Critical Path Method: – In project management, any overshooting of the scheduled end date may result in financial penalties, but also the deterioration of relationships with your client. Timeliness is therefore essential and the critical path method (CPM) is an effective tool to achieve this.
The critical path is the set of activities to be completed so that the project is completed by the defined date. The critical path method lets you know how long each task will take before finishing the project. You use this information to determine the end date of the project. If a task takes longer than expected, then the project end date is delayed. The duration of certain tasks can be extended without affecting the project.
Critical path tasks are called “critical tasks” because they are critical to the success of the project. Consequently, they must not be delayed; otherwise the entire project will be delayed. Their margin for maneuver is therefore zero. Appearing in the 1950’s in the United States, this method is now used internationally for all types of projects, whether in construction, aerospace, computing, product development or research.
Principles of Critical Path Method
The Project Management Body of Knowledge (PMBOK) defines the critical path as a defined sequence of activities that determines the duration of the project.
To use the critical path method, you must first determine:
- The list of all the tasks necessary for the realization of the project,
- The dependencies between each of these tasks,
- The duration of each task
Once this information is in your possession, the CPM calculates the longest path of all tasks to complete the project. This method also gives you the earliest and latest dates at which each task can start and finish without lengthening the project duration. Thus the Critical Path method determines which critical tasks, i.e. those on the longest path, and those that can suffer delays without affecting the project.
This method allows both to produce a precise schedule that guides the project team, but also to monitor the performance of the project by comparing what is planned with what actually happens on a daily basis.
Process Critical Path Method
CPM is a technique for schematizing a set of tasks in the form of an arrow diagram. Here are the key steps of the Critical Path method:
- Identify all the tasks of the project: with the help of your team, list all the tasks necessary to accomplish your project. List only the most important tasks without going into the subtasks because the critical path would then become too complex to manage.
- Define the order of tasks and their dependencies: determine which tasks must be performed first, and then define the dependencies between each task. To help you, ask yourself the following questions:
- Which task must take place before it begins?
- What task should be completed at the same time as this task?
- What task should start immediately after it is completed?
- Calculate the duration of each task: Estimate the time required to complete each task based on previous projects and the experience of your team members. Depending on the size of the project, the durations will be counted in days or weeks.
- Draw the diagram in a network: manually or with software, draw the graph representing all of your tasks according to their order and dependency. This graph helps you visualize your tasks and the relationships between them with the arrows.
- Identify the critical path: Identify the critical tasks, i.e. the most important tasks for the project. These are the ones that have the longest deadlines. This is the critical path. Adding all these critical tasks gives you the total duration of the project. Mark the critical path in a visible way. You can focus your energy on the strategic activities of the project and ensure that the deadlines are met.
- Refresh the diagram: As the project progresses, you will learn about the actual duration of the tasks. Take advantage of this to update your diagram. This makes it possible to recalculate the critical path, but also to have a more realistic view on the project’s deadlines. You will know if you are on time, early or late, and you can act accordingly.
Advantages and Disadvantages Critical Path Method
The critical path method offers several advantages:
- A visual representation of all the tasks of the project,
- A clear presentation of the time required to complete each task,
- Follow-up of tasks in order to avoid delays
It allows you to identify the most important tasks of the project, those that you must follow rigorously in order to avoid delays.
This approach also reduces uncertainty because you have to calculate the shortest duration and the longest duration for each project task. This forces you to consider the unexpected and unforeseen events that may occur during your project. So you avoid unpleasant surprises.
The CPM therefore reduces delays and improves budget compliance through more accurate and efficient project management.
- The critical path method is not suitable for large projects because it becomes too complex and difficult to manage.
- This methodology does not allow for effective monitoring of the distribution of project resources.
- The duration of the tasks may be overestimated. In addition, tasks are rarely completed early, even when possible, as the tendency is to use the full amount of time granted rather than only what is needed.
The Critical Path method helps you identify the most important tasks of your project, those that have a real impact on the success or failure of your project.
In order to ensure the effectiveness of this method, it is important not to forget tasks and to clearly establish the links of dependency between each task. Ideally, appoint a team leader who will be responsible for monitoring the progress of the project, progressing the tasks along the critical path and ensuring that no non-critical tasks become critical during the project.