The I-66 HOT lanes, opening next summer inside the Beltway, will follow the pattern set by the I-95 Express Lanes seen here and eliminate the exemption for hybrid vehicles. (Linda Davidson/The Washington Post)

The Aug. 1 groundbreaking ceremony for the I-66 HOT lanes project inside the Capital Beltway sparked many questions from travelers who wanted to know precisely how this new thing would affect them.

This is only natural. Most travelers don’t spend their commute time pondering grand transportation strategy. They want to know when they will get there and how much it will cost. That leads to common concerns such as this about the high-occupancy toll lanes.

Dear Dr. Gridlock:

If you are driving alone and outbound during evening rush hour, will you have to pay a toll to go to Dulles International Airport on the I-66 portion?

— Mike Doan, Arlington

Today, motorists have an exemption from the high-occupancy vehicle rules on I-66 inside the Beltway when they are going to or from Dulles Airport as air travelers or transporting air travelers.

According to the Virginia Department of Transportation policy, “You are not permitted to use I-66 inside the Beltway during HOV hours if you are going to the airport to eat, get coffee, get gas or any other reason other than boarding a plane or picking someone up at the airport.”

Despite that restriction, the airport exemption is one of the reasons it’s so difficult for police to enforce the HOV rules. If they see a solo driver during the carpool hours, how are they supposed to know the person is an air traveler without stopping the vehicle and asking the driver for some proof?

That’s one of the exemptions scheduled to end the day the HOT lanes become operational next summer.

For the HOT lanes hours — 5:30 to 9:30 a.m. eastbound and 3 to 7 p.m. westbound — drivers will need to have an E-ZPass transponder. If they’re going to be driving alone, they’ll need the regular E-ZPass to pay the variable toll. If they plan to drive with a passenger at least occasionally, they will want the E-ZPass Flex, which can be switched from the toll-paying mode to an “HOV” setting to claim the free ride for carpoolers.

Virginia Transportation Secretary Aubrey Layne, an advocate for the HOT lanes plan, thinks air travelers will be okay with this trade-off. They might pay a few dollars in tolls in exchange for a reliable trip during the busy hours on I-66 inside the Beltway.

Me, I just think these E-ZPasses have gotten complicated enough. There doesn’t need to be a third setting for “air traveler.”

Also, I’ve heard from so many legitimate HOV drivers who call for better enforcement of the rules so they can keep moving. They send reports to me about how many solo drivers they observe during their rush-hour commutes.

If everybody needs an E-ZPass and the settings can be monitored remotely by the police, it makes the enforcement task easier, as has become the case on the other HOT lanes along the Capital Beltway and I-95/395 in Northern Virginia.

The other exemption that’s on the way out is the one for solo drivers of hybrids. That exemption, which was supposed to be temporary, should have been allowed to sunset years ago, as more commuters bought their way into HOV lanes by purchasing hybrids.

Some of my best friends drive hybrids — but there’s no justification for allowing the hybrid exemption to continue. I was glad to see that it disappeared from the I-95 corridor when the HOV lanes became HOT lanes. And the state government is right to be consistent about ending the exemption on I-66 as the inside- and outside-the-Beltway sections are converted from HOV to HOT.

The outside-the-Beltway drivers probably will be able to keep their exemptions until the end of the upcoming construction project that creates two HOT lanes in each direction by the end of 2020.

Virginia’s research on I-66 suggests that the hybrid exemption probably would need to end by then anyway so that the state could stay in compliance with federal rules against degrading the average travel times in HOV lanes.

Those are the main issues that concerned drivers this past week as the inside-the-Beltway plan advanced from concept to construction. There are bound to be many more, since the HOT lanes are the most complicated road system we have in the D.C. region.

Please continue to send in your questions, and we’ll work this out together.

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, 1301 K St. NW, Washington, D.C. 20071, or ­email drgridlock@washpost.com.