The Virginia Highway Department has released the preliminary verdict on I-66, certifying with numbers what everyone in Virginia already knows. The use of the new highway linking the Capital Beltway to the Theodore Roosevelt Bridge quadruples after rush hour, which is a nice way of saying that only a quarter of the people who could use it during rush hour are doing so. The reason, of course, is HOV-4.

HOV-4 is not a robot. It is a bureaucratic infliction on the English language that stands for high occupancy vehicles, and in this case it restricts use of the highway to cars containing at least four persons between 6:30 and 9 a.m. and 3:30 to 6:30 p.m. This is the legacy of William T. Coleman, a former U.S. secretary of transportation, who was trying to reach a compromise with the residents of Arlington so the road could be built. He decided that I-66 should be for the exclusive use of high occupancy vehicles during rush hour, and he set the minimum at four people. The penalty for violating HOV rules is a monstrous $45 fine.

HOV rules have been the source of considerable controversy, however, since a lot of people had planned on using the road their taxes financed, but a number of them didn't have the foresight to move into a home that was convenient to the homes of three other people they could carpool with. And the controversy has led to some confusion. Not long ago, I was traveling into Washington with two other people at the uncustomarily early hour of 8:45 a.m. when one of them assured me that the rules had just been changed to HOV-3 from 8:30 to 9 a.m. We drove onto the nearly empty highway, and as the policeman started following us, I started wondering who would pay the fine.

I don't know if the policeman decided that we were close enough to HOV-4 to pass, or if he thought there was a child in the carseat, but in any case he drove off at the next exit, presumably to return to his spot and wait for the next malefactor. While this is a nice opportunity to say thanks to the policeman, it is also an opportunity to point out that HOV restrictions might be explained somewhat more clearly. It is, for example, possible to approach some entrances to I-66 and see a sign that merely announces "HOV-4" and the hours, without any explanation as to what "HOV-4" means.

Not long after we pulled away from the benevolent policeman, we got near Rosslyn, still traveling on what seemed like a private road. To our right, there was an enormous traffic jam of people headed toward Key Bridge. I do not want to think about what they were saying as they looked over at the empty lanes of I-66.

David Gehr, of the Virginia Department of Highways and Transportation, says the hours when cars with less than four people are banned were set by his department. He defends them, saying that carpools and vanpools with more than four people are actually using the road as early as 6:30 a.m. He also says his department does not plan to reduce the carpool minimum to, say, three people during rush hour. He predicts that the carpool growth on I-66 someday will match the carpool boom on Shirley Highway.

He says there have been a lot of complaints about the restrictions but that there have also been a lot of calls from people in carpools and people who live near the highway urging the department to stand by its ban. "We said 20 years ago that the road should be six to eight lanes wide, based on projected demand. That demand has materialized." But only a four-lane road materialized to meet that demand. HOV-4, he says, "is a means of managing a scarce commodity."

Highway officials point out that it takes time for people to organize carpools. It might, however, take people a lot less time to organize carpools if they had to find three people sharing destinations instead of four.

I-66 has been open since Dec. 22, 1982, and about the only thing that's been proven so far is that HOV-4 is a terrific way to keep cars off the road. The economic incentives for carpooling are enormous. But the empty lanes in rush hour are testament that the delicate balance between incentives and what people can manage has not been struck. Rush-hour commuters have a strong case to make for relaxing the restrictions. The highway cost $275 million, but an awful lot of people have good reason to feel they've been had.