基于车道的瓶颈交通流失效识别实证研究

An Empirical Study for Identifying Traffic Breakdown at Bottlenecks

交通流失效识别是确定交通状态、制定交通管理策略的关键。为精细化识别各车道交通状态的差异,提出以车道为基础,利用速度变形累积曲线将每个时间间隔内的速度波动"转折点"放大,较为精确和直观地确定各车道的瓶颈交通流失效时间。相比于以往基于断面和基于阈值的识别方法,该方法更为精细和客观,不仅能有效识别路段的半拥挤状态,也可以深入分析拥挤的横向、纵向传播特性。以上海市快速路军工路出口匝道附近作为研究对象,结果表明,出口匝道附近的拥挤一般先由最外侧车道开始,平均经4min之后扩散到最内侧车道,但在向上游纵向蔓延的过程当中,内侧车道反而比外侧车道更容易发生交通拥挤。

Identification of traffic breakdown is critical for evaluating traffic flow states and making decision on traffic operation plan.In order to detect the differences of traffic conditions among the lanes in detail,a lane-based method is proposed,which is able to identify breakdown accurately and in an intuitive way.The occurring time of traffic breakdown is determined by enlarging the 'turning point' of speed fluctuations at each time interval using speed transform cumulative curve.Compared to the traditional section-based and threshold-based methods,the proposed lane-based method is more accurate and objective which can not only differentiate the semi-congested states,where only some of lanes are congested,but also show the longitudinal and transverse propagation characters of traffic congestion in depth.The off-ramp at the Jungong Expressway Road in Shanghai is used as a case study and the results show that the breakdown actually occurs on the outermost lane firstly and then spread to innermost lane after an average of 4minutes.When the congestion propagates to the upstream,the inner lanes tend to be more congested than the outer lanes.