## SUMMARY

In this chapter we looked at the problem of allocating physical resources, both among the multiple activities of a project and among multiple projects. The continuous problem to the PM is finding the best trade-offs among resources, particularly time. We considered resource loading, allocation, and leveling, and presented methods and concepts to aid in all these tasks.

Specific points made in the chapter were these:

• The critical path method (CPM) is a network constructed in the same manner as PERT but considers the possibility of adding resources to tasks (called crashing) to shorten their duration, thereby expediting the project.

• The resource allocation problem is concerned with determining the best trade-offs between available resources, including time, throughout the duration of a project.

• Resource loading is the process of calculating the total load from project tasks on each resource for each time period of the project's duration.

• Resource leveling is concerned with evening out the demand for various resources required in a project by shifting tasks within their slack allowances. The aid of a computer is mandatory for realistic projects.

• There are two basic approaches to addressing the constrained resources allocation problem:

Heuristic methods are realistic approaches that may identify feasible solutions to the problem. They essentially use simple priority rules, such as shortest task first, to determine which task should receive resources and which task must wait. Optimizing methods, such as linear programming, find the best allocation of resources to tasks but are limited in the size of problems they can efficiently solve.

• For multiproject scheduling, three important measures of effectiveness are schedule slippage, resource utilization, and level of in-process inventory.

• When a new project is added to a multiproject system, the amount of slippage is directly related to the average resource load.

• Mathematical programming models for multi-project scheduling aim either to minimize total throughput time for all projects, minimize the completion time for all projects, or minimize the total lateness (or lateness penalty) for all projects. These models are limited to small problems. There are a number of heuristic methods, such as the resource scheduling method, available for the multiproject scheduling problem.

In the next chapter we move to the ongoing implementation of the project and consider the project information systems used for monitoring progress, costs, performance, and so on. The chapter also describes some available computer packages for this function.