Glossary
Crashing
schedule compression by added resources
Crashing shortens the project duration by adding resources to activities on the critical path. The logic of the schedule stays unchanged, the costs rise.
Alongside fast tracking, crashing is one of the two classic schedule compression techniques. Typical measures are additional staff, overtime, weekend work or buying in a service. The sequence stays the same, only the duration of individual activities drops.
The economic criterion is the cost slope, the price per unit of time saved:
(crash cost - normal cost) / (normal duration - crash duration)
Shorten the activity on the critical path with the lowest cost slope first, then the next cheapest. Keep three points in mind:
- Only the critical path counts. Accelerating an activity with float costs money without moving the project end.
- Recalculate after every step. The compression can make another path critical.
- More staff does not help linearly. Additional people need onboarding and coordination. On an already delayed project, this can push completion back even further, known as Brooks's law.
Crashing buys time with budget, fast tracking buys time with risk. In practice both are combined and the result is secured with a baseline and the planned/actual comparison.
