Resource Scheduling

After the objective of a project has been explicitly specified, one of the important constraints to be considered is the means or resource by which it is to be attained. A resource is a physical variable, such as labour, finance, equipment and space, which will impose a limitation on time for the project. When the resources are limited and conflicting demands are made for the same type of resource, a systematic method for the allocation of resources becomes essential. Resource scheduling usually incurs a compromise and the choice of this compromise depends on the judgment of managers.
There are basically two approaches in solving such a problem, resource leveling and resource allocation. In resource leveling, the total project duration is maintained to the minimum level, but the activities having floats are shifted so that a uniform demand on the resources is achieved. In other words, the constraint in the case of resource leveling operation would be the project duration time. In resource allocation, the main constraint would be on the resources. If the maximum demand on any resource is not to exceed a certain limit, the activities will then have to be rescheduled so that the total demand on the resource at any time will be within the limit. The project duration time consequently is exceeded.

Complexity of Network Scheduling with Limited Resources
Problems of resource scheduling vary in kind and severity, depending upon the project and the organizational setting. The problem of scheduling activities so that none of the resource availabilities are exceeded and none of the precedence relationships are violated is an exceedingly difficult task. Scheduling projects with limited resources is a large combinatorial problem. That is, there are a very large number of combinations of activity start times – each combination representing a different schedule - too large to enumerate even with a computer.
Heuristic Programs
In recent years a good deal of work has been done in the development of heuristic programs for solving large combinatorial problems. Heuristic programs for resource scheduling may take one of the following two forms:
i. Resource Leveling Programs. These attempt to reduce peak resource requirements and smooth out period-to-period assignments, within a constraint on project duration.
ii. Resource Allocation Programs: These allocate available resources to project activities in an attempt to find the shortest project schedule consistent with fixed resource limits.

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