Motorists on the George Washington Parkway who hit the gas when no police cars are in sight may soon discover they're still being watched.

National Park Service officials said yesterday they are experimenting with automatic radar-equipped cameras on the parkway that will snap pictures of speeders in the act and allow police to send a summons through the mail.

Under the project, which officials believe would be among the first of its kind in the nation, the Park Service--which oversees the federal road--and the National Highway Traffic Safety Administration have installed cameras at Gravelly Point near Reagan National Airport and at Turkey Run, just north of the CIA exit.

Audrey Calhoun, superintendent of the parkway, said the park service will test the cameras, which cost $100,000 each, for six months. If the test is successful, she said, owners of cars that speed will begin finding tickets in their mailboxes.

"The speed on the parkway and all the aggressive driving . . . it's been a problem for years," Calhoun said. She said the search for ways to expand enforcement got a push from a notorious 1996 incident on the road, when three people died after two motorists carried on a high-speed driving duel.

In one recent effort to discourage speeding, Park Police placed portable radars with message boards along the highway to remind drivers how fast they were traveling. That seemed to slow many people down, but they sped up again after the signs were taken away, Calhoun said.

The Park Police force isn't large enough to constantly patrol the entire 27.5-mile highway, she said. "We don't have enough officers," Calhoun said.

The cameras operate much like those that are used to catch red-light runners at intersections, designed to photograph the license plate of the offending car so the registered owner can be identified and sent a traffic citation.

The cameras, long used in Europe, have the capacity to photograph license plates 180 feet away and can track traffic in both directions. The two experimental parkway cameras will target only northbound vehicles to start.

Calhoun said the idea for the cameras came from the federal traffic agency, which is funding the project. The six-month trial will help officials determine whether the technology can produce accurate data and clear pictures, Calhoun said. If so, more cameras will go up, she said.

James Tuton, president of American Traffic Systems Inc. of Arizona, which is supplying the equipment, said yesterday there was no question about the accuracy of the system. He said jurisdictions in many western states have used similar systems on mobile units for more than a decade, but that the George Washington Parkway project involves the first fixed cameras that will operate automatically.

When the system is up and running, "we're going to see fewer crashes and speed will decrease dramatically closer to the speed limit," Tuton said.

In a recent survey conducted by the American Automobile Association, 65 percent of those polled in the Washington area supported using cameras to catch speeders, contrary to polls of a few years ago when such systems were strongly opposed. But a significant 22 percent remain strongly against cameras, worrying that they are an invasion of privacy, AAA Mid-Atlantic spokesman Lon Anderson said.

It is significant that a federal agency is undertaking the radar-camera program, because it remains questionable whether local jurisdictions could do so without special state legislation. Virginia, for example, had to pass a law in 1995 to ensure that tickets issued automatically to red-light runners couldn't be challenged in court.

Calhoun said the Park Service felt it could go forward with the project because the parkway falls under federal rules. But she said officials also will use the six-month testing process to ensure that the tickets would hold up in court.

"We have looked at our regulations," she said, "and initially our view is that we think we can do it."

CAPTION: Heavy traffic dominates a view looking south along the George Washington Parkway at the second overlook.