A new and efficient heuristic for scheduling projects with resource restrictions and multiple execution modes

This paper presents a heuristic procedure for solving non-preemptive resource-constrained project scheduling problems in which resources are limited but renewable from period to period. Associated with each activity is a set of possible durations and the corresponding resource requirements, and the objective is to minimize the overall project duration. Unlike other heuristics that consider schedulable activities separately and schedule only one activity at a time, the heuristic proposed in this paper enumerates some schedulable combinations of activities and chooses from them the one having the best value for an evaluation criterion. It is shown that, based on a set of 240 randomly generated problems, the proposed heuristic outperforms the best heuristics proposed in the open literature up to the moment when this research was done.