Towards a metaheuristic for routing order pickers in a warehouse

In this paper we will deal with the sequencing and routing problem of order pickers in conventional multi-parallel-aisle warehouse systems. For this NP-hard Steiner Travelling Salesman Problem exact algorithms only exist for warehouses with at most three cross aisles. We propose a new approach were the problem of routing order pickers in multiple-block warehouses is translated into a classical Travelling Salesman Problem. Our approach allows for the use of the more powerful (meta)heuristic search procedures developed for amongst others the Vehicle Routing Problem and the Vehicle Routing Problem with Time Windows. To the best of our knowledge, a certain approach has not yet been used in literature on order picking.