Post impact trajectory of vehicles at rural intersections

Abstract

This report describes the path of vehicles after a collision with another vehicle at a rural intersection. The information was obtained from in-depth investigations of 70 intersection crashes. For ease of analysis, both rear end crashes and collisions involving vulnerable road users were excluded; heavy vehicles were included. The vehicle that had right of way most commonly had an impact speed of between 80 and 99 km/h and the impact point was on the front of the vehicle. The vehicle that was required to give way most commonly had an impact speed of between zero and 20 km/h and was struck between the front of the vehicle and the B-pillar. After the vehicle-to-vehicle impact, half the vehicles travelled more than 18 metres, 20% more than 34 metres and 10% more than 50 metres from the centre of the intersection. The most common direction of the vehicle following the initial impact was found to be between 15 and 30 degrees, from the original direction of travel of the through vehicle. Intersection geometry, speed zone, impact point and mass ratio influence the nature of the post impact trajectory. The results show that many vehicles travel a large distance at a shallow angle following an intersection collision, so extending a barrier on the through road (the road with right of way) up to the intersection may have some benefit. Clear zones surrounding the intersection would aid in creating a safe system providing they are of adequate size. Removing hazards around an intersection would have the added benefit of increasing site distance.