longest path on ND and the most important part
• Any delays on the CP will lead to delay of the project
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17. FLOAT
• Also known as slack, total float and path float
• Is computed for each task by subtracting EFT from
the LFT
( @ the early start from the late start)
• Is the amount of time the task can slip without
delaying the project finish date.
• Free float is the amount of time a task can slip
without delaying the early start of any task
that immediately follows it.
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19. EXAMPLE
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Activity Precursor Duration (week)
A - 7
B A 6
C A 5
D A,B 4
E B,C 3
F D,E 2
1. TABLE 1 shows the activities and the durations required to complete a
construction project, including the precursor activity.
Refering to the TABLE 1:
i) draw the project network diagram.
ii) state the activities on the critical path.
iii) calculate the minimum duration of the project.
20. 20
project network diagram
A
D
C
E
F
B
STAR
T END
0 7 7
0 0 7
13 4 17
13 0 17
7 6 13
7 0 13
7 5 12
9 2 14
14 3 16
14 1 17
17 2 19
17 0 19
19 19
19 19
0 0
0 0
activity
ES D EF
LS F LF
