Decrease the Total Float of Preconstruction Activities using As Late As Possible Constraint

As discussed in our previous articles, effectively managing and optimizing total float is a critical aspect of developing a reliable and realistic baseline schedule. Total float, when strategically controlled, helps ensure that key project activities remain on track and that early warning signs of potential delays can be addressed proactively. In this article, we will explore an additional technique to decrease the total float associated with preconstruction activities, such as shop drawing submittals, material approvals, method of statement, and other essential preparatory tasks. By applying this method, planners can better align the preliminary stages of the project with critical milestones, enhancing schedule realism and improving the likelihood of timely project delivery.

Here are some links to previous articles talking about other methods and techniques to decrease the total float:

The Application of Start-to-Finish [SF] Relationship in Primavera P6

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Primavera P6 Best Practices: How to Manage Shop Drawing Submittals with Activity Linking vs Lag Time

As Late As Possible Constraint

As Late As Possible is scheduling constraint in Primavera P6 that schedules an activity as late as possible without delaying its successor activities. Unlike other constraints that impose a fixed start or finish date, As Late As Possible allows Primavera to position the activity dynamically at the latest possible time within the logical sequence of the project.

As can be seen in the screenshot above, setting a date to the activity after assigning a constraint is not possible, meaning that it will be dynamically moved according to the logical sequence; you do not add a date to it.

You can read more about the activity constraints in Primavera P6 from here.

Methods Used to Manage Preconstruction Total Float

Usually, the high float is always found in the preconstruction activities because they do not depend on each other, unlike the construction activities.

So, to decrease the total float, we have several methods that can be used if it is accepted by the consultant:

1. Lags between the start Milestone and the submittals. (Previously explained)

2. Linking activities together. (Previously explained)

3. Constraint. (This article)

Using As Late As Possible Constraint to Decrease the Total Float of Preconstruction Activities

In this example, there is a gap between the “Activity Shop Drawing Approval A” and the “Construction Activity A” resulting in a 5-day total float. In a mega project, the total float might be higher, this example is only for illustration.

You need to assign the “As Late As Possible” constraints on all the activities before the construction activity to shift all the preconstruction activities near the construction activity date. Meaning that in the shop drawings, you need to assign the As Late As Possible constraint to the submittal activity and the approval activity to shift them right before the construction activity to decrease the total float.

In a mega project, it is not logical to assign manually; you can show the “Primary Constraint” column and open the Preconstruction WBSs that you want to add this constraint to in order to decrease the Total Float.

Assign the constraint to the first activity, then scroll to the final activity you want to assign this constraint to, press on it while pressing the shift button, and you will find that all the activities in between were selected. Then press (Ctrl + E) together.

After finishing this step, you now have As Late As Possible constraints assigned to the preconstruction activities to decrease the total float in your baseline schedule.

Conclusion

Assigning the “As Late As Possible” constraint to preconstruction activities, such as submittals and approvals of shop drawings or procurement or method statement, can be a valuable strategy in managing and minimizing total float within a project schedule. By strategically delaying non-critical tasks without affecting the overall project timeline, planners can create a more focused and realistic representation of activity timing. This approach not only helps to better prioritize resources but also supports more accurate float calculations and schedule risk assessments.

You can enroll in our Construction Project Planning Intermediate Level with P6 course to learn more scheduling tips and tricks.

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