Overview
- Both crashing and fast-tracking are schedule compression techniques.
- Both techniques aim to compress the project schedule without compromising on the scope.
Crashing
Crashing is a schedule compression technique that involves determining an approach that brings maximum reduction in project duration with least incremental cost and risk, and without changing the scope.
In Crashing, project schedule is compressed by adding more resources to the project, or working overtime to the critical path activities. The key here is “critical path activities”. If you apply additional resources to non-critical path activities, it would not result in a compressed schedule.
Drawbacks of Crashing
- Increased Risks
- Increased Costs
- May not always result in a compressed schedule
Fast Tracking
Fast tracking is a schedule compression technique that reduces the project duration by performing critical path activities in parallel that were originally planned to be performed in sequence.
in Fast Tracking, activities which are usually performed in sequence are performed in parallel, to compress the schedule.
As with Crashing, the goal of Fast Tracking is to shorten the duration of the critical path. Therefore, Fast Tracking only works when activities can be overlapped to shorten the critical path duration.
Drawbacks of Fast Tracking
- Increased Risks (especially quality risks)
- Rework
- May also increase project costs
Differences between Crashing and Fast Tracking
In Crashing, schedule is compressed by applying additional resources, working overtime, etc. to critical path activities, whereas in Fast Tracking, activities which are usually performed in sequence are performed in parallel, to compress the schedule.
In the diagram above, the normal case represents a project with 3 phases, and a duration of 12 weeks with one resource assigned throughout.
With Fast Tracking, some parts of the projects are performed in parallel resulting in a schedule compression by 3 weeks, with one resource assigned throughout. Phase 2 overlaps with phase 1 in weeks 3 and 4, and phase 3 overlaps with phase 2 in week 6.
With Crashing, additional resources are added to the project to compress the schedule by 4 weeks, while performing the phases in sequence. Phase 1 and Phase 2 have two resources assigned, while phase 3 has three resources assigned.
Note that the above example does not imply that Crashing is more effective than Fast Tracking, or the other way around.