基于驾驶行为共性建模的速度-密度关系研究

Study on the Speed-density Relationship Based on Modeling Common Characteristics of Driving Behavior

为了能对车流的速度-密度关系进行准确描述及对现实交通中的速度陡降现象进行解释,首先提取出驾驶行为共性:(1)驾驶员利用与渴望车速对应的心理车头间距来判断前方的交通流状况;(2)驾驶行为中加速或减速行为是驾驶员根据前车传递的交通信息和自己对此信息的时间和空间理解来进行的,并且以回波速度向后传递。此后,在对这些驾驶共性进行数学描述的基础上建立一种以车头间距和驾驶员反应时间等为参数的回波速度和速度-密度关系模型,通过分析模型中驾驶员反应时间这个参数在加速和减速时的不同选择对速度陡降现象进行解释。最后,使用MATLAB7.0软件数值模拟计算回波速度和速度-密度关系,计算结果表明:回波速度最大值与相关文献给出的值吻合,速度-密度关系曲线与观测的数据吻合,驾驶员反应时间变化是产生速度陡降现象的根本原因。

In order to describe the speed-density relationship well and truly and to interpret the phenomena of speed drop occurred in real traffic, the common characteristics of driving behavior were put forward first, namely, （ 1 ） the front states of traffic stream were judged by the mental headway corresponded the desired velocity by drivers; （2） accelerating or decelerating behavior was selected by front vehicle transferring traffic information and by drivers＇ comprehension of the information from the view of time and space, and transferred backwards at the echo wave speed. Recurred to the mathematical descriptions of the common characteristics of driving behaviors, a series of formulations on the wave speed and the speed- density relationship were provided, which were presented by parameters of headway and drivers＇ reaction time and so on. Based on analyzing the driver＇ s reaction time parameter, which was selected differently in these models during acceleration and deceleration, the phenomena of the speed drop occurred in real traffic was interpreted. Finally the curves of the echo wave speed and the speed-density relationship were obtained in the MATLAB 7. O. The numerical simulation results indicate that the maximal value of echo wave speed tallies the values in the literatures and the curves of the speed-density relationship tallies the observed data and change of the reaction time is the essential reason of the speed drop.