Dear Dr. Gridlock:

What are the chains I see hanging from the axles of school buses?

Kyle Thompson

Leesburg

They are adjustable devices that will whip ice and snow in front of the tires, giving them better traction.

I-95's HOV Schedule

Dear Dr. Gridlock:

Would you kindly inform me which days and hours the HOV lanes along Interstate 95 are open to the north and to the south?

Roger Mudd

McLean

The barrier-divided Interstate 395/95 HOV-3 lanes are open to everybody, including non-carpoolers, as follows:

Southbound:

From 1 to 3:30 p.m. and from 6 to 9 p.m. Mondays through Thursdays.

From 1 to 3:30 p.m. Fridays, and from 6 p.m. Fridays until 2 p.m. Saturdays.

Northbound:

From 9 to 11 a.m. and from 11 p.m. to 6 a.m. Mondays through Thursdays.

From 9 to 11 a.m. Fridays.

From 4 p.m. Saturdays to 6 a.m. Mondays.

HOV-3 hours are 6 to 9 a.m. northbound and 3:30 to 6 p.m. southbound, Mondays through Fridays.

Parents Should Teach

Dear Dr. Gridlock:

We recently moved to Virginia and are interested in recommendations for a commercial driving school. How much should it cost for classroom and behind-the-wheel instruction?

Jeff and Joanna Carra

Woodbridge

I suggest that parents take charge of basic driver training. Take trips during spring break and in the summer. Ride with your children until you feel they are ready to drive solo.

Put them in all sorts of basic and challenging driving situations: changing lanes, merging, interstate driving, nighttime travel, the Capital Beltway, stopping for an animal, snow, ice, rain, passing on a two-lane road, running off a road and getting back on, city driving, recognizing red traffic lights and parallel parking.

Simply reaching a 16th birthday is not a good reason to get a license. I suggest that completing 1,000 miles of local driving and 1,000 miles of interstate driving is a better barometer.

A Good Start

Dear Dr. Gridlock:

This is a fan letter to you and the Car Guys. Long before my daughter was old enough to drive, I decided she would take one of those daylong defensive driving classes you are always recommending. She took the Car Guys class on Labor Day weekend, and this morning it really paid off.

My daughter, who is still driving on her learner's permit, handled a very dangerous situation with skill and aplomb. Her dad and I are still scared, but she was fine.

She was driving south on Interstate 270 this morning from Gaithersburg to her bus stop at Tilden Middle School. Usually she stays in the right lane, but this morning we were running late, and my husband suggested she get in the carpool lane to save time. Just as she was moving into the lane, another driver attempted to enter it. He was aimed right at us.

My daughter quickly steered the car to the left and partly onto the shoulder, then smoothly pulled it right back. This is a traffic challenge that new drivers often mess up. They oversteer and go off the road, or they panic as they go off the road and jerk the steering wheel too far in the other direction. My daughter handled it like a pro.

Thank you, Car Guys, and thank you, Dr. Gridlock, for recommending them. I now have some reassurance that my daughter may be a safe solo driver when she gets her full license.

Melissa Yorks

Gaithersburg

Thanks for the feedback. Car Guys of Rockville can be reached through 800-800-GUYS.

I trust that you will continue with her training and will allow a license only when you are comfortable that she has the necessary skills to go solo. Sounds like she has made a good start.

No Butts About It

Dear Dr. Gridlock:

Another pet peeve is smokers who toss lit cigarettes out open automobile windows. This is personal, because I have experienced a lit cigarette coming into my car and burning my seat. It is a dangerous practice and could cause harm to others.

Rosalie Goosby

Dale City

What a disgusting habit.

A Vote for Cab Meters

Dear Dr. Gridlock:

I'm not a cabdriver or a frequent rider, but anyone who can count can see that what's fair is fair. A cab ride in rush hour is going to take longer and prevent the driver from accepting other fares. It should cost more -- otherwise, we're likely to find cabs disappearing during rush hour because they can't afford to run at a loss.

Riders do not want to pay extra to be stuck in traffic, but if cab businesses or employees are instead forced to absorb that cost, they'll have to either raise overall rates to compensate or stop providing the service.

Meters are the way to go.

Mark D. Hall

Mount Vernon

Somehow, cabs using the zone system are available during rush hours.

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 to receive e-mail, at drgridlock@washpost.com, or faxes, at 703-352-3908. Include your full name, town, county and day and evening telephone numbers.