Increasing returns in transportation and the formation of hubs
研究了运输中的密度经济和距离经济如何导致运输成本内生，并探讨了在此条件下可行枢纽结构的间距和层级关系。
The spatial structure of transport networks is subject to increasing returns in transportation, distance, and density economies. Transport costs between locations are thus, in general, endogenous, and are determined by the interaction between the spatial distribution of transport demand and these increasing returns, although such interdependence has long been ignored in regional models. By using a simple model, the present paper investigates the characteristics of viable hub structures (in terms of spacing and hierarchical relations) given the presence of density and distance economies in transportation.