consumable resources

In the PERT/CPM scheduling techniques (see “The Program Evaluation and Review Technique (PERT): Incorporating activity time variability in a project schedule” and “The Critical Path Method (CPM): Incorporating activity time/cost trade-offs in a project schedule”), project activities are characterized by their estimated duration(s) and project networks are constructed by adding precedence relations between these activities. It is therefore implicitly assumed that these activities do not require resources during their execution (or alternatively, the assumption is that the resources are unlimited in availability). In practice, activities need resources during their execution that are often limited in availability. These resources have been classified in two basic categories, as follows:

• Renewable resources
• Consumable resources