测算了长三角地区高速公路网络和城镇体系空间结构的长度维数,分枝维数、集聚维数、网格维数、关联维数等分形维数。研究表明,长三角地区:(1)高速公路网已具备分形结构特征,并以上海市为中心区域按自相似性向外延展;但路网密度尚未饱和,有待进一步加强,在连通性上还有更大发展空间;(2)城镇体系分布表现出自相似性结构,总体上仍呈空间集聚格局;但是基于220个县级城镇单位的随机分布出现了非向心性态势,说明城镇体系与高速公路网络尚未实现整合,网络需要完善;(3)地级以上城市之间的高速公路网络的联通度已经达到了甚至超过了极限水平。

The relationship between transport network and urban system is the frontier of transport geography and urban geography. At present, such kinds of researches in China pay much more attention on both air and railway modes other than highway network. The spatial distribution of regional cities has statistical fractal features that tend to optimize the evolution of regional urban system. So, there are great theoretical and practical implication to reveal the urban system fractal features and its dominating rules, and this has become an everlasting scientific question for academy over last decades in China. On the other hand, the urban system fractal features imply that the corresponding transport network has the features of self-similarity. With the deepen studies on urban system fractal, more and more researches focus on the fractal features of transport network, but actually there less progress on such kind researches in China, especially on the highway network over lass 10 years. This paper introduces the status of the construction of the express highway network and the urban system development in Yangtze River Delta area. The paper concludes: (1) the expressway network has already being a fractal structure and it features the network extending outward by self-similarity with Shanghai as the regional center. The calculation of the fractal dimensions' values show that the expressway network's density has not been saturated and should be intensified further, and also the connectivity of the expressway network should be upgraded; (2) the regional urban system's spatial distribution has self-similarity feature, but the expressway network has not been integrated with the urban system network based on the analysis of 220 cities at county level. The analysis reveals that the regional urban system's random distribution takes a non-concentric pattern; (3) the expressway network's connectivity between cities which are at prefecture level and above has reached even exceeded the limit level.