Dear Dr. Gridlock:

Why do so few people use turn signals anymore? There seems to be some sense that they are optional, but I thought you had to use them any time you make a turn.

— Julia Johnson,

Chevy Chase, Md.

More and more drivers are writing in to say they see fewer and fewer motorists using turn signals. Drivers should use them for all turns.

Johnson is from Maryland, so here’s what the Maryland driver’s manual says: “Other drivers and pedestrians on the road must know what you are going to do if they are to keep out of your way. You let them know through hand signals, turn signals, headlights, brake lights and by the position of your vehicle.”

This is pretty basic stuff but worth noting during the holiday season, when so many people are out walking on their gift-buying missions. Turn signals aren’t there to declare a driver has the right of way so others should swerve, brake or leap out of the way. They show a driver’s intentions. That helps other drivers and cyclists, and it also helps pedestrians at intersections.

The Maryland manual makes a follow-up point: “Don’t trust the other driver to do what you think he or she should do or what you would do in that person’s place. For example, if the person’s turn signal is flashing, don’t assume that the driver will make a turn. Plan ahead and decide what to do if the driver does not turn in the direction shown by the turn signal.”

I like citing the driver’s manuals, because they’re full of practical wisdom that many of us forgot long ago.

Which lane is right?

Dear Dr. Gridlock:

You state that slower-moving traffic should be on the right. Can you enlighten me as to why in the United States there seems to be no interest in encouraging driving according to this principle?

When we were in France a decade ago, we traveled on expressways where there were three lanes — fast, medium speed and slow. It worked wonderfully. Here, there seems to be no attempt either locally or nationally to encourage this kind of driving, much less mandate it. Is this another example of Americans not wanting the government to “interfere” in their lives?

— Wayne Bert, Arlington

Since Bert is in Virginia, I’ll cite the Commonwealth’s manual on this one: “If you are traveling slower than the traffic around you on a multi-lane highway, drive in the right-hand lane.” That’s standard guidance for drivers. Maryland puts it this way: “You should keep to the right, except when your vehicle is about to overtake and pass another vehicle or cyclist, or to make a left turn.”

Here again, these are very sensible instructions. Crashes are more likely to happen if drivers are traveling at very different speeds in the same lane. If a motorist is going so slowly as to create a problem for other drivers, a police officer could issue a ticket for impeding the flow of traffic.

Those of you who participated in the great Thanksgiving getaway and drove far from D.C. on interstate highways probably saw most drivers playing by these rules. In fact, travelers sometimes write in to describe highway signs that say, “Slower traffic keep right.”

It works well when the traffic volume is relatively low, and I agree it’s the proper way to drive on highways under most circumstances. But I have several concerns.

First, there’s no provision that says it’s okay to speed in any lane.

And there are plenty of times in the D.C. area when drivers will use the left lane for reasons other than passing. For example, a Virginia-bound driver on the Capital Beltway’s outer loop approaching the spot in Bethesda where traffic on the right splits off for Interstate 270 is probably going to favor the left lanes.

And we have way too many left-hand exits and entrances where drivers will encounter other drivers who are accelerating or decelerating. The ramp that leads from eastbound I-66 onto the inner loop is a notorious example.

Also, given the traffic volumes on the Beltway, I-395/95, I-270 and I-66, it doesn’t make sense to post signs saying they’re for passing only. Imagine how much more congested those highways would be at rush hour if the left lanes were kept clear for “passing only” traffic.

But you can’t imagine that situation. You know that as lanes become more crowded, more traffic moves over to the left. The drivers may be doing so with the hope — the dream — of passing the cars in the right lane, but it’s not to be. The volume is just too great.

Finally, the lead driver in the left lane may indeed be passing the car to the right, just not as quickly as the trailing driver would like. That’s not the same as driving slowly in the left lane.

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