Friday, February 15, 2008

Compressing Project Duration

Have you ever heard the saying, "You may delay, but time will not," by Benjamin Franklin? As a project manager, don't you sometimes wish that you could just stop the clock? This is especially true when a project's schedule needs to be shortened so it will be finished before its scheduled date.

You could use duration compression to shorten the project schedule. PMBOK defines duration compression as, "shortening the project schedule without reducing the project scope."

There are two duration compression techniques commonly used by project managers to meet imposed dates or other schedule objectives. These techniques are: crashing and fast tracking.

Crashing a project schedule involves analysis of cost and schedule trade-offs to obtain the maximum duration compression (shortening of the project schedule without changing the scope), with the least amount of cost. This technique is usually the last choice for project managers.

Crashing the schedule may not always be the most feasible option for your project. It often results in increased project costs and the addition of extra resources. The rules of thumb for crashing a schedule are always crash or shorten tasks on the critical path and choose to crash tasks that will have the least impact on the project's budget.

Consider this example. Palmcom Computers has just reviewed its draft schedule for a new computer design project. It has discovered that the original plan has to be crashed to complete the project sooner than initially anticipated. Palmcom realizes that the objective of crashing its planned schedule is to come up with the best project end date.

Since crashing involves building a plan without regard to resources, Palmcom has restructured its schedule to include additional resources.

Fast tracking
Fast tracking involves looking at a project plan and assessing when it is practical to do work in parallel instead of sequentially. It works best where there are activities that are somewhat independent of each other. Fast tracking the schedule compresses the project schedule by overlapping activities that would normally be done in sequence, such as design and construction.

Consider this example. Sol-car, an automobile manufacturer, is designing a new solar-powered vehicle. Sol-car has just been notified by a major supplier that the panels it has ordered will not be available until May 15. The company has recently announced that it will unveil this new automobile on June 21. Therefore, this delay in shipment may cause a delay in the project's completion date.

Based on this information, Sol-car reviews its project schedule. It has decided that the last phase of the project will have to be adjusted to compensate for the previous delay. The last phase of this project would include the body assembly, the frame construction, the painting, and the final testing and marketing. The network diagram on the left is the original schedule, and the diagram on the right is the fast tracked schedule.

Looking at this schedule you can see that the activities are sequential in nature, with a finish to start dependency. This means that the preceding activity must be completed before the next activity can start.

Sol-car has fast tracked this schedule by moving activity D, which is somewhat independent of the other activities. Activity D will run concurrent to activities B and C. However, this can only occur if activity D's required resources are available.

Although these methods of project duration compression may seem like the answer to a project manager's prayer, there are disadvantages that should be taken into consideration. Can you think of what these disadvantages might be?

Fast tracking often results in rework and increases risk of a project being over budget. For example, there is an increased risk that the activity will not be performed properly when activities are overlapped. If this does occur, the activity will have to be redone.

Crashing often increases a project's cost. For example, if additional resources are added to crash a project activity, the labor costs on the project will be more than originally anticipated.

Although there are risks involved with duration compression, the ultimate goal is to bring a project back on track and end up with an improved, shorter duration. Either crashing or fast tracking will help you achieve that goal.

No comments: