武汉都市圈路网空间通达性分析

以武汉都市圈为例.通过距离算法、拓扑算法和空间句法模型,构建系列通达性数理模型.定量分析武汉都市圈路网发育的空间结构性规律:武汉都市圈路网整体发育水平和通达性格局保持高度相关性和一致性.空间差异显著;通达性遵循距离衰减律,空间收敛整体效应明显.呈现三大等级圈层和"中心-外围"结构:高等级路网发育不均衡.引起时空距离通达性圈发生"摄动"变形,呈西北-东南向倾斜的"Y"字形结构:拓扑连接等通达性圈更是出现"破碎化",交通轴线网络呈"轴一辐"式和"鱼骨刺"状空间伸展序:同时,路网发育的等级差异性也导致整个网络伺服效率和应对"拥堵"能力的低下,并形成沿长江东西向、沿京广南北向两条带状集成核.成为整个路网的第一等级交通轴线,控制整个都市圈网络连接性,强化交通轴线交汇处-武汉市的中心性优势:路网通达性这种等级空间格局与圈域城镇体系、交通设施和社会经济发展状况密切相关.尤其是与高速公路为代表的高等级路网发育水平,表现出复杂的共轭协调关系.

Spatial Accessibility of Road Network in Wuhan Metropolitan Area

Spatial accessibility plays an important role in urban development and has been a prerequisite to the linkage and development of regional integration.Taking Wuhan metropolitan area as an example,we built a series of aecessibility models based on geometric and topologic distance.The proposed models are then applied to examine the spatial structural properties of the road network of Wuhan metropolitan area.It is found out that(1)there is a high uniformity and consistency between the entire development level and accessibility pattern of the road network of Wuhan metropolitan area;(2)significant spatial difierences are detected in the road network.i,e,. distance decay and spatial constringency for the entire road network;(3)thus,the network shows an obviotis grade-layer structure and core.periphery structure;(4)but high-class road network evolves unevenly,which causes the asymptotic deformation of the circles represented spatial-temporal accessibility.with the result that the total structure has a"Y-shaped"pattern from northwest to southeast;(5)the spatial distribution pattern of the topologic accessibility of the road network are scattered,and some skeletons and axes can be found.which results in the"axis-spoke"style and"fish spur"shape of the whole road network.The above structures and patterns of the road network have a great impact on the transportation system of the city.For instance.some roads with very low accessibility are easy to have traffic jam and low efficiency for distributing traffic flow to the entire road network;some skeletons such as the east-west roads along the Yangtze River and the north-south roads along the Beijing-Guangzhou Railway have been very important to accommodate the traffic flow of the entire road network.We also found that the spatially uneven accessibility pattern of road network has a close relationship with the city and town system.transportation facilities and social-economic development of the area.It should also be noted that there is a complex reciprocal-coordinate relationship between highly developed road networks.Therefore.the metropolitan area should pay more attention to the construction of transport infrastructure,especially those high-grade traffic lines and joints,because they are propitious to the servo and validity of road network;secondly,we should better develop some secondary cities in order to form a multi-polar structure of road network,which could enhance the balance and stability of total road network:thirdly.the construction of regional expressway network should be strengthened in order to promote the operation level and efficiency of road network.