Critical Path Method CPM is a project scheduling technique used in project

management.

In this method, a project model is constructed, that includes:

Work breakdown structure or the list of interdependent activities of the project.

The specific duration or time value allocated to each activity.

Dependencies between the activities.

Critical Path Method

Any process or project can be defined as a set or series of activities that need to be carried out in order to complete that process.

Activities have dependencies, based on which a network of activities can be made.

The longest path in duration, amongst the paths in the network, from start to end of the process, is known as the Critical Path, and the activities that make up the critical path are known as critical activities.

Critical Path Method - StepsStep 1: Make the WBS (work break-down structure) or identify the

activities that form the project, and their respective durations.

Step 2: Establish an activity sequence, clearly identifying which activity precedes which ones, and what activities can be completed simultaneously.

Step 3: Develop the network diagram. Project network is basically making a WBS of the project, modelled to represent the precedence of activities, where the arcs represent the precedence and the nodes represent the activities.

A B

Critical Path Method - StepsFor the following WBS of a project:

Network Diagram

Critical Path Method - StepsStep 4: Identifying the Critical Path:

For this step, we need to determine following four time factors for each activity: 1. Earliest Start Time (ES): The earliest an activity can start once all the

predecessor activities are over.

2. Earliest Finish Time (EF) = ES + Activity Duration

3. Latest Finish Time (LF): the latest an activity can finish that ensure project completion on time.

4. Latest Start Time (LS) = LF – Activity Duration

Critical Path Method - Steps Based on these parameters, activity slack can be calculated, Slack = LS- ES = LF-EF If Activity Slack = 0, the activity is a critical activity, otherwise it is a non-

critical activity. For calculating ES (early start) of an activity:

• Take the maximum of the predecessor activities’ EF (early finish) time, as an activity can start the earliest only when all the predecessor activities end.

For calculating the LF (late finish) times:• The LF of an activity is the minimum of all the following activities’ LS (late

start) times, as an activity can latest finish only before the first following activity starts.

Critical Path Method - Steps

Step 5: Calculate the project duration, based on the duration of Critical Path, by adding the duration of the critical activities.

Step 6: Update the network diagram throughout the project implementation process based on the actual project progress to refine the activity and project predictions.

Critical Path Method

It is an incredibly common and powerful tool used across the garment industry today.

But it’s only as powerful as the data entered into it—if estimations are off, if resources aren’t calculated correctly, the entire project may fail.

Take ample time to to identify the critical activities of the project, in the project planning phase itself.

Critical Path Method Tools• https://www.smartsheet.com/critical-path-method

• http://www.brighthubpm.com/software-reviews-tips/66584-the-pros-and-cons-of-free-critical-path-software/

• http://www.vertex42.com/ExcelTemplates/critical-path-method.html

• https://www.lucidchart.com/pages/pert-diagram/pert-chart-critical-path

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