Critical Path Method (CPM)

Critical Path Method (CPM) is a project management technique that allows Project Manager to analyze project activities. And helps to find out which activities have least or no re-scheduling flexibility. These activities considered as mission critical activity and project duration schedule completely depend on completion of these activities. Not only that this tool also help project manager to predict the completion of the project and forecast of delay to the stakeholders.

The whole chain of these activities is called as critical path. Activities that fall in this path cannot be delayed at all. Any delay completion of any of these activities will end up with delay project completion.

Steps to calculate Critical Path

A critical path is a network of activities where each activity is linked to its following activity. In this network each activity represents itself as a node in the network. And the links connecting each node represent the timeline or schedule of the activity completion. To identify the critical path and calculate the schedule of the same following steps needs to be performed by the project manager.

Step 1: Create work break down structure (WBS)

Refer to my earlier post on WBS (  While creating WBS, put extra caution on the sequence of activities and Estimate time. This requires detail understanding of the scope document, activity list and the linking sequence. Linking the activities should be done very carefully and properly. Any mistake or wrong presentation will lead the path in false direction and eventually produce erroneous project completion date.

Time for each activity can be estimated using previous experience and taking support of the subject matter expert. The estimation accuracy will help to get more clearly critical path.

After finishing the listing of activities, sequencing and estimation of time, it is time to picturize the whole activity network.

Step 2: Identify the Critical Path

The critical path is the longest duration path of the network. Activities located in this path cannot be delayed without delaying the project. Therefore critical path analysis is one of the most importance elements of project planning. There are few parameters that help to identify Critical path and these are….

Early Start (ES): The earliest time to start an activity considering prior activity is been completed (this is must)

Early Finish (EF): The earliest finish time for an activity.

Late Finish (LF): Latest time for an activity must be completed.

Late Start (LS): Earliest time for an activity must start.

How to view the critical path in MS project

To view the critical path in MS project, click on view menu and select network diagram. All activities in red color are in critical path. Or click on view menu, click on more views and select detail Gantt.

Thats all for today………….


About Mamun Shaheed

I love to imagine....I guess thats the only thing that keeps me going and going and going....
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