[论文解读] A pedestrian hopping model and traffic light scheduling for pedestrian-vehicle mixed-flow networks

Yi Zhang, Rong Su+2 more|arXiv (Cornell University)|May 15, 2017

Traffic control and management参考文献 11被引用 6

一句话总结

本文提出了一种新型行人跳跃模型及混合交通流城市网络的信号配时集成框架，通过混合整数线性规划（MILP）与离散谐波搜索（DHS）结合行人与车辆动力学。研究结果表明，行人对车辆延误的影响可量化为分段常数函数，且优化的信号配时显著降低了中等规模网络中的行人不满与车辆延误。

ABSTRACT

This paper presents a pedestrian hopping model and a traffic signal scheduling strategy with consideration of both pedestrians and vehicles in the urban traffic system. Firstly, a novel mathematical model consisting of several logic constraints is proposed to describe the pedestrian flow in the urban traffic network and its dynamics are captured by the hopping rule, which depicts the changing capacity of each time interval from one waiting zone to another. Based on the hopping mechanism, the pedestrian traffic light scheduling problems are formulated by two different performance standards: pedestrian delay and pedestrian unhappiness. Then the mathematical technique and the meta-heuristic approach are both adopted to solve the scheduling problem: Mixed integer linear programming (MILP) formulation for pedestrian delay model and discrete harmony search algorithm (DHS) for both pedestrian delay model and unhappiness model. Secondly, a mathematical model about the vehicle traffic network, which captures drivers psychological responses to the traffic light signals, is introduced. Thirdly, a traffic light scheduling strategy to minimize the trade-off of the delays between pedestrians and vehicles is proposed. Finally, we translate this traffic signal scheduling problem for both pedestrians and vehicles into a MILP problem which can be solved by several existing tools, e.g., GUROBI. Numerical simulation results are provided to illustrate the effectiveness of our real-time traffic light scheduling for pedestrian movement and the potential impact to the vehicle traffic flows by the pedestrian movement.

研究动机与目标

• 为应对城市交通拥堵加剧的挑战，整合行人与车辆的信号控制。
• 利用一种新颖的跳跃规则建模行人流动力学，捕捉时间间隔内容量的变化。
• 将行人延误与行人不满双重作为信号配时的性能指标。
• 开发一种集成优化框架，平衡行人与车辆之间的延误。
• 通过基于权重的敏感性分析，量化行人网络对整体车辆网络延迟的影响。

提出的方法

• 利用逻辑约束与跳跃规则构建行人跳跃模型，描述等待区域之间随时间变化的动态容量。
• 构建两个性能模型：一个基于MILP最小化行人延误，另一个基于离散谐波搜索（DHS）最小化行人不满。
• 引入宏观车辆流模型，整合驾驶员对信号配时的心理响应。
• 采用集成MILP公式，结合行人与车辆延误目标，通过可调权重平衡权衡。
• 利用从逻辑表达式推导出的混合整数线性约束，表示信号配时与行人移动。
• 在3×3至10×10的网络上进行数值仿真，评估不同预测时域与权重分配下的性能。

实验结果

研究问题

• RQ1 如何利用跳跃机制与逻辑约束有效建模城市人行横道中的行人流动力学？
• RQ2 行人移动在多大程度上影响车辆网络延迟，且该影响是否可量化？
• RQ3 是否存在一种统一的信号配时策略，可同时最小化行人延误与行人不满，同时平衡车辆延误？
• RQ4 行人与车辆延误的不同权重分配如何影响整体系统性能与信号切换频率？
• RQ5 预测时域与网络规模对基于MILP的调度方法可扩展性有何影响？

主要发现

• 行人对车辆网络延迟的影响最适于描述为分段常数函数，表明在达到阈值前，行人权重的微小变化影响甚微。
• 当行人权重低于2时，其对总网络延迟的影响可忽略不计，提示需提高权重以匹配车辆网络的敏感度。
• 与仅最小化延误的模型相比，DHS算法能有效降低信号切换频率，尤其缓解了小规模行人团体的长时间等待。
• 基于MILP的方法在中等规模网络（最大10×10）中实现了高效的实时调度，但在大规模城市网络中可扩展性受限。
• 仿真结果证实，集成模型有效降低了行人不满，并在两种交通模式间实现了延误的平衡，信号协调性有明显改善。
• 车辆网络对行人网络变化的敏感度低于行人网络对车辆网络的影响，表明车辆网络动力学主导整体延迟行为。