Accuracy and sensitivity of yaw speed analysis to available data 2019-01-0417
Accident reconstructions rarely have complete data with which to determine vehicle speed, and so must bracket the true value with a range. Previous work has shown the effect of friction uncertainty in determining speed from tire marks left by a vehicle in yaw. The goal of the current study was to assess improvements in the accuracy of vehicle speed estimated from yaw marks using progressively more scene and vehicle information. Data for this analysis came from staged S-turn maneuvers that in some cases led to rollover of the SUV test vehicles. Initial speeds were first calculated using the critical curve speed (CCS) formula on the yaw marks from the first portion of the S-maneuver. Then computer simulations were performed with progressively more input data: i) the complete tire marks from the whole S-maneuver, ii) measured vehicle mass, iii) measured suspension stiffness and damping, and iv) measured steering history. Simulations based on the complete tire marks improved the average error compared with the CCS equation. Adding the remaining input data to the simulations did not further improve the accuracy of the reconstructed vehicle speed.
Bradley E. Heinrichs, Janice Lee, Cole Young