Integrating collaborative and outsourcing strategies for yard trucks assignment in ports with multiple container terminals

In container terminals, yard trucks (YTs) are mostly used for transporting containers between storage yards and berthing positions of vessels. Even though keeping a large number of YTs ensures lower service times especially at peak periods, but this way is not cost-effective for container terminals due to daily volatility of demand. In literature, outsourcing and collaborative strategies have been investigated as alternatives to keep a large number of YTs to alleviate possible bottlenecks arising in peak periods. The outsourcing strategy means renting additional YTs for a container terminal. While collaborative strategy is implemented by sharing YTs among multiple container terminals with adjacent locations. However, these two strategies have been dealt with separately in literature. This paper presents a new MIP model which considers the two strategies simultaneously. The proposed model is solved using a rolling horizon heuristic. Numerical experiments are performed to evaluate the performance of the proposed approach.