AN EXPERIMENTAL EXAMINATION OF SELECTED MANEUVERS THAT MAY INDUCE ON-ROAD UNTRIPPED, LIGHT VEHICLE ROLLOVER - PHASE II OF NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION'S (NHTSA'S) 1997-1998 VEHICLE ROLLOVER RESEARCH PROGRAM

This report documents the results of testing potential maneuvers to measure on-road, untripped, rollover propensity. Twelve test vehicles, covering a wide range of vehicle types and classes were used. Three vehicles from each of the following categories were tested: passenger cars, light trucks, vans, and sport utility vehicles. The vehicles were tested with candidate vehicle characterization and untripped rollover propensity maneuvers. The vehicle characterization maneuvers were designed to determine fundamental vehicle handling properties while the untripped rollover propensity maneuvers were designed to produce two-wheel lift for vehicles with relatively higher rollover propensity potential. The vehicle characterization maneuvers were Pulse Steer, Sinusoidal Sweep Slowly Increasing Steer, and Slowly Increasing Speed. The rollover propensity maneuvers were J-Turn, J-Turn with Pulse Braking, Fishhook #1 and #2, and Resonant Steer. The degree of lift produced for each vehicle/maneuver/steer direction scores were combined to produce two ratings: Steering Maneuver Score and Pulse Braking Score. The Steering Maneuver Score was based on J-Turn, Fishhook #1, and Fishhook #2 results and the Pulse Braking Score was based on J-Turn with Pulse Braking Results. The Steering Maneuver Scores were found to be related to the vehicle static and dynamic rollover stability metrics. The Pulse Braking Score was related more to whether or not the vehicle had 4-wheel anti-lock brakes (4WAL) or not. For those vehicles that did not have 4WAL, the Pulse Braking score did relate to static and dynamic rollover stability metrics. The Lateral Acceleration at Rollover was also determined for each vehicle and was not found to be related to either the static or dynamic rollover stability metrics.