Surrogate safety measures have been recognised as suitable tools for a warning strategy. As one such measure, the time to collision (TTC) is the time remaining to a collision if the collision course and speed remain unaltered. To apply the TTC in discriminating dangerous situations, a critical threshold (TTC*) must be determined. However, a method for calculating this threshold is yet to be presented. Previously, the critical threshold has been considered as a constant value, but the value of TTC* changes the calculated probability for a crash at each time instant. In this work, a method was developed for calculating TTC* based on driver characteristics, environmental conditions, the type of preceding object and the microscopic traffic parameters of the subject vehicle based on an adaptive neuro fuzzy inference system and motion mechanics. For this purpose, data were first collected from a driving simulator. Then, to compare the collision probability calculated based on a dynamic TTC* (DTTC*) and a static TTC* (STTC*), microscopic traffic data were obtained from Modares highway in Tehran, Iran. Assessments indicated that, statistically, there is a significant difference between DTTC* and STTC* results. This finding might help to enhance the capability of in-vehicle collision-avoidance systems to prevent rear-end collisions.

中文翻译：

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计算临界碰撞时间的动态阈值作为安全措施

替代安全措施已被认为是预警策略的合适工具。作为此类衡量标准之一，碰撞时间 (TTC) 是碰撞过程和速度保持不变时碰撞的剩余时间。要将 TTC 应用于辨别危险情况，必须确定临界阈值 (TTC*)。然而，尚未提出计算该阈值的方法。以前，临界阈值被认为是一个常数值，但 TTC* 的值会改变计算的每个时间点的碰撞概率。在这项工作中，基于自适应神经模糊推理系统和运动力学，开发了一种基于驾驶员特征、环境条件、前方物体的类型和主体车辆的微观交通参数来计算 TTC* 的方法。为此，首先从驾驶模拟器收集数据。然后，为了比较基于动态 TTC* (DTTC*) 和静态 TTC* (STTC*) 计算的碰撞概率，从伊朗德黑兰的 Modares 高速公路获得了微观交通数据。评估表明，从统计上看，DTTC* 和 STTC* 结果之间存在显着差异。这一发现可能有助于增强车载防撞系统防止追尾碰撞的能力。