中文摘要：

以交叉口运行效率为目标，运用概率论、排队论和交通流理论对无信号交叉口左转车道的设置依据进行研究．假设车流到达率服从泊松分布，根据左转与直行车辆的相互作用过程和运行特性，推导了无信号交叉口左转车道设置的左转交通量阈值表达式，并讨论了模型中的参数：受左转影响的直行车停车概率的限值、左转穿越对向车流的临界间隙和进口道车道数．对典型情况进行模拟计算，绘制了左转车道设置的准则图表．对计算结果分析得出了无信号交叉口设置左转车道左转交通量的变化规律．研究成果为左转车道的设置提供了定量化的依据．

英文摘要：

Treatments of left-turn are the most difficult problem at intersections. Left-turn lane guidelines for unsignalized intersections were studied using probability theory, the theory of queue and traffic flow theory. The study objective is the operation efficiency. The interaction between left-turn vehicles and through vehicles and operation characteristics were analyzed. The equation of left-turn threshold volume for left-turn lane installation at unsignalized intersections was derived. The traffic flow arrival rate was supposed as Poisson distribution. Parameters were discussed. The first is the stop probability of through vehioles influenced by left-turn vehicles; the second is the critical gap and the third is approach lane number. Simulation and calculation were done for the general conditions. Tables and figures of left-turn lane warrants for unsignalized intersections were established. Variation laws of left-turn threshold volume for left-turn lane installation were obtained by analyzing the calculation result. The conclusions present numerical guidelines for left-turn lane installation at unsignalized intersections.