Abstract: In this paper,based on Earlng probability distribution, freeway vehicle flow are divided into twokinds of following and non-following car’s traffic flows.A great quantity of data is used to check thevalidity of the distribution. The probability density function of non-following headway and formulations of random variables of two kins of traffic flows are deduced.

Key words: headway, following cars, non-following cars, probability distribution, random variable

摘要： 本文以爱尔朗分布为基础，将高速公路上车辆分为队状跟车和非跟车两种类型交通流，用大量实地观测数据检验分布的特性，推导出非跟车流车头间隔的概率分布函数和仿真用的两种交通流的随机变量公式．

关键词: 车头间隔, 跟车, 非跟车, 分布, 随机变量