LAUSR

Abstract Objective In-vehicle traffic lights have been demonstrated as an effective method to assist drivers in crossing unsignalized intersections, by displaying virtual traffic lights inside vehicles based on vehicle-to-vehicle communications. However, previous studies assumed that all the vehicles were equipped with vehicular communications, of which the deployment might last for decades. Therefore, it is necessary to consider the application of the system in partial deployment scenarios. This study aimed to analyze the influences of in-vehicle traffic light system on driving safety at unsignalized intersections within different penetration rates. Methods Driving simulator experiments involving 18 participants were performed. Evaluation indexes including post-encroachment time, maximum acceleration stroke of ego vehicle, and times of near miss incidents were investigated for different penetration rates of vehicular communications. Results Significant differences were observed between the conditions when no in-vehicle traffic light was used and when the penetration rate was 100% for the post-encroachment time (p = 0.02), and the maximum acceleration stroke of ego vehicle (p = 0.05). Meanwhile, it was found that the post-encroachment time slightly decreased, and the times of near miss incidents slightly increased when the penetration rate increased from 0% to 50%. However, the post-encroachment time was still longer for different penetration rates, compared to the condition when no in-vehicle traffic light was applied. Conclusions The results indicated that the in-vehicle traffic light system could significantly improve driving safety at unsignalized intersections when the penetration rate was 100%. For partial deployment conditions, it is essential to speed up the deployment of vehicular communication-based driver assistance systems within early deployment stage, especially when the penetration rate was within 50%, to ensure driving safety.