Vehicle blind zones and pedestrian safety at intersections: identifying high-risk scenarios using mathematical simulations.

Objective: This study presents a novel simulation-based methodology to systematically assess how vehicle blind zones, intersection geometry, and the speed and direction of both vehicles and pedestrians interact to influence pedestrian visibility at intersections. Focusing on a diverse set of vehicle designs and intersection scenarios, the framework identifies high-risk situations where blind zones may critically impair a driver's ability to detect and respond to crossing pedestrians.

Methods: Blind zone data from 20 vehicles representing a range of classes were used. A custom simulation code modeled interactions between crossing pedestrians and vehicle blind zones in four intersection geometries: baseline, narrow lane, wide lane, and offset crosswalk. For each geometry, vehicle speed (4.2 m/s or 15 km/h, 5.6 m/s or 20 km/h, 6.9 m/s or 25 km/h), vehicle trajectory (straight, left, right), and turning trajectory (sharp, average, wide) were simulated. Crossing pedestrians were modeled for two travel directions (from the driver-side and passenger-side A-pillar) at three speeds (0.8, 1.2, 1.8 m/s). Output metrics included time the pedestrian spends in the blind zone, percentage of crossing time in the blind zone, and available driver reaction time once the pedestrian is visible to the driver.

Results: Vehicle blind zone areas ranged from 242 to 478 m². Pedestrians were predominantly obscured during left-turn maneuvers, especially when approaching from the driver-side A-pillar, resulting in an average time in the blind zone of 1.7 s compared with 0.8 s for passenger-side approaches. Lower vehicle speeds combined with fast pedestrian speeds further increased this duration, while higher speeds reduced the available driver reaction time. Intersection geometry and turning radius also affected these metrics. Regression analyses indicated that although blind zone area did not predict total obscuration time, it was significantly associated with delayed pedestrian entry/exit and longer available driver reaction time.

Conclusions: This study used a novel simulation methodology to demonstrate that vehicle blind zones can critically affect pedestrian visibility, particularly in left-turn scenarios involving driver-side pedestrian approaches. While blind zone area is an important metric, finer design features (e.g., A-pillar dimensions) and dynamic factors such as vehicle speed, turning behavior, and intersection layout play a crucial role in determining pedestrian visibility.