A decade and a half after the conversation began, the D.C. region’s commuters still are trying to figure out the HOT lanes concept.

It isn’t just a matter of understanding how to navigate the high-occupancy toll lanes. They want to know where these things came from.

Some have dim memories of discussions involving the Virginia Department of Transportation. Others are just beginning to focus on this major change in highway travel because they heard the Interstate 95 Express Lanes go HOT on Dec. 29.

In late November, one traveler asked me: “Is there any chance of reversing VDOT’s decision to create a full-time toll road that also requires the use of the E-ZPass transponder?”

That ship sailed years ago, as the Virginia government locked in HOT lanes leases on the Capital Beltway and I-95 for most of this century. Even though the network is now 40 miles long, Virginia isn’t done.

When you hear about planning for HOT lanes on I-66, keep in mind the following brief history of the current program. Notice that as the early plans evolved, we didn’t get exactly what the advocates hoped for or the critics feared.

In the late 1990s, commuters were begging for relief from congestion, and transportation departments were running out of money and space for traditional highway-building solutions.

HOT lanes, already used in California, piqued interest. Some saw this system as a way of getting more use out of the region’s High Occupancy Vehicle (HOV) lanes. For others, the use of a variable toll to manage traffic was an attraction. The tolls also appealed as a way of covering the construction costs.

“I would expect that people would be skeptical at first,” Maryland Transportation Secretary John D. Porcari told Post reporter Alan Sipress in 1999. Porcari was right about that. In fact, one of the skeptics was Maryland Gov. Parris N. Glendening (D), who in 2001 killed a plan to test HOT lanes on Route 50 a day after Porcari announced it.

“It’s unfair in terms of the economic impact” on commuters, Glendening told The Post’s Katherine Shaver.

Early on, Lon Anderson of AAA Mid-Atlantic shared that view. “The rich will roll and the poor will poke,” he said recently, quoting one of his early descriptions of the HOT lanes system.

But by late 2003, Anderson had become a reluctant convert, as he saw the revenue for roads projects drying up. “They’re getting desperate,” he said of the region’s commuters.

Virginia transportation officials also were getting desperate. In 2002, Northern Virginia voters had rejected a proposal to raise the sales tax by a half cent per dollar to finance transportation projects.

By 2004, Virginia’s state and local officials were seriously interested in private proposals to build and operate HOT lanes on the west side of the Capital Beltway and along 56 miles of I-95/395 from the D.C. line to Massaponax.

The I-95/395 system proposed by the Fluor Virginia firm was described as a Bus Rapid Transit/HOT Lanes System. The lanes wouldn’t be just for toll payers and carpoolers. Express buses would use the HOT lanes to travel between stations just off the highway.

Many officials reacted favorably. “As long as transit is an integral part of the . . . project, it could be a great boon,” Fairfax Supervisor T. Dana Kauffman told Post reporter Lisa Rein.

But there also was widespread concern. Unlike the Beltway system, the I-95/395 version would in part convert HOV lanes to HOT. The extra toll-paying traffic might slow the ride for commuters participating in the corridor’s very successful carpool system.

“Any reduction of the incentive to carpool will reduce HOV usage,” Bob Hugman of Woodbridge wrote in an April 2004 Dr. Gridlock column.

Virginia officials signed a deal for the Beltway express lanes in 2005, hoping — optimistically — that they could be open by 2010.

“It means a new opportunity for HOV and transit, and it means a choice for drivers who want to pay for a faster commute,” Transportation Commissioner Philip A. Shucet said. That also may have been a bit optimistic.

Two years after the opening, the lanes work as billed for the increasing numbers of toll payers. But the hoped-for surge in carpooling and bus transit has yet to blossom.

Development of the I-95 project was slowed, and the length was reduced 29 miles, partly because of a lawsuit filed by Arlington County.

Concerns among the carpoolers eased as planners worked with them. But like its Beltway sister, the 95 Express Lanes are opening without the robust system of commuter buses once envisioned as “bus rapid transit.”

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 drgridlock@washpost.com .