WASHINGTON-Government proposals on antilock braking systems for trucks, buses and truck tractors satisfy neither safety advocates nor the trucking industry, according to comments submitted to the National Highway Traffic Safety Administration. Truckers, truck makers and ABS manufacturers feel that the NHTSA recommendations are arbitrary, unworkable and a ``flagrant'' violation of the agency's mandate.
Safety watchdogs, on the other hand, say NHTSA didn't go far enough in its ABS proposals to ensure the braking safety of heavy vehicles.
Last September, NHTSA published a Federal Register notice on ABS. The agency proposed requiring antilock brakes on all heavy vehicles ``to improve the lateral stability and control of these vehicles during braking,'' according to the notice.
On April 12, the agency published a supplemental notice on ABS that proposed a requirement for heavy vehicles to have antilock braking systems that independently control each wheel on at least one axle. Safety advocates, as well as some truck manufacturers, told NHTSA they favored such a regulation.
Leading the opponents to this proposal is the American Trucking Associations.
``Mandating design standards will only stifle innovation in ABS development and lock manufacturers and fleets into a system that may prove to be less than optimal and would require NHTSA to revise the rule constantly,'' the ATA said in the May issue of its Maintenance newsletter.
The ATA expanded its criticism in its comments to NHTSA, accusing the agency of proposing a design standard when its Congressional mandate allows only performance standards.
``The design restrictions preclude anything but electrical/electronic systems, thereby prohibiting mechanical systems,'' the organization said.
``Further, these restrictions will impair efforts to develop new electrical/electronic technologies-technologies that could solve the well-documented reliability problems associated with existing systems.''
Unlike the ATA, the American Automobile Manufacturers Association (AAMA) was one of the groups recommending independent ABS controls. Nevertheless, the association found NHTSA's proposal wanting.
``The proposed definition of `independently controlled wheel' does not accommodate widely used ABS algorithms and control technologies,'' the AAMA said. ``Chassis and vehicle dynamics engineers should be left to make these decisions based on vehicle performance testing, available ABS technology, specific vehicle usage considerations, etc.''
On the other hand, safety advocates like the content of the NHTSA proposal, but feel it should be strengthened.
``(I)t is clear that the agency intends to exclude semi- and full trailers from this requirement,'' said the Advocates for Highway and Auto Safety. ``Independent wheel control on both tractors and trailers is an action that is necessary to deal with the poor braking stability especially of combination heavy vehicles operating on surfaces with split coefficients of friction.''
A final NHTSA ruling on truck and bus ABS is expected soon.