We model the vertical investment of a container shipping line in the port capacity in a two-port system. Our analytical and numerical analyss suggests that the relative scale of the capacity investment depend on the initial port capacity and the relationship between the ports. When a port has a sufficiently large initial capacity and the ports do not have highly complementary operations, a vertical investment leads to higher investments. Moreover, the investment of a shipping line in a port always increases its own profit and reduces the competitor’s profit. However, when compared with port self-investment, vertical investment always reduces the local social welfare.

我们以两端口系统中的港口容量为模型，模拟了集装箱运输线的垂直投资。我们的分析和数值分析表明，容量投资的相对规模取决于初始港口容量和港口之间的关系。当港口的初始容量足够大且港口没有高度互补的运营时，垂直投资会导致更高的投资。此外，在港口投资航运线总是会增加自己的利润，并降低竞争对手的利润。但是，与港口自有投资相比，垂直投资总是会减少当地的社会福利。