8.3 Critical Path Method - Philadelphia University · 2013-11-06 · Engineering Skills,...

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

8.3 Critical Path MethodDr. Tarek A. Tutunji

Philadelphia University, Jordan

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

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.

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

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.

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

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.

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

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

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

CPM network Basics

A B5

Duration for task A is 5 units

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

CPM network

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

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

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

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

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

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

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

CPM Example

Start A

C

EB F

D

End

0

4

4

5

2

1 2

1

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

CPM Example

Start A

C

EB F

D

End

0

4

4

5

2

1 2

1

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

CPM Example

Start A

C

EB F

D

End

0

4

4

5 ?

2 ?

1 2

1 ?5 > 1+2

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

CPM Example

Start A

C

EB F

D

End

0

4

4

5

2

1 2

1

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

CPM Example

Start A

C

EB F

D

End

0

4

4

5

2

1 2

1

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

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

Dr. Tarek A. TutunjiEngineering Skills, Philadelphia University

Conclusions In this sequence, Critical Path Method was

introduced.

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