P6 Professional narrows the necking of Gantt chart bars to indicate periods when you have activity nonwork intervals. Let’s take a look.
The Gantt chart is at the center of Primavera P6. The more of the right type of information you have on Gantt chart the better you can interpret your schedule’s situation. And you want to be deliberate about everything you include on the Gantt chart canvas.
Primavera P6 Professional has features to display both calendar nonwork time and activity nonwork intervals on the Gantt chart. The calendar nonwork periods detail is not usually recommended as it clutters the Gantt chart with distracting graphics. The P6 Professional activity nonwork intervals visuals are more helpful and do not detract from your schedule’s true narrative.
This article demonstrates the distracting trait of the calendar nonwork time setting and perhaps the more useful activity nonwork intervals option.
Calendar Nonwork Time
Primavera P6 Professional has a Gantt chart graphical feature that narrows the task bar (makes the necking thinner) during calendar and/or activity nonwork time. As mentioned, the calendar nonwork time necking crowds the Gantt chart with excessive graphical minutiae. The calendar nonwork time for weekends and holidays works, but the necking of weekday work/nonwork periods is bothersome. Let us demonstrate.
Figure 1 is a screenshot of a schedule without necking for calendar nonwork time. (Note the schedule option is set to progress override.)
That same schedule and timescale using calendar nonwork time narrow necking displays in Figure 2. (Note the schedule option is set to progress override.)
As you can see, the resulting lumps, Figure 2, that mimic weekday calendar work and nonwork times diverts your attention away from the more pertinent activity work and nonwork intervals.
There are ways to adjust the calendar nonwork time necking graphics. They are presented in the blog Non-work Time Necking on Primavera P6 Gantt Chart Bars.
These solutions, however, may require more attention and effort than you may want to devote to highlighting calendar work and nonwork time. We recommend you leave the ‘Calendar nonwork time’ setting off for most scheduling situations. Exceptions may include extended holidays.
Activity Nonwork Intervals
Activity nonwork intervals appear when workday efforts are in a current nonwork state. The classic example is suspended/resumed tasks. Out-of-sequence activities are a common cause of nonwork intervals. Driving relationships also create nonwork intervals.
Activity Nonwork Intervals – Setup
Let us consider bar necking settings for ‘Activity nonwork intervals’. Figure 3 displays the bar necking settings with ‘Calendar nonwork time’ off and the ‘Activity nonwork intervals’ active.
Confirm that the ‘Activity nonwork intervals’ are on for the actual work, remaining work, and critical remaining work bar definitions, Figure 3. Observe the narrow necking graphics for these bar definitions in the preview column, which indicates narrow bar necking on.
The actual work bar definition is for completed work. The remaining work bar displays tasks that have remaining effort and total float. (These total float tasks can be delayed up to the specified number of float days without postponing the end date of the project.) The critical remaining work bar is for tasks that have a total float of zero or less.
If there are other bar definitions graphically displaying tasks with some measure of total float, e.g., near critical tasks that have total float between 0.1-day and 10-day, these bar definitions also should have the ‘Activity nonwork intervals’ option active.
Activity Nonwork Intervals – Scenarios
Now that P6 Professional is set to only display ‘Activity nonwork intervals’, let us consider scenarios where activity work/nonwork intervals appear. What follows are situations where activity work and nonwork intervals display.
Suspended and Resumed tasks:
The first scenario occurs when a task effort is suspended then resumed after a period, Figure 4.
Observe the narrow necking on activity B, Figure 4. For more details on suspending work in Primavera P6 Professional consider the blog Suspending Work Using Primavera P6 Professional.
Out-of-Sequence Task with Retained Logic:
The next scenario is out-of-sequence work with the schedule options set to retained logic, Figures 5 and 6.
In retained logic, the activity, despite occurring out-of-sequence, continues to honor the predecessor relationship which creates the nonwork interval appearing as a thinner bar on the Gantt chart. See the narrow necking on activity D, Figure 6.
Out-of-Sequence Task with Progress Override:
Continuing we have the same schedule and out-of-sequence work but with progress override schedule option set, Figures 7 and 8.
In this out-of-sequence scenario the task completely ignores the predecessor finish-to-start (FS) relationship. The out-of-sequence activity work continues so the narrow necking is limited. Observe in Figure 8 that activity D continues work on Monday after the data date. (The 3-days total float on activity C is float time between the conclusion of task C and the end of task E.)
Out-of-Sequence Task with Actual Dates:
We proceed again with the same schedule and off kilter progress. This time the scheduling option is set to actual dates, Figures 9 and 10.
In this situation, as with retained logic, the out-of-sequence activity continues to honor the predecessor relationship creating a nonwork interval. In Figure 10 consider the thinner bar region for activity D. (Note, also, that the total float of the predecessor activity C is negative 8-days, which warns that the predecessor task is behind in relation to the out-of-sequence task D.)
In-Progress Task C and No Driving Relationship:
Next, we have a schedule that includes an in-progress task C with no driving relationship, Figure 11.
Here the work schedules to continue as soon as possible (ASAP) after the completed work, so the nonwork necking on task C is minimal in Figure 11.
C and B-to-C Finish-to-Finish (FF) Driving Relationship:
Then we have this same schedule but including a B-to-C Finish-to-Finish (FF) driving relationship, Figure 12.
This time there is clearly visible a thinner necking region separating the actual progress from the remaining work, which is driven by the FF relationship between tasks B and C. The schedule’s task C is driven by the requirement that it cannot conclude until task B finishes.
Summary
Every graphic feature you include on the Gantt chart canvas should direct your stakeholder’s attention to the true schedule situation. Though displaying ‘Calendar nonwork time’ visuals is possible in practice it provides too much information, and it distracts from the more pertinent ‘Activity nonwork intervals’ necking.
The ‘Activity nonwork intervals’ graphics setting in the scheduling options adds value and should be toggled active.
Display activity nonwork graphics for actual work, remaining work with total float, remaining work with near critical total float, and critical remaining work bar definitions. Having made the ‘Activity nonwork intervals’ bar necking setting active, the necking details will make distinct several conditions: suspended and resumed tasks, out-of-sequence tasks with retained logic, out-of-sequence tasks using progress override, out-of-sequence tasks with actual dates, and in-progress tasks with and without a driving relationship.
In this way the narrow necking on the Gantt chart guides you and/or your stakeholders to glean more insight into the true scheduling situation.
If you want a more in-depth article on the differing settings for out-of-sequence tasks refer to the blog Options for Scheduling Progressed Activities in P6.