Critical Path Method

Critical Path Method is the longest duration path in a given network or the minimum time that is required to complete the project. This method is used to find the duration of the project. Here are the steps to find the critical path.

1. Draw the network diagram based on the dependencies of the activities.

2. Find the number of the paths from the network diagram. Number of paths means the paths which are traversing from start of the project to the end of the project.

3. Find the duration of each path by adding the duration of all the activities from the respective path.

4. The highest duration path is the critical path. And this itself is the duration of the project.

After finding the critical path one can find the total float or slack. Total float is nothing but how much an activity can be delayed without affecting the overall schedule of the project or the immediate start of the successor activity. How to calculate the total float? You need to follow two steps. One is forward pass and the second is backward pass. Forward pass is moving from start of the project by adding the duration of each of the activity and backward pass is moving from end of the project to the start of the project by subtracting the duration of each activity. After carrying out these steps you will find four values Early Start (ES), Early Finish (EF), Late Start (LS) and Late Finish (LF).

EF=ES + duration of the activity LS=LF - duration of the activity

Calculate total float using the formula

Total Float=LS-ES or LF-EF

The critical path activities will be always having zero total float whereas non critical path activities will be having float.

Critical Path method is used in Develop Schedule process.