Post-Collision Run-Out Vehicle Deceleration Based on Real-World Data

In traffic accidents, the run-out is the phase after impact until reaching a final rest position. Analyzing and reconstructing this phase is a task leading sometimes to a broad bandwidth of results. This can be due to the unknown driver’s reaction and braking behavior. The well-known literature describes rollout decelerations, but these exclude the influence of the driver, particularly with regard to accident situations. Measurement data from real-world collisions can help quantifying the vehicle’s deceleration during the run-out and thus at least partially close the existing research gap. Therefore, this study deals with the systematic evaluation of real-world measurement data from intersection collisions collected by accident data recorders. The high-frequency acceleration and speed data of 45 accident vehicles with impact velocities up to 70 kph were processed for this purpose; characteristic values for the run-out phase were calculated in each case and then statistically evaluated. Results in terms of mean deceleration rates are presented as well as conclusions about driver’s post-collision behavior. On the one hand, the data reveal that it is extremely unlikely that a vehicle will not be actively braked by the driver during run-out and, on the other hand, that braking with maximum deceleration is also unlikely. The results indicate a mean resultant run-out deceleration with respect to time of 4.5 m/s² and with respect to distance of 4.1 m/s². This means more intensive braking by human drivers after a collision than typical deceleration in normal everyday driving activities and is comparable to intervention of advanced driver-assistance systems. These findings can assist the reconstructionist analyzing intersection accidents in quantifying or narrowing down the level of deceleration of a vehicle in run-out and for this reason the driver’s post-collision behavior.