重庆市交通网络的可达性时空特征及其演化规律

可达性是度量区域交通网络结构通达性的有效指标。本文以1997、2001、2004、2008和2012年为时间断面,以加权平均旅行时间为指标,对重庆市陆路交通网络中节点区县可达性时空特征及演化规律进行了研究。结果表明：重庆市交通可达性总体呈现以主城区为中心向外围区域递减的“核心-边缘”模式,可达性等值线大致呈不规则环状分布;随着路网的不断完善,可达性水平由中心向外围呈圈层式优化,各区县的可达性有大幅度的提升,但不同阶段可达性提升幅度不同,第1、2阶段（1997-2004年）可达性相对第3、4阶段（2004-2012年）而言优化程度更为显著。由于可达性值变化幅度与其初始值有关,所以,边缘地区可达性值提高幅度始终大于中心地区,区县可达性差异逐渐缩小,可达性分布趋于均衡。由于空间经济分布具有明显的不均衡性,可达性与经济发展之间具有一定的互动耦合关系,交通网络的区域效应显得更为复杂。交通网络如何与城市体系合理匹配,形成良性互动的“交通-城市-经济”复合系统,是未来区域交通建设规划应该重视的内容。

Spatial-temporal Characteristics of Chongqing Transport Network Accessibility and Its Evolution Pattern

Accessibility, as an important index to represent the effectiveness of regional traffic network structure, takes a vital role in transport status research and transport network planning and designing. However, it is hard to find previous researches on the spatial-temporal characteristics of transport network accessibility and its evolution pattern, especially cases concerning the inland mountainous regions. In this paper, those characteristics and the evolution pattern of all nodes (districts) in Chongqing transport network in 1997, 2001, 2004, 2008 and 2012 were analyzed and evaluated by using the weighted average travel time as the indicator. The results show that the accessibility of Chongqing declined gradually from the city center (Yuzhong district) to the city edges. During 1997-2012, with the enhancement of transport network, the accessibility of all nodes was dramatically improved. Comparatively, the growth of accessibility during 1997-2004 is higher than that during 2004-2012. Because the variation of accessibility values has a close relationship with its initial value, the accessibility increase in the marginal areas is greater than that in the central areas. Among the cities, the differences in accessibility gradually narrow, and the accessibility coefficient gradually reaches an equilibrium distribution. Because of the imbalance of the spatial distribution of economy, there is a certain interactive coupling relationship between economic development and accessibility. And the regional effect of the transport network is more complicated. How to properly match the transport network to the urban system is the content of the regional transportation construction planning, and the government should pay more attention into it in the future.