View of the southbound Express Lanes near Duke Street in Alexandria. (Linda Davidson/The Washington Post)

Dear Dr. Gridlock:

You raised some interesting points in the HOV vs. HOT lane debate. However, I think one of the major — and sometimes overlooked — drawbacks of high-occupancy toll lanes is the fact that they inadvertently contribute to the transportation inequity problem.

Recognizing that high-occupancy vehicle lanes are often underused, many road agencies have turned to the use of high-occupancy toll lanes to allow vehicles with fewer than the required number of occupants to use the restricted lanes for a fee. In theory, road users who are willing and able would accept that fee for reduced travel time. In doing so, the general-purpose lanes would become less congested.

Although HOT lanes thus have the potential to benefit all road users, the benefits are often skewed to those with higher incomes.

Several counties in the Washington area consistently rank among those with the highest-earning median household incomes in the United States. The higher-than-average salaries in the region probably affect the number of drivers who are willing to pay a toll to cut their travel times. In fact, so many drivers may be willing to pay that HOT lanes may become congested despite the efforts of dynamic tolling.

One potential solution to alleviate congestion in the HOT lanes is to raise the HOV threshold from HOV2 to HOV3. But this policy may create additional equity issues. It removes only nonpaying users [those unwilling or unable to pay the toll] from the restricted lanes. Thus, the decreased congestion in the HOT lanes may disproportionately benefit higher-income earners.

For consumers representing the lowest 20 percent of income earners, “transportation costs account for approximately 32 percent of their after-tax income,” according to the U.S. Department of Transportation “Beyond Traffic” study,

Although public transportation offers a solution for some, the DOT study reveals that only a quarter of jobs in low-skill and middle-skill industries in major metropolitan areas are accessible via a transit ride of less than 90 minutes.

There are significant counter-arguments to be made. The money collected via HOT lanes translates into funding for highway maintenance, road construction and other transportation improvement projects.

Nevertheless, we’re faced with a Catch-22. On the one hand, proponents of HOV lanes can argue that representatives of all income brackets have it in their means to use those lanes. On the other hand, proponents of HOT lanes can argue that the money raised by those lanes benefits the very infrastructure on which commuters rely — especially those commuters who cannot afford to live within city limits.

Mark L. Franz, assistant director of outreach and technology transfer for the National Transportation Center, University ofMaryland

DG: When governments make decisions about major transportation projects, they are making decisions for commuters yet to be born.

The Metro’s Silver Line, Maryland’s Intercounty Connector and Virginia’s HOT lanes are going to last a long time.

The HOT lanes were built through public-private partnerships, which require the state to give the private companies a long-term lease so they recoup their investment. Drivers get extra lanes now, but the private partners get revenue from tolls for most of the century.

That longevity is one more reason to pay attention to the issues that Franz and others have raised about the HOT lanes program.

I listened last week as Marcia Hook of Dunn Loring made a similar point while protesting the HOT lanes plan for Interstate 66 in a statement to the region’s Transportation Planning Board.

The Interstate 495 express lanes “contract has a term of 75 years,” she said. “Now go back 75 years to 1940. Imagine what a deal signed by transportation planners then would look like today. Would that contract make sense today, 75 years later, without the benefit of understanding the nearly eight decades of change and technological innovations that were to come?”

People who live in Dunn Loring and Vienna have a very personal concern about Virginia’s HOT lanes plan for outside the Capital Beltway, because they live in areas that could be affected directly by widening the interstate.

But these residents and commuters who live all along the I-66 corridor are raising issues that must be addressed, about the fairness and practicality of the state plan.

Four members of Congress from Virginia see it that way, too. They sent a letter to Virginia Transportation Secretary Aubrey Layne.

The basic message from U.S. Reps. Gerald E. Connolly (D), Robert J. Wittman (R), Don Beyer (D) and Barbara J. Comstock (R) was: Not so fast.

“The far-reaching implications of your proposal on commuters and neighborhoods, the rapid timetable proposed, and the lack of public input into the planning process are deeply troubling,” the letter to Layne said. “Left unaddressed, these concerns would make it difficult for us to build support and consensus for this project.”

The HOT lanes projects for I-66, inside and outside the Beltway, are the biggest highway program in the Washington region. They would add to an already extensive network of HOT lanes on the Beltway and Interstate 95.

But the region’s experience with HOT lanes as a transportation solution began in November 2012. That’s not much time to learn whether the system can adequately address the social concerns and practical issues raised by people such as Franz and Hook. And they need to be addressed now, so the grandchildren of today’s commuters won’t have to do it.