Chapter 6: Resource Utilization

The consideration of resources adds another dimension to planning and scheduling. It is necessary to estimate the types and quantities of resources required to perform each activity. Resources can include people, materials, equipment, tools, facilities and so forth. A resource requirements plan shows the expected utilization of resources by time period during the time span of the project.

In many projects, the quantities are limited. Several activities may require the same resources at the same time, and there may not be sufficient resources available to satisfy all the demands. If sufficient resources are not available when required, some activities may have to be delayed until a later time when resources are available. Therefore, resources can constrain the project schedule.

Resource-Limited Scheduling

Resource-Limited Scheduling is a method for developing the shortest schedule when the quantity of available resources is fixed. This method is appropriate when the resources available for the project are limited and these resources limits cannot be exceeded. 

For a large project that requires many different resources, each of which has a different limit of availability, resource-limited scheduling can get very complicated. Various project management information systems are available that can assist with this process.

Resource-Limited Scheduling will extend the project completion time, if necessary; keep it within the resource limits. It is an iterative method in which resources are allocated to activities based on the least slack. When several activities need the same limited resource at the same time, the activities with the second slack time have the first priority. If resources are left over, the activities with the second least slack have the next priority and so forth. If other activities need the resources but the resource has been totally allocated to higher-priority activities, the lower-priority activities get delayed; as their slack becomes worse they eventually move up the priority ladder. This delaying of activities can extend the project completion time.