Department of Mechanics and Maritime Sciences, Chalmers University of Technology, Göteborg, Sweden.
Department of Industrial and Materials Science, Chalmers University of Technology, Göteborg, Sweden.
Traffic Inj Prev. 2022;23(7):428-433. doi: 10.1080/15389588.2022.2103120. Epub 2022 Jul 28.
Crashes between cars and cyclists at urban intersections are common, and their consequences are often severe. Typical causes for this type of crashes included the excessive speed of the cyclist as well as car drivers failing to see the cyclist. Measures that decrease the cyclists' speed may lead to safer car-cyclist interactions. This study aimed to investigate the extent to which cyclists may approach intersections at a lower speed when nudged to do so.
Visual flat-stripe nudges were placed on bicycle lanes in the proximity of uncontrolled intersections (with a history of car-cyclist crashes) in two locations in Gothenburg, Sweden. This specific nudge was the one obtaining the best results from a previous study that tested different nudges in controlled experiments. Video data from the intersections were recorded with a site-based video recording system both before (baseline), and after (treatment), the nudge was installed. The video data was processed to extract trajectory and speed for cyclists. The baseline and treatment periods were equivalent in terms of day of the week, light, and weather conditions. Furthermore, two treatment periods were recorded to capture the effect of the nudge over time in one of the locations.
Leisure cyclists showed lower speeds in treatment than in baseline for both locations. Commuters were less affected by the nudge than leisure cyclists. This study shows that visual nudges to decrease cyclist speed at intersections are hard to evaluate in the wild because of the many confounders. We also found that the effect of visual nudges may be smaller than the effect of environmental factors such as wind and demographics, making their evaluation even harder.
The observed effect of speed might not be very high, but the advantage both in terms of cyclist acceptance and monetary cost makes an investment in the measure very low risk. This study informs policymakers and road authorities that want to promote countermeasures to intersection crashes and improve the safety of cyclists at urban intersections.
汽车与自行车在城市交叉口相撞的事故很常见，其后果往往很严重。此类事故的典型原因包括自行车骑行者速度过快以及驾驶员未能看到自行车骑行者。降低自行车骑行者速度的措施可能会导致汽车与自行车骑行者之间的交互更安全。本研究旨在调查在何种程度上，当被引导这样做时，自行车骑行者可能会以较低的速度接近交叉口。
在瑞典哥德堡的两个地点，在无控制的交叉口（有汽车与自行车碰撞事故史）附近的自行车道上放置了视觉平条纹提示物。这种特定的提示物是之前在受控实验中测试不同提示物时获得最佳效果的提示物。使用基于现场的视频记录系统在交叉口记录视频数据，在安装提示物之前（基线）和之后（处理）进行记录。视频数据经过处理，提取自行车骑行者的轨迹和速度。从星期几、光线和天气条件来看，基线和处理期是等效的。此外，在其中一个地点记录了两个处理期，以捕捉提示物在一段时间内的效果。
休闲自行车骑行者在两个地点的处理期的速度均低于基线。与休闲自行车骑行者相比，通勤者受提示物的影响较小。本研究表明，在野外很难评估视觉提示物降低交叉口自行车骑行者速度的效果，因为存在许多混杂因素。我们还发现，视觉提示物的效果可能比环境因素（如风和人口统计学）的效果小，这使得它们的评估更加困难。
观察到的速度影响可能不是很高，但从自行车骑行者接受度和货币成本的角度来看，这种措施的投资风险非常低。本研究为希望促进交叉口碰撞对策并提高城市交叉口自行车骑行者安全性的政策制定者和道路管理部门提供了信息。
