Vehicle scheduling under the warehouse-on-wheels policy

The warehouse-on-wheels (WOW) policy is a widespread concept to implement material supply in just-in-time production systems. Instead of storing part inventories directly on the shop-floor where space is notoriously scare, the transport vehicles that deliver the materials serve as mobile storages, either while waiting in the trailer yard or while docking at inbound delivery gates. We investigate a vehicle scheduling problem under the WOW policy between a single distribution center and a production facility. Multiple containers of parts each associated with an individual delivery date and a–potentially individual–capacity requirement are to be shipped to the factory. The docking time of transporting vehicles is determined by their respective freight from the delivery date of the most urgent container up to that of the least urgent one. Only then, a vehicle may return to the distribution center to transship another subset of containers. We formalize the resulting vehicle scheduling problem under different objectives, investigate the computational complexity of the problem and develop efficient solution procedures for important problem variants.