Federal Motor Vehicle Safety Standards; Air Brake Systems

On July 27, 2009, NHTSA published a final rule that amended the Federal motor vehicle safety standard for air brake systems by requiring substantial improvements in stopping distance performance on new truck tractors. In response, the agency received eight petitions for reconsideration. The agency has already responded to most of the issues raised in the petitions. This document responds to the one outstanding issue raised in the petitions, stopping distance performance requirements at lower initial speeds. Based on testing results and our concern that the current requirements might not be practicable, NHTSA is slightly relaxing the stopping distance requirement for typical loaded tractors tested from an initial speed of 20 mph by increasing the distance from 30 feet to 32 feet and for unloaded tractors tested from an initial speed of 20 mph by increasing the distance from 28 feet to 30 feet. We believe no other changes are necessary.