基于GIS的城市交通网络分形特征研究

针对目前城市分形研究注重城市体系，对大都市城市个体形态生成演化的分形本质研究相对滞后的特点，尝试通过城市交通网络结构演化这一新的层面，拓展城市演化的分形本质研究，简要介绍了交通网络空间结构的分形测度-半径维度的定义，地理意义与测算方法，以上海基础交通网络信息GIS为支撑，分别对上海城市全域，浦西、浦东两分地域，几个行政城区进行了分形维数测算，结果表明，就城市全域而言，依据原城市“中心”与新开发的浦东陆家嘴“中心”所测算的分维数分别为1.56与1.66，二者相接近，也与国外一些相似的研究结果报道一致，表明交通网络存在分形本质的城市共性，就浦东浦西两分割地域而言，开发历史悠久的浦西中心城区，交通网络密度与复杂度远高于浦东地区，反映在分形维数上浦西1.57远高于浦东的1.37，就行政辖区而言，历史久远的中央商务区所在的卢湾、静安两区。分维数高于新发展的宝山、闵行，突显了老建成区的道路，交通网络的复杂性特征，论证了分形理论在城市内部结构和形态演变研究中的可应用性，初步揭示了上海交通网络空间结构在全市地域和有关行政区内的分形特征，讨论了交通网络的空间结构与经济发展的联系。

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.