Department of Civil Engineering, National Institute of Technology Silchar, Silchar, India.
Traffic Inj Prev. 2024;25(2):219-227. doi: 10.1080/15389588.2023.2289343. Epub 2024 Jan 2.
The vehicular traffic in the cities is becoming more complex in developing countries like India due to the rising population and rapid urbanization. With the annually increasing road accidents, a study on the effective safety assessment of heterogeneous traffic conditions is needed. The study aims to evaluate the safety of heterogeneous traffic by spotting the critical conflicts with respect to the speed of the involved vehicles.
The current study proposed Critical Following Speed instead of using a single threshold value for safety assessment in mixed traffic. Critical Following Speed was proposed by comparing the stopping and the available distances between the involved vehicles and used to identify the critical conflicts. With this, the study uses the speeds of both the leading and the following vehicles to judge the nature of the conflict. Three unsignalized four-legged intersections (S-1, S-2, and S-3) and two straight road sections (S-4 and S-5) were selected as the study area in Trichy, India. Post Encroachment Time (PET) and Time to Collison (TTC) were used as surrogate indicators to assess the crossing or merging and rear-end conflicts, respectively.
The average PET and TTC values were between 1.25 and 1.73 s in the study locations. The overall percentage of critical conflicts indicated the non-safer crossing and merging maneuvers in three locations. The other two locations were experiencing safe rear-end conflicts, as the percentages of critical conflicts were below 4%. Various combinations of leading and following vehicle types were examined for the contribution of critical conflicts. The proposed methodology was validated with the 4-year accident data and a good relation was obtained.
Fast-moving vehicles were responsible for the less safe maneuvers with a higher collision probability in all the study locations. The correlation between critical conflicts and road accidents shows the effectiveness of the proposed approach in the traffic safety assessments for mixed traffic. This approach could be employed even in countries with homogenous traffic conditions instead of using a single threshold value. The correlations also show the potential of the proposed Critical Following Speed as a surrogate safety indicator for safety evaluation in the future.
在印度等发展中国家，由于人口增长和快速城市化，城市中的交通变得更加复杂。由于道路事故逐年增加，因此需要对异质交通条件的有效安全评估进行研究。本研究旨在通过识别与所涉及车辆速度有关的关键冲突来评估异质交通的安全性。
本研究提出了关键跟驰速度，而不是在混合交通中使用单一阈值进行安全评估。通过比较所涉及车辆的停车和可用距离来提出关键跟驰速度，并将其用于识别关键冲突。通过这种方式，该研究使用领先车辆和跟随车辆的速度来判断冲突的性质。选择印度蒂鲁吉的三个无信号四路交叉口（S-1、S-2 和 S-3）和两个直线路段（S-4 和 S-5）作为研究区域。侵占时间（PET）和碰撞时间（TTC）分别用作评估交叉或合并和追尾冲突的替代指标。
在研究地点，平均 PET 和 TTC 值在 1.25 到 1.73 秒之间。在三个位置，关键冲突的总体百分比表明交叉和合并操作不安全。另外两个位置的追尾冲突是安全的，因为关键冲突的百分比低于 4%。检查了各种领先和跟随车辆类型的组合，以确定关键冲突的贡献。该方法已通过 4 年的事故数据进行了验证，结果表明两者之间存在良好的关系。
在所有研究地点，快速行驶的车辆都导致了不太安全的操作，碰撞概率更高。关键冲突与道路事故之间的相关性表明了该方法在混合交通安全评估中的有效性。即使在交通条件均匀的国家，也可以采用这种方法，而不是使用单一阈值。相关性还表明，所提出的关键跟驰速度作为未来安全评估的替代安全指标具有潜力。
