Critical Path Method - What Is It And How Can It Help You?

By Author: Simon Buehring
Total Articles: 45
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What is CPM?

The CPM (Critical Path Method) is a way of organising the necessary steps to project completion. It enables you to assess task priority, resources required and possible shortcuts.

CPM is based on the creation of a sequence of dependent tasks (i.e. tasks that can only be performed after earlier tasks are complete). Performing Critical Path Analysis on this sequence allows you to work out possible parallel sequences (i.e. tasks that can be performed simultaneously). The Critical Path is the longest chain of dependent tasks required.

How much does it cost?

The CPM is free to use. You can apply it to your project simply by following six simple steps.

Training in CPM, covered by some project management training courses, is a useful way of getting past the basics, and CPA software is available for more comprehensive analysis of the data.

Six Simple Steps

1) Specify the individual tasks necessary for project success

For example:

Project Goal - prepare a perfect breakfast-in-bed on Mother's Day
Necessary Tasks:
Fry the eggs and bacon
Heat ...
... up the baked beans
Buy a Sunday newspaper
Buy flowers
Make the hash browns
Find a recipe for the hash browns
Buy the ingredients
Make a shopping list
Make a pot of coffee
Cook the tomatoes and mushrooms
Find a vase
Put flowers in the vase

2) Determine sequences of tasks

If I try to do the tasks in the order that they occur to me (see above) then my project will result in a mess of broken eggs and burnt coffee! Before embarking on my project I need to put the tasks into order of dependency and priority. Analysing my

3) Draw network diagram

A CPM network diagram illustrates the dependency relationships between each tasks. I cannot fry the eggs and the bacon until I have bought the ingredients. I cannot make a shopping list until I have found a recipe.

4) Identify the critical path (the longest chain of dependent tasks)

For example:

Find a recipe for hash browns > Make a shopping list > Buy ingredients > Make hash browns

5) Estimate completion time

I need to work out how long each task will take me.

By adding up the estimated completion time for each activity in the longest chain of dependent tasks, I will be able to work out the maximum duration of the project.

6) Update for progress

I might have estimated that finding a vase would only take me five minutes. If I discover that all of our vases are broken then I have to either increase my schedule and budget to allow for the purchase of a new vase, or come up with an alternative solution (like a tall glass or a jug) or reduce the scope of the project and go without the flowers.

Updating for progress is a vital part of the CPM, as it ensures that expected project duration and outcomes remain viable. Even more essential, however, is risk assessment. If I had taken into account the possibility that there might not be any vases then I might have found a solution earlier on.

The Critical Path Method is an important Project Management tool. It enables Project Managers to work out the most efficient task route, task priorities and the most effective ways of shortening project duration through simple organisation and analysis of the data.

Simon Buehring is a project manager, consultant and trainer. He works for KnowledgeTrain which offers PRINCE2 course in the UK and overseas. He can be contacted via the KnowledgeTrain prince2 exam website.