DOT Prepares to Issue New Rule to Cut Truck Stopping Distance

The Department of Transportation is preparing to issue its long-delayed rule that would slice the stopping distance for large trucks by as much as 30%.

DOT’s National Highway Traffic Safety Administration on June 10 sent its proposed rule to the White House for review by the Office of Management and Budget, setting the stage for publication later this year and likely implementation in 2011.

The stopping-distance rule, which has been in the works for several years, is expected to require Class 8 trucks traveling 60 mph to stop within 249 to 284 feet. Trucks now are required to stop within 355 feet.

NHTSA issued its proposed rule in December 2005 after several years of study, but publication was postponed several times during the Bush administration.

Aaron Schwass, director of foundation brakes for Bendix Spicer Foundation Brake, said moving the rule to OMB was “a positive sign . . . I think the Obama administration sees stopping distance as something that’s needed.”

Schwass said he expected the rule would become effective in September 2011.

Paul Johnston, senior director of compression and braking products at Meritor Wabco, said one factor contributing to the long delay was fleets’ desire to deal with changing federal emission rules.

Truck engine changes to meet 2007 and 2010 exhaust emissions requirements put “a tremendous burden on the industry, and I think that had something to do with the timing,” Johnston said.

In its 2005 proposal, NHTSA said it would cut the required stopping distance 20% to 30%. Tim Kraus, president and chief operating officer of the Heavy Duty Manufacturers Association, told Transport Topics recently he expected the agency to call for a reduction “in the 25% to 30% range.”

Kraus said his organization’s members, who manufacture brakes and brake parts, are “prepared” to meet the new rule’s requirements.

NHTSA said the proposed new stopping distance could be met using enlarged versions of the S-cam drum brakes now prevalent in the industry.

Jim Tipka, vice president of engineering for American Trucking Associations, said trucks could continue to use drum brakes to meet even the higher end of the scale with “what is essentially the high-mileage package today . . . which is a larger front brake.”

However, Tipka added that in some applications, air disc brakes may be necessary “particularly in short wheelbase situations where tractor stability with a heavy brake imbalance could be put in question.”

Johnston said many trucks that now come with steer-axle brake drums 15 or 15.5 inches in diameter and 4 or 5 inches wide would have to use 16.5-by-5-inch drums.

On the rear, brakes may have to be wider, he said.

The larger drum brakes would add about 90 pounds to a truck’s weight and cost $1,000 to $1,500 more per axle.

One thing brake company officials agreed on was that, for most applications, the proposed rule would not require air disc brakes, which would cost more than larger drum brakes.

Johnston said disc brakes would be less susceptible than drum brakes to “fade,” i.e., the loss of stopping power on repeated heavy applications.

However, Johnston said the proposed rule did not change the current fade-resistance test, and Schwass said, “Drum brakes meet the current requirement.”

Kraus said HDMA’s brake council has “been heavily involved with NHTSA . . . making sure there’s been some thought put into it so that they don’t do something so generic that it unenforceable.”

He warned that even though the agency isn’t expected to move beyond its initial proposal, NHTSA should “look at some of the challenges if they put forward a very aggressive goal which could lead to driving certain technology over another, which is not their place.”

Tipka said he didn’t think NHTSA would change the rule from its earlier proposal enough to require new technology.

“Unless they would make a substantial change to the stopping distance requirement, like making it for 70 mph, I don’t see that happening,” Tipka said. “If they made a change, the rule would have to be further delayed.”

Review by OMB is the final step before a regulation is published in the Federal Register. The White House agency has at least 90 days to review any new regulation or changes to existing regulations.