Solving a dock assignment problem as a three-stage flexible flow-shop problem

Abstract- This paper presents a model for a dock assignment problem based on the situation encountered in a practical case. Trailers are assigned to gates during a specific period in time for loading or unloading activities. The parking lot is used as a buffer zone. Transportation between the parking lot and the gates is performed by additional resources called terminal tractors. The problem is modeled as a three-stage flexible flow shop, where the first and the third stage share the same identical parallel machines and besides that, all stages share a different set of identical parallel machines. Different mathematical formulations are given and a Lagrangian relaxation approach is examined to solve this flexible flow-shop problem