Resource leveling in construction by optimization

Resource leveling is needed in construction to avoid the difficulties associated with the large variations in resource usage. This paper presents an integer-linear optimization model of resource leveling (single resource, continuous activities) which guarantees the optimal leveling. The objective function of the model minimizes the absolute deviations between the resource requirements and a uniform resource level, between consecutive resource requirements, or between the resource requirements and desirable nonuniform resource levels. The model requires as input the critical path method (CPM) scheduling results, from which the constraints and objective function of the model are established automatically by an interface program. Extensions of the model to multiple resources and trade-off of cost scheduling are suggested. The model is applicable to activity-on-arrow, activity-on-node, and precedence networks and is intended for small-to mediumsized construction projects.