环形放射状城市常规与需求响应公交联合优化研究

Joint Optimization of Conventional Transit and Demand Responsive Transit for Ring-radial Cities

针对环形放射状城市扩张过程中常规公交线网出现线网资源利用失衡、乘客出行时间过长的问题,本文设计一种常规公交与需求响应公交分层布局的双模式线网结构。基于连续近似方法,构建混合整数优化模型,以最小化公交平均运营和乘客平均时间成本之和为目标函数,根据乘客出行空间分布构建确定性的出行模式及路径选择细分方法,推导各项成本组成,求解常规公交线间距、站间距及双模式公交发车间隔等决策变量的最佳值。采用混合启发式算法对模型进行求解,并以成都市五环内环形放射状公交网络为例,验证所提双模式公交网络的有效性。优化结果表明:与单模式常规公交线网对比,双模式网络可以分别降低18.37%的乘客成本以及4.97%的公交运营成本,具体表现为减少常规公交31.85%的站点和线路建设成本以及24.36%的运营里程;系统各项成本随平均客流密度的增加呈幂指数下降并趋于稳定;同时给出不同客流密度分布条件下,系统关键设计参数的建议值。

This paper focuses on the unbalanced utilization of network resources and long travel time of passengers for the conventional transit network during the ring-radical cities'expansion and proposes a modal network structure with a hierarchical layout of conventional transit and demand-responsive transit.Based on the continuous approximation method,this paper uses a mixed-integer program to minimize the sum of expected passenger cost and agency costs.A deterministic mode split and route choice model is embedded and cost components are derived based on passengers'groups.Then,decision variables such as the stop and line spacing of the conventional transit and the headway of bimodal transit systems are optimized and a hybrid heuristic is proposed to solve the problem.At last,to verify the effectiveness of the designed network,a case study is conducted on a real-world ring-radial network within the fifth ring of Chengdu City.The results indicate that compared with the conventional transit network,the proposed system can reduce passenger costs by approximately 18.37%while effectively reducing operating costs by approximately 4.97%.The proposed system can reduce the construction cost by 31.85%,and reduce the travel distance by 24.36%for conventional buses.System cost decreases exponentially with the increase of average passenger flow density and the values of key design parameters under different conditions can be provided through the proposed method.