How to compress a schedule

You are scheduling a project using Primavera P6 and find, after updating, that the project is going to be late. Instead of rushing to management with the bad news, let’s first look at a few scenarios that would allow the project to be put back on schedule. In Primavera P6, we always have the option of producing “what if” scenarios that allows us to use approaches to shortening the project. Be aware that you should export and save the project plan before making any major changes.

• 1.Use relationships to overlap activities.
• • This method is probably the easiest method but requires the use of more resources to accomplish activities that are now happening simultaneously. More resources means more dollars spent.
  • 
    
  • On a positive note, there is a possibility that some of the simultaneous activities have economies of scale, meaning one resource can perform multiple functions at once such as a backhoe both excavating a pond and simultaneously filling a trench with the spoils. Management may have not taken into account these synergies within all activities when the schedule was first developed.
• 2.Add resources to reduce durations.
  • Adding resources may be infeasible due to the fact that the resources are not available and, as in the previous example, adds to the overall cost of the project.
  • 
    
  • On the plus side, some under-allocated resources from your project or other projects within the company may be utilized which helps your organization’s overall economic health.
• 3.Break down long activities.
  • Breaking down long activities may enable you to overlap new activities that resulted from their parent activity. Again, referring to our first point, more resources are required which means more of the budget spent.
  • 
    
  • As an advantage, shorter activities do give a more detailed picture of the project. Management has the benefit of being able to better analyze the activities and possibly “trim the fat”.
• 4.Changing calendar assignments by either putting critical activities on a longer workweek or adding exceptions to non-work time.
• By changing calendar assignments, you are now working on days that were originally non-working days, therefore adding more resources to the project.
• 
  
• From a positive standpoint, there may be additional room in the budget for these unexpected work days, however management would consider this a “last resort” as profit margin shrinkage would be a result.

• Criteria for Selecting Activities to Crash:

  There are several characteristics that mark or highlight an activity that exists on the Critical Path as a better candidate for crashing.

  
  1. Must be on the Critical Path. Crashing noncritical activities that already have slack only buys more slack and doesn’t shorten the project duration. Only critical path activities drive the project and crashing them will shorten the project duration.

  
  2. Precedes multiple activities. When an activity bottlenecks numerous succeeding activities, it is a great candidate to shorten. Once this activity is shortened, it allows the multiple activities to begin.

  
  3. Long duration. An activity that has a long duration offers more potential time gain from crashing it.

  
  4. Lower cost per period gained. Activities that cost less to crash are preferred. These include those requiring lower paid, lower skilled workers or other resources that are otherwise sitting idle.

  
  5. Early in the project (the Sunshine Rule). If you fail in crashing the activity and it takes longer than planned, it is still early in the project. Thus you still have recovery time. Also, typically demand on resources early in the project is lower than other times, and they should be readily available.

  
  6. Labor-intensive. When an activity is low skill labor intensive, it is easy to add people to help complete the project early. When an activity requires high skills to complete, it may be hard to find qualified individuals who are capable of completing the task.

  
  7. Subject to common problems. Try to pick activities that are subject to higher probability of common problems. Shortening the duration lowers the exposure time and lessens the chances of having a problem.