Resource Leveling and Critical Resources

The critical path method of scheduling assumes unlimited resources to accomplish the project. This is true even when the schedule is resource loaded because the critical path does not take into account resource overallocation. That is, a worker can be assigned to any number of parallel activities, regardless of workload. As discussed in Best Practice 3, resource leveling adjusts the scheduled times of activities or work assignments of resources to account for the availability of resources and to improve the schedule’s accuracy and credibility. Resource leveling can be relatively simple as in reassigning work from overallocated resources to underallocated resources or delaying activities until resources are available.

Leveling resources allows management to identify critical resources—those that will delay the program finish date if they are unavailable for specific activities. If resource allocation is an issue that must be addressed in the schedule, the program end date will be determined not solely through network logic but also by considering resource availability. The sequence of activities that drive the program finish date, based on both network logic and resource availability, is called the resource critical path or the resource constrained critical path or critical chain. Although the resource critical path is complex and not easily derived by even the most sophisticated schedule software, it represents the most realistic model of activities and resources that determine the minimum possible duration of the program. Once critical resources are determined, management can attempt to facilitate their work by, for example, hiring additional help, providing an uninterrupted work environment, or negotiating vacation time so that critical work is not delayed. If management focuses solely on critical activities without taking into account critical resources, it risks ignoring or overworking a program’s most valuable assets or jeopardizing the project’s timely completion.