Drivers pass through toll booths at the Chesapeake Bay Bridge. (Bill O'Leary/Washington Post)

Some people who study our transportation problems are thinking about the unthinkable: Tolling lanes that are now untolled.

The closest we’ve come to that in the D.C. region is the project now converting the I-95 High- Occupancy Vehicle lanes in Virginia to high-occupancy toll lanes. That idea hasn’t generated overwhelming support among commuters, and solo drivers who use the HOV lanes at off-peak times are downright hostile to the plan because the lanes will be tolled 24 hours a day.

There are basically two reasons to toll existing highway lanes, as opposed to new lanes, such as Maryland’s Intercounty Connector or Virginia’s 495 Express Lanes. One reason is to manage congestion. The other is to pay for repairs and upgrades.

Washington Post polls have shown support for tolling new lanes. In the most recent poll, conducted in June, 62 percent said they supported using adjustable tolls to spread out the flow of traffic. The question cited the 495 Express Lanes as an example.

This was seven months after the express lanes opened, and 35 percent of the poll respondents said they had tried them. Among those, 69 percent said it was worth it.

But none of that is the same as supporting tolls on highway lanes that have been around for a long time.

Robert Poole, director of transportation policy at the Reason Foundation, a think tank, has been thinking a lot about how to fix the nation’s interstate highway system. Congress is getting nowhere with proposals for either raising the federal gas tax or finding a substitute to finance the rebuilding of the half-century-old system.

Poole’s study modeled a tolling system charging 3.5 cents per mile for cars and 14 cents per mile for trucks, indexing it annually for inflation. He said almost all of the rebuilding and upgrading costs could be covered that way.

The key: Get Congress to allow the states to impose tolls on any interstates they choose. Today’s federal law is very restrictive in that regard.

It’s not very likely that Congress would liberalize the tolling rules. That’s partly because of the nature of Congress and partly because of public skepticism.

I sensed that skepticism Thursday when about 80 Virginians who are members of the Shepherd’s Center of Fairfax-Burke allowed me to use them as my focus group on tolling. Many of them are retirees who no longer commute, but they have decades of experience as both commuters and interstate travelers.

There was a rumble in the crowd when I raised the issue of tolling existing lanes, even to support something as well regarded as the interstate system. Some wanted to be sure they would see a return on their tolling investments. Some don’t like the idea of getting E-ZPasses to pay for tolls. Some wondered how tolling and taxing work together. We were taxed to pay for the interstates, and now we’re going to be tolled for them?

That’s a fair question, especially in our region, where Virginia and Maryland have just imposed tax programs designed to raise more money for transportation improvements.

But Patrick D. Jones, the executive director of the International Bridge, Tunnel and Turnpike Association, attended the Reason Foundation news conference on the tolling proposal and offered a visual demonstration to rebut the frequently asked question, “Didn’t I already pay for this road?”

Jones lifted up a bag of ice he had paid for. The obvious problem, Jones noted, was that he had paid for it 20 minutes earlier.

It was a hot day, so the bag was a mess. “We can stop the deterioration by refrigeration, but that requires money,” he said.

Our highways aren’t deteriorating quite as fast, and we’ve got more time to save concrete and steel than ice. But given the glacial pace of our national problem-solving, it’s good to get started.

Dr. Gridlock also appears Thursday in Local Living. Comments and questions are welcome and may be used in a column, along with the writer’s name and home community. Write Dr. Gridlock at The Washington Post, 1150 15th St. NW, Washington, D.C. 20071 or e-mail