Do you want to monitor a task that can take place during a date range, i.e. during a window of opportunity? If so, here’s one way you can take advantage of the Primary and secondary constraint feature in Primavera P6 Professional.
Primavera P6 Professional has ‘start on’ and ‘finish on’ primary constraints that support monitoring activities that either need to start on a particular date or finish on a particular date. What if, however, you want to monitor the status of a task that can take place during a particular date range?
For example you want your ‘Final Quality Assurance Inspection’ to take place the last week of September because that is when the required inspector plans to be onsite. So you have a one week window of opportunity that the final inspection can begin and conclude. Defining this acceptable date range to support monitoring can be modeled using both a primary and a secondary constraint.
This article discusses how to insert and monitor a secondary constraint in Primavera P6 Professional.
We have in Figure 1 our demonstration schedule.
This is a Pipe Repair & Improve project. We want to monitor the ‘Final Quality Assurance Inspection’ to ensure it takes place during the last week of September when the inspector is onsite. To do this we first insert a ‘Start On or After’ primary constraint to mark the first day of inspector onsite availability, Figure 2.
The ‘Start or After’ start date is set to 25-September-2017, Figure 3.
We also define a ‘Finish On or Before’ secondary constraint in Figure 3. The ‘Finish On or Before’ finish date is set to Friday, 29-September-2017, Figure 4.
Now that we have our primary and secondary constraints fully defined let’s observe how to monitor our ‘Final Quality Assurance Inspection’ activity based on project progress.
First we update our estimated ‘Install Piping & Couplings’ task duration to 2-days; we plan to finish one day earlier than originally planned, Figure 5.
With this update our ‘Start On or After’ primary constraint informs us in the total float column that we can delay progress by one day and still be ready for our inspector on Monday, 25-September-2017.
Next we update our estimated ‘Install Piping & Couplings’ activity duration to 8-days, Figure 6.
This delay could be caused by any number of reasons, such as material delivery delays. Now the total float column is warning that we will miss the inspector’s availability window by 1-day. So we need to find a way to speed up progress by 1-day to successfully complete the project.
Primavera P6 Professional supports both primary and secondary constraints. Secondary constraints are not available for ‘Start On’, ‘Finish On’, ‘Mandatory Start’, and ‘Mandatory Finish’ primary constraints.
The primary/secondary constraint combination works well with a ‘Start On or After’ to ‘Finish On or Before’ definition. So, the primary/secondary constraint combination helps us monitor project progress in relation to a window of opportunity.