车速离散性对高速公路实际通行能力的影响

Effects of Speed Dispersion on Capacity of Freeways

基于平均速差的车速离散度定义,研究了车速离散对高速公路实际通行能力的影响.研究发现,车速离散度与服务水平较高的纯自由流条件下的实际通行能力之间无明显关系,对于服务水平较低的状态,实际通行能力在车速离散条件下明显低于理论通行能力.基于车辆安全跟驰行为分析,建立了车辆速度、车头间距以及车速离散度之间的关系模型,并在此基础上得出了高速公路实际通行能力的车速离散度修正因子模型.

This paper studies the effects of speed differences on the practical capacity of freeway based on the speed dispersion definition of Average Speed Difference. It is found that there is no obvious relationship between speed dispersions and the practical capacity under high level of service,while under medium and low level of service the practical capacity is lower than the theoretical capacity on the effects of speed dispersions. Based on the analysis of safe car-following behaviors,the relations among vehicle speed,space headway and speed dispersion are established,from which the modifying factor model of practical capacity of speed dispersions is derived.