The word "slug" generally doesn't conjure up anything positive. Slugs are slow, slimy things that don't seem to serve a real purpose. Except for the slugs that line the Interstate 95 corridor in Virginia.

The Washington, D.C., region is part of an unusual, self-perpetuated social experiment called slugging. You may think of it as glorified hitchhiking or casual car pooling, but most would have to agree: It's a success.

Here's how it works: At the numerous commuter lots along the I-95 corridor, and at a number of commercial lots as well, people gather for rides. Drivers who need an extra passenger or two to qualify for a quicker commute in the high occupancy vehicle (HOV) lanes will pull into these lots looking for passengers.

Most of the lots are organized to the point that potential riders heading toward Rosslyn will gather on one side of the lot, riders heading to the Pentagon at another, and so on. Much of the information is passed by postings on bulletin boards at the offices, by word of mouth or on one of the three Web sites that have grown up to serve this audience.

The riders get a free ride into work, and the drivers get to use lanes that are generally less congested and move a bit quicker. It would seem to be a win-win situation.

Why such a goofy name?

Here's the best explanation I've heard for the name: Slugging started in the early 1970s, when Virginia opened the first HOV lanes. Back then, just about all of the bus fares were paid in coins and bus drivers were taught to watch for counterfeit coins, or "slugs." Because there were few, if any, commuter lots, many slugs gathered near bus stops in order to get rides. It was the bus drivers that began to call these "counterfeit" commuters by the name that has stuck for 30 years: slugs.

Things are very confusing now at the Pentagon. They have one line for the entire slug community. I know my country is at war, but didn't the president tell us to get back to normal? The Metro has returned to normal. Isn't there a reason to return the slug lines back to normal as well?

- Pablo, Occoquan

I agree with you to a degree, Pablo. But I think everyone would agree that it's much better to err on the side of safety. The slug lines started being moved further away from the main building about a year ago as the bus stops were being moved. This is all done in the name of safety and doesn't reflect any slight on the part of Pentagon officials.

Many of the planners at the Pentagon actually appreciate the ability of slug lines to reduce the number of cars in the parking lots. Fewer cars make the job of managing traffic throughout the complex a bit easier.

I'm told it could be a while before the multiple pickup points come back. If this is confusing, perhaps some of the slugs could organize and go back to one of the areas in Pentagon City. Several were set up after Sept. 11 when the Pentagon parking lots were shut down or severely restricted.

Let me know what happens over there.

I mentioned that there are several Web sites that serve the slugging community. These sites have everything, from breaking news (usually changes in lot availability) to lost and found to complete guides on slugging etiquette. You can find the sites at www.slug-line.com, www.slug-lines.com and www.slugvirginia.com.

Many of the commuter lots along I-95 were added because of the Springfield "Mixing Bowl" construction. I think they did this to get more people to use public transportation and to car pool. What's going to happen to those lots when the construction project is done?

- Mary, Lake Ridge

That's a really good question, Mary, and I turned to the Virginia Department of Transportation's Joan Morris for an answer.

"Those lots are staying," Morris says. "When we started construction of the Mixing Bowl, we planned on adding 1,200 spaces. But we've added 2,400 spaces already and have many more on the way. In fact, we will have a total of 15,000 spaces along the I-95 corridor between Fairfax and Spotsylvania counties."

At the same time, Morris points out that some of the lots are being leased by VDOT and the leases probably won't be renewed when the construction is finished. One of the leased lots is at the Macy's store at Springfield Mall.

VDOT is also in the midst of studying all their lots and looking at where they might expand. One of the lots still underutilized is the one at Route 123 and I-95. This 700-space lot went through a major renovation last year in an attempt to make it more accessible.

Lastly, if you're wondering why slug lines don't or won't work elsewhere, consider this. Many of the riders and drivers work for the same company: the federal government. The three-passenger requirement makes it more difficult for drivers to qualify. Finally, the HOV lanes in the corridor have limited access; there are only a few places where a driver with bad intentions could divert course.

Slug lines aren't for everyone. You have to be able to deal with numerous personalities and driving habits. There are stories about cars with old food and other trash in them combined with drivers who seem intent on beating everyone to the exit.

But more often than not, people enjoy them and they work. Thirty years of experience should prove that.

Steve Eldridge is a veteran traffic reporter in Virginia, Maryland and Washington. For more Sprawl & Crawl, tune in daily to WTOP-FM 107.7 or WTOP-AM 820 or 1500. Send questions or comments to Sprawl and Crawl, The Journal, 6408 Edsall Road, Alexandria, VA 22312; e-mail to steve@sprawlandcrawl.com; fax to (703) 846-8366.