8.3 Critical Path Method - Philadelphia University · 2013-11-06 · Engineering Skills, Philadelphia University Dr. Tarek A. Tutunji Critical Path Method (CPM) There are similarities

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

8.3 Critical Path MethodDr. Tarek A. Tutunji

Philadelphia University, Jordan


Overview In the previous sequence, Gantt Chart was introduced.

In this sequence, another graphical project planning technique, the Critical Path Method (CPM) will be presented.


Critical Path Method (CPM) There are similarities between CPM and Gantt Chart.

In order to do the CPM, First, you have to

Identify the tasks.

Specify the dependency among the tasks.

Estimate the task duration.


CPM Network In a CPM network, tasks are shown as nodes.

Arrows are used to connect the nodes.

The duration of the tasks are written above the arrows.

A connected series of nodes are used to show the dependencies among tasks.

The order of tasks is given by the flow of the connections left to right.


CPM network Basics

A B Task A must finish before task B starts

A C

B

Tasks A and B must finish before task C starts

AC

B

Task A must finish before either task B or C start


CPM network Basics

A B5

Duration for task A is 5 units


CPM network


CPM Example Consider a construction project with the tasks defined

in table below

Task Name Duration Predecessor

A Excavation 4 --

B House Foundation 5 A

C House Gutter 2 A

D House Base 1 C

E House Wall 1 B,D

F House Roof 2 E


CPM Example

Start A

C

EB F

D

End

Task Name Duration Predecessor

A Excavation 4 --

B House Foundation 5 A

C House Gutter 2 A

D House Base 1 C

E House Wall 1 B,D

F House Roof 2 E

0

4

4

5

2

1 2

1


Critical Path

Critical Path is the sequence of tasks that defines the minimum amount of time for the project to be completed.

These are the tasks that a delay within will delay the entire project


CPM Example

Start A

C

EB F

D

End

0

4

4

5

2

1 2

1


CPM Example

Start A

C

EB F

D

End

0

4

4

5

2

1 2

1


CPM Example

Start A

C

EB F

D

End

0

4

4

5 ?

2 ?

1 2

1 ?5 > 1+2


CPM Example

Start A

C

EB F

D

End

0

4

4

5

2

1 2

1


CPM Example

Start A

C

EB F

D

End

0

4

4

5

2

1 2

1


CPM Example

Start A

C

EB F

D

End

0

4

4

5

2

1 2

1

Critical Path A B E F

Minimum Duration for finalizing the project: 4+5+1+2=12


Conclusions In this sequence, Critical Path Method was

introduced.

An detailed project example was used to clarify the use of CPM.

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8.3 Critical Path Method - Philadelphia University · 2013-11-06 · Engineering Skills, Philadelphia University Dr. Tarek A. Tutunji Critical Path Method (CPM) There are similarities