城市过江通道交通流速度和密度关系研究

Study of speed-density relationship of urban river-crossing passage

为确定城市过江通道交通流特性是否符合经典的速度-密度关系模型,研究了四川泸州市沱江一桥上的过江交通流。利用视频检测技术,获取了包含高峰期、平峰期等各种交通运行状态的交通流流量、速度数据,经过数据清洗、转换后,对速度和密度数据进行了回归分析和显著性检验,并计算得到了交通流特征参数自由流速度和阻塞密度。结果显示,城市过江通道的进城方向更适宜Greenshields的线性关系模型,出城方向更适宜Underwood的指数关系模型。桥头段和桥中段交通流特征参数的差异性,表明了桥头交织段规划、设计与管理对提高过江桥梁衔接段通行能力的重要性,相关部门应合理组织进城方向下游、出城方向上游的交通流,以改善区域交通运行质量。

In order to determine whether traffic flow characteristics of urban river-crossing passage are consistent with the classical models of speed-density,the traffic flows on the First Luzhou Tuojiang River Bridge are researched.Video detection technology is used to obtain traffic flow and speed data including all kinds of traffic conditions,such as during fastigium and normal period.After data cleaning and conversion,speed and density data are regressive analyzed,significance test is made,and traffic flow characteristic parameters,such as free-flow speed and jam density,are calculated.The results show that the linear model of Greenshields is more suitable for the direction of entering cities of urban river-crossing passage,while the exponential model of Underwood is more suitable for the direction of leaving cities.The difference of traffic flow characteristic parameters between bridge approaches and bridge mid pieces show that government departments should pay attention to the planning,design and management of the weaving segment on bridge approaches to improve the traffic capacity of cohesive segment of river-crossing bridge and organize reasonably the traffic flows of the downstream section of entering cities and the upstream section of leaving cities.