In her June 24 letter, Karyn Molines supported the use of photo radar on the Beltway and asked whether I "ever drive the Beltway."

I have been a licensed driver for 21 years. I drive about 35,000 miles a year, about 75 percent of that on interstate highways, much of it on the Capital Beltway.

When I first started driving, we had realistic interstate speed limits set by qualified engineers. And because they were realistic, they were generally obeyed.

In 1973, for example, according to the state highway administration, 85 percent of traffic on interstates posted at 70 mph drove at no more than 73 mph. From a police standpoint, speed-limit enforcement was relatively easy. Further, those who did speed then were clearly driving dangerously, not because their speed was high, but because they were driving faster than the flow of traffic.

Engineers have long known that controlling speed variance, rather than reducing speed, is the key to improving safety. Those who drive much faster or slower than the flow of traffic are at an increased risk of an accident, regardless of whether they are obeying the speed limit. That may be hard for a "law-abiding citizen," as Karyn Molines terms herself, to accept, but it is true.

Our current speed limit (set by politicians rather than engineers) defies both logic and the good judgment of most drivers. Consequently, it is almost universally disobeyed, even by police officers. Clearly the 55-mph limit lacks public support, is unworkable and needs to be changed. In a democracy, the reasonable actions of ordinary citizens ought not to be illegal.

Instead we are told by our leaders that those of us who exceed the speed limit -- up to 85 percent of us on rural interstates -- are dangerous and need to be controlled with devices like photo radar.

The arguments against photo radar's application, accuracy and legality are too lengthy to repeat here: suffice it to say that, as a civil libertarian, I find the concept frightening. I will worry about the future of our society if most citizens, in Karyn Molines's words, "welcome the radar cameras with open arms and visible license plates." GIFFEN B. NICKOL Bel Air

Rare is the opportunity to turn would-be lawbreakers into unwitting law-enforcers. But that opportunity has arrived with Virginia's plan to catch speeders through installing unmanned, camera-equipped radar guns along the commonwealth's highways.

The problem with the plan is not "Big Brotherism" but a failure to see through the "forest" of regulatory due process to the "trees" of a solution that is as elegant in its simplicity as it is diabolical in its irony.

This solution would require three changes to the plan. First, elimination of the camera. Second, unmanned radar guns that could be moved. And third -- and this is the kicker -- a repeal of Virginia's ban on radar detectors, so that those who own such devices could fulfill their oft-professed purpose of using them to abide by, not violate, the speed laws. You see, their radar detectors wouldn't be able to differentiate between unmanned radar sites and those monitored by police, and so they would have to slow down for both. No doubt, the rest of the traffic would follow suit.

Such a revised plan would cut down on speeding without violating any rights of privacy, without judicial intervention or delay and without the expense of complex automatic camera systems. In a strange twist of fate, manufacturers of radar detectors might one day find themselves being cited by the state for their contribution to the safety and welfare of Virginia's citizens. RICHARD LINN McLean