The Department of Transportation has begun fleet testing of new anti-lock braking systems for heavy trucks - 10 years after a series of truck accidents in Utah and elsewhere led to the abandonment of an earlier generation of similar brakes.

The department tried in 1971 to require that all new trucks be built with anti-lock brakes. Subsequent accidents on I-15 in Salt Lake City led then-Rep. Dan Marriott, R-Utah, to lead opposition to the the system in Congress. A federal court ruled in 1978 that the requirement was "unreasonable and impractical," and DOT abandoned it.The earlier braking systems used electronic components that picked up stray electrical signals such as ignition spark noise and malfunctioned. The Utah accidents killed several people when heavy trucks plowed into their cars when the brakes locked or failed to hold.

The new generation of brakes, according to DOT, use computer electronics much more resistant to stray signals and the harsh environment of truck or auto use.

The truck test will take two years and will be carried out by 13 companies including Transport Service Co. of Chicago and KMD Inc. and DiPietro Trucking Co. Inc., both of Seattle.

National Highway Traffic Safety Commissioner Diane Steed said she hoped to avoid the mistakes of the original design which she said was inadequately tested before being placed in service.

NHTSA has estimated that as many as one-third of all truck accidents are caused by inadequate brakes.

Luxury automobiles including Mercedes, Cadillac and Lincoln now offer anti-lock brakes, with auto manufacturers planning to make them available on many cars as a $800 to $1,000 option in the next few years.