Crashing & Fast Tracking A Schedule, Made Simple

You’ve checked your data, then rechecked it.  No doubt, your project is over schedule compared to the baseline.  As a project manager, what are you going to do to correct the project?  We can change the order of tasks, add resources or people to the project, change scope, or some combination.

If the primary need is to get your project back on schedule, you’ll have to compress the schedule without changing the project scope.  Your two primary options are Fast Tracking or Crashing the schedule, but what’s the difference?  Let’s take a closer look at these two schedule compression techniques and make it simple to understand them.

Fast Tracking

This technique is simply doing critical path activities in parallel, instead of in series as planned.  There is a primary presumption that the dependencies for the activities to be fast tracked are discretionary, so you are effectively just removing those dependencies as a barrier to starting an activity.

Do you just grab your network diagram and look at which activities on the critical path can be done simultaneously?  While this may sound like the easiest thing to do, there are several considerations before committing to this change in plans:

  • There is inherent risk in making this schedule change, and you should update your risk log accordingly.  Be especially aware that the results of the parallelized activities may need to be reworked, as they may not be as expected initially.
  • You are potentially increasing the number of communication channels, or at least creating the need for closer correlation between the activities.  Pay close attention to the additional effort involved in coordinating the activities.
  • There was a reason you initially had the activities in series, possibly because the same person was to do both activities or there was a limitation on equipment.  Be sure you have the expertise, hardware, or software available to handle the additional workload for the duration of the fast tracked activities.
  • Another consideration is that if a deliverable, say information, was to be available prior to the start of a future activity, you may need to make some assumptions about that input as a basis to run the activity earlier than planned.

What if you’ve fast tracked activities as much as you can, but it doesn’t compress the schedule enough?  You’ll need to consider “Crashing the Schedule” to find alternative ways to complete activities faster.

 

Crashing

Crashing is a technique where you’ll be paying for increased amounts of work (time) for a period in the project.  In fact, project duration can often be reduced by assigning more workers to project activities. This could be in the form of overtime, and by assigning more resources (workers, material or equipment). The reduction in the normal activity duration is referred to as crashing. Crashing is usually measured in terms of dollars, for the activities to be crashed. There is necessarily increased project costs, as you are adding unplanned personnel or other resources to the project to get more done in a shorter period of time than originally planned. The primary consideration in crashing is how to get the most cost-effective solution in place for the decrease in schedule duration.  Identify all of the possible solutions, and pick the most efficient ones first. In essence, you select that subset of critical path activities which, when compressed, enable all current critical paths to become shorter, and do so at the least cost. These are the main steps in crashing a schedule:

  • Choose that activity on the critical path which is cheapest to crash.
  • Crash that activity till either another path becomes critical or the activity is fully crashed.
  • No further crashing is possible when at least one critical path cannot be reduced.
  • You also need to pay close attention to your assumptions.  For example, doubling the number of people working on a project doesn’t necessarily translate to a doubled productivity rate.  Or, if you purchase software to automate some tasks or activities, there may be a learning curve that slows down progress on the other activities.

 

So, which technique should you choose?

If costs are the primary consideration, you should always choose fast tracking first.  If deadlines, liquidated damages, penalties or milestone deliveries are more important than costs, selecting crashing may be more appropriate.  In any scenario, you may want to select a combination of the techniques to balance risks, costs, and schedule.

Time for a Quiz:

 

 

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