Truck Braking requirement increased to .48 from 0.33

[brian]

The new NHTSA FMVSS standard requires that a fully loaded tractor-trailer traveling at 60 miles per hour come to a complete stop in 250 feet. This will require an average braking drag of 0.48. The old standard required a complete stop within 355 feet (which was an average drag of 0.33).
The new regulation will be phased in over four years beginning with 2012 models. The new rule should speed up the introduction of the latest brake technology into America’s freight hauling fleets and will help truck drivers avoid collisions with other vehicles.
The new rule applies only to truck tractors, and does not include single-unit trucks, trailers and buses.
49 CFR Part 571, Docket No. NHTSA–2009-0083, RIN: 2127-AJ37, Federal Motor Vehicle Safety Standards; Air Brake Systems:

• "...the amended standard requires those vehicles to stop in not more than 250 feet when loaded to their gross vehicle weight rating (GVWR) and tested at a speed of 60 miles per hour (mph). For a small number of very heavy severe service tractors, the stopping distance requirement will be 310 feet under these same conditions. In addition, this final rule requires that all heavy truck tractors must stop within 235 feet when loaded to their “lightly loaded vehicle weight” (LLVW).

See the final rule