In The News

Two-Year Lead Time for New Brake Standard

Truck manufacturers have two years to prepare for tough new braking standards on air-braked heavy-duty tractors.

Starting in August 2011, a typical fully loaded tractor-trailer at 60 miles per hour must be able to stop in 250 feet, 30 percent less than the current standard of 355 feet.

This will require either beefier drum brakes or disc brakes, or a mix of the two, according to the National Highway Traffic Safety Administration, which wrote the rule.

The agency estimates that it will cost $211 per three-axle tractor to heavy-up the standard S-cam drum brake so it can meet the requirement. Disc brakes would be considerably more expensive: $1,475 per tractor.

Shorter stopping distances will reduce the number and severity of truck crashes, saving more than the rule will cost, the agency said. It estimates that once all tractors are equipped to meet the standard - a process that will take years - there will be 227 fewer fatalities and 300 fewer serious injuries per year. And, the rule will prevent $169 million in property damage per year.

The rule, posted by NHTSA last week, has been in the works since 2005. In its initial proposal, the agency said it was considering shortening the stopping distance requirement between 20 and 30 percent, and asked for comments. Most in the transportation community supported the idea of shortening the distance, although there were differences over how far the agency should go. Safety advocacy groups, for example, pressed for the 30 percent reduction, while truck manufacturers tended to support a reduction in the range of 20 to 25 percent.

NHTSA said it found that the 30 percent reduction would produce more than twice the savings in lives and injuries than the 20 percent reduction. In terms of property damage, the benefit of the 30 percent reduction was five times greater than the 20 percent reduction. And, the agency found, for most tractors the 30 percent reduction could be achieved by using beefed-up foundation brakes that are readily available.

The agency considered and dismissed the idea of mandating disc brakes in all tractors. The brakes will meet the standard, but their safety benefits have not been quantified, the agency said.

In detail, the rule sets stopping distances for fully loaded tractor-trailers traveling at 60 mph:

250 feet for a tractor with two or three axles and a gross vehicle weight rating of 70,000 pounds or less. This covers practically all of the national fleet. 310 feet for severe service tractors with three axles and a rating greater than 70,000 pounds. 250 feet for a tractor with four or more axles and a rating of 85,000 pounds or less. 310 feet for a tractor with four or more axles and a rating greater than 85,000 pounds.
Trucks that are not loaded will have to stop from 60 mph in 235 feet, a 30 percent reduction. This applies to all tractors, including severe service units.

The agency is making no changes in the emergency brake stopping distance, nor in the dynamometer test requirements that the tractors must meet in order to pass muster.

A key element in the rule is the lead time it gives manufacturers to get ready. The two-year lead-in applies to three-axle tractors with a rating of 59,600 pounds or less - which NHTSA describes as the typical fleet unit. The agency believes that manufacturers will have little difficulty meeting this schedule with enhanced drum brakes or disc brakes.

Severe-service tractors and two-axle tractors will get more time, though. The agency said it will give these configurations four years to comply because it believes manufacturers need to do more testing.

The agency said it expects that a standard three-axle tractor will be able to meet the new requirement with bigger drum brakes on the steer and drive axles - basically larger and wider versions of the standard S-cam brake.

Severe-service and two-axle tractors are likely to need disc brakes at all wheels, the agency said.

The complete rule can be found at www.nhtsa.dot.gov .

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