Effectiveness of Stability Control Systems for Truck Tractors

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Effectiveness of Stability Control Systems for Truck Tractors

J. S. Wang

This Research Note describes the process of deriving the effectiveness rates of electronic stability control systems (ESC) and roll stability control systems (RSC) in truck tractors that are used by the National Highway Traffic Safety Administration to estimate the benefits of these systems. ESC and RSC are two types of stability control systems that have been developed for heavy vehicles. RSC is designed to mitigate on-road, untripped truck rollovers by automatically decelerating the vehicle by applying the foundation brakes and reducing engine torque output. ESC includes the RSC function described previously but it has added capability that allows it to also mitigate severe oversteer or understeer conditions that can lead to vehicle loss-of-control (LOC), by automatically applying selective brakes to generate a yawing moment that helps the driver maintain directional control of the vehicle. Thus, ESC is designed to mitigate both untripped rollover and LOC crashes. Therefore, the definition of ESC for heavy trucks is different from that specified in Federal Motor Vehicle Safety Standard No. 126 (FMVSS No. 126) for light vehicles with a gross vehicle weight rating (GVWR) of 10,000 pounds or less. For simplicity, hereafter, rollovers represent first event on-road, untripped rollovers.