Dear Dr. Gridlock:

I read Steven Snodgrass's letter [Dr. Gridlock, Nov. 10] about the best time to merge when your lane is ending, and I couldn't agree more that pulling all the way forward and zippering in an alternating fashion is courteous, is safe and has the least negative effect on traffic flow. The problem I have encountered, however, is that many drivers seem to feel that pulling all the way forward is somehow rude or obnoxious.

You would not believe the dirty looks and gestures that I often get as I pass long lines of cars sitting in the through lane as I pull forward in my ending lane.

When I do attempt to zipper at the end, I often encounter through-lane drivers who close the gap so aggressively that merging is impossible. I've even encountered drivers who will deliberately drive in both lanes so as to prevent the use of the ending lane -- a practice that disrupts the flow of traffic.

If all drivers would simply get on board with the zippering concept and use both lanes as they are designed, no drivers would need to feel cheated, and the flow of traffic would be better for everyone.

Ken Carlson

Bristow

The zipper method works well in Europe, I understand. But here, you'd have to have local transportation authorities get behind a public education campaign and post signs to take turns, and I've seen no effort to do that.

Unless we have a cultural shift in understanding and accepting the zipper method, then it's everyone for themselves at the point of the merge. Pretty inefficient.

Commuters vs. Clifton

Dear Dr. Gridlock:

I live and work in the town of Clifton, and the speeding commuters have made getting into and out of town difficult and dangerous.

The commuters have their own desires, and we have ours. Eventually, the traffic will become so backed up that commuters will seek another route.

There is enough political clout in my area to stop any road widening or straightening, so that is a big no-go.

A midcounty connector between Fairfax and Prince William counties is another dead issue: too expensive, and too many local folks oppose it.

Besides, when would we have enough connectors? Would a few dozen in the metropolitan area be enough? How about a few hundred? Many areas have cut-through traffic woes; why would Clifton's congestion in particular call for a midcounty connector?

For better or worse, most property values in the metropolitan area will decline due to commuting distances, crowding, traffic congestion and overpopulation. Eventually we will reach a toxic level of people in the metro area, and large employers will relocate, taking their employees away and giving the rest of us some breathing room.

So I guess the solution is to tolerate the situation until the poor wretches who make the long commutes give up the ghost. I don't need to; I work at home.

Raymond Van Lienden

Clifton

If you work at home, you've won the game, except for the commuters who jam your local roads and make it impossible for you to get out of your driveway.

Eventually, I think employers will have to allow computer-based employees to work from home. I'm not sure there is any other choice.

Virginia's Routes

Dear Dr. Gridlock:

One of the many things I ponder on my early morning runs through suburban neighborhoods is that it seems every residential street in Virginia has a route number posted on a black-on-white sign at intersections.

Does anyone use those numbers? Why?

Steve Royster

Baileys Crossroads

They are state route numbers, posted by the Virginia Department of Transportation to keep track of every street in its inventory, according to Ryan Hall, a VDOT spokesman. Street names change, he said, but the route numbers stay the same.

Those numbers also indicate that the street has been accepted into the state system and is eligible for state snow-clearing, he said.

Bridge Is Incident-Prone

Dear Dr. Gridlock:

Does the Wilson Bridge attract incidents such as breakdowns, stalls or fires? I'm not asking about accidents; it makes sense that they're more likely to occur on the narrow, rickety bridge. There are typically several of these other incidents each week on the bridge. For example, there was a car fire on the bridge this morning, Nov. 21.

Obviously, traffic reports are more likely to focus on an incident at a chokepoint, where there will be greater impact, than on an incident where there is more room to maneuver. I don't hear nearly as many reports of incidents on the Capital Beltway near the bridge. So, does it seem as if there are more incidents on the bridge than on roadways?

I don't drive over the bridge much anymore.

Andy Feltman

Arlington

The bridge attracts a lot of attention because there are no shoulders, and minor incidents can create long backups. What shoulder space there is, to the left and right, is just four feet wide -- not big enough to let a rescue vehicle or a wrecker get through, according to John Undeland, spokesman for the Wilson Bridge project.

The new bridge, which will be completed in 2008, will have 10-foot-wide shoulders on both the right and left. Plus, it will have five lanes in each direction, instead of the three in each direction we have now.

Those improvements should reduce the number of serious incidents on the bridge, which was built to accommodate 75,000 vehicles a day and now carries more than 200,000.

Airport Arrivals

Dear Dr. Gridlock:

You were recently asked about getting one's guests from Dulles International Airport to Alexandria. I wanted to let you know about the 5A Metrobus. This bus departs Dulles once an hour on the half-hour, from 6:28 a.m. until 11:40 p.m. daily.

The 5A Metrobus could take guests to the Rosslyn Metro station, and from there they could take the Blue Line to Alexandria. This Metrobus costs $3.

Can you pass this on? All of this information can also be found at www.wmata.com.

Sharon A. Affinito

Transportation Planner

Rideshare Program

Loudoun County Office of Transportation Services

Thank you. And for information about ride-sharing in Loudoun, Ms. Affinito might be a good resource. Contact her at saffinit@loudoun.gov or 703-771-5251.

Try It Yourself

Dear Dr. Gridlock:

I am writing in regard to the police roadside sobriety test that requires one to stand on one foot for a count of 30.

I participate in a thrice-weekly morning wellness program, and one of our challenges is to stand, unsupported, on each foot for 10 seconds. Many, if not most, of the 15 or so of us in the group are unable to fully meet this challenge. Doing so for a count of 30 -- even a rapid one -- is ridiculous!

And, at that hour of the morning, it's safe to say that none of us is "under the influence."

Please use your bully pulpit and access to law enforcement agencies to get this laughably unrealistic test eliminated.

John Henderson

Annapolis

I had trouble standing on one foot for 10 seconds. I'd like to hear from anyone who has been asked to use that test to demonstrate field sobriety. Seems ridiculous.

Improving Metro

Dear Dr. Gridlock:

I enjoy your column very much. I have been retired now for seven years, but how well I remember my efforts to commute from Southern Maryland to the District. I have a very economical solution to the access/egress problem on Metro trains.

Each train has two doors, right? Why doesn't Metro advertise profusely for several weeks and then implement the following: Mark the doors boldly in large lettering, inside and out, with "Front Door - Enter Only" and "Back Door - Exit Only," and post large signs inside the cars reading "Exit Through Rear Door Only."

Thus, everyone will know they can enter only through the front door. Upon arriving at their destination, passengers can exit through the rear door, leaving the front entrance of the car open for boarding passengers.

Is that idea too simple or radical for today's commuters?

Jacqueline D. Marini

Helen, St. Mary's County

Controlling the flow of passengers works elsewhere. Of course, each side of a Metrorail car has three sets of doors: one at each end and one in the center.

On the BART subway system in the San Francisco Bay area, customers line up on marked areas on the platform and board the cars politely in single file, I'm told, in contrast with the mad rush here to get on and off.

For a long time, Metro officials told Dr. Gridlock that marked entry points couldn't be used here because the Metro trains didn't have precise enough braking systems to halt at a specific, marked place on the platform; hence, lining up wouldn't work.

Now, however, Metro has made braking adjustments and plans to test platform markers at three stations: Union Station, Metro Center and Gallery Place-Chinatown. Test results could be ready by spring. A new, more urgent "Doors Closing" announcement also will be tested.

This is an important concept. I'm hoping it works here.

Transportation researcher Diane Mattingly contributed to this column.

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