Critical Path Method: How to Use CPM for Project Management

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The Critical Path Method (CPM) – also referred to as critical path scheduling – is the most widely used construction scheduling methodology. The benefit of using CPM scheduling is to help project managers, project owners, project team members, and subcontractors identify the critical tasks that should be completed in order to successfully complete the project on time.

CPM Scheduling is widely used in the construction industry and is the specified methodology in many California public works projects. CPM scheduling allows project managers to identify task interdependencies and identifies the shortest time in which a project can be completed. CPM scheduling identifies the activities that are critical to the timely completion of the project.   The critical path is the longest sequence of activities that must be finished to complete the project. If these critical tasks aren’t finished on time, the project will take longer to complete than expected.

Why Use CPM?

CPM Scheduling has the following major advantages:

Identifies the dependence and interdependence relationships of all activities in a schedule

• Can be used to compare planned completion dates with actual completion dates

• Provides an accurate and detailed representation of the forecasted completion dates of the various project activities.

• Demonstrates how a change in one or more activities impacts other activities in a schedule

• Facilitate effective resource management

• Can be used to manage the resources and cost associated with each activity

• Data that you collect today can be used to better manage future projects

Unanticipated project delays can affect project workflow and the critical path. As a result, your project costs can rise sharply, if not mitigated properly. Project managers can identify project delays utilizing CPM scheduling as a project management tool and gives them an opportunity to either mitigate the delay, where possible, or notify the Owner of an unavoidable delay and request a time extension.

How Does CPM Scheduling Work?

CPM scheduling utilizes the forward pass and backward pass algorithm to calculate the project’s total float, critical path (zero total float) and an activities early start/early finish and late start/late finish dates. A knowledgeable contractor can use this information to keep his project on track. Often however, a project will run into delays and/or unforeseen events that will push a project’s completion date out. A properly maintained CPM Schedule will track and project these delays. It is at this point that a contractor and owner can discuss and apply different techniques to mitigate these issues before the delay to the project becomes critical. Some of these techniques are as follows:

Fast tracking/schedule compression: In fast tracking, activities that would have been performed linearly are performed concurrently. Performing activities concurrently is an option not without limitations. Overpopulating a work area (stacking of trades) may overwhelm available access in attempting to achieve realistic results.

Acceleration: This schedule compression technique involves allocating more resources in order to speed up projects. When you assign additional resources, be careful as this method often results in extra costs to be incurred by the contractor which should be incorporated into a contract change order, when possible, before proceeding. Inform the project stakeholders in advance.

CPM scheduling is a very complex and expensive project management tool, but properly built and maintained one can save a project an untold amount of time & money. If you need assistance in implementing and maintaining your CPM schedule for your project, then please feel free to contact our P6 CPM schedule experts.

The Swaney Corporation – Crowe Construction offers top-notch professional construction management services. We help construction project owners, contractors, subcontractors, and anyone who need assistance improve project profitability, efficiency, and scalability. To make an appointment with one of our experts, call (707) 665-9668.

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