城市快速路常发性瓶颈交通流失效生存分析模型

Survival Analyses of Traffic Flow Breakdown at Urban Expressway Recurring Bottlenecks

摘要:

瓶颈处交通流失效（Breakdown）是导致快速路拥堵的重要原因，其致因则是交通需求、驾驶行为及设施设计等多因素交互作用的结果。针对快速路常发性瓶颈失效的随机特征，基于海量检测数据，提出了快速路瓶颈失效的生存分析模型。该模型首先以速度、密度组合阈值法判断失效是否发生；然后统计失效发生时刻及发生前的交通流参数，利用生存函数描述失效发生概率与瓶颈通行能力的关系；进一步采用COX回归模型分析瓶颈失效的影响因素。上海市内环三个典型双车道常发性瓶颈点（外线广中路入匝道、内线武宁路入匝道、外线武宁路入匝道）277个交通流失效事件分析表明，在50%的失效概率下，三个瓶颈每车道通行能力分别为1341veh/h，1552veh/h，1662veh/h；通过调控主线车速及驶入匝道流量可对瓶颈失效起到有效的保护作用。利用该方法可精细化确定瓶颈点概率通行能力，并为快速路主动交通管理措施设计提供理论依据。

Abstract:

One of the important factors causing urban expressway congestion was traffic flow breakdown at bottlenecks, which resulted from mutual effects of traffic demand, driving behavior and road geometry. Aiming at probabilistic nature of breakdown at urban expressway recurring bottlenecks, survival analyses models of breakdown were proposed based on the detector data. Firstly, breakdowns were identified according to speed and density thresholds. Secondly, traffic parameters during and before breakdown were counted, and relationship between probability of breakdown and bottleneck capacity was described by survival function. Finally, factors of bottleneck breakdown were analyzed by COX regression models. 277 breakdown events were collected from three typical two-lane recurring bottlenecks (Guangzhong on-ramp in inner-circle, Wuning on-ramp in inner-circle and outer-circle) at inner-ring expressway in Shanghai. Analyses results showed when the probability of breakdown was less than 50%, the single lane capacities of the three bottlenecks were 1341veh/h, 1552veh/h and 1662veh/h respectively. It can effectively protect breakdown of bottlenecks to adjust or control speed of main lane and ramp volume. The probabilistic capacity of bottleneck would be quantified more precisely according to the proposed method, which also could supply the scientific basis for active traffic management strategies design.