New bounds and algorithms for the transshipment yard scheduling problem

In a modern rail-rail transshipment yard huge gantry cranes transship containers between different freight trains, so that hub-and-spoke railway systems are enabled. In this context, we consider the transshipment yard scheduling problem (TYSP) where trains have to be assigned to bundles, which jointly enter and leave the yard. The objective is to minimize split moves and revisits. Split moves appear whenever containers have to be exchanged between trains of different bundles, whereas revisits occur if a train has to enter the yard twice, because some container dedicated to this train was not available during its first visit. We extend the basic TYSP, so that additional real-world requirements of modern rail-rail yards, e.g., the one currently constructed in Hannover-Lehrte, are considered. We provide complexity proofs for different problem settings and present several heuristic procedures as well as one exact algorithm. The paper concludes with computational results showing the efficiency of the proposed algorithms.