An exiled Soviet engineer and an American security consultant say they are nearly ready to market an anti-terrorism system designed to halt gate crashers with their own horsepower.

"It is quite an old Indian trap idea," said Alexander Gorlov, professor of mechanical engineering at Northeastern University and chief designer of the Terrorist Vehicle Arresting System, which can demolish a 15,000-pound truck traveling at 50 mph.The trap consists of two cables and a net stretched across an entryway. If an intruder tries to drive through, the tension on the net and cables rotates a 1,500-pound, spiked turnstile that slams into the side of the vehicle, forcing it against a barrier.

After the 1986 terrorist attack that claimed the lives of 241 Marines in Beirut, security officials recognized the need for a more reliable defense against car bomb attacks.

Steel barricades that rise from the ground to stop intruders in their tracks have been installed at the entrances of the Capitol, the White House and many other government buildings in the United States and abroad.

Ed Newell, a Boston resident who worked as a law enforcement consultant much of his 77 years, said those 1,500-pound barricades are difficult to maintain.

"You've got to raise and lower that mass for every vehicle that comes and goes all day long, every day, waiting for 10 years for some guy to crash," Newell said. "People walk by and they see this thing standing there and it makes them think that these people (inside) have a bunker mentality."

In the system developed by Gorlov and Newell, only the 150-pound cables and nylon net that hang a foot off the ground need to be raised and lowered. The cables slide into a groove in the ground at the flip of a switch to admit authorized vehicles and can be returned to position in one second.

The turnstile stands at the side of the road, swinging into action only when a gate crasher drags on the net.

Gorlov and Newell have some testing to complete. "But now we've developed all the details and, practically speaking, we're ready for mass production," Gorlov said.

They said believe they can sell the recently patented system for between $15,000 and $25,000.

Gorlov, 56, and his wife, Ella, former professors at Moscow universities, were banished from the Soviet Union 13 years ago and settled in Brookline.

He said he was exlied because of his friendship with Nobel laureate Alexander Solzhenitzsyn, who chronicled Gorlov's brush with the KGB in his novel "The Oak and the Calf."