考虑行人保护策略的交叉口信号配时优化模型

为促进平面交叉口的行人交通安全，本文基于美国国家电气制造商协会(NEMA)的双环相位标准，将行人专用相位(EPP)、行人同步保护相位(CYPP)以及行人前置相位(LPI)这3种行人保护策略整合到一起，以信号周期和行人-右转车的冲突点数量最小化为目标，构建交叉口信号配时优化模型。在假定交通参与者遵守信号规则的前提下，除LPI策略中远端行人与右转车冲突外，其余冲突点经模型优化后皆可消除，并且机动车的通行效率能够得到维持。该模型属于0-1 混合整数线性规划问题(BMILP)，可用分支定界法求解。选取南京市两个交叉口进行实例研究。结果表明：在交叉口几何尺寸及交通流量较小时，模型倾向于得到 EPP 方案，否则倾向于得到 CYPP和LPI方案；在进口道设有直右共享车道或右转相位不易满足最大饱和度限制时，模型倾向于得到LPI方案。

Intersection Signal Timing Optimization Model Considering Pedestrian Protection Strategies

To promote pedestrians' safety at intersections, this paper establishes a signal timing optimization model based on the NEMA dual-ring standard by incorporating three pedestrian protection strategies, i.e., exclusive pedestrian phase (EPP), concurrent yet protected phase (CYPP), and leading pedestrian interval (LPI). The model aims at minimizing the cycle length and the conflicts between right-turn vehicles and pedestrians. By supposing that the traffic users obey the signal rule, the model can eliminate most of the conflicts, leaving only the conflicts between far- side pedestrians and right-turn vehicles under LPI control. The model belongs to Binary-Mix- Integer- Linear- Program (BMILP) and can be solved by the branch-and-bound method. Two intersections in the city of Nanjing are selected for a case study. The results show that when the intersection size is small and the traffic volume is low, the EPP is more likely to be obtained; the CYPP or LPI is otherwise. When the shared through-right lane is set in the intersection arm or the right-turn phase is not easy to meet the maximum volume-to-capacity ratio, LPI is more likely to be obtained.