The critical path - What is it and why is the method helpful?

There is always talk of the critical path. Everyone knows that there are tasks and processes in planning that have to be carried out exactly on time, as well as tasks that can tolerate a delay without jeopardising the success of the project. The critical path method is therefore interesting, because it deals precisely with the scheduling and prioritisation of project activities. The use of this method is therefore always useful and not only when your projects often take longer than initially planned.
Man standing in front of large Gantt Chart.

The differentiation - critical and non-critical tasks

So what is the critical path method, often also found under its English name Critical Path? How do you find the critical path in your project and how can this help you to become a better project manager? To get to the bottom of these questions, let's look at where the term comes from and who sort of invented the critical path.
First, a definition: the critical path is the longest sequence of tasks on a timeline that affect the completion date. On the critical path, therefore, you will find all tasks that can only begin when another task has already been completed. So if you string together all the tasks that meet this criterion, you will know the minimum time your project will take.

Is not everything critical?

No. For example: You are constructing a building with four floors. You can only build the first floor when the ceiling of the ground floor has been completed. The roof can only be placed on the building when all the exterior walls are in place. This is, of course, very simplified, but it explains the critical path quite clearly. In contrast to these critical tasks, a non-critical task would be, for example, the creation of a flower bed next to the building. This allows you to start independently and the task can still be completed on time. The flower bed does not have to wait until the first floor or the fourth floor are finished. You can start it when, for example, the walls are not quite finished, but not with the roof. Every day that it takes longer to finish the exterior walls delays the start of work on the roof and thus the final date. Logical.

The origins

However, the principle of the critical path did not originate in the construction industry.
It was developed in the late 1950s during the Manhattan Project, a US nuclear weapons programme. Since then, the method has been further developed. It can be applied to all types of projects. Many already incorporate the critical path method into their project work, unconsciously or quite deliberately.

The advantages

First of all, it is generally useful to get an overview of all project tasks. This applies regardless of the size and complexity of the projects, but it becomes more important with increasing complexity. All project managers probably agree on this.
Opinions differ on the question of how best to achieve and maintain this overview. There are real schools of thought on this. In almost all methods, there is the approach of prioritising tasks according to their importance. There are also different ways to define importance. You can focus on the tasks you like to do or the tasks you hate and therefore want to get over with quickly. You can start with tasks that have all the prerequisites for completion or you can choose tasks where your supervisor wants to see results quickly.
You can also take a more scientific approach to prioritisation and use the critical path method. This way you avoid a situation where a new important task cannot start because another important task is not yet completed. Focus on completing each task that builds on the other, rather than tasks that can wait. Even if there are good reasons to tackle these tasks now.

The Gantt Chart

As with the house building example, you certainly have an idea of what tasks follow each other in your targeted project. Your milestones have been worked out, you have moved backwards from the completion date and so you can see when the project needs to start for timely completion. To see the critical path, it is a good idea to create a Gantt Chart. Here you look at all your tasks and then decide which of the tasks build on each other. Let's stay with the example of building a house: The walls can only be put up when the foundation is in place. The foundation can only be poured when the excavation pit has been dug. The lamps, on the other hand, can be selected and ordered at any time. No other task has to be completed before you can select the lamps. In a good programme for Gantt charts, the critical path shows up very quickly. You line up the tasks that build on each other next to each other. This creates a timeline in which the tasks cannot overlap. You can now group all other project steps around this line. The main focus is now on the principle of never postponing a task on the critical path because of a non-critical task.
Authot: IAPM internal

Key words: Project management, Methods, Tips, Knowledge

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