New Delhi, India.
Traffic Inj Prev. 2021;22(4):330-335. doi: 10.1080/15389588.2021.1908544. Epub 2021 Apr 13.
The S-shaped function of probability of pedestrian fatality with respect to impact speed of vehicle is well known in road safety literature. However, the implication of this evidence for changes in speed for a population of drivers has not been explored.
An integrated model has been developed to estimate pedestrian fatalities resulting from changes in speed of traffic. The model uses combined relative risks of injury crash rate of drivers and probability of pedestrian fatality resulting from an injury crash. Two approaches have been used-an individual approach using probability distribution of speed, and an aggregate approach, using only mean speed. The application of the model has been demonstrated using four case studies with speed of traffic before and after an intervention.
It is found that even small reductions in mean speed translate to large reductions in pedestrian fatalities. The risk contributed by speeding vehicles is highly disproportionate to their share in vehicle population. In a case study from Delhi (India), in which at-grade junction was replaced with a grade-separated junction, 74% of risk of pedestrian fatalities is contributed by less than 5% speeding vehicles (>50km/h). Changes in mean speed is a poor indicator of changes in injury risk if the standard deviation of the distribution also changes significantly. A surprising finding was that large variation in the S-shape of pedestrian fatality risk function has relatively small effects on overall results.
A new model has been developed to estimate changes in pedestrian fatalities resulting from changes in traffic speed. The application of the model using four speed-related interventions emphasize that deterrence of a small proportion of drivers using speed enforcement can have large implications for pedestrian safety.
道路安全文献中已知，车辆碰撞速度的行人死亡率概率呈 S 形函数关系。然而，这种证据对驾驶员群体速度变化的含义尚未得到探讨。
已经开发了一种综合模型来估计交通速度变化导致的行人死亡。该模型使用驾驶员受伤事故发生率的相对风险和受伤事故导致的行人死亡率的概率来进行估算。使用了两种方法——一种是使用速度概率分布的个体方法，另一种是仅使用平均速度的综合方法。使用四个案例研究来演示模型的应用，这些案例研究涉及干预前后的交通速度。
结果发现，即使平均速度略有降低，也会导致行人死亡率大幅降低。超速车辆造成的风险与其在车辆总数中的份额极不成比例。在印度德里的一个案例研究中，平交道口被立交取代，74%的行人死亡风险是由不到 5%的超速车辆（>50km/h）造成的。如果分布的标准差也发生显著变化，那么平均速度的变化是受伤风险变化的不良指标。一个令人惊讶的发现是，行人死亡率风险函数的 S 形变化较大对总体结果的影响相对较小。
已经开发了一种新的模型来估计交通速度变化导致的行人死亡变化。使用四个与速度相关的干预措施来应用该模型，强调使用速度执法来遏制一小部分超速驾驶员可以对行人安全产生重大影响。
