Dear Dr. Gridlock:

I thought your answer to Mike Mills on Sunday [Sept. 29] was inappropriate. We have enough distractions to be listening to Books-On-Tape while we drive. Driving here demands our full attention. Who can concentrate on a book?

Sharon Anderson

Nokesville

Many readers have highly recommended audio books as a way to combat commuter tedium. I haven't heard them express your concern.

The Source of Va. Tags

Dear Dr. Gridlock:

Mystery solved! Most of those Virginia license-plated cars Douglas Taylor sees commuting in morning rush hour in Southern Maryland are coming from Virginia's Northern Neck, across the Gov. Harry W. Nice (Route 301) Bridge.

Check the map -- it's a straighter shot to the metro area than going to Fredericksburg and I-95.

Dave Rutherford

Woodbridge

Dear Dr. Gridlock:

I was somewhat amused, for want of a better word, by Mr. Taylor's letter in the Oct. 3 column. Please allow me to rewrite the letter from a Virginian's point of view.

I am amazed at the number of Maryland license tags I see on cars commuting in the morning in Virginia. Is there some kind of advantage to keeping your car registered in Maryland if you live in Virginia?

I'm not sure about any advantage for keeping Virginia tags while living in Maryland, but there sure are a couple of reasons for keeping Maryland tags in Virginia. No personal property tax to pay, and no state inspection every year.

Maryland tags aren't the only out-of-state tags I see on a daily basis. I know we have a lot of military members in the area who are allowed to maintain the tags from their home of record, but I don't believe all are in the military.

Joe Cupurdija

Woodbridge

Dear Dr. Gridlock:

Douglas Taylor of Indian Head is puzzled by the number of Virginia license tags he sees commuting from Southern Maryland [Dr. Gridlock, Oct. 3].

As a fellow resident of Charles County who lives off U.S. Route 301, I can account for at least some of them.

Many Virginia cars cross the Potomac River bridge from King George County, Virginia, on Route 301, then take back roads to Route 210 (Indian Head Highway) to get to their jobs in the District.

Carol Rife

Bel Alton

Dear Dr. Gridlock:

A reader asks why there is such a large number of cars commuting from the Southern Maryland area with Virginia tags.

This probably has something to do with the Navy transferring its Naval Air Systems Command Headquarters from Crystal City to Patuxent River a few years ago.

This would also include the contractors who support this Navy activity.

I suspect a large numbers of these employees lived in Northern Virginia.

Darrell Bachman

Kent Island

Double-Thinking an Idea

Dear Dr. Gridlock:

It seems clear that we will never solve our traffic problem with new roads because of the political difficulty of gaining approval for new routes.

The solution to our overburdened traffic system is to increase capacity without building new roads. Why not simply double-deck the existing roads?

Doubling the capacity of the Beltway and I-95 will do an enormous amount to solve our traffic problems.

The engineering problems will be difficult but solvable. I envision building the upper-deck sections in modules and positioning them with helicopters. That may not prove feasible, but our society is good at solving difficult construction problems.

This will cost an enormous amount of money and will save an enormous amount of time, money and hassle.

Stuart Plattner

Bethesda

Every now and then I get a letter suggesting the Beltway be double-decked. One of the problems is that building an elevated interstate highway (in effect, on a bridge) is infinitely more costly and more expensive to maintain than building a new road on a flat right of way.

Look at the Woodrow Wilson Bridge: $2.5 billion to build a new bridge and interchanges on each side. That is a fraction of the length of the Beltway.

I don't think the money is there for double-decked undertakings.

Go-and-Stop Method?

Dear Dr. Gridlock:

I wonder if you have any opinion on the British way of handling traffic lights. It's been a while since I have been there, but at the time their lights went from red to yellow to green. From green, they went directly to red.

This avoided having people mashing down on the gas when the yellow light warned of the light turning red, as people do here. Green to red means stop -- now.

Yellow means that cars waiting at a red light could proceed with caution, after checking for any cars not able to stop for the instant red light.

Robert Boise

Temple Hills

And we think we've got a problem with red light running now! Wow. You mean you're tooling along a secondary road at 45 mph, and as you approach a green light it suddenly and without warning changes to red? Can we say "Screeech!" and "Ka-boom!" and rear-end collisions?

I don't see how this could work here, but as always, I will consider the wisdom of the readership. I'd like to hear your views.

Transportation researcher Diane Mattingly contributed to this column.

Dr. Gridlock appears Sunday in the Metro section and Thursday in Prince William Extra. You can write to Dr. Gridlock, 1150 15th St. NW, Washington, D.C. 20071. He prefers to receive e-mail, at drgridlock@washpost.com, or faxes, at 703-352-3908. Please include your full name, town, county and day and evening phone numbers. Dr. Gridlock cannot take phone calls.