摘要
以武汉城市圈为研究区,借助ArcGIS9.3、Pajek2.7和SPSS16.0等软件,从节点重要性、可达性、集聚性3个方面定量揭示了复杂城乡道路网的空间异质性:①高度节点重要性呈幂律分布,表现出无标度性,低度节点重要性则基本呈钟型泊松分布,呈现一定的随机性,导致整个圈域节点的重要性分布曲线既不遵循钟型泊松分布也不遵循幂律分布,出现"涌现"性;节点度值空间分布较均匀,呈现点状特征和弱集聚性,具有明显间断性和跳跃性,表现出一定的"中心-边缘"和"等级圈层"的复合结构;②节点的可达性主要由网络平均路径长度、紧密度和介数指标表达,其中道路网平均路径长度较大,节点交通联系呈线状组织,遵循距离衰减律,成等级圈层分异,但受快速干道影响明显,空间收敛减慢,发生"摄动"变形,形成两条以南北京珠高速和东西宜黄高速为轴的城市交通走廊;节点的紧密度系数较随机网络小,但高紧密度节点在空间分布上较为集中,呈现出一定的"中心-边缘"空间格局;节点的介数指标相对较高,呈现指数分布,空间分布较均匀,但仍呈现出一定的"等级圈层"分异;③网络的集聚性空间差异显著,形成多个大型网络社团,网络的聚类系数近似为零,局部呈现耦合性质,高聚类系数节点集聚成"半月形"展布,低聚类系数节点分布较为离散。
Studies on the complexity and non-linearity of the spatial structure of road networks have attracted increasing attention during the past several years.However,few efforts have been devoted to the spatial and structural properties of large-scale road networks.In addition,most of current studies focused on either spatial morphology of road networks or structural pattern of road structure,while a comprehensive analysis on the spatial restriction of road network structures is ignored.To fill in the knowledge gap,this article introduces a series of approaches to uncover the spatial influences on the structural characteristics of general road networks.The road network of Wuhan Metropolitan Area(RNWMA) is taken as a case study and the spatial heterogeneity of the structure of RNWMA is analyzed from three aspects with the help of software including ArcGIS9.3,Pajek2.7 and SPSS16.0.Three aspects of spatial heterogeneity of the RNWMA are studied,which are importance of road intersections,accessibility of road intersections and clustering of road intersections.For each property,both statistic analysis and spatial distribution analysis are carried out.Results are visualized by map or chart.Possible explanations are also given.It is found that in the RNWMA: 1) the importance values of roads with high accessibilities in RNWMA follows a power-law distribution,which may indicate that the RNWMA is a scale-free network.While the importance values of roads with low accessibilities follow a Poisson distribution.The co-existence of scale-free and random properties for roads with different accessibility makes the entire road network a complex system with some"emergent"properties;2) the average length of the shortest path between two roads is relatively large.While the traffic links between two roads in terms of topological distance follow the law distance decay and obvious hierarchy circles can be observed.The spatial convergence of the shortest path length is significantly influenced by roads with high hierarchy(e.g.expressway) and shows perturbation deformation.Two urban transportation corridors,i.e.,the Beijing-Zhuhai(north-south) and Yichang-Huangshi(west-east) are observed.Besides,statistically the values of the betweenness of road intersections show exponential distribution although spatially they are relatively even;3) The clustering coefficient for the RNWMA approaches zero,while several network communities are observed.The spatial distribution for the road intersections with large value of clustering coefficient are"crescent"like,and road intersections with low clustering coefficient values are sparsely distribution in the region.Attempt made in this study will not only help to interpret the structural organization and growth in a limited geographical space,but also shed light on visual analytic means for geographic environments.It is our hope if the findings of this article can provide any alternatives for current road network study,and give practical supports for the construction of urban-rural road network.
出处
《地理科学》
CSCD
北大核心
2012年第4期426-433,共8页
Scientia Geographica Sinica
基金
国家社会科学基金项目(11CJL048)
华中师范大学研究生教育创新基金项目(2010004)资助
关键词
空间复杂性
复杂网络模型
城乡道路网
武汉城市圈
spatial complexity
Complex Network Model
urban-rural road network
Wuhan Metropolitan Area