拥挤流状态下城市快速路交通流时空特性

为了定量分析拥挤流状态下城市快速路交通流时间和空间特性,首先采用自相关函数法判断交通流率、占有率和速度时间序列的平稳性;其次,研究拥挤流状态下交通流参数空间传递特性;最后,基于混沌分析中的G-P算法建立模型将非平稳的交通流参数时间序列转化为平稳时间序列.研究表明:拥挤流状态下,交通流率表征为平稳的时间序列,速度和占有率属于非平稳时间序列;空间上,上游断面对下游断面的速度参数具有传递作用,下游断面的速度参数对上游具有回溯影响,当时间延迟为2 min时,取嵌入维为4进行相空间重构,可将速度时间序列转化为平稳的时间序列.

Spatial and Temporal Characteristics for Congested Traffic on Urban Expressway

The authors analyzed spatial and temporal characteristics of traffic flow under congested traffic based on detection data on urban expressway.First,autocorrelation function method was adopted to analyze the stationary of traffic flow parameter time series;Second,the spatial characteristics,which included the impact between the upstream and downstream sections,were analyzed by using detection data;At last,a model was developed to convert non-stationary speed time series to stationary time series based on G-P algorithm.The empirical research shows that traffic flow and occupancy are stationary time series,speed is non-stationary time series under congested traffic.The speed at upstream section could impact speed at downstream section through the transfer effect,the speed at downstream section could impact on speed at upstream section through the feedback effect.The speed can be converted to stationary time series by phase space structure with time delay of 2 min and embedding dimension of 4.