Optimal Investment in Transportation Infrastructure When Middlemen Have Market Power: A Developing‐Country Analysis
构建多阶段空间模型，分析发展中国家交通投资如何影响营销成本和竞争，发现从农民角度看投资主要通过增强竞争带来收益，但若忽略此效应可能导致投资不足，且最优投资取决于运输成本的相对重要性。
Abstract Transportation costs and buyer market power reduce prices and income received by farmers in developing countries. Transportation costs directly affect the marketing margin and also exacerbate market power by limiting farmers’ access to buyers. This article develops a multistage spatial model to determine optimal investment in transportation improvements, taking account of impacts on marketing costs and competition. The beneficial impact of investments from farmers’ perspective is mainly through enhanced competition, meaning significant under‐investment may occur if this effect is ignored. However, the optimal investment depends on the relative importance of transportation costs; in some settings, transportation improvements reduce farm prices because buyers rationally over‐compensate farmers for these costs.