Schedule Updating and Project Control - Construction Project Scheduling and Control - page 179

This case emphasizes the importance of communication and that the scheduler
cannot and must not make assumptions without the knowledge and consent of the
project manager.
Importance of Updating Remaining Duration
When updating a schedule, some activities may be in progress, that is, started but not
completed. Actual duration is calculated automatically as:
Actual duration = DataDate − Actual Start Date
The finish date of the activity is usually determined when the scheduler inputs one
of these three variables:
• Remaining duration
• Percent complete
• Expected finish date
If the activity is progressing as planned, remaining duration and percent complete
will agree with each other. Scheduling computer programs such as Oracle Primavera
P6 tie them together by default but allow the user to untie them. This untying is nec-
essary when the activity is not progressing as planned. For example, the activity Install
Doors had an original duration of 8 days (5 workdays per week, Monday through
Friday). It started on Wednesday, 15 OCT 2014. The data date is (end of) Friday, 17
OCT 2014. If the activity is progressing as planned:
Actual Duration = 17 OCT 2014 - 15 OCT 2014 + 1 4 = 3 days
Remaining Duration = 8 − 3 = 5days
Percent Complete = Actual Duration/Original Duration = 3/8 = 37.5%
Now, in a different scenario, let's assume that 3 days after its start, things are
not going well. The activity Install Doors is only 25% complete, but the foreman
believes he can pick up the slack and finish on time. The remaining duration is still
5 days. The scheduler has to untie the remaining duration and percent complete
and then input them independently. The At Completion Duration is still 8 days.
However, if productivity continues at the same pace as in the first 3 days, then
there is no need to untie percent complete and remaining duration. When the
scheduler inputs percent complete = 25%, the computer automatically calculates
the remaining duration as 9 days. In this case, the At Completion Duration will be
3 + 9 = 12 days.
4 We added 1 day because the start date in computer software is taken as the beginning of the day. We chose
to have the data date as the end of the day. So, 3 days of the activity duration passed: 14, 15, and 16.