The Optimization On The Railway Network Form Of Transportation Hub Cities

The constructions of railways exert great influences on prompting the urban economic development, accelerating the urbanization process and orienting the urban spacial structures in the past decades. Especially, with the transportization and urbanization process speeding up, the focus of transport development has been changed from the lines and corridors between cities and regions to the connections in the network nodes (cities). And the railway network has to make corresponding internal requirements to improving network efficiency while not impeding the development of cities, so how dose the railway network improve the efficiency while coordinating to the relationship with the city? At this point, the railway must change its network form to adapt to such a request.The paper chooses the railway hub cities as the object of study, and focuses on the network form of railways imply an important key function to coordinate the relationship between city and railway, and figure out the methods of optimizing configuration on the transport resources. The paper advances theoretical analysis on the content and optimizing mechanism of railway network form by using transport resources allocation theory and the "Product-Resource-Network economy" (PRN) pattern of transportation economic theory. And on this basis, it has conducted the empirical and case study on the typical abroad and domestic railway hub cities, which implemented the railway improvement projects. Overall, the major contents and conclusions of the paper basiclly include the following several parts:Firstly, through a review of related research, the paper found that there are three main fields about the relationship and interactive mechanism between railway and city development, including the influence of the transport infrastructure on the urban development, the influence of the railway networks on the urban development, and the transport resource allocation theory, which provides a useful reference and theoretical basis for this paper.Secondly, the paper presents the concept of the "Railway Hub City", pointing out that the main reason for the interaction between railway and city is the superposition and conflict between transport node function and urban function, which the railway city contains. And the paper constructs a general describe model (GDM) about the evolution of the railway network form of a railway hub city, which implying that the stage evolution discipline and the development tendency. Thirdly, the paper constructs a optimizing model for railway network form, which based on the relationship between railway network form and transport resource configuration. And the modal points out that the optimaiztion of the railway network form, including location of the railway nodes, laying pattern of railway routes and configuration of railway connections, will optimize the transport resource allocation, save transport costs, enhance the effect of network econcomy and accelarte the urban economic development. And on this basis, from the view of the "Product-Resource-Network economy" (PRN) pattern of transportation economic theory, the paper analysises the optimazing mechanism of the railway network form, which includes the interactive mechanism betweens' the locations of the railway nodes and the special match of transport "demand-spply", the laying pattern of railway routes and the optimizing agglomeration of transport resources and configuration of railway connections and the realization of transport network economy. Then, the paper figures out the main factors, which determined the optimization of railway network form by using the "Transportation Network Form Structure" (TNFS) analysis method, and presents that the transport plan is the basic approach for optimizing railway network form.Fourthly, based on the theoretical analysis of above, the paper takes the Berlin Central Station in Germany, the Chicago CREATE program and Los Angeles Alameda Corridor in America, and "railway grade separation program" in Taibei city and Shijiazhuang city of China, as the cases to the empirical study, and verifies the conclusions of this paper. The conclusion of the study shows that, with reinforcing the central location of passenger nodes, putting the rail cargo facilities out of the urban area, implementing rail routes grade separated, and installing efficiency railway connection system, the optimization of railway network form will improve the efficiency of railway system while coordinating to the relationship with the city.Finally, the paper analysises the questions that we have been faced during the process of planning and construction of the Beijing railway hub, and using the theory and the model that the paper presented, the paper puts forward several corresponding policy recommendations and suggestions in order to optimize the railway network form.