Resource loading describes the amounts of individual resources an existing schedule requires during specific time periods. Therefore, it is irrelevant whether we are considering a single work unit or several projects; the loads (requirements) of each resource type are simply listed as a function of time period. Resource loading gives a general understanding of the demands a project will make on a firm's resources. It is an excellent guide for early, rough project planning. Obviously, it is also a first step in attempting to reduce excessive demands on certain resources, regardless of the specific technique used to reduce the demands. Again, we caution the PM to recognize that the use of resources on a project is often nonlinear. Much of the project management software does not always recognize this fact [ 20).
The PERT/CPM network technique is well suited for the job of generating time-phased resource requirements. A Gantt chart could be adapted, but the PERT/CPM diagram, particularly if modified to illustrate slacks, will be helpful in the analysis used for resource leveling. Let us illustrate with the PERT/CPM network used as an example in the previous chapter. The network (Table 8-2) reappears as Figure 9-3, and resource usage is illustrated for two hypothetical resources, A and B, on the arcs. The expected activity time is shown above the arc and resource usage is shown in parentheses just below the arc, with the use of A shown first and B second—e.g., (5,3) would mean that five units of A and three units of B would be used on the activity represented by the arc. Figure 9-4 shows the "calendarized" PERT/CPM diagram, similar to the familiar Gantt chart. Resource demands can now be summed by time period across all activities.
The loading diagram for resource A is illustrated in Figure 9-5a, and that for resource B in Figure 9-5b. The loads are erratic and vary substantially over the duration of the project. Resource A, used in tasks a, b, and c, has a high initial demand that drops through the middle of the project and then climbs again. Resource B, on the other hand, has low initial use but increases as the project develops. The PM must be aware of the ebbs and flows of usage for each input resource throughout
Was this article helpful?
What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.