Selection of auto-carrier loading policy in automobile shipping

Auto-carriers are widely used to ship automobiles by land from origins to destinations. To enable the compact storage of multiple automobiles, auto-carriers are specially designed such that automobiles can only be loaded and unloaded through a common exit of an auto-carrier, which complicates the automobile loading and unloading operations. This study is motivated by the lack of consensus in the automobile shipping literature regarding whether reloading operations should or should not be prohibited while auto-carriers are en-route. The impact of a loading policy on auto-carrier shipping is not well understood in the literature. We thus examine two types of loading policies (namely reloading prohibited versus allowed), and design network-based optimization methods for each resulting policy variant. We then conduct extensive numerical experiments based on the data from the Southeast region of the USA to investigate the impact of a loading policy on automobile shipping operations through a trade-off analysis between solution quality and computational burden. We find that two proposed policy variants when reloading is allowed can achieve a desirable compromise between cost efficiency and computational effort. A full-scale analysis involving 10 auto-carriers with various capacities further confirms that with these policy variants, substantial cost savings are achieved with reasonable computation effort. The research findings from this article are expected to inform the choice of an appropriate auto-carrier loading policy for automobile transportation companies.