Trucks Scheduling in a Multi-product Cross Docking System with Multiple Temporary Storages and Multiple Dock Doors

In order to reduce costs and increase efficiency of a supply chain system, cross docking is one of the most important strategies of warehousing for consolidation shipments from different suppliers to different customers. Products are collected from suppliers by inbound trucks and then moved to customers by outbound trucks through cross dock. Scheduling of trucks plays important role in the cross docking system. In this paper, we consider a single cross dock multi-product with multiple dock doors which sequence of products and trucks scheduling are specified simultaneously. Also, we have considered multiple temporary storages with different capacities and equipment, each of which is used for a specific set of products. These products are perishable; so, avoiding from storage is necessary. A two- level optimization model for this problem is proposed. The first level includes scheduling of inbound and outbound trucks aim to minimizing makespan and second level is maximizing direct shipment in order to reduce the level of storage. The problem is mathematically formulated by a mixed integer, nonlinear programming (MINLP). A real data set is used to solve the model and results confirm better efficiency and less storage.