The performance of the urban rail transit system depends largely on the operation efficiency of its feeder system. An improved way is proposed in this paper to calculate the accessibility index which is used for evaluation of feeder lines, and both passengers’ waiting time and the competition between different access modes are considered. Different from previous research, this paper focuses on whether and how the geometric shape differences affect the performance of fixed-route feeder lines. The impacts of line shape on accessibility are analysed by derived formulas for calculating accessibility under ideal conditions. The finding emerging from this study is that the accessibility of feeder lines differs obviously due to their shapes, given the same conditions of total line length, stop spacing, and vehicle fleet size. The service area of feeder lines with branches or a loop is closer to the rail station compared with that of linear lines, thus leading to fewer passengers served but shorter average travel time under specific routing plans. For further exploring the universality of the above finding, route alignment optimization models to maximize accessibility are built for different shaped lines. The optimal solutions of different shapes are obtained and compared in the cases of random generation to analyse the impacts of shapes on accessibility under different line length conditions.

中文翻译：

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不同几何形状的馈线可达性研究

城市轨道交通系统的性能在很大程度上取决于其支线系统的运行效率。本文提出一种改进的计算可及性指标的方法，该指标用于评价支线，同时考虑了乘客的等候时间和不同的可及性之间的竞争。与以前的研究不同，本文着重于几何形状差异是否以及如何影响固定路线支线的性能。通过导出公式来分析线形对可访问性的影响，以计算理想条件下的可访问性。从这项研究中得出的发现是，在总线长，停靠间距和车队规模相同的条件下，支线的可达性由于其形状而明显不同。与线性线路相比，带有分支或环形线路的支线服务区域更靠近火车站，因此在特定的路线计划下，服务的乘客减少了，但平均旅行时间却缩短了。为了进一步探索上述发现的普遍性，针对不同形状的线构建了路线对齐优化模型以使可访问性最大化。获得了不同形状的最优解，并在随机生成的情况下进行了比较，以分析形状对不同线长条件下可及性的影响。针对不同形状的线建立了路线对齐优化模型，以最大程度地提高可及性。获得了不同形状的最优解，并在随机生成的情况下进行了比较，以分析形状对不同线长条件下可及性的影响。针对不同形状的线建立了路线对齐优化模型，以最大程度地提高可及性。获得了不同形状的最优解，并在随机生成的情况下进行了比较，以分析形状对不同线长条件下可及性的影响。