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You’ve probably heard about the critical path method (CPM) in construction, but what exactly is it? And why do I, Jason, sometimes get after it? Should you be using it, and what should you know about it from a realistic data standpoint? We’re going to cover that right now. 

What Is the Critical Path Method in Construction?

The Critical Path Method (CPM) is a technique used to identify the tasks necessary for project completion and to determine your schedule and flexibilities. In project management, the critical path is the longest sequence of activities that must be finished on time for the overall project to be completed on schedule.

How to Create a CPM Schedule

Here’s a step-by-step guide to building a CPM schedule:

1. Specify Each Activity

First, name each activity properly using verbs and nouns. Ensure you have the right duration for each task, confirmed with trade partners and from historical data and production rates. This step involves inputting all activities into your scheduling software.

2. Identify Activity Dependencies

Next, identify the dependencies between activities. This creates your activity sequence. In your software, or by hand, you’ll draw the logic ties (e.g., start-to-start, finish-to-start, start-to-finish) to link activities in the proper sequence.

3. Draw the Network Diagram

Link all activities through their logic ties to create a network diagram. If you’re using software, this is usually presented in a Gantt format or as a precedence diagram, making it easier to see dependencies.

4. Estimate Completion Time

Estimate the completion time for your entire network or schedule. Ensure the durations fit within the overall project timeline.

5. Identify the Critical Path

Using an algorithm, your software will identify the longest path of activities, considering all logic ties and durations. This longest path becomes your critical path, and it’s crucial because any delays here will delay the entire project. Other paths will have float (project float and free float), indicating how much they can shift before becoming critical.

6. Update the Diagram

Regularly update your schedule to track progress, identify problems, and create recovery schedules. Monitoring the critical path and the success of your project is key.

The Purpose of the Critical Path Method

CPM is designed to create an overall network of activities with a critical path to identify start and end milestones and to confirm that these milestones can be met within the schedule. However, there are practical challenges to using CPM effectively.

Common Problems with the Critical Path Method

1. Complexity

CPM schedules can be complex, giving a false sense of security. Initial schedules are rarely correct, and the project team must see and correct the plan.

2. Accessibility

These schedules are often detailed and lengthy, making them hard to read and understand. Trade partners, workers, and foremen may not engage with them, leading to a disconnect.

3. Flow Issues

CPM schedules can disrupt the essential trade flow, stacking trades on top of each other, which is impractical and leads to incorrect critical paths and durations.

4. Difficulty in Updating

Updating a CPM schedule can be cumbersome due to the number of activities and logic ties, often leading to outdated schedules that don’t reflect the field’s reality.

5. Potential for Abuse by Owners

Owners may misuse CPM schedules to deny claims and push contractors, causing a chain reaction of stress and inefficiency throughout the project team.

Important Reminders When Using the Critical Path Method

If you must use CPM, here are some crucial points:

  • Ensure proper trade flow and phase planning.
  • Include buffers to account for inevitable delays.
  • Make sure the entire team understands the plan, which is challenging with traditional CPM.

For a more effective approach, consider alternative scheduling methods like the Takt Production System, Last Planner, and Scrum. These methods can help you meet contract requirements while maintaining project efficiency.

If you need help transitioning away from CPM or using it more effectively, I offer free assistance to show you and your contractors how to run schedules without the downsides of CPM.

Check out the blog post linked below to learn more about construction scheduling and how you can improve your project management practices. Let’s work together to make your projects smoother and more successful.

I hope you’ve found this blog post informative. On we go!

If you want to learn more we have:

-Takt Virtual Training: (Click here)
-Check out our Youtube channel for more info: (Click here) 
-Listen to the Elevate Construction podcast: (Click here) 
-Check out our training programs and certifications: (Click here)
-The Takt Book: (Click here)

Discover Jason’s Expertise:

Meet Jason Schroeder, the driving force behind Elevate Construction IST. As the company’s owner and principal consultant, he’s dedicated to taking construction to new heights. With a wealth of industry experience, he’s crafted the Field Engineer Boot Camp and Superintendent Boot Camp – intensive training programs engineered to cultivate top-tier leaders capable of steering their teams towards success. Jason’s vision? To expand his training initiatives across the nation, empowering construction firms to soar to unprecedented levels of excellence.

On we go!