Yard traffic and congestion in container terminals

In container terminals, the yard is the zone where containers are stored: it serves as a buffer for loading, unloading and transshipping containers. Yard is usually the bottleneck of the terminal, as traffic, congestion and capacity issues mainly originate from there. A berth&yard allocation plan assigns ships to berths and containers to yard blocks: a typical objective is to minimize the total distance traveled by the carriers to transfer containers from the quayside to the yard. Although congestion issues are usually disregarded, operations are often slowed down because of overloaded areas in the yard. In particular, we are interested in evaluating and reducing traffic congestion induced by the berth&yard allocation plan at the operational level. In this work, we firstly present quantitative indicators we devised to measure congestion in the terminal network and to capture its effects on terminals efficiency. These measures are then combined to provide new objective functions, other than traveled distance, which are used in the design of berth&yard templates; a local search algorithm which minimizes congestion is presented. Computational results are analyzed and discussed.