INVESTIGATING SURFACE CHARACTERISTICS FOR ACCIDENTS INVOLVING EMERGENCY BRAKING

When crashes involve emergency braking it is most important to determine the surface characteristics and the appropriate drag factor for the involved vehicle(s). Often little attention is paid to all the variables which effect vehicle/surface interaction. Those variables include microtexture, macrotexture, water film depth, vehicle mass, and vehicle speed at braking. This paper mentions some results of an Australian study into the effects of vehicle mass and loading on emergency braking stopping distance. Information from a study of the relationship between vehicle speed and onset of aquaplaning is also presented. It was found that wet surfaces and loaded vehicles could increase emergency stopping distances by up to 40 percent for the same vehicle. The difference in emergency braking capacity for vehicles of different mass and loading was also found to be very significant with about 30 percent variation between large and small sedans. (a) For the covering entry of this conference, please see IRRD abstract no. 878344.