两条四车道城际高速公路交通流实测研究

Study on Traffic Flow Measurings of Two 4-lane Intercity Highways

改进了交通流视频检测方法,对G2京沪高速和G60沪昆高速交通流进行了实地拍摄、数据采集和分析.发现高货车比例的城际高速公路交通流与城市快速路存在不同的特征,客车与货车具有明显的分道行驶行为,速度概率分布呈现"双峰"特征.从远城段到近城段,货车的平均速度变化不大,客车则有明显的降速行为."速度-密度"、"流量-密度"关系都具有强非线性的特征,这种非线性在密度很低时就已出现.实测速度数据的算术平均值与"按帧平均速度"、时间平均车速及空间平均车速差异都很小,在工程计算中可以相互替代.采用本文的密度测量方法,能够准确计算流量,为视频检测方法的在线应用提供了可能.

The method of traffic video screening is improved and then is used to collect data from the traffic videos taken from Jinghu Highway G2 and Hukun Highway G60. The data reveals that the characteristics of traffic flow on intercity highways, where the proportion of trucks is remarkable, differ from those on urban expressways;cars and trucks distinctly segregate themselves into different lanes, resulting in double peaks in the probability density distribution of speed. The average speed of trucks changes little between the locations near and far from the urban area, while the average speed of cars significantly decreases at the former location. The relationships of speed- density and flow-density both show strong nonlinearity, which has emerged under low density. The algorithms of average speed is also compared, and it is found that the differences among the arithmetical average value, the frame-averaging value, the time-averaging value and the space-averaging value are so small that they can be substituted by each other in engineering calculations. The measuring method of density adopted in this paper can be used to calculate flow accurately, which offers possibility of online application of video screening method.