Concentric and Corridors Development
研究了交通技术进步与大城市集聚经济的正向互动，指出城市呈同心圆扩张，而沿交通干线的都市圈可能发展为经济走廊，并用美、德案例佐证，为都市圈研究提供新视角。
There has been a positive interaction between traffic technical progress and agglomeration economies in the big cities,and inter-urban traffic improvement is also conducive to large cities,so that the cities continue growing.At the same time,large cities also tend to pay more pollutants governance efforts.Large cities also continue to adjust their industry to advanced services in structures and to the urban central in space.Central city and the around places respective as area hub and wheels are tight each other by spoke signifying their interdependency.Urban development displays concentric expansion in geography.The possibility that metropolitan areas in the shine of some of the traffic trunk develop into economic corridors will be enhanced.At present,concentric expansion is more significant than the corridor development.The development potential of the cities on large-scale corridor will be better than others.Some urban development in the United States and Germany is used as an example of these arguments.The new perspective and content for the study of metropolitan areas is proposed because of these findings.