GIS- based Study on Fractal Features of Urban Traffic Network in Shanghai

Until recently,most of researches on the fractal properties in cities have been concentrated upon city systems;a research on the fractal property implicated in the evolution of city (metropolis) form has not been paid sufficient attention to. This paper makes a new effort to extend a research on city's fractal property from the basis and view of structure and evolution of traffic network of the city. Firstly,the paper briefly introduces the principles, geographical meanings and measurement method of radial dimension, which is one of the most important fractal dimensions to characterize the fabric of traffic network. Then by using the radial dimension to measure and analyze the fabric of the traffic network in the whole city proper, Pudong and Puxi areas and four administrative districts of Shanghai. The results indicate that, as a whole city proper of Shanghai, two fractal dimensions measured by different measurement centers,i. e. an old central business district center and a new developed Lu Jiazui center, are 1. 56 and 1. 66 respectively, which is similar to some results reported by foreign scholars and implies that the fractal in traffic network of city is of common and essential characteristic of city fractal. In respect of different two areas of Puxi and Pudong in Shanghai, fractal dimension in Puxi (1.57) is higher than that in Pudong (1. 37). It is in accordance with the fact that all infrastructures including traffic network of a developing and constructing Pudong new area has not a capacity to replace a position and role of Puxi in the city of Shanghai. In respect of four administrative districts,a fractal dimension of the traffic network in two old administrative districts have a higher dimension than that in new developing districts. A complete and convenient traffic and road network is a longer historical constructing process. The paper excavates the fractal feature of the special structure of the traffic network within the whole area and different districts of the city,demonstrates the possibility of employing fractal theory to study the urban interior structure and morphological evolution, and explores the relationship between the special structure of traffic network and the development of the economy in the city.