Uncertain Resource Availabilities: Proactive and Reactive Procedures for Preemptive Resource Constrained project Scheduling Problem

Project scheduling is the part of project management that deals with determining when intime to start (and finish) which activities and with the allocation of scarce resources to theproject activities. In practice, virtually all project managers are confronted with resourcescarceness. In such cases, the Resource-Constrained Project Scheduling Problem (RCPSP)arises. This optimization problem has become popular over the last few decades because ofits practical relevance to various industrial and research fields. Numerous procedures havebeen developed in the literature for finding either optimal or heuristic solutions for theRCPSP.Resource constrained project scheduling problem under stochastic circumstances have beenconsidered in recent decades where uncertainty is modeled by means of activities’ duration.In this research we study an extension of basic stochastic RCPSP in which availability ofresources is not predefined. Activities follow preempt-resume mode in case of any disruptiondue to resource infeasibility. A solution for this variant of RCPSP is defined in three steps byutilizing heuristic procedures for creating initial schedule, adding time and resource buffers inorder to yield proactive schedule and applying reactive policies to encounter with unhandledbreakdowns. Computational experiments depict that proposed combined procedure achievesignificant performance gains over the use of each method separately.