It’s good to note critical activities that cannot delay without negatively impacting schedule completion. But what about activities that are already behind schedule? These are your super critical tasks that require adjustment to meet project completion goals.
The critical path is an important scheduling parameter; it determines the length of your schedule. Activities along the critical path have zero total float, which indicates that they cannot delay without delaying the project completion.
Of course if they complete as planned than the schedule deadline is met, which is great. Sometimes though an activity has negative total float. This means that this activity is already behind schedule. And the scheduler must find ways to optimize the schedule to eliminate negative total float and meet the desired project completion goals.
In these situations it is helpful if the Gantt chart distinguishes activities that cannot delay from activities that are already behind. This is possible by defining a super critical bar definition to highlight activities that have negative total float.
This article describes how to create a super critical Gantt chart bar to note activities that have negative total float, i.e. activities that are behind schedule.
We begin with our demonstration schedule, Figure 1.
This schedule has a finish on or before constraint on dig cable trench that is generating negative total float. Our Gantt chart, however, does not warn us of this negative total float because it does not distinguish between activities that have zero total float from activities that have negative total float.
Let’s create a unique Gantt chart bar definition to differentiate activities that have negative total float from activities that have zero total float. Select View | Bars to access the bars dialog, Figure 2.
Name the bar Super Critical, Figure 3, and select the Remain Bar timescale.
The remaining bar timescale option sets the Gantt chart to display Super Critical bars only for remaining duration. Actual work uses the actual bar timescale to specify completed work.
Proceed and make the bar relevant for all normal and negative float activities, Figure 4.
Further, give the Super Critical bar a unique bar style as displayed in the preview and defined in the bottom frame bar style tab, Figure 4. Select OK and the schedule appears as in Figure 5.
Well, in Figure 5 we see a portion of our Super Critical bar, the ends. The issue is that P6 overlays bars lower in the bars dialog stack on top of bars higher in the stack. So move the Super Critical bar below the other bar definitions, Figure 6.
Now we see our Super Critical bars, Figure 7, but with remnants of the critical remaining bar.
To remove this overlap or the critical remaining bar remnants we create a new standard filter for all activities that have total float of zero, Figure 8.
Set the filter of the critical remaining work bar to normal and standard critical, Figure 9.
Now the Gantt chart differentiates Super Critical bars from critical remaining work, Figure 10.
If we progress our schedule through the end of January, Figure 11, we see the effect of our Bars dialog timescale specification.
Bars previous to the data date (DD) display as actual work and remaining work after the data date appears as Super Critical, noncritical, or critical.
Critical activities are important to note as they determine your schedule duration. It is further good to differentiate between activities that have no float from activities that have negative total float. Activities that have negative total float require immediate attention to realign the schedule with project schedule completion goals.
Schedulers can alert stakeholders of negative float activities by defining a Super Critical bars definition. It also should be noted that P6 Professional comes with a default negative float bar definition that uses the negative float timescale alert stakeholders when activities are coming in late and by how much.