Scheduling freight trains in rail-rail transshipment yards

Transshipment yards, where gantry cranes allow for an effcient transshipment of containers between different freight trains, are important entities in modern railway systems and facilitate the general shift from point-to-point transport to hub-and-spoke railway systems. Modern rail-rail transshipment yards accelerate container handling, so that multiple smaller trains with equal destination can be consolidated to a reduced number of trains without jeopardizing on time deliveries. An important problem continuously arising during the daily operations of a transshipment yard is the train scheduling problem, which decides on the succession of trains at the parallel railway tracks. This problem with a special focus on resolving deadlocks and avoiding multiple crane picks per container move is investigated within the paper on hand. A mathematical program along with a complexity proof is provided and exact (Dynamic Programming) and heuristic (Beam Search) procedures are described.