This paper incorporates key stylized facts about the transport sector into the conventional international oligopoly model and explores how protectionist policies perform differently when transport costs are endogenous and subject to the backhaul problem (i.e., the imbalance of shipping volume in outgoing and incoming routes). A country’s protectionist policies, which benefit domestic firms and harm foreign firms in the conventional model, can harm domestic firms and benefit foreign firms if carriers avoid the backhaul problem. Protectionist policies may also lead to a facilitating practice. In the absence of the backhaul problem, both domestic and foreign consumers lose from protectionist policies.

本文将有关运输部门的关键典型事实纳入传统的国际寡头垄断模型，并探讨了当运输成本是内生的并受到回程问题（即出入境航线运输量不平衡）的影响时，保护主义政策的表现如何不同。如果运营商避免回程问题，一个国家的保护主义政策在传统模式下有利于国内公司并损害外国公司，但可能损害国内公司并有利于外国公司。保护主义政策也可能导致便利的做法。在不存在回程问题的情况下，国内外消费者都将受到保护主义政策的影响。