Improving road safety is hugely important with the number of deaths on the world's roads remaining unacceptably high; an estimated 1.35 million people die each year as a result of road traffic collisions (WHO, 2020). Current practice for treating collision hotspots is almost always reactive: once a threshold level of collisions has been overtopped during some pre-determined observation period, treatment is applied (e.g. road safety cameras). Traffic collisions are rare, so prolonged observation periods are necessary. However, traffic conflicts are more frequent and are a margin of the social cost; hence, traffic conflict before/after studies can be conducted over shorter time periods. We investigate the effect of implementing the leading pedestrian interval (LPI) treatment (Van Houten et al. 2000) at signalised intersections as a safety intervention in a city in north America. Pedestrian-vehicle traffic conflict data were collected from treatment and control sites during the before and after periods. We implement a before/after study on post-encroachment times (PETs) where small PET values denote a near-miss. Hence, extreme value theory is employed to model extremes of our PET processes, with adjustments to the usual modelling framework to account for temporal dependence and treatment effects.

翻译：改善道路安全至关重要，全球道路交通事故死亡人数仍高得令人无法接受；据估计，每年约有135万人死于道路交通事故（WHO, 2020）。目前处理事故热点的实践几乎都是被动应对：一旦在某个预定观测期内碰撞事故超过阈值，就会采取相应处理措施（例如安装道路安全摄像头）。交通碰撞事故较为罕见，因此需要较长的观测周期。然而，交通冲突更为频繁，且是社会成本的边际因素；因此，交通冲突的前后对比研究可以在较短时间内完成。我们研究了在北美洲某城市信号交叉口实施行人提前放行间隔（LPI）处理措施（Van Houten等，2000）作为安全干预的效果。在干预前和干预后阶段，从处理地点和对照地点收集了行人-车辆交通冲突数据。我们对侵入后时间（PET）进行了前后对比研究，其中较小的PET值表示近碰撞事件。为此，我们采用极值理论对PET过程的极值进行建模，并对常规建模框架进行了调整，以考虑时间依赖性和处理效应。