Critical Path Method

The Critical Path Method was developed in the 1950s. Various ways of project planning were developed that enabled Project Managers to map and understand the relationships between tasks. These methods include precedence diagrams, network on arrow, PERT and others. They used different notation, but they enabled the planner to identify the Critical Path through a project.

Critical Path Definition

The Critical Path is the series of tasks that must finish on time for the entire project to finish on schedule. Each task on the critical path is a critical task. You can also think of it as:

• the longest path from start to finish
• or the path without any slack,
• the path corresponding to the shortest time in which the project can be completed.

The best way to understand the Critical path is to see an example

Below is a table showing the precedence of tasks for a simple CD/DVD publishing project

Critical Path Example

Mapped out as a precedence diagram we can clearly see the project logic.

This is a simple diagram and you may well be able to spot the critical path already. You may also have noticed that some tasks could be delayed without impacting the critical path i.e. without impacting the end date of Duping and packaging. Most projects are much more complex and the Project Manager will need to follow a process to calculate the critical path and identify the slack in the project.

The critical path is Project start - Write contents - Testing and glass master - Duping and packaging.