Impact analysis of additional ambulance vehicle beacons

Abstract

This work is a preliminary study on behalf of the Bavarian Red Cross (BRK) and examines if and what effect on traffic safety can be measured when BRK ambulance vehicles are equipped with additional beacons on the front fender next to the front lights. Several studies document the high crash risk particular during emergency drives. The BRK endeavors to decrease the crash frequency of their ambulance vehicles by improving their visibility especially at intersections and narrow gateways. Therefore, the additional beacons need to be evaluated, which is the purpose of this study. In order to evaluate the effect of additional beacons, 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 ana lyzed. The use of Surrogate Safety measures appeared to be not practicable to obtain statistica l significant results due to few interacting trajectories and no critical situations. Instead in dicators like maximum deceleration, position and time of braking and reaching walking speed etc. of single trajectories were used. 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 beacons. Furthermore, road users on average braked 3.5 m earlier, less intensely and reached walking speed 4 m earlier when ambulance vehicles were equipped with additional beacons. A follow-up study will examine video material of longer time frames and different locations to enlarge the samples size and thus to gain more significant results. Particular attention will be paid to urban intersections, which are the most critical spots for ambulance vehicles. Moreover, the use of Surrogate Safety Measures will be examined.