A unifying approach to shift design and rotating workforce scheduling

In many organizations, human resources are a primary cost driver. Therefore, careful scheduling of this resource is paramount. The shift design and scheduling process involves several steps from the recognition of staffing requirements to the deployment of an operational schedule. Based on the staffing requirements and shift design constraints, a set of workable shifts is devised. The shift scheduling process then determines the number of employees and assembles these shifts into a shift schedule, consisting of work shift and rest sequences. Due to their complexity, shift design and shift scheduling problems are often decomposed. This study investigates an integration of shift design and scheduling, focusing specifically on the rotating workforce scheduling problem. In addition to the shift design objective, we model an ergonomics objective for the quality of the schedule. We propose a compact network flow formulation and graph representation that ensures feasible shift designs by modeling the schedule as an Eulerian cycle of work and rest sequences. Experiments indicate that our approach is able to quickly solve problem instances based on benchmark sets for the shift design and rotating workforce scheduling problem. Furthermore, our results indicate that integrated planning improves ergonomics compared to a sequential approach.