Assessment of the safety benefits of HUD warning under high-risk pedestrian crossing event in the connected environment.

The head-up display (HUD) warning system in a connected environment is expected to improve driving behavior and enhance pedestrian crossing safety. While existing research has preliminarily examined the effectiveness of HUD warning system in avoiding pedestrian collisions, scant attention has been given to the microcosmic influence on driving behavior and a precise quantification of its overall benefits, especially in high-risk pedestrian crossing scenarios. To investigate these influences, this study employed driving simulations to construct six connected scenarios: three warning systems (Baseline/head-down display(HDD)/HUD) × two weather conditions (clear weather/foggy weather). Data on the driving behavior of 34 drivers across these scenarios were collected. The whole spatial change process of driving behavior in pedestrian crossing events is described from the microscopic level, and the influence law of warning system and weather conditions on reaction, acceleration and deceleration behavior is analyzed. A comprehensive index system reflecting the safety level of the risk-avoidance stage, the recovery level of the recovery stage and the stability level of the overall stage was constructed to explore impact characteristics and utilities of the three warning systems under different weather conditions. The study found that the speed space variations under HDD and HUD conditions were more gentle compared to Baseline conditions, especially in the HUD group, but there were differences in individual adherence to HDD and HUD systems. The results of two-way repeated measures ANOVA and fuzzy comprehensive evaluation indicated that compared to the Baseline and HDD, the HUD warning system improves the safety level and stability level under clear and foggy weather conditions, but does not have a significant advantage in the recovery level. Specifically, the HUD system enables drivers to react earlier, complete risk avoidance earlier, execute smoother acceleration and deceleration maneuvers, and maintain more stable lateral control. Overall, the HUD warning system helps drivers achieve optimal driving performance in a connected environment, even in more hazardous foggy conditions. The research results can provide support for relevant departments to evaluate and improve HUD system in a targeted manner.