In Primavera P6, the critical path is the sequence of critical activities within the schedule. Critical activities have no float – they must start and finish on time to ensure that the project completes on time. Because of this, the critical path represents the minimum duration required to finish the project.

By default, P6 will just display one critical path – known as the most critical path. These activities show as red bars on the Gantt chart. It’s very important to watch the progress of critical path activities. However, you may also want to view additional float paths as well – such as the next most critical path. These are useful to track, as they could easily become a part of the most critical path if there are any delays. In P6, we can view multiple critical paths using options in the Schedule window.

This article will outline how to calculate multiple float paths in Primavera P6. First, we’ll look at how to set up a multiple float path layout. Then, we’ll look at how to calculate this information using the options in the Schedule window. The following examples are from Primavera P6 Professional 23. However, this process is the same for all versions of P6 Professional. 

Setting Up a Layout for Multiple Float Paths

Calculating multiple float paths won’t adjust your project data. Instead, it will just give you more insight on which path each activity is a part of. If you plan on calculating multiple float paths, you will need to first set up your layout to view this information. Specifically, you’ll need to add some columns to the Activities table.

To add columns to the table, select View > Columns. Within the Available Options box, expand the Multiple Float Paths category. There’s only two columns here: Float Path and Float Path Order. I recommend adding both of these to the table by double clicking on each of them. If you don’t already have the Total Float column displaying, I recommend adding that as well. With these columns added to the table, select OK to close the Columns window.

The Float Path column will display which float path the activity is on. The Float Path Order column will display where the activity is in its float path. Currently, these columns are blank. This is because the program is currently only accounting for the most critical path. In order to fill in these columns, we will need to tell P6 to calculate multiple float paths.

Calculating Multiple Float Paths

To allow the program to calculate multiple float paths, navigate to the Schedule tool by selecting Tools > Schedule. Within the Schedule window, select Options.

The Schedule Options allow you to adjust how P6 schedules the project. To adjust the float paths, select the Advanced tab. Here, check off the box to calculate multiple float paths. Currently, P6 is only calculating information for the Critical Path. Checking this box will cause the program to account for other float paths in the schedule as well.

Total Float vs. Free Float

Next, you can choose how to calculate the float paths. You can choose to either calculate these paths using Total Float or Free Float.

Total Float is the amount of time you can delay or extend an activity without delaying the project’s finish date. When using Total Float, the tool will first determine which activity relationship has the most critical total float. Using this as the starting point, the tool will then continue to determine which activities have the most critical total float among all possible paths. It will only stop once it reaches an activity with no relationships. The path that contains these activities is known as the most critical path.

Free Float, on the other hand, is the amount of time you can delay an activity without delaying the start of its successor. When using Free Float, the tool will define critical float paths based on the longest path. After identifying the most critical path, the tool will calculate the remaining sub-critical paths.

Number of Paths and Ending Activity

Next, you can choose which activity should end the float paths. This, most generally, will be the last activity in your schedule. Along with this, you’ll need to choose the number of critical float paths to calculate. 

In this example, I’m using a very small project with 3 obvious float paths. In this case, I’ll set this option to 3. However, if you are working with a longer schedule, you may want to increase this number.

Once you have finished with the options, select Close. Then, press Schedule to schedule the project with these settings.

Multiple Float Path Results

After scheduling, the activities will look the same within the Gantt chart. However, data is now available within the Float Path and Float Path Order columns. The Float Path column will show which float path each activity is a part of. In this example, I have 3 float paths, so each activity has a number from 1-3 listed. The Float Path Order column displays where the activity is within its float path. For example, Activity A is the first activity on the most critical path, so its Float Path is 1 and its Float Path Order is also 1. Activity B is the next activity on the most critical path, so its Float Path is 1 and its Float Path Order is 2.

To make the float paths easier to see, you can group activities by their float path. To adjust the activity grouping, select View > Group and Sort. Under Group By, select Float Path from the dropdown menu. Then, press OK.

Now, each float path will display grouped together in the table and the Gantt Chart. The float path order is determined by how critical the activities are in the schedule. The first float path, being most critical, only includes activities with 0 days of float. The second float path’s activities each have 1 day of float, and the 3rd float path’s activities each have 2 days of float.

It’s often nice to see the different float paths in this manner, as any delay that occurs in the project could make any of these paths the new critical path. You will want to monitor paths that are near critical, along with the critical path. This can help ensure that they don’t lose too much float and delay the project’s completion over time.

Summary

When using Primavera P6, it’s important to track your project’s critical path. The critical path is the sequence of critical activities. These activities must start and finish on time to ensure the project completes on time. Ultimately, the critical path determines the duration of the project. By default, only the most critical path will display – but you can choose to display other float paths as well. With multiple float paths displaying, you can track your schedule as it changes over time. If any delays occur, activities on a secondary float path might become a part of the most critical path. As your project progresses, it’s recommended to not only look at the most critical path but also the near critical paths as well. This can help you keep your project on track, even when the unexpected occurs.

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Lauren Hecker is the instructor for the Primavera P6 Professionals training courses. To see her next open enrollment course, please visit our calendar. To schedule an onsite or custom course, please contact us!