Development and evaluation of a network scheduling procedure based on utility theory

Activity networks have been widely used in the planning, management, and control of building construction projects since their introduction in the 1950s. As the popularity of activity networking procedures has grown, so has the theory underlying the various procedures. Procedures are presently available that consider both technological and non-technological constraints and offer solutions solved optimally or heuristically. However, activity networks typical of building construction projects have not lent themselves to efficient optimal solutions because of their size, complexity, and diversity. Therefore, various heuristic scheduling procedures have been developed to solve this class of problem pragmatically if not optimally. A disadvantage to the heuristic scheduling schemes available is that they follow a set of rigid heuristics and therefore may not be sensitive to a variety of differing network types or a variety of constraints. This study undertakes the development of a scheduling procedure that is heuristically based but that is sensitive to any variety of network types or constraints imposed by the scheduler. This is accomplished by combining all pertinent factors through a utility analysis and scheduling each activity based on the results of this analysis. The factors that are considered pertinent for the purpose of this study are the activity times based on technological constraints, network complexity, resource usage and availability, resource unit cost, and total activity cost. These factors are combined through the use of an additive utility model and prioritized to yield a scheduling sequence. Four different activity networks are tested under a variety of resource constraints and resource limitations. The resulting schedules are evaluated based on their relative performance and on their comparative performance against schedules generated by another heuristic procedure and by an optimum procedure.