49 CFR Part 571 136 This proposes to establish a new Federal Motor Vehicle Safety Standard No. 136 to require electronic stability control (ESC) systems on truck tractors and certain buses with a gross vehicle weight rating of greater than 11,793 kilograms (26,000 pounds). ESC systems in truck tractors and large buses are designed to reduce untripped rollovers and mitigate severe understeer or oversteer conditions that lead to loss of control by using automatic computer-controlled braking and reducing engine torque output. In 2012, we expect that about 26 percent of new truck tractors and 80 percent of new buses affected by this proposed rule will be equipped with ESC systems. We believe that ESC systems could prevent 40 to 56 percent of untripped rollover crashes and 14 percent of loss-of-control crashes. By requiring that ESC systems be installed on truck tractors and large buses, this proposal would prevent 1,807 to 2,329 crashes, 649 to 858 injuries, and 49 to 60 fatalities at less than $3 million per equivalent life saved, while generating positive net benefits.