快速路匝道瓶颈特性与临界流率模型

Properties of bottleneck at ramp of expressway and related critical flow model

对快速路汇入匝道瓶颈的特性进行实测数据研究。以密度和速度组合阈值法判断匝道瓶颈拥堵的发生,统计分析拥堵发生时的主线、匝道流量特征;基于跟驰理论和交通波理论分析了匝道合流区处由匝道车辆汇入对主线交通流造成的干扰,提出了主线交通流形成崩溃的条件;建立交通流崩溃临界主线-匝道流量模型,并用实测数据对模型参数进行标定,结果显示交通波速为24.6km/h,堵塞密度为113.8veh/km。研究表明,所提模型对于交通流崩溃临界条件的描述与实测数据具有很好的一致性。

This paper studies the characteristics of bottleneck at ramps of expressway based on empirical data.First,the density-speed combined thresholds are used for recognizing bottlenecks,and the flows of the main stream and the ramps are analyzed statistically.Then,the influence of ramp merging on the main stream is studied on the basis of car-following theory and ki-nematics wave theory.The condition resulting in breakdown phenomenon is proposed and the critical flow model regarding to the relation of flow in the main stream and the ramp is established.The model is calibrated with the field data.It is found that the speed of the traffic wave is 24.6 km/h and the jam density is 113.8 veh/km.The results show that the critical flow condition of the traffic breakdown described by the proposed model is well consistent with the empirical data.