Import tariffs and transport prices
研究了贸易自由化过程中进口关税如何影响运输价格，发现规模经济效应强于市场势力，关税下降会带动运费下降。
Abstract This paper discusses how import tariffs interact with transport prices in episodes of trade liberalization. We develop a model of a transport industry that operates under imperfect competition and economies of scale. Double marginalization due to market power reduces the effects of trade liberalization, while a larger trade volume may support them due to economies of scale. We use a large data set of maritime transport data and combine them with tariff data to find that economies of scale beat market power: a decline in the tariff implies a decline in freight rates.