The Secret to the Critical Path Method in Construction

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If only structures were easy to section off and build. You could section off that maze of a third floor and build the terrace before building the foundation, or lay out bathrooms before concrete is even set. Unfortunately, as we all know, construction is a sequential process. You can’t tackle the roof before the first twenty floors are built.

construction critical path method

While smaller construction jobs allow for spontaneous planning, bigger projects require construction project management. The construction critical path method (CPM) is a tool that many project managers use, often with their construction management software, to help figure out the best steps to take to finish a job efficiently. This critical path method, otherwise known as critical path scheduling, is one of the most frequently used construction planning techniques.

How can you apply it to your own construction business? Follow this simple guide to start implementing the critical path method in your construction projects.

1. Breakdown everything you have to do.

Planning your critical path is not so different from planning out your Gantt chart.  Like with Gantt charts, tasks tend to be dependent on each other—you can’t start part C until you’re done with A and B. These are called “sequential” activities. And as with Gantt charts, there are also “parallel” activities, where contractors or subcontractors can work on a part of the job without compromising another task.

List out what activities you need to complete before the job is done. Break out a chart of these tasks and specify how long each will take, whether they’re sequential or parallel to another task, and what they’re dependent on. Use this information to determine the earliest start date.

2. Use construction management software to organize this information.

There is a host of construction management software options that help construction managers lay out their critical paths. For example, Phoenix Project Manager 4 is a scheduling tool that cuts out extraneous features. It can tell construction managers what their total float is (or what tasks can be put off without delaying the project is), or what the longest path is. While construction managers have long solved these problems by hand, it’s easier and more accurate for software to take care of these calculations.

There are also free critical path software options. For example, Open Workbench is an open source option for Windows.  Though it’s not construction specific, and I’d only recommend it to seasoned project managers. RationalPlan is another popular free option, though it’s largely used in conjunction with Microsoft Project.

Using critical path-specific software is really the key to using the critical path method effectively. Without it, you’ll end up with unwieldy equations and complications that would drag down the entire planning process of your construction project.

3. Identify the critical path.

The critical path is the longest path that ultimately leads to the project’s completion. Its “drag” is equal to its duration. Once the critical path is identified, construction project managers can start to calculate dependencies (how tasks interact with each other) and “activity-based resource dependencies” (which is really just a fancy way of saying where and how a construction company is spending their time and money on a project). This is an area where enterprise resource planning software may come in handy, because large construction firms may want to use the critical path method for more than one intertwined project.

4. Build!

Once you’ve outlined the critical path and calculated how long your project should take, how much it should cost, and how it falls in line with your other projects if you’re an enterprise firm, get those contractors and subcontractors ready. It’s time to use your plan to build a gorgeous building.

Should you run into difficulties, it’s easy to use critical path method software to adjust schedules and reevaluate resource planning. Since it does all the calculations for you, simply fine-tune one task’s expected end date and—like magic!—the critical path calculations are all altered in one go.

More?

The critical path method is an incredibly common and powerful tool used across the construction industry today. But with that in mind, remember that it’s only as powerful as the data entered into it—if estimations are off, if resources aren’t calculated correctly, the entire project may fail. Take ample time to plan and schedule out your project.

Do you use the critical path method? Do you use related software? Tell us your stories below!

Header by Abby Kahler

Looking for Construction Management software? Check out Capterra's list of the best Construction Management software solutions.

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About the Author

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Rachel Burger

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Rachel is a former Capterra analyst who covered project management.

Comments

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Thanks for those nice & valuable information, To open a group of projects is independent from the data date. As far as I know the only impact would be for scheduling, float, longest path.
What you did was exactly what I suggested

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Hi, Rachel. I cam e to your website after a Google search on “critical path” and “drag”. You have written a good article, but the info on drag is not quite correct. You wrote: “The critical path is the longest path that ultimately leads to the project’s completion. Its ‘drag’ is equal to its duration. ” If you go to the Wikipedia page for “critical path drag”, it reads: “Critical path drag is the amount of time that an activity or constraint on the critical path is adding to the project duration. Alternatively, it is the maximum amount of time that one can shorten the activity before it is no longer on the critical path or before its duration becomes zero.” Drag is a relatively new critical path metric, so it is understandable if you are not yet completely familiar with it. If you wish to discuss it further, please feel free to contact me.

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