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Critical Path Method for Construction

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What is the Critical Path Method (CPM) in construction management?

The Critical Path Method (CPM) is the most popular way to plan construction projects because it helps builders finish them quickly. CPM shows the fastest possible way to finish a project. It maps out every single step involved in a project, but it can be very complicated for big projects. There are computer programs that make it easier. These programs show which steps of the project might cause delays. Knowing where the problems might happen will help you plan and use your team in the smartest way possible. That's why CPM is so important among construction experts.


What is the purpose of the critical path?

The main purpose of the critical path is to ensure that projects stay on track. It shows the steps of the construction project that must be completed on time in order to finish the entire project on schedule. It's the longest chain of tasks that have to happen one after the other. 


Some construction projects may have more than one critical path. This means there are several chains of tasks that all need to be completed on time. If there's a problem with any of the critical paths, the entire project could be delayed.


The critical path helps to identify the parts of a project that are most likely to cause delays. You can then make plans to prevent those delays. 


What are the benefits of the critical path method?

CPM is a helpful tool because it shows which parts of the construction project are the most important to finish on time.  By understanding which steps need to happen when, you can finish your project more efficiently.


Let's say there are two important jobs that need to be done at the same time, but they both require the same equipment, CPM helps you decide which job to do first so that you don't have delays.


Here are some of the key benefits of using the critical path method in construction:


  1. Help focus on what's important - CPM shows you the tasks that must be finished on time to avoid delaying the entire project. This helps you know where to focus your attention.

  2. Finish projects faster - CPM can help you reorganise tasks and find ways to finish your projects faster.

  3. Keep track of your progress - When you know how all the tasks are connected and how long they should take, it's easier to see if you’re on schedule. This can help you to quickly fix any problems that might come up.


The critical path method helps turn a complicated project into a plan that is easy to understand. This helps a construction team talk to each other more clearly, stay organised, and find problems early.  


What are the examples of critical path method?

CPM is used to plan very large and complicated construction projects. It helps builders coordinate many different jobs so a project can be completed as quickly as possible.


For example, Emaar Properties, a Dubai-based real estate company, used CPM to construct the Burj Khalifa. It helped the team organise their work so they could build the tower in only six years. CPM helped in scheduling the delivery of materials and figuring out which jobs needed to be done in which order.


The critical path method is also used in a newer modern methods of construction called prefabrication. In prefabrication, parts of a building are made in a factory and then shipped to the construction site. 

It helps plan when each part of the building needs to be made, shipped, and installed at the construction site. This helps the project stay on schedule.


How do you calculate CPM in construction?

Knowing the critical path for a large project can be very complicated. However, there is a step-by-step process you can follow to calculate it.


Here's how to calculate the critical path:


Step 1: Figure out how long each task will take. You also need to know what other jobs need to be finished before each task can start.

Step 2: Once you're done with step 1, know when each task can be completed. If a task takes two weeks to complete, and the job must be finished before it starts on day 1, then this task can start on day 15.

Step 3: Next, you'll have to find out the longest possible chain of tasks that need to be completed one after the other. This is the critical path, and it tells you how long the entire project will take (at the very least).


As mentioned earlier, there are computer programs that can help you calculate the critical path for very complex projects. However, even if you use a computer program, it's good to understand how to calculate the critical path yourself. This will help you stay on top of your company's project and keep it on track.


Application of CPM in construction

CPM can be used to plan many different types of construction projects. Here are a few examples:


Infrastructure planning - It can help with infrastructural planning when building roads, bridges, and railroads. It also ensures the construction team follows all the rules and regulations.


Building skyscrapers - CPM can help plan how to build a skyscraper floor by floor, and how the different parts of the building (like the foundation and the electrical system) need to be built in a certain order.


Building houses and large communities - CPM could help plan the order a house should be built. It can also help the team plan for delays, such as when they can't get the materials they need.


This method could also help plan how to build a whole community, including everything from getting the right permits to building homes and community spaces.


If you want to learn new construction techniques, you can read more about the Construction 2025 strategy here.


Steps to implement CPM in construction projects

Here are the steps you can take to use CPM to plan a construction project:


Step 1: Make a list of every task. Write down every single thing that needs to be done to finish the project, even the small stuff.

Step 2: Now, put the tasks in order. Figure out what needs to happen before each task can start. For example, you need to get planning approval before you can dig the foundation, and you need to put up the walls before you can put on the roof.

Step 3: You can start drawing the critical path map. Make a plan that shows all the tasks and the order they need to be completed. This will help you visualise the project.

Step 4: Once you're done drawing out the plan, figure out how long each task will take. Talk to the team who will be doing the work to get a good idea of how long each task should take to complete. It's also a good idea to look at how long similar tasks took on past projects.

Step 5: Find the critical path. As we've stressed, the critical path is the longest chain of tasks that have to be completed one after the other. This is the minimum amount of time it will take to complete the project.

Step 6: Keep the plan updated. As you work on the project, make sure you keep track of your progress and update the plan. This will help you stay on track and avoid any problems.


Challenges and limitations

CPM is a great tool for planning construction projects, but it does have some limitations. Here are a few of the challenges you might face when using CPM:


  • Estimating how long things will take - It can be hard to know exactly how long each task will take to complete. If you guess wrong, your whole schedule could be thrown off.

  • Changes in plans - Sometimes, things happen that you didn't plan for, such as bad weather or problems with getting the materials you need. If this happens, you will need to update your plan, which can be time-consuming.

  • Unexpected problems - A single mistake can cause big delays. For example, if you the right permits or permissions on time, it could mean you can't start construction when you planned to.


Companies can work around these challenges by having backup plans for when things go wrong. Your company should also stay flexible and be prepared to make changes to the CPM as needed.

Despite these challenges, CPM is still very useful. It can help you see the big picture and understand how all the different parts of your project fit together.


Wrapping up

Building projects can be very complicated. CPM can help you uncomplicate things by putting things in order and planning when they should happen.


With this method in place, the whole team will know what needs to happen and when so they can finish on time and on budget.


And lastly, CPM shows you where the problems might be and how to fix them. It helps make the most complicated projects seem a lot easier.


Disclaimer: Information displayed in this article is correct at the time of publication, but note that legislation changes periodically. The information contained on this page is intended as an overall introduction and is not intended as advice from a professional. Travis Perkins aims to avoid, but accepts no liability, in the case that any information stated is out of date.