Dear Dr. Gridlock:

I commute on Interstate 66 and am having a hard time understanding the purpose of the red X and green arrow on the far right travel lane.

Why do these signals exist? Is there a way that VDOT can monitor the traffic and open up these lanes when volume seems to be the issue? I specifically notice this problem on Saturday and Sunday afternoons.

It’s bad enough that I have to sit in traffic Monday through Friday, but also on Saturday and Sunday, too, because of the red X. Why is this lane closed for use on Saturday and Sunday?

— Eugenia Martin, Fairfax

A new system called “active traffic management” is going to change what drivers see — and maybe what they experience — on Interstate 66, one of the most congested highways in the D.C. region.

On the very worst part of I-66, the part between Route 50 and the Capital Beltway, the X’s and arrows regulate access to the shoulders.

These were not built to be regular travel lanes, but when highway departments don’t have the space or the money to widen roadways, they look for more ways to use the room they have. The surging demand on I-66 led the Virginia Department of Transportation to open the shoulders to all traffic at peak times.

The green arrows invite drivers into the eastbound lane from 5:30 to 11 a.m. and the westbound one from 2 to 8 p.m. weekdays. Those hours have remained unchanged since 2008. It’s a form of traffic management, but not a very active one.

This summer, VDOT plans to start work on a project that should deliver what Martin is hoping for, once the new system opens, perhaps by the end of 2014. Sensors and monitors will feed information about traffic conditions to a management center that can send messages back to drivers via electronic lane markers and message boards.

The overall project will affect traffic on I-66 from inside the Beltway out to Haymarket, but here’s the part Martin will find most interesting: Between Route 50 and the Beltway, the active monitoring system can regulate use of the shoulders at all hours, based on travel demand.

Highway marketing

A report from Transurban, the company operating the 495 Express Lanes, noted a survey finding that almost half of Beltway drivers — potential customers for these new E-ZPass-only lanes — don’t have E-ZPass transponders. This letter writer saw that as a marketing problem.

Dear Dr. Gridlock:

Tysons Corner mall, for instance, has many large banners advertising the lanes, but not even a kiosk where one could set up an account and walk away with the device. This situation seems to be the case across Northern Virginia. A lesson for retailers: Make buying easy.

— Terence Kuch, Falls Church

I’ve heard from many drivers who say they don’t want to go to the trouble of getting transponders. Transurban doesn’t sell them, but Pierce Coffee, the company’s director of marketing, would like as many people as possible to have them:

“You can also pick up an E-ZPass or E-ZPass Flex at many retail locations in the area and begin using it right away. Next time you do some grocery shopping, grab your E-ZPass on the way out of the store. VDOT has E-ZPass On-the-Go kits available for sale, and that includes an E-ZPass transponder, mounting strips, installation instructions and a $15 prepaid toll balance to use as soon as you want.”

Joan Morris, a spokeswoman for VDOT, said Virginia E-ZPass is adding 22 Giant store outlets this spring. Passes also are available at some Wegmans and AAA Mid-Atlantic retail stores. People who want them can also go to or call 877-762-7824. Morris said VDOT will continue to monitor sales and review locations.

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