AN EXPERIMENTAL EXAMINATION OF SELECTED MANEUVERS THAT MAY INDUCE ON-ROAD, UNTRIPPED LIGHT VEHICLE ROLLOVER: PHASE I-A OF NHTSA'S 1997-1998 VEHICLE ROLLOVER RESEARCH PROGRAM

Abstract

This report documents the results of Phase I-A testing for the National Highway Traffic Safety Administration's (NHTSA's) 1997-1998 Light Vehicle Rollover Research program. This phase was an initial, exploratory study of using test track maneuvers to quantify on-road, untripped rollover propensity. This study examined a broad range of maneuvers that might induce on-road, untripped rollover including: J-Turn, J-Turn With Pulse Braking, Brake and Steer, Steering Reversal, Toyota Fishhook, Double Lane Change, Split-Mu Two Wheels Off-Road Recovery Simulation, and Toyota Fishhook With Pulse Braking. Three vehicles were selected for the Phase I-A testing. The vehicles selected were a 1984 Ford Bronco II, a 1997 Jeep Cherokee, and a 1990 Toyota 4Runner. These test vehicles were not in new condition. None of the test vehicles necessarily performed as would new vehicles without outriggers. However, this was not important for the Phase I-A research. The goal of the Phase I-A research was maneuver selection and test procedure development, not vehicle characterization. After the analysis was complete, it was decided that the following maneuvers should be evaluated further as part of NHTSA's rollover research: J-Turn, J-Turn With Pulse Braking, Toyota Fishhook, and Toyota Fishhook With Pulse Braking. The Brake and Steer maneuver did not produce two-wheel lift for the vehicles. The Steering Reversal procedure has many potential steering profiles and was replaced by the steering reversal profile specified in the Toyota Fishhook procedure. The Double Lane Change and Split-Mu Two Wheels Off-Road Recovery Simulation maneuvers had the potential for greater driver variability, had steering reversal type inputs found in more repeatable maneuvers, and produced two-wheel lifts less frequently than did the Toyota Fishhook maneuver.