WASHINGTON (AP) _ Government traffic safety experts, in their never-ending effort to curb highway speeding, hope to use an old weapon in a new way they believe will convince some heavy-footed drivers to ease up on their accelerators.

Federal officials are looking for ways to get stationary radar units at highway construction sites, dangerous curves and other areas. The idea is that speeding drivers who use radar detectors will slow down, not realizing that the nearest trooper might be miles away.

Jeffrey Miller, deputy director of the National Highway Traffic Safety Administration, said the plan would require Federal Communications Commission cooperation. He said it could turn radar detectors into safety tools.

But advocates for radar detectors, which are owned by between 12 million and 15 million drivers, say the gadgets are the best defense motorists have against radar errors and unwarranted tickets.

Radar detector opponents, including the government and insurance companies, categorize the devices with burglary tools. Both, they say, are used by lawbreakers.

Brian O'Neill, head of the Insurance Institute for Highway Safety, said a study conducted in Maryland and Virginia showed that one out of every eight cars has a radar detector, while nearly a third of big trucks have them.

The study showed that 22 percent of cars without the units exceeded the speed limit, while more than 40 percent of those with detectors drove faster than the posted limits.

The study revealed as many vehicles with radar detectors in Virginia, where they are illegal, as in neighboring Maryland, where they are allowed.

Laws banning radar detectors in Virginia, Connecticut, and Washington, D.C., date back to the 1960s. The only recent statute is a scheduled New York ban of the units in commercial vehicles.

In California, state police must pace speeders the old fashioned way because that state's legislature refuses to allow them to use radar. However, some local police use it.

Some insurance companies have tried to avoid accepting customers with radar detectors. But the Government Employees Insurance Co. (GEICO) has found it tough to defend its refusal of insurance to radar detector users. In March, a Maryland court ruled against the practice, and surcharges for detector users have been struck down by insurance company regulators in several other states.

''We're not interested in people who tell us up front they're planning to speed. We're not interested in lawbreakers,'' GEICO spokesman August Alegi said.

In 1986, Congress rejected a move to force states that raise speed limits from 55 mph to 65 mph to outlaw radar detectors.

''It unleashed such a torrent of irate letters and telegrams that, so far as I know, nobody in Congress has mentioned the subject since,'' said the NHTSA's Miller.

''When something is that widespread and popular, it's difficult to attack it successfully,'' he said.

Miller said speed has been underestimated as a major national safety problem with the focus on seat belts and anti-drunken driving efforts.

The NHTSA is backing an experiment on the Capital Beltway, the busy freeway that circles Washington, D.C., in which a photograph is taken of a speeding vehicle and a ticket mailed to the owner.

The system, in which no tickets will initially be issued, has raised the concern of the American Civil Liberties Union, the American Automobile Association and other groups.

''There goes due process out the window,'' said Chuck Terlizzi, Maryland coordinator for the National Motorists Association.

Government and private safety advocates also are using or considering other ways of catching speeders, including devices that employ laser beams or measure speed without emitting a radar beam.