ABSTRACT

The critical gap is typically used to determine the capacity at unsignalized intersections. A few studies have been carried out on the estimation of the U-turn critical gap at uncontrolled median openings. In this research, the critical gap was calculated using four well-known methods, Maximum Likelihood Method (MLM), Ashworth’s, Raff, and acceptance curve for different types of U-turn vehicles at four uncontrolled median openings in Iran. The data were collected using video recording. The results showed that MLM is the best method for calculating the critical gap according to the conditions of Iran. According to this method, the average critical gap was obtained 3.23 seconds, which was very low compared to other countries. Moreover, the result of MLM showed that the critical gap for Heavy Vehicles (HVs) drivers was almost less than car drivers, indicating the behavior of HVs drivers was more aggressive.

摘要

临界间隙通常用于确定无信号交叉口的通行能力。已经对不受控制的中间开口处的 U 形转弯临界间隙的估计进行了一些研究。在这项研究中，使用四种众所周知的方法计算临界间隙，即最大似然法 (MLM)、Ashworth's、Raff 和不同类型 U 型转弯车辆在伊朗四个不受控制的中间开口处的接受曲线。使用视频记录收集数据。结果表明，根据伊朗国情，MLM是计算临界差距的最佳方法。根据这种方法，平均临界差距为3.23秒，与其他国家相比，这是非常低的。此外，传销的结果表明，重型车辆（HV）驾驶员的临界差距几乎小于汽车驾驶员，