A bi-objective model for robust resource-constrained project scheduling

A common problem which arises in project management is the fact that the planned schedule is often disrupted by several uncontrollable factors like additional time that might be required for rework and correction of detected defects. As a result, project managers are often unable to meet the promised completion dates. It is therefore vital to take into account such possible disruptions and their potential negative consequences at the project schedule design stage. In this paper, we address the issue of designing a project schedule which is not only short in time, but also less vulnerable to disruptions due to reworks and other undesirable conditions. To that aim, we introduce the concept of schedule robustness and we develop a bi-objective resource-constrained project scheduling model. We consider the objectives of robustness maximization along with makespan minimization. We develop a tabu search algorithm in order to generate an approximate set of efficient solutions. Several variants of the algorithm are tested and compared on a large set of benchmark problems.