The Critical Path Method

The critical path method is used to derive the critical activities—that is, activities that cannot be delayed without delaying the end date of the program. The amount of time an activity can slip before the program’s end date is affected is known as “total float.”

Critical activities have the least amount of float and, therefore, any delay in them generally causes the same amount of delay in the program’s end date. Activities with total float within a narrow range of the critical path total float are called “near-critical” activities, because they can quickly become critical if their small amount of total float is used up in a delay. Management must closely monitor critical and near-critical activities by using sound schedule practices.

Unless the IMS represents the entire scope of effort and the effort is correctly sequenced through network logic, the scheduling software will report an incorrect or invalid critical path. That is, the critical path will not represent the activities affecting the program finish date. With no accurate critical path, management cannot focus on the activities that will be detrimental to the program’s key milestones and finish date if they slip.