中文摘要：

以加权平均旅行时间为指标,1986年、1994年、2005年为时间断面,探讨了长江三角洲地区公路网络中主要节点城市可达性空间格局及其演化规律,并结合公路货运特征（货运量区位商）分析了各节点可达性水平对其发展的影响.结果显示：研究期内,可达性空间格局总体变动不大,其值以上海、苏州、嘉兴为中心向外围呈不规则环状增高;公路网络的逐步完善极大地提高了区域内主要城市间的可达性,但不同阶段可达性演化特征不同,第二阶段（1994～2005年）可达性提升较之第一阶段（1986～1994年）更为显著;可达性值变化幅度与初始值有关,可达性值变率在第一阶段由北往南逐渐降低,而在第二阶段呈多极格局;随路网的不断完善,可达性水平由中心向外围呈圈层式优化;多数城市可达性状况优于平均水平,各节点城市相对可达性在第一阶段变化不大,但分布趋向于不均衡,第二阶段改变较大并趋于均衡分布;各节点城市可达性对其发展的影响可分为良好支撑、相对制约和基本适应三种类型.

英文摘要：

Based on the highway network map in 1986, 1994 and 2005, choosing weighted mean travel time as indicator, the spatial structure and evolution of major cities highway accessibility in the Yangtze River Delta （YRD） are elaborated in this paper. Considering the characteristics of highway transportation, the impact of accessibility level on city development is also analyzed preliminarily. Some conclusions are drawn as follows. In the 20 years, the spatial structure of accessibility in the YRD has little change; Shanghai, Suzhou and Jiaxing are the center with the lowest accessibility value, and the value increases from the center to the surrounding. The improvement of highway system upgrades the accessibility of major cities in this region, but the evolution takes on different characteristics in the two research stages, and the accessibility upgrade in the second stage （1994-2005） is greater than that in the first stage （1986-1994）. The changing extent of accessibility value is related to the initial value, and changing rate of accessibility value decreases from the northern part to the southern at the first stage, but takes on multi-core pattern at the second stage. With the improvement of highway system, the accessibility optimizes from the center to the surrounding. Most cities in this region are above the average level in accessibility, and the city relative accessibility has changed less at the first stage but more at the second stage. Standard deviation analysis of accessibility coefficient shows that the equilibrium of the accessibility distribution descends at the first stage and ascends at the second stage. Considering the highway freight local quotient, the impact of accessibility level on the city development is classified into three categories： promotion, restriction and adaptation. With these results, some suggestions about the development of highway system in this region and some loci for further study are proposed.