The accuracy and timing of pedestrian warnings at intersections: the acceptance from drivers and their preferences

The safety of vulnerable road users at traffic intersections is critical. Driver assistance systems can improve safety but have to rely on accurate detection of hazardous situations. Given the complexity of pedestrian movement, detection of pedestrian presence and prediction of their behaviour are not always without error. Drivers' attitude towards such errors is an important issue for the effectiveness of the system. An online questionnaire survey has been carried out to investigate drivers' acceptance of the system under different reliability and accuracy configurations. The results show that safety warnings of pedestrians are generally found to be useful, although false positives and false negatives tend to reduce its pleasantness. The system is found to be most useful for right turn movement at a busy intersection, compared to through movements and quiet intersections. Drivers also find false alarms more acceptable than false negatives. In terms of timing of the warning message, drivers prefer to receive it earlier rather than later.