Cost of Time
- or who's duration is it anyway? -
you can't get your work done in the first 24 Hrs, work nights!
Keywords: Time cost tradeoff, Acceleration, Duration, Optimum crew size.
The Cost of Time - or who's duration is it anyway? [P009]
Probably the most common action undertaken by schedulers everywhere is assigning a duration to a task; most of us do this almost automatically. Generally it is only when a dispute arrises the complex interaction of the factors discussed in this paper come into play. The purpose of this paper is not to reach any conclusion on what is the ‘correct’ way to assess durations (we suggest there is no universally correct answer this question), rather to put into one place the multiple factors that should be considered by competent planners and managers.
The initial planning decisions concern the project framework used to define the task:-
Once the task is determined, and the overall project framework set; the issues concerning the estimation of the optimum task duration come into play:
Once the task durations have been determined, the next factor to consider is the overall scheduling process; balancing schedule logic, working times, tasks durations and resources to achieve the overall project objectives, whilst allowing appropriate contingency times for risks. This process frequently requires adjustments to the pre-determined optimum duration for a task to achieve contractual objectives, balance resources and/or meet imposed constraints. But this is only the beginning……
As the project progresses, the need to accelerate frequently arrises, generally caused by a delaying factor earlier in the project. Reducing the overall duration of the remaining part of the schedule is relatively simple (on paper) – achieving ‘acceleration’ in the work place is altogether more difficult. Some of the factors to be considered are:-
Starting a project ‘right’ seems to be the best way to avoid problems. EV and Earned Schedule data suggests the trend by the 20% stage is set and unlikely to be bettered. Therefore, when confronted with the need to accelerate, it is probably wise to think vary carefully about what fundamental changes will be made before simply cutting a few durations. And the critical thing about fundamental change is that it is usually expensive!