One of the more uncommon activity types in Primavera P6 is the WBS (Work Breakdown Structure) Summary activity type. Yes, understanding the benefits and features of this activity type will definitely add another arrow to your quiver.
There are six different activity types in Primavera P6. The most popular of these activity types are the start and finish milestones and task dependent activity types. The majority of your activities may be described with these three activity types, including project progress markers (milestones) and tasks dependent on the default project calendar.
Also, Primavera P6 is one of the few major commercial scheduling tools to offer a Level of Effort activity type. This type is used for tracking overhead efforts that should not be on the critical path. These include such items as project management, support and administration. The resource dependent activity type helps to adjust the task duration, accordingly, based on the specific personal calendar of a resource.
This brings us the subject of this article; the WBS Summary activity type. This activity type was added to Primavera P6 in 2005 with the release of version 5.0. What is the purpose and value of this activity type? This Primavera P6 feature has several benefits, all of which will become more apparent from reading this article and by experimenting with its use in your schedules.
This article describes several of the features and uses of the WBS Summary activity type. However, this is not an exhaustive list of WBS Summary activity type applications.
The schedule for our WBS Summary activity demonstration is in Figure 1.
This schedule is divided into three phases: install piping, install thrust block, and quality assurance. Notice that we already have two WBS Summary activity types defined: ‘Summary Pipe Install’ and ‘Summary Thrust Block Install’.
Let’s add another WBS Summary activity type for quality assurance. The procedure is to first highlight activity G and select the + Add button. Change the Activity ID so that it comes immediately before activity G. Enter the name ‘Summary Quality Assurance’. In the activity type column select ‘WBS Summary’ activity type. Recalculate the schedule and the ‘Summary Quality Assurance’ WBS Summary activity will appear as displayed in Figure 2.
As you can see from the schedule, the WBS Summary activities are performing the same function as the summary bars; they roll up the original duration and start and finish dates of activities in their respective work breakdown structure (WBS) elements. Also, they span the length of all the activities making up the WBS element.
Just like the summary bars they will expand and contract as the associated activities increase or decrease in duration. Additionally, they are labeled. Note also that in our schedule they appear as red critical activities, which makes sense because they are on the critical path. They do not require relationship assignments, which is what differentiates the WBS Summary activity from the Level of Effort activity.
What makes the WBS Summary activity standout from the summary bar is that you can assign resources to it. Why would this be useful? Well for one, this makes the WBS Summary activity an ideal tool for top-down resource planning and estimating. It allows you to place resource estimates at a higher level, without having to populate all your detailed activities with resources.
The cost of the WBS element equates to all the resources assigned to the WBS Summary activity, or it could reflect the elements of a fixed price contract. Figure 3 displays a schedule with three WBS Summary activities.
Both the ‘Summary Pipe Install’ and ‘Summary Thrust Block Install’ have resources assigned. The ‘Summary Quality Assurance’ activity has no resource assignments. Instead it is assigned a fixed price fee of $14,000, as per the budgeted labor cost column.
Another feature of the WBS Summary activity that sets it apart is that it will automatically progress its % complete value based upon the progress of activities within the WBS Summary bar’s WBS element. In Figure 4 we have progressed activity A of the pipe installation process.
The ‘Summary Pipe Install’ activity automatically updated in conjunction with activity A’s update. We did not even have to say the ‘Summary Pipe Install’ activity was started; its update is automatic. Again, the value of this is a high level view of your project progress. You can even create a simple filter to display only WBS Summary activities, which will provide a high level view of the project schedule and progress.
One more benefit of the WBS Summary activity is that it will display WBS element summary information when the group layout is other than the WBS layout. In Figure 5 we have grouped the layout by the activity calendars.
Of course, for this schedule there is only one calendar. But notice that the WBS Summary activities roll up the durations of all activities associated with them. In Figure 6 we have grouped the layout by critical activities.
Note where there is only one WBS summary bar, the WBS Summary activities fill in the gaps and describe the durations of each WBS element.
It appears at first glance that the Primavera P6 WBS Summary activity duplicates the features of the summary bars. However, the WBS Summary activities have a few functions that set it apart from the summary bars.
The ability in P6 to assign resources to the WBS Summary activity makes it valuable for top-down high level estimating. The automatic progressing of the WBS Summary activity also makes it helpful for high-level viewing of schedule progress.
Last, not all grouping layouts display summary bars, so here again the WBS Summary activity comes in handy. Again, this is not an exhaustive treatise of WBS Summary activity features and benefits. I encourage you to experiment with WBS Summary activities in your schedule, and, perhaps, other uses for this Primavera P6 tool will become apparent. Indeed, we’d be interested to learn how you might be using WBS Summary activities in you schedules.