Publication

This study aims at providing basic understanding of driver responses to headlight and sound warning coming from another vehicle, in a critical situation. A possible application is the implementation of systems for automatic activation of the warnings. A simulator study of a critical frontal collision situation was conducted in order to examine usefulness of four different warning modalities (light, sound, sound and light, no warning) from a principal other vehicle (POV). The posted speed was 70 km/h and the critical situation was created using a secondary task and simultaneously turning the vehicle towards the oncoming POV. In total, 48 participants drove 30 km while performing the secondary task, announced by a vibration in the seat, and experiencing light and/or sound warnings from oncoming traffic. The behavioural results of the simulator study indicate tendencies that the warning provides an increased safety by making the driver respond, in a proper manner, to the dangerous situation. Some of the indications for this were faster response time in the critical situation, shorter glance time away from the road and degraded performance in the secondary task. The combined warning, where both the horn and headlight is used, had a larger effect than the light or sound warnings alone. The participants are generally positive towards the warning and the warning modalities; 65% are positive towards auditory warning, 75% towards visual warning and 85% towards the combination warning of sound and light. Considering automatic activation of the warnings; the current scenario represent a situation which is at the limit of what available sensing system is capable of i.e. a warning is issued 2,8 second before collision, which yields a distance of ~110 meters at 140 km/h relative velocity.