Abstract
Anti-lock brake systems (ABS) have become common on most passenger cars and light trucks in North America yet ABS braking performance can vary widely between vehicle makes and on different road surfaces. The present ABS designs restrict wheel lockup which may be inefficient for gravel and snow covered roads where locked wheels can produce much higher deceleration rates. Based on the growing number of public complaints of poor braking on gravel roads, tests were conducted to determine the performance variation between vehicles with different ABS controllers and between the same vehicle with and without its ABS activated. Significant deceleration differences were noted.