Definicion

Páginas: 35 (8560 palabras) Publicado: 7 de enero de 2013
Chapter 9
Resource Allocation
In the previous chapter we looked at a special type of resource allocation problem, that of allocating time among project tasks, better known as scheduling. Now we consider the allocation of physical resources as well. Also, we are concerned with using resources in both individual and in multiple, simultaneous projects. The subject relates directly to the topic ofscheduling because altering schedules can alter the need for resources and—just as important—alter the timing of resource needs. At any given time, the firm may have a fixed level of various resources available for its projects. The fixed resources might include labor-hours of various types of special professional or technical services, machine-hours of various types of machinery orinstrumentation, hours of computing time, and similar scarce resources needed for accomplishing project tasks. For example, if the need for some resource varies between 70 and 120 percent of resource capacity, then that resource will be under utilized (and wasted if no alternative use exists) at one point in the project and in insufficient supply at another. If the project schedule can be adjusted to smooth theuse of the resource, it may be possible to avoid project delay and, at the same time not saddle the project with the high cost of excess resources “just to make sure.”
‘This chapter addresses situations that involve resource problems. We discuss the trade-offs involved, the difference between allocation to one project and allocations between multiple projects, the relationship between resourceloading and leveling. ´and some of the approaches employed to solve allocation problems, including the Critical Path Method (CPM) and several other well-known techniques.
Although CPM is not actually a resource allocation method, we include it here because we view time as a resource, and trade-offs between time and other resources are a major problem in resource management. Finally, we note themajor impact that current project management software has had on the PM´s ability—and willing--ness—to deal with resource loading and leveling.
• 9.1 CRITICAL PATH METHOD
In Chapter 8 we mentioned that CPM ¡s similar to PERT In the original versions of CPM and PERT there was one important difference. CPM included a way of relating the project schedule to the level of physical resources allocatedto the project. This allowed the PM to trade time for cost, or vice versa. In CPM, two activity times and two costs are specified, if appropriate, for each activity. The first time/cost combination is called normal and the second set is referred to as mask. Normal times are “normal” in the same sense as the m time estimate of the three times used in PERT.
Crash times result from an attempt toexpedite the activity by the application of additional resources—for example, overtime, special equipment, additional staff or material, and the like.
It is standard practice with PERT/CPM to estimate activity times under the assumption of resource loadings that are normal To discuss a time requirement for any ,task without some assumption about the level of resources devoted to the task makes noreal sense. At the same time, it does not make sense to insist on a full list of each and every resource that will be spent on each of the hundreds of activities that may comprise a PERT/CPM network Clearly, there must have been some prior decision about what resources would be devoted to each task, but much of the decision making is, in practice, relegated to the common methods of standard practiceand rules of thumb. The allocation problem requires more careful consideration if it is decided to speed up the accomplishment of tasks and/or the total project. We need to know what additional resources it will take to shorten completion times for the various activities making up the project.
While standard practice and rules of thumb are sufficient for estimating the resource needs for normal...
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