Balancing comfort and efficiency: Optimal deceleration rates at crosswalks and intersections in automated driving

• Test track study with a real automated vehicle (AV) explored the impact of deceleration rates and traffic conditions on passenger comfort in crosswalks and intersection scenarios. • Deceleration rates of −1.5 m/s 2 to −2.5 m/s 2 enhanced comfort and perceived safety. • Harsher deceleration (−3.5 m/s 2 ) was acceptable when pedestrians appeared suddenly at the crosswalk. • At intersections, comfort was unaffected by approaching vehicles at lower deceleration rates. • Findings support adaptive deceleration strategies for balancing safety, comfort, and efficiency. Understanding passenger comfort in automated vehicles (AVs) is critical for advancing highly automated driving systems. This test track study was conducted with 41 participants who are accustomed to European driving norms. It examined how deceleration rates and environmental factors influence passenger perceptions in two scenarios: crosswalks and blind intersections. The participants were driven by a real AV, which braked using deceleration rates of −1.5 m/s 2 , −2.5 m/s 2 , and −3.5 m/s 2 . Additionally, the visibility time of an approaching pedestrian was manipulated in the crosswalk scenario, while the presence or absence of an approaching vehicle was varied in the intersection scenario. The results show that passengers generally prefer lower to medium deceleration (−1.5 m/s 2 , −2.5 m/s 2 ) rates but accept higher rates (−3.5 m/s 2 ) when a pedestrian becomes visible more unexpectedly. In the intersection scenario, comfort ratings were less influenced by the presence of an approaching vehicle than by the deceleration rate, with lower and medium deceleration rates being favoured. These findings are valuable for the development of AVs. The study suggests that tailoring AV deceleration to specific traffic scenarios can improve passenger comfort. It can help AV developers to define driving styles that passengers perceive as comfortable and safe, without compromising efficiency.