基于路网数据和复杂图论的中国城市交通布局评价

城市化的快速发展推动了我国城市道路网的不断扩张和发展。城市道路网是一个动态、开放、自组织的空间复杂网络,构成了城市的结构框架,研究城市道路网的结构特征对路网规划和城市建设有着重要的应用价值。在国内城市道路网络结构特征的相关研究中,很少有学者基于道路走向的视角对整个城市路网结构进行研究,也缺少对全国主要城市路网的整体性评价。本文选取我国一、二线及新一线49个城市作为研究区和2020年2月的城市道路网作为实验数据,首先采用图论和玫瑰图的方法对49个城市的道路网方向特征进行可视化,定性分析城市路网的复杂结构,然后基于最值比R、道路首位度S、过阈值比T、走向顺序φ和路网密度δ等5个路网指标对49个城市的道路网进行聚类分析,从而探究我国城市路网的分布特征。结果表明,我国城市主要以南北和东西走向为城市道路的主导向,部分城市因地形的影响沿着有利于城市交通和居民生活的方向规划道路;基于路网指标的聚类得到了十字正交型、十字状向风车状扩散型、风车状向圆弧四角星扩散型和混合复杂型等4类城市道路网类型,这4类城市路网在方向分布特征上具有显著差异,突出表现在有序性和复杂性;从路网类型的空间分布来看,十字正交型和十字状向风车状扩散型路网大多分布在我国的内陆地区,而风车状向圆弧四角星扩散型和混合复杂型路网则大多分布在沿海地区。本文主要通过分析我国一、二线及新一线城市道路网的分布特征,探究了我国主要城市交通路网的布局现状,能够为城市新区道路规划和路网布局优化提供参考依据。

Delineating China's Urban Traffic Layout by Integrating Complex Graph Theory and Road Network Data

The rapid development of urbanization has promoted China's urban road network's continuous expansion and growth. The urban road network is a dynamic, open, and self-organized spatial complex network, which constitutes a city's structural framework. The study on urban road networks' structural characteristics can provide a significant application value for road network planning and urban construction. In the related studies of the structural characteristics of urban road networks, few scholars have paid attention to the whole urban road network structure from the perspective of road alignment in China. Besides, recent studies lack an overall evaluation on the road network of major cities in China. In this paper, 49 cities, including the first- and second-tier and first-tier new cities in China, are selected as study areas and the urban road network data in February 2020 are taken as experimental data. Firstly, we use the graph theory and rose diagrams to visualize the road network's directional characteristics in 49 cities. The complex structure of the urban road network is qualitatively analyzed. Then, we select five road network indicators including the maximum ratio R, the road primacy degree S, the ratio over threshold T, the orientation-order φ, and the road network density δ. Based on the five indicators, cluster analysis is carried out for the road networks of 49 cities in this paper. And the characteristics of the spatial distribution of urban road network in China are explored. The results show that the north-south and east-west roads are the main alignment of urban roads in China. Because of the influence of terrain, some cities plan routes along the direction, which is favorable to traffic and resident's living. Based on the clustering of road network indicators, four types of the urban road network are obtained, including cross orthogonal type, cross to windmill type, windmill to arc type, and mixed complex type. There are significant differences among four types of the urban road network in directional characteristics highlighted in complexity and order. In view of the spatial distribution of road network types, road networks of cross orthogonal type and cross to windmill type are mainly distributed in China's inland areas. In contrast, road networks of the windmill to arc type and mixed complex type are mainly distributed in coastal areas. This paper explores the current traffic layout in major cities in China by analyzing the characteristics of road network's distribution in the first- and second-tier and first-tier new cities in China. This study can provide a reference for road planning and optimization of road network layout in new urban districts.