The rate of deceleration experienced by a vehicle in an emergency stop has a significant bearing in whether a crash will occur or not. Skid marks, scuff marks and yaw marks found on the road after a collision or near miss are all indicative of high-deceleration events. Skid-to-stop tests are often conducted by the Police at the collision or incident scene to quantify the tire-to-road deceleration rate. If the tire-to-road coefficient of friction can be quantified, estimates of speed can be made using conventional Newtonian-based speed formulae. Fundamentally, road design standards are derived based on projected rates of deceleration in a hazard-avoidance scenario, with effects on stopping sight distance calculations and other geometric considerations. At present, design equations are highly conservative and do not account for the performance of modern ABS (Automatic Braking Systems) or other ADAS (Advanced Driver Assistance Systems) which may operate in an emergency stop.Published and independent controlled emergency braking test results have been distilled in this study to determine a representative range of deceleration rates experienced by the vehicle fleet. A total of 1,187 tests have been evaluated. The results identify various vehicle characteristics which will influence the rate of deceleration (drag factor) achieved in an emergency stopping event and demonstrate the evolution (improvement) of ABS-performance over time.
Allied Forensic Group: Tia Gaffney; Delta-V Experts: Blake Winter