Project schedules tend toward tardiness, but what can be done to make schedules more reliably on time? Schedule buffer similar to a cost contingency helps projects become more reliable.
Project plans are generally more optimistic than reality. Reasons for this disconnect are that project plans do not consider: inefficiencies in the handover of tasks between resources, workplace congestion, coordination among contributors, and the multitasking of critical resources. One would think that not accounting for these delay effects would be counter balanced by contributors padding their estimates. But this is not the case. Once a duration is entered in the project plan (whether conservative or optimistic) it becomes subject to all the drag effects of Parkinson’s Law and procrastination.
So even conservative duration estimates can tend toward lateness in execution. What can be done then to make activity durations both competitive and reliable? Include a schedule buffer similar to a cost contingency line item in the schedule. Budget line items are not padded and the overall project protected from overspending with a cost contingency line item. This same approach works well to protect the schedule and keep activity durations competitive.
Schedule Buffer
This article discusses how to include a schedule buffer so that schedule duration remains competitive and reliably on time.
Cost contingencies allow for competitive pricing while providing sufficient protection from cost overruns. In the same way schedule buffer supports aggressive activity duration estimates and protection from schedule delays. But schedule buffer only works well when it is owned and controlled by management. Debate may arise about who actually owns the buffer, which leads some to hide the schedule buffer. The great debate whether or not to hide buffer is considered in the following blog Visible Schedule Time Buffers.
It is common practice to make buffer part of back-end activities like commissioning. We recommend the more forthright approach to schedule buffer. Buffer can be strategically located before mobilization, major convergence points, or final project delivery. Again, it is most important for schedule buffer, wherever located, to be managed by the project manager. Buffer should only be expended when permission by management is granted.
We have in Figure 1 a project schedule.
Figure 1
This schedule has two paths that are equally critical. The duration estimates in these two paths include padding. The end date of the project is June 22, 2018.
In Figure 2 we adjust the activity durations to remove padding and make them more realistic and competitive.
Figure 2
Note the original baseline and the current activity durations. Time savings by shaving off the duration estimates are combined in a Buffer activity. The project is still scheduled to end on June 22, 2018.
We, however, have a much more reliable schedule that has much less Parkinson’s Law or procrastination related drag. (Parkinson’s Law says that work tends to fill the time allotted.) Team members work harder and sooner, according to their more aggressive activity durations. And a delay on either critical path may be absorbed by the buffer. This gives the project manager a tool to extend respective activity durations when necessary.
Hopefully, all activities go according to plan estimates and the project ends early. If not, the schedule, including the buffer, is still a much more reliable schedule. Work is performed with more sense of urgency and the project manager can distribute buffer, accordingly, to activities truly in need of extension.
Summary
Line item schedule buffer similar to line item cost contingency encourages a good working pace and improves reliability. The key factor that makes schedule buffer work is that it is owned and controlled by management. Possible argument over who controls buffer, may lead some to hide buffer in their back end schedule activity efforts like commissioning.
We believe buffer works best when it is clearly visible in the schedule. And buffer helps limit the negative effects of Parkinson’s Law and procrastination. Further, buffer is an additional project management tool to extend only those activities in real need of adjustment. Thus, buffer makes the schedule more reliable, as the project manager begins with a compressed schedule and directs the extension of activities, accordingly, and only where truly required.
For more schedule reliability and buffers consider reading “Advanced Scheduling Handbook for Project Managers” by Jeremie Averous and Thierry Linares.