Do You Understand the Critical Path Method?

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By Ramiro Rodrigues

 

The term path is used for a sequence of activities that are serially related to each other.

 

Imagine, for example, that your colleagues have decided to organize a barbecue. After dividing up the work, you are responsible for hiring the catering services. For this task, you are likely to have to look for recommendations, check availability and prices, analyze the options and then choose the best one. These four activities are a path. In other words, they are a sequence of activities that must be carried out sequentially until a final goal is achieved.

 

A project manager’s job is to estimate the duration of each planned activity. And if we return to our example, we could consider the possible durations:

  • Activity 1: Seek professional recommendations—three days
  • Activity 2: Make contact and check availability and prices—six hours
  • Activity 3: Analyze the options—one day
  • Activity 4: Select the best option and confirm—two hours

 

This sequence of activities will last 40 hours, or five workdays. And since the whole barbecue has been divided among various colleagues, other sequences (or paths) of activities—such as choosing the venue, buying drinks, organizing football, etc.—will also have their respective deadlines.

 

The critical path will be the series of activities that has the longest duration among all those that the event involves.

 

Let's imagine that the longest path is precisely this hiring of the catering services. Since the process is estimated to take five days, the barbecue cannot be held at an earlier time. And if it were held in exactly five days, all the activities involved in the path have no margin for delay. This means that if, for example, my analysis of options is not completed on the date or within the duration planned, then the barbecue provider will not be selected in time, which will invariably lead to the postponement of the barbecue—and leave a bad taste in my co-workers' mouths.

 

Under the critical path method, there is no margin for delay or slack. If there is a delay in any activity on that (critical) path, there will be a delay in the project. At the same time, other "non-critical" paths can withstand limited delays, hence the justification of the term.

 

It is the duration of this path that is setting "critical" information for all projects—when all the work will have been completed.

 

Do you use the critical path method in your work? If so, what are your biggest challenges?

Posted by Ramiro Rodrigues on: September 21, 2018 04:42 PM | Permalink

Comments (19)

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Thank you

Thanks for explaining the critical path by example of the barbecue.

I work on project that use critical path method in construction schedules. The biggest challenges are ensuring the schedulers are knowledgeable in the construction methods and sequence of activities for the projects, activities are properly linked to predecessor and successor activities, and that changes in work sequencing are strongly managed to retain the activity links established at the project start.

Thanks for this reminder on CPM Ramiro.

Good article Ramiro! You provided excellent examples of the critical path.

Thanks Ramiro for sharing.

Very interesting, thanks for sharing.

Thank you so much for sharing.The illustration is pertinent.

I work with a client who uses critical path heavily, and it's interesting to see how they define it so well yet rarely stick to the actual path. The path is constantly shifting forward a few days, and surprises can push the project off the path. I think it's a good visualization exercise to "see" the critical path just to know the dependencies, but know that things rarely work out that smoothly.

Excellent information on CPM. Thanks a lot for sharing!

Thanks for sharing this valuable guide on CPM.

For large projects, managing the huge amount of activities and dependency relationships is daunting.

Using Critical Chain method with CPM will increase the planning accuracy of resource availability and allocation. Juggling both methods is a complex challenge too.

The critical path is used in many types of project, that is a nice simple way to explain it.

thanks

Thanks for using a simple but practical way to explain the CPM.

Great and practical example. Thanks for sharing.

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