Solving resource-constrained project scheduling problems under different activity assumptions

Abstract

Much research has focused on Resource-Constrained Project Scheduling Problems (RCPSP(A)), where the focus has been on limited or even inadequate resources as a type of risk to implement project activities and decrease completion time. Activity interruption assumptions are considered in this paper. The RCPSP(B) is the RCPSP(A) when the non-preemption assumption is relaxed but the RCPSP(D) is the RCPSP(A) when both the non-preemption and the fixed resources are relaxed. A fundamental assertion of this paper is that the A, B, and D scheduling interruption categories can be interchanged with sufficient managerial effort. Effectively, this becomes a constraint relaxation problem. Because the capacity to manage scheduling interruptions is limited, the issue is which category A activities should be relaxed to type B and D, and which category B activities should be relaxed to type D. This paper introduces the interruptible and flexible planning project activity concept and presents a heuristic method to accomplish the reassessment of category types from A to B and D. First, the heuristic changes the interruptible activities (IAs) under categories A, B, and D. Secondly, critical interruptible activities (CIAs) that have significant impacts in reducing the project makespan are identified. This increases the manager's decision choices with respect to scheduling activities as category type A, B, or D. The methodology facilitates an understanding of how A, B, and D interpretability assumptions affect the project makespan and helps project manager to selectively choose how specific activities in a project should be managed.