城市快速路瓶颈交通震荡特性研究

A Study of Traffic Oscillations at the Bottlenecks on Urban Expressways

采用基于长期累计值与近期均值比较思想的累计移动序列法对上海市快速路系统中典型瓶颈路段（驶入匝道、驶出匝道）交通震荡的传播速度、振幅以及移动时间步长、背景车速与振幅的关系等特性进行研究。结果发现震荡始于瓶颈排队下游,自下游向上游传播,传播速度保持在20～25km/h;在不同移动时间步长下,2类瓶颈震荡振幅与移动时间步长的相关系数分别保持在0.964 2～0.999 8及0.982 2～0.999 4,表现了高度正相关性;而背景车速与振幅无显著相关性。最后发现,道路基础设施布局影响振幅的变化,震荡传播超越驶入匝道后,振幅被削弱;震荡传播超越驶出匝道后,振幅被放大,该结论可为快速路匝道控制算法提供参考数据。

Traffic oscillations at the typical bottlenecks（on-ramp,off-ramp）on the expressways of Shanghai are investigated.A method of cumulative movement sequence,which is based on comparisons between cumulative values for a long term and mean values for a short term,is used.The features of the traffic oscillations including propagating speeds,amplitudes and the relationships among amplitudes,moving step size and background speeds are analyzed.It is found that the oscillations arise in the downstream part of the queue at a bottleneck and propagate to the upstream with a nearly constant speed of about 20～25km/h.Under different moving step size,the correlation coefficient between the amplitude of an oscillation and the moving step size at 2types of bottlenecks are 0.964 2～0.999 8and 0.982 2～0.999 4,which shows a high positive correlation.No significant correlation is found between the amplitude of an oscillation and the background speed.Finally,study results also indicate that the layout of road infrastructure plays an important role in amplifying or impairing the amplitude：the amplitude is amplified when the oscillation crossed a diverging ramp,but the opposite result is shown on a merging ramp.The study results of this paper could provide a basis for designing on-ramp control algorithm for expressway bottleneck areas.