Schedule Compression

According to PMBOK, schedule compression shortens the project schedule without changing the project scope, to meet schedule constraints, imposed dates, or other schedule objectives.

Whether the project is late or the project manager has been asked to shorten the duration, these techniques can be used to compress a schedule:

Compression Technique Benefits Cautions

Fast-tracking

Review the critical path to determine which sequential tasks on the critical path could be done in parallel, or partially parallel to each other (in other words, determine where can task relationship dependencies on the critical path be changed)

Ensure the critical path has not changed after fast-tracking.  If it has, compress the new critical path.  If another path's duration is now the same as this critical path, assess if the risk of managing two critical paths can be handled.

  • no additional costs
  • it can add additional risks to the project; ensure the additional risk can be managed before proceeding
  • could result in rework
  • beware of fast-tracking tasks that require the same resources
  • tasks chosen for fast-tracking should have a duration longer than the number of days required to shorten the schedule

Crashing

Review the tasks in the critical path to determine which tasks could be shortened by adding additional resources

  • find the tasks that can be reduced the most with the least cost
  • crashing techniques may include
    • add new resources
    • overtime
    • provide incentives to current project team
    • pay extra to expedite delivery of goods

Ensure the critical path has not changed after crashing.  If it has, compress the new critical path.  If another path's duration is now the same as this critical path, assess if the risk of managing two critical paths can be handled.

  • no significant increases in risk
  • crashing adds to the costs of the project
  • results are typically positive with minimal costs initially, but as project manager continues to crash schedule, costs will start to increase significantly
  • if the schedule is crashed by acquiring new resources, account for risks due to the time it may take to find these new resources and the learning curve before they are truly productive
  • not all tasks can be completed in a shorter time by adding more resources
  • costs for crashing will be differ by task

Resource re-allocation

Re-allocation moves resources from tasks that are not on the critical path to tasks that are on the critical path.

  • more effective utilization of current resources without increasing costs or changing scheduling logic
  • ensure resources have the appropriate skills
  • only effective if resource moved from non-critical path task to a critical path task

View video explanation of fast-tracking and crashing.