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Advantages and Disadvantages of Critical Path Method

written by: Rupen Sharma, PMP • edited by: Ronda Bowen • updated: 5/18/2013

Even the most advanced and well-thought of process or product has its fair share of pros and cons. The critical path method is no exception. In this article, we’ll discuss the advantages and disadvantages of critical path method.

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    CPM Impacts the Project Schedule

    The critical path method helps you identify the most important activities, which can impact the project schedule. As such, this method is useful in creating project schedules and managing high-risk activities on the critical path. Even the most well thought-through process will inevitably have some disadvantages - critical path method is no exception!

    Let’s explore the pros and cons of critical path method.

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    Looking at the Pros

    There many pros of using the critical path method during project planning and execution. The critical path method:

    • Makes dependencies visible between the project activities; this is done by constructing project network diagrams or precedence diagrams
    • Organizes large and complex projects, hence allowing a more systematic approach to project planning and scheduling, project execution, and risk management
    • Enables the calculation of the float (slack) of each activity.The float tells you exactly how long an activity can come in late without it impacting the project schedule.
    • Encourages the Project Manager to reduce the project duration by optimizing the critical path and using compression techniques as applicable
    • Increases visibility of impact of schedule revisions, which are usually necessary when major milestones have been missed or when the risk of missing a major milestone looms large
    • Enables the Project Manager to optimize efficiency by allocating resources appropriately, consequently the overall cost can be reduced
    • Provides opportunities to respond to the negative risk of going over-schedule by identifying the activities that are most critical

    For large and complex projects, it is best to use specialized software. These software generate data, such as activity float, automatically for you. Next, let’s take a look at some Critical Path Method disadvantages.

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    Being Aware of the Cons

    There aren't many disadvantages to the Critical Path Method. Mentioned below are the cons of the Critical Path Method.

    • For large and complex projects, there’ll be thousands of activities and dependency relationships. Without software it can be mighty difficult managing this. To make matters worse, if the plan changes during project execution then the precedence diagram will have to be redrawn. Fortunately, we do have relatively cheap software that can handle this with ease.
    • One of the advantages of drawing a project precedence diagram is that you can print and stick in the project area. The precedence diagram enables the team to stay focused on project activities. Project team members are always cognizant of the critical path since it is visible everyday. However, for large projects with thousands of activities, it may be difficult to print the project network diagram. You would most definitely need a plotter.

    The Critical Path Method does not account for resource and resource allocation. Critical Chain will be handy in these situations. A good book to read on Critical Chain is called Critical Chain by Eliyahu M. Goldratt.

    This article explored the pros and cons of Critical Path Method. To learn how to use it illustrated with an example, read the Identify the Critical Path by Using a Precedence Diagram article.