Abstract

On a rural road with large deviations in vertical road surface, a fatal traffic incident took place. Tire marks found on the scene of the incident indicated a high velocity for the involved passenger car. To research the influence of the road profile on the dynamic vehicle behavior, driving tests with a similar vehicle were performed. Because of the safety risks involved at higher speeds, the testing speed was limited. In order to acquire knowledge about the behavior at higher speeds, the road profile was measured using only a vertical accelerometer attached on a unloaded trailer. The acceleration signal was processed into a displacement signal which was used as input for a road holding simulator (four poster) on which the replacement vehicle was tested. Comparison between road tests and four poster simulations led to a validation of the method. This allowed for simulating higher speeds on the four poster to acquire knowledge about the vehicle's behavior in its natural frequency or worst case scenario. The four poster testing allowed for analyzing the tire normal forces which proved insufficient at certain moments to allow for safe road holding at higher speeds than the road was intended for. All in all. this research method and its results gave sufficient grounds for further testing and research, which in term confirmed the fact that the cause of the accident was likely a too high vehicle speed.