The 95 Express Lanes (middle lanes) extend just a bit north of the Beltway now, but Virginia plans to move the terminus up to the Pentagon area. (Linda Davidson/The Washington Post)

Highway commuting is often described as a grind, the same ol’ same ol’. But many of those who do it daily are sensitive to change. This column addresses some of the concerns that travelers have raised this summer, starting with the setup now underway on Interstate 66 for the high-occupancy toll lanes.

Dear Dr. Gridlock:

Will you please clarify the occupancy rules for the HOT lanes inside the Capital Beltway? Does HOT allow single-occupancy vehicles to drive during rush hour as long as they pay, or are they subject to fines and tickets?

You noted that with the end of the Dulles Airport exemption, single-occupancy vehicles going to the airport can use an E-ZPass on I-66. Hope that doesn’t apply to all traffic.

Also, will HOV2 or HOV3 be toll free with E-ZPass Flex?

— Ben Feldman, the District

When the HOT lanes open on I-66 inside the Beltway next summer, solo drivers can use them if they pay the toll via their E-ZPass transponders. This is the same deal the soloists have right now on the Beltway and I-95 express lanes.

HOV2 drivers, which means drivers with at least one passenger, can get a free ride if they have an E-ZPass Flex transponder in the “HOV” setting. Here again, that’s the same deal drivers get on the other HOT lanes.

But that is set to change in 2020, when the free-ride carpool standard will toughen to HOV3, meaning a driver and at least two passengers.

Dear Dr. Gridlock:

In regard to the new I-66 HOT lanes inside the Beltway: Is every lane inbound and outbound going to be HOT requiring an E-ZPass? Will anyone traveling inbound or outbound have to have a transponder in their vehicle at all times?

If I occasionally want to travel on I-66 into the District from Northern Virginia, would I need a transponder? What about tourists driving in from the west who don’t have a clue how the E-ZPass works?

— Lee Handley, Takoma Park

This is complicated, and there won’t be anything else quite like it in the nation. During the peak time in the peak direction, all the lanes in that direction will be under the HOT rules. So all drivers will need some type of
E-ZPass, either to pay the variable toll or to claim the free ride as a carpooler.

On the other highways in Northern Virginia where HOT lanes exist, drivers can choose to stick with the regular lanes, where there’s no tolling and no need for an E-ZPass.

Dear Dr. Gridlock:

Can you explain the reasoning behind Virginia exempting motorcycles from paying tolls in HOT lanes and not hybrids?

— Dick Tobey, Annandale

Motorcycles are permitted by federal law to use HOV lanes, according to the Federal Highway Administration. The rationale is that it’s safer to keep two-wheeled vehicles moving in the HOV lanes than to have them travel in stop-and-go traffic in the regular lanes.

That federal free pass for motorcycles continues in Virginia’s HOT lanes. The state government created the temporary exemption for the hybrids in the HOV lanes on the condition that it would not gum up traffic for carpoolers.

The government had been planning to allow that to expire anyway as traffic speeds in the HOV lanes deteriorate. HOT lanes have to meet the same average traffic speed standards the HOV lanes do.

Dear Dr. Gridlock:

I’m wondering what’s going on with all the brush clearing along either side of the Beltway in Maryland from the American Legion Bridge past Interstate 270.

Trees with trunks more than a few inches in diameter remain, but everything else from five or six feet high down to the ground has been cut and removed (and sprayed with herbicide?) out to the chain-link fence. So all the vines above are dead and brown too (no loss there).

— Richard Kerr, Bethesda

The targets are invasive vines and plants. The Maryland State Highway Administration says the $2 million eradication project will be done in fall 2018 but shouldn’t have much impact on traffic in Montgomery County because the work is on grassy shoulders and medians.

The state’s contractor, Ed’s Plant World of Brandywine, is going after porcelain-berry, kudzu, Canada thistle and mile-a-minute weed, among other species. The plan is to remove them by cutting and herbicide treatments, monitor the results, treat any new sprouts that emerge, and plant native trees and ground cover.

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