The Safety Impact of Additional Blue Lights of Rescue Vehicles

Abstract

This work is a preliminary study on behalf of the Bavarian Red Cross (BRK). It examines if and to what effect an impact on traffic safety can be measured when BRK ambulance vehicles are equipped with additional blue lights on the front fender next to the front lights. The high crash risk particular during emergency drives has been reported in numerous studies. The BRK endeavors to decrease the crash frequency of their ambulance vehicles by improving their visibility especially at intersections and narrow gateways. Therefore, additional side flash lights have been proposed. The purpose of this study is to evaluate the effectiveness of these flash lights. In this context, emergency drives conducted with equipped and unequipped ambulance vehicles were compared. More precisely, the exit of a BRK station and the surrounding road segment was observed for 14 days by a video camera, which enables computer-vision aided analysis of the traffic. Within this time frame, 38 traffic situations of unequipped and 13 situations of equipped ambulance vehicles could be observed. The trajectories of interacting road users in these situations were analyzed. The use of Surrogate Safety measures appeared to be not practicable to obtain statistical significant results due to few interacting trajectories and no critical situations. Instead, indicators for the adaption of road users to ambulance cars leaving the station were used, like deceleration, position and time of braking and time of reaching walking speed. The indicators showed, that road users entered the observation area slower encountering equipped ambulance vehicles - probably due to prior braking - than was measured at emergency drives without additional flash lights. Furthermore, road users on average were breaking 3.5 m earlier, less intensely and reached walking speed 4 m earlier when ambulance vehicles were equipped with additional flash lights.