The document discusses critical path method (CPM) network analysis for project planning. CPM was developed in 1957 to plan construction and maintenance projects. It involves identifying all tasks, durations, dependencies and calculating earliest and latest start/finish times to determine the critical path that dictates the project duration. An example CPM network is provided and analyzed to identify the critical path.

1. CPM Network Analysis
Prepared By :
Parth Desani
Civil Engineer

2. Critical Path Method (CPM)
Critical Path Analysis
Project Network
Concurrent Activities
Situations in network diagram
AOA & AON Project Networks for House
Network example

3.  Critical Path Method (CPM)
• E I Du Pont de Nemours & Co. (1957) for construction of new
chemical plant and maintenance shut-down
• Deterministic task times
• Activity-on-node network construction
• Repetitive nature of jobs
 Identify and prioritise the activities
 Identify which activities MUST be done before
others
 EST – identify earliest start time
 LFT – identify latest finish time
 Identify the FLOAT – tasks which can be
completed outside the critical path
 Identify the critical path – points connecting ESTs
and LFTs (where these are the same)

4. Nodes: Show the start and finish of a task
1 2
Node numbers showing order of
activities in the left hand semi-circle
of each node.
3
Earliest Start Time (EST)
5
Latest Finish Time (LFT)
A
3
B
5
Arrows
indicate the
order of the
tasks, the
letter above
shows the
order, the
time period
below the
arrow
The Critical Path

5.  Use of nodes and arrows
Arrows  An arrow leads from tail to head directionally
• Indicate ACTIVITY, a time consuming effort that is required to perform
a part of the work.
Nodes  A node is represented by a circle
- Indicate EVENT, a point in time where one or more activities start
and/or finish.
Network analysis is the general name given to certain specific techniques
which can be used for the planning, management and control of projects
• Activity
– A task or a certain amount of work required in the project
– Requires time to complete
– Represented by an arrow
• Dummy Activity
– Indicates only precedence relationships
– Does not require any time of effort

6.  Event
• Signals the beginning or ending of an activity
• Designates a point in time
• Represented by a circle (node)
 Network
• Shows the sequential relationships among activities using
nodes and arrows
Activity-on-node (AON)
nodes represent activities, and arrows show precedence relationships
Activity-on-arrow (AOA)
arrows represent activities and nodes are events for points in time
Project Network

7. 2 3
Lay foundation
Order material
(a) Incorrect precedence
relationship
(b) Correct precedence
relationship
3
42
Dummy
Lay
foundation
Order material
1
2 0

8. A
B
C
A must finish before either B or C can start
A
B
C both A and B must finish before C can start
D
C
B
A
both A and C must finish before either of B or D can
start
A
C
B
D
Dummy
A must finish before B can start
both A and C must finish before D can start

9. darla/smbs/vit
9
3
2 0
1
3
1 1
1
1 2 4 6 7
3
5
Lay
foundation
Design house
and obtain
financing
Order and
receive
materials
Dummy
Finish
work
Select
carpet
Select
paint
Build
house
AON Project Network for House
1
3
2
2
4
3
3
1 5
1
6
1
7
1Start
Design house
and obtain
financing
Order and receive
materials
Select paint
Select carpet
Lay foundations Build house
Finish work

10. For clarity, this list is kept to a minimum by specifying only immediate relationships,
that is relationships involving activities that "occur near to each other in time".
The key question is: How long will it take to complete this project ?

11.  Is this a Start Activity?
 Is this a Finish Activity?
 What Activity Precedes this?
 What Activity Follows this?
 What Activity is Concurrent with this?
darla/smbs/vit
11

12. Path
• A connected sequence of activities leading from
the starting event to the ending event
Critical Path
• The longest path (time); determines the project
duration
Critical Activities
• All of the activities that make up the critical path

13.  CPM Network
a, 6
f, 15
b, 8
c, 5
e, 9
d, 13
g, 17 h, 9
i, 6
j, 12

14.  ES and EF Times
a, 6
f, 15
b, 8
c, 5
e, 9
d, 13
g, 17 h, 9
i, 6
j, 12
0 6
0 8
0 5

15.  ES and EF Times
a, 6
f, 15
b, 8
c, 5
e, 9
d, 13
g, 17 h, 9
i, 6
j, 12
0 6
0 8
0 5
5 14
8 21
6 23
6 21

16.  ES and EF Times
a, 6
f, 15
b, 8
c, 5
e, 9
d, 13
g, 17 h, 9
i, 6
j, 12
0 6
0 8
0 5
5 14
8 21 21 33
6 23
21 30
23 29
6 21
Project’s EF = 33

17.  LS and LF Times
a, 6
f, 15
b, 8
c, 5
e, 9
d, 13
g, 17
h, 9
i, 6
j, 12
0 6
0 8
0 5
5 14
8 21
21 33
6 23
21 30
23 29
6 21
21 33
27 33
24 33

18.  LS and LF Times
a, 6
f, 15
b, 8
c, 5
e, 9
d, 13
g, 17
h, 9
i, 6
j, 12
0 6
0 8
0 5
5 14
8 21
21 33
6 23
21 30
23 29
6 21
4 10
0 8
7 12
12 21
21 33
27 33
8 21
10 27
24 33
18 24

19.  Float
a, 6
f, 15
b, 8
c, 5
e, 9
d, 13
g, 17
h, 9
i, 6
j, 12
0 6
0 8
0 5
5 14
8 21 21 33
6 23
21 30
23 29
6 21
3 9
0 8
7 12
12 21
21 33
27 33
8 21
10 27
24 33
9 24
3 4
3
3
4
0
0
7
7
0

20.  Critical Path
darla/smbs/vit
20
a, 6
f, 15
b, 8
c, 5
e, 9
d, 13
g, 17 h, 9
i, 6
j, 12