The Primavera P6 Finish On Or After (FOOA) constraint supports situations when an event must occur either at the same time or before the completion of an effort.
The start and finish of a project is comparable to the movement of a train. The train slowly gains speed until it reaches velocity. Likewise, the train gradually decelerates and comes to a halt. So certain events have to take place to get a project up and running, and certain events have to occur to bring it to a successful close.
The key word is successful. Guiding a Primavera P6 project to an agreeable close may require the insertion of a FOOA constraint. Broad usage of constraints is discouraged in scheduling. You typically want activity durations and network logic to drive the start and finish dates of activities.
Sometimes, however, the scheduler may better suit the true schedule narrative by inserting a constraint. The FOOA constraint may better describe a situation where an event must occur simultaneously or before the finish of an effort to lead the project to a favorable conclusion.
This article demonstrates a situation when insertion of a FOOA constraint provides the best representation of the true schedule storyline.
We have in Figure 1 our demonstration project.
This is a piping repair and improvement project. Bringing this project to a successful close requires the insertion of a FOOA constraint. In our scheduling situation the government contracting officer for the final quality assurance inspection is not available till on or after Wednesday, September 25, 2019. The government contracting officer must inspect the worksite and confirm that the installation meets quality assurance requirements.
Network logic has the final inspection taking place on Monday, September 23, 2019. We need to insert a FOOA constraint, so that the final inspection does not conclude until on or after Wednesday when the government contracting officer is available.
We proceed with our FOOA constraint insertion by selecting the final quality assurance inspection activity and the status tab in the bottom details, Figure 2.
In the constraint section we choose the Finish On or After primary constraint. We set the date to September 25, 2019, Figure 3.
We recalculate the schedule and the final schedule displays similar to Figure 4.
You may observe on the Gantt chart that the critical path now has a discontinuity; activities upstream of our constraint activity have become non-critical. This is because our FOOA constraint delays the final quality assurance inspection until on or after Wednesday. This generates 2 days total float on write quality assurance report, which means the write quality assurance report effort can delay 2 days and still not postpone the project end date.
This creates the break along our critical path. Critical path discontinuities is one reason that insertion of activity constraints is discouraged. Some guidelines only accept activity constraints specifically written in the contract. But in our schedule the FOOA helps consider the availability of the government contracting officer and its impact on the closing phase of the project schedule.
It’s good practice to let network logic determine the start and finish date of schedule activities. Sometimes, however, you have a schedule situation that is best described by the insertion of an activity constraint. The FOOA better models scenarios where an effort cannot complete until an event driven date occurs.
In our demonstration Primavera P6 project schedule, the final quality assurance inspection cannot conclude until the government contracting officer is available to inspect the worksite, and approve the quality of the deliverable.
So, the FOOA constraint delays conclusion of the inspection effort until the availability of the government contracting officer. The FOOA therefore slowly decelerates our piping repair and improvement project to bring this schedule to a successful (quality approved) conclusion.