Question: What do the options in the Resource Assignments section of the Calculation tab in the User Preferences dialog do?
From time to time I get asked about this setting in Primavera P6 Professional and what impact it’s having on a schedule. Let’s take a look at the options, and then I’ll explain what it all means.
The title for the section is Resource Assignment and below that is the following statement.
“When adding or removing multiple resources on activities…”
a) – Preserve the Units, Duration and Units/Time for existing assignments
b) – Recalculate the Units, Duration and Units/Time for existing assignments based on the activity Duration Type
Let’s talk about ‘a’ first. What this means in simple terms is that, when you assign a resource to an activity it will be assigned with its default Units/Time setting, and when a second resource is added to that same activity, Primavera P6 will assign that resource with its default Units/Time format. It will do this regardless of whatever Duration Type setting may be in place for the activity.
For example, we have a five day duration activity that requires one Electrician and one Technician. We assign the Electrician and that resource arrives with its default units/time setting of 8 hours per day.
When we add the Technician, that resource also arrives with its default units/time setting of 8 hours per day.
As you can see in the above figure, this gives the activity 80 hours of labor over the five days as evident in the Budgeted Units field in the Resources tab and the Budgeted Labor Units column. This happens regardless of the activity’s Duration Type, which in this example had been set to Fixed Duration & Units. So preference setting ‘A’ “Preserve the Units, Duration and Units/Time for existing assignments” overrides the Duration Type and puts each resource on the activity with full default units/time values.
Now about that second option ‘b’.
This option instructs Primavera P6 to honor the Duration Type setting for the activity. So in the above situation with our Electrician and Technician being assigned to an activity with a Duration Type of Fixed Duration & Units, we would see the Electrician’s effort get cut to 4 hours per day, and the Technician would also be recalculated to 4 hours per day, because that Duration Type preserves the overall hours to that of the first assigned 40 hours. So you can see below how P6 honored the Fixed Duration & Units Duration Type and divided the work between the two labor resources at the point where the Technician was assigned.
The simplest way to think if these two options is to say that the first option to Preserve the Units, Duration and Units/Time overrides the Duration Type and assigns every resource with default options.
The second ‘Recalculate’ option tell Primavera P6 to honor the activity’s duration type.
Admittedly this is a slight oversimplification of what’s going on here, but for the purposes of anticipating the effect of this setting on your resource assignments, this article achieves its intended purpose.
And to put it yet another way…