The Right Rule

The industry must be heard on"stopping distance" regulations.


One of the things that is becoming more and more evident in the heavy duty truck industry is the impact of government.

One topic in particular is the proposed "Stopping Distance" rulemaking put forth by the National Highway Traffic Safety Administration (NHTSA). In Decem-ber 2005, NHTSA released its long-expected notice of proposed rulemaking for Federal Motor Vehicle Safety Standards (FMVSS), Air Brake Systems, in which the agency proposes to amend its air brake standard to improve the stopping distance performance of truck tractors.

NHTSA has proposed to reduce the required stopping distance for truck tractors equipped with air brakes by 20 to 30 percent, but the agency believes that the technology for achieving this performance exists today. Given that some vehicles produced today are able to comply with proposed reductions in stopping distance by only modifying foundation brakes, NHTSA is proposing that truck makers comply within two years of a final rule.

The major issue facing NHTSA is identifying what new level of stopping performance should be established in FMVSS No. 121. NHTSA's plan to upgrade the air brake standard will have a substantial effect on the heavy-duty industry as a whole, particularly those that manufacture heavy-duty brakes and components.

It is our belief that NHTSA should look for a performance requirement and not a design requirement that looks like a performance requirement. We are asking NHTSA to establish reasonable performance targets that are not tilted toward a specific technology and which consider the entire range of tractor configurations and vocational uses. We cannot be caught in a notion of one size fits all. As we all know, that is far from the case in our industry.

While air disc brakes and electronically controlled braking are available, NHTSA says its research indicates that many standard 6x4 tractors would be able to comply with its proposed reduction in stopping distance through use of larger drum brakes. NHTSA estimates that three percent of existing tractors already comply with a 30 percent improvement versus the minimum standard.

A 20 percent improvement in braking performance would save an estimated 104 lives, while a 30 percent improvement is projected to save 257 lives, NHTSA said. Improvements of 20 to 30 percent also would reduce property damage by $32 million or $166 million, respectively.

Potential compliance costs depend on whether larger S-cam drum brakes or disc brakes are used to achieve the required performance level. The agency estimates that a 20 percent reduction in stopping distance would cost the industry $14 million to $119 million, while a 30 percent reduction would range from $20 million to $170 million.

There's little question that air disc brakes are being refined and improved and that there will likely be a migration toward this technology. In fact, air disc brakes are already being offered by many of our members and as optional equipment by several tractor OEMs. However, we believe there should not be a direct mandate for them. The final NHTSA rule will most likely hasten the change toward air disc brakes, but we believe an across-the-board mandate is inappropriate. Ultimately, we believe there will be a mixture of vehicles with bigger drums, some with discs, and many with both.

While NHTSA is only addressing truck tractors in this rule, the agency has expressed concern over the braking performance of other types of heavy vehicles (i.e. trailers, straight trucks and buses) as well. Additionally, an issue exists with equipment matching (i.e. drum and disc mixed configurations) for fleets employing new equipment. NHTSA has indicated it may address stopping distance requirements for those vehicles in a future rulemaking, which we believe would be a wise decision.

The Heavy Duty Brake Manufacturers Council (HDBMC), a technical council of HDMA, is working with NHTSA to ensure that the concerns of the heavy duty commercial vehicle industry braking-system and component manufacturers and their customers are understood by NHTSA and incorporated into the overall rulemaking.

This content continues onto the next page...

We Recommend