A view of the many lanes of traffic through Tysons, with both high-occupancy toll lanes and the regular lanes of the Capital Beltway. Virginia is warming to a plan for express lanes on Interstate 66, but the evidence so far that HOT lanes are good for traffic management is problematic. (Robert Thomson/The Washington Post)

Virginia’s top transportation officials have made no final decisions, but they are showing a lot of interest in putting tolled express lanes in place of the HOV lanes on Interstate 66 outside the Capital Beltway.

They like two things: Tolling is a widely used method of managing traffic. And it’s also a way of paying for megaprojects, either by adding more revenue for the government to spend on highway improvements or by creating an incentive for private companies to do the work for the government in exchange for the toll money.

So far, the evidence that this works out for everybody’s benefit is limited.

The Washington region’s one set of high-occupancy toll lanes opened on the Capital Beltway in November 2012. Initial toll revenue was below projections made in a study done before the HOT lanes construction began.

The study, which also preceded the Great Recession’s impact on the local economy, may have reflected an optimism bias on the part of consultants about future traffic volumes and about the willingness of drivers to pay tolls.

Granted, the HOT lanes are performing better now.

The latest report from Transurban, the company that operates the 495 Express Lanes on the Beltway, shows its average tolls and toll revenue are increasing. For the three months ending in June, average daily toll revenue was up 45 percent over the previous quarter, to $90,654. The average toll was up almost 9 percent, to $2.83. The maximum toll charged for a full 14-mile trip was $11.85.

The average number of trips taken on a workday was 43,325, up almost 24 percent compared with the same quarter in 2013.

But will the early track record of under-performance — compared with expectations — make it more difficult for Virginia to negotiate a favorable deal with private partners on
I-66? A better deal means more travel improvements can be included in the overall package, which Virginia transportation officials estimate could cost $2 billion to $3 billion.

Meanwhile, what evidence do we have so far that HOT lanes are good for traffic management?

Charles Kilpatrick, Virginia’s commissioner of transportation, told me that he regards the Beltway HOT lanes as a success, because they have improved travel for everyone. They’ve opened up an option for drivers to get a reliable trip in exchange for a toll. And they’ve created an incentive to either car pool for a free ride or take a commuter bus.

Traffic also appears to be less congested in the regular lanes, he said. It looks that way to me, too, but our evidence is anecdotal. There’s no traffic study yet.

And if we do wind up with statistics showing that traffic is easing in the regular lanes, what are we to make of that? Would it be an endorsement for the HOT lanes as a traffic management concept?

Maybe. But statistics showing that traffic in the regular lanes is less congested also could be an echo of the recession.

And if the regular lanes’ traffic is easing because of the express lanes’ construction, is that an endorsement of the HOT lanes concept or simply a reflection of what happens when you add four lanes to any highway?

Then again, an improvement might simply tell us that whenever you stop tearing up 14 miles of major highway, the traffic flow improves.

One of Virginia’s key goals for the Beltway project — as it will be for the I-66 improvement project — is to decrease the number of solo drivers in the corridor by increasing the incentives for car pooling and commuter bus travel.

Here again, we have only preliminary returns. Fairfax and Prince William counties both launched commuter bus services to take advantage of the Beltway express lanes. Virginia began offering a new type of E-ZPass transponder called the Flex to attract car poolers taking advantage of a free ride.

In Transurban’s most recent quarterly report, the percentage of vehicles paying tolls — meaning they aren’t a car-pool vehicle or a bus or another exempt category such as a motorcycle or emergency vehicle — remains at about 91 percent of all express lanes users. This will probably prove to be a lesson in the need for a more robust system of buses and park/ride lots to support express-lanes travel.

These notes of caution are meant to be just that. It’s not an argument against building HOT lanes. I-66 needs a big, well-financed solution, and as Virginia Transportation Secretary Aubrey Layne said this month, that’s unlikely to occur without a private partner, one that will need an incentive, such as toll revenue, to invest in the project.

I hear from many drivers who prefer the Beltway express lanes to the regular lanes. I’m one of them. Based on more than a year of experience with them, I no longer look at the toll prices on the message boards. I want that reliable trip.

But Virginians can and should ask questions and avoid assumptions as the discussion about the I-66 program gets more intense.

Lights for safety

Dear Dr. Gridlock:

Daytime headlight use is now required on the Chesapeake Bay Bridge. If your vehicle is equipped with daytime running lamps, does the use of daytime running lamps (in the daytime) meet the “headlight use” requirement?

Thomas DeVaughan, Alexandria

DG: Yes. That’s according to Sgt. Kevin Ayd, speaking for the Maryland Transportation Authority police, who enforce the traffic rules on the Bay Bridge.