An Introduction To The Critical Path Method


An Introduction To The Critical Path Method

Critical Path Method (CPM) is a project management technique that helps you plan, analyze and schedule complex projects.  Every project is comprised of a number of different activities and tasks that are interconnected and critical to the success of the project.

CPM is a very powerful tool that enables you, the Project Manager, to identify what the longest path is for your planned tasks that are needed in order to identify initial start and finish dates as well as allow you to meet your deadlines.

Determining your critical path allows you to know which activities are crucial to getting your project completed, and which ones don’t have a serious impact on the development of your project and may be delayed.

Critical Path Method Steps

The following steps are included in the Critical Path Method:

  1. Identify activities

The project scope is used to break down the work into a list of all the activities. All activities are given a name along with a target date and duration.

  1. Determine the sequence of your activities

This step is the most important one since it provides you with a clear view of how the activities are connected and helps you establish what the dependencies are since some activities depend on others being completed.

  1. Create a network of activities

After you have determined how your activities depend on one another the network diagram can be created.  You can then use arrows to connect activities based on what their dependence is.

  1. Determine completion times for all of your activities

Estimating the amount of time each activity is going to take can help you determine how much time is needed for completing the entire project.

  1. Find your critical path

When a network of activities is examined it helps you identify the longest sequence of your activities on a critical path according to the following parameters:

Early Start (ES) – this is the earliest time that a certain activity will be started provided that the preceding activity is complete.

Early Finish (EF) – this is the earliest time needed for finishing an activity

Late Finish (LF) – this is the latest time needed for finishing the project without any delays

Late Start (LS) – this is the latest start date when a project can begin without any project delays

If any task that is on the critical path is delayed, the entire project will be delay.  The path where no delays are allowed is the critical path.

Not every activity in a project is equally as important.  Some will have a significant impact on your project’s critical path making them critical, while others won’t make a big difference to your project if they end up being delayed.

Using the Critical Path Method can help you determine which activities have total float and which are critical.  However, if there are serious delays to any of your floating activities, they can became critical and your entire project will be delayed.

The Critical Path Method enables you to identify all of your activities, and then determine how long each one will take to complete, and then determine what the longest path is, which is called the critical path.

Although there are some activities that can occur at the same time, all of your activities must be completed by the time that the critical path has identified.

Since floating time is not part of the critical path it means that all of your other activities are crucial.  So if one of the activities on your critical path is delayed by 5 days, then there will be a 5 day delay on your entire project.

How CPM Is Affected By Resource Limitations

Of course, we all would love to use the Critical Path Method to make all of our projects run smoothly. However, our projects can still be affected by certain limitations and new dependencies may be created.  For instance, if the number of members on your team drops suddenly down to 7 from 10, you will be faced with a resource constraint or resource limitation.

In this type of situation, your critical path will change and become a resource critical path.  Resources relating to each of your activities will become a very integral part of your overall process.

It means some of your tasks will need to be done in a different order.  This can cause delays and the project will end up being longer than anticipated.

Critical Path Method Benefits

Tasks are prioritized

Clear insight is provided into the timeline of your project that allows you to reduce the time needed to complete your project

Planned vs. actual progress can be compared

Early risk assessment

Your team members can be redistributed in a more efficient manner

Helps to keep your team focused

Using the Critical Path Method allows you to remain focused on the bigger picture and provides you with a clear view of all of the activities involved in your project as well as their potential outcomes.

The biggest advantage to Critical Path Method is that it allows you to reschedule tasks that are less important so that your efforts can be focused on optimizing your work so that delays can be avoided.