Abstract: To improve the degree of expressway network accessibility and reachability level of urban agglomeration, the optimization model reflecting the characteristics of urban agglomeration was established and the imperial competition algorithm was improved to explore the optimization effect of the layout by taking the Ha-Chang urban agglomeration as a case study. Firstly, expressway travel time was used to determine the accessibility level of urban agglomeration, and the optimization model was established by considering accessibility, distance and other parameters. Then the evolution operator was introduced to improve the algorithm, and the imperial competition algorithm based on evolution (ICAE) was constructed. Finally, the constraints were determined and solved according to the characteristics of the Ha-Chang urban agglomeration, and the optimization scheme was determined by using the solved nodes and the surrounding road network. The study shows that: the improved algorithm improves convergence accuracy by 16.4%, reduces time by 42.4%, which solves a total of 6 nodes, plans to build 6 new expressways and renovates 14 expressways. After optimization, the coverage of 2h traffic circle of expressways in the urban agglomeration reaches 65.3% and the level of traffic circle of 14 counties rises. The proposed optimization scheme enlarges the scope of 2h traffic circle of the urban agglomeration.

Key words: traffic engineering; road traffic; expressway network; imperial competition algorithm; urban agglomeration accessibility

摘要： 为提升城市群高速公路网通达程度和可达性水平，建立了体现城市群特征的优化模型，并改进了帝国竞争算法，以哈长城市群为案例，探究布局优化效果。采用高速公路出行时间确定城市群可达性等级，通过考虑可达性、距离等参数建立优化模型；引入进化算子改进算法，构建进化帝国竞争算法；根据哈长城市群特征确定约束条件并求解，利用求解节点和周边道路网确定优化方案。研究表明： 改进的算法收敛精度提高16.4%，时间缩短42.4%，共求解出6个节点，规划新建高速公路6条，改建高速公路14条，优化后的城市群高速公路2 h交通圈覆盖范围达到65.3%，14个县域交通圈等级上升，优化方案扩大了城市群2 h交通圈范围。

关键词: 交通工程；公路交通；高速公路网；帝国竞争算法；城市群可达性