Critical Path Method (CPM)

The critical path is a method of managing a project effectively. We have seen how the critical path is determined and how the float or slack is determined. Using the notion of float, the project manager can direct his or her efforts where they will do the most good. Activities that are found to have float, particularly those that have large amounts of float, can be managed less intensely than other activities in the project plan. This is because activities with float can be delayed without affecting the project completion date. Conversely, the activities that have zero float cannot be delayed without affecting the project completion date. These activities should be managed carefully by the project manager and the project team. In the critical path method of managing projects, another term for float is ‘‘free float.’’ This is somewhat different than the float we have discussed up until now. One of the problems with managing by float is that if an activity is delayed within its float, it may be necessary to reschedule many other activities as a result. Free float is the amount of time an activity can be delayed without affecting the project completion date or requiring any other activity to be rescheduled. This is important because rescheduling the remaining activities in the project can cause great confusion for the project team, and the project manager can quickly lose credibility. The use of free float prevents much of this problem.