Directional imbalance of freight rates : evidence from Japanese inter-prefectural data

By analyzing a comprehensive dataset on transport transactions in Japan, we describe a directional imbalance in freight rates by transport mode and examine its potential sources, such as economies of density and directionally imbalanced transport flow. There are certain numbers of observed links which show asymmetric transport costs. Instrumental variable analysis is used to show that economies of density account for deviation from symmetric freight rates between prefectures. Our results show that a 10% increase in outbound transport flow relative to inbound transport flow leads to a 2.1% decrease in outbound freight rate relative to inbound freight rate.

Agglomeration and directional imbalance of freight rates : the role of density economies in the transport sector

This paper examines the conventional assumption that bilateral transport costs are symmetric. We develop an economic geography model with transport sector in which asymmetric freight rates can occur as a result of density economies. Comparing this to models without density economies, we show that agglomeration of economic activities is more likely to emerge and that multiple equilibria can emerge for some parameters. Then we show the change in its bifurcation and stability of equilibrium and conclude that economies of density in transport flows can act as an agglomeration force.