Dear Dr. Gridlock:

I spent a week driving with my family across Southern California. Most of the drives were, unfortunately, during morning and evening rush hours. But I experienced very few instances of totally congested highways.

The reason for the good driving experience was the extensive use of left-side Carpool-2 lanes, combined with the larger number of other lanes to handle drivers who were not carpooling.

There may be several things we can learn from the California highway system:

1) More than 700 miles of the highways in Southern California reserve the left-most lane for Carpool-2 (same concept as our HOV-2). There is almost always a Carpool-2 lane available, and many times they have their own access and exit ramps. The two-passenger requirement is in effect at all times.

The lanes are separated from the center and right lanes by a double yellow line. You can enter or exit a carpool lane only at designated areas.

On average, Southern California commuters using the Carpool-2 lanes save 36 minutes each day.

2) According to both the California Department of Transportation and the California Highway Patrol, the violation rate on most Carpool-2 lanes is extremely low. The main reason is that Carpool-2 violations result in a minimum $341 fine. The second reason is that the police actively patrol and enforce the carpool law.

— Gordon Jarratt, Oak Hill

The two things I like best in Jarratt’s description: The separation of the lanes and the heavy fines for violators. The most successful HOV lanes in the D.C. area are separated from regular traffic. Those are the lanes on Interstates 95 and 395. The least successful allow cheaters to weave in and out. Interstate 66 is an example.

Most of our carpool lanes provide very little room for safe enforcement, and that’s another problem. A few years ago, Virginia increased its fines in response to complaints about cheaters. The fine for a serial offender is $1,000 plus three points on a driver’s license, but the first-offense fine is only $125.

We won’t wind up with an HOV system as extensive as California’s. Our planners are adding tolled lanes or a hybrid of HOV and tolls, when they add lanes at all.

Targeting tailgaters

Many drivers responded a letter about bad driving behavior [Dr. Gridlock, Dec. 15] by offering strategies to combat tailgaters.

Dear Dr. Gridlock:

I have one that works beautifully. I simply lift my foot off the accelerator when someone is following too closely, and the car s-l-o-w-l-y  slows down; it isn’t long till the tailgater can’t stand it and goes around me. This is also safer than tapping the brakes off and on as some do.

— Diane Martin, Ashburn

Dear Dr. Gridlock:

I have found that using flashers or brake tapping will likely increase the chances of an accident already on the threshold of happening. I have discovered quite by accident that when I hit my windshield washer, the excess sprays up and over my car and onto vehicles following too closely, causing them to activate their wipers.

Usually, I need to clean my windshield just a couple of times before the offending tailgater backs off or moves around.

— D. Edwards, Springfield

These solutions are recommended by many drivers, and can be effective. I like that they’re not responding to aggressive driving with more aggressive driving. Edwards, for example, notes this already is a dangerous situation and strives for a measured response.

Be the adult.

But I worry that even such low-key measures still require drivers to pay too much attention to what’s happening behind them, diverting their attention from the road ahead.

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