THE RIGHT THING: FOR WHOM THE BOOTH TOLLS

"If they don't know how to merge, they shouldn't be on the road," my wife often mutters -- if you consider a mutter an utterance that could be heard from several cars over through closed windows -- when we get stuck behind a line of traffic that bottlenecks because of drivers who don't know how to seamlessly move from two lanes into one.

As a native Bostonian, my wife learned to drive among those whose offensive-driving skills are legendary. She knows the ways of the road, including who has the right of the way in a rotary -- or a roundabout, depending on where you live -- and, while she can get from any point A to any point B faster than I can, she's never had a speeding ticket. There was the time that a stray policeman's horse crashed into the back of her Chevy Impala as she was waiting at a stop light on Dorchester Avenue, but no one could have seen that one coming.

So when a question about proper toll-booth ethics arises, I turn first to my wife.

Here's the question: If there are only three booths accepting cash and a long line at each booth, what obligation, if any, does a waiting driver have to someone who drives past in another lane until, right before the booths, he or she signals a desire to cut into the line of waiting cars, all of whom have been waiting for much longer than has the new arrival?

My wife ponders the question, but before she can answer I introduce an additional consideration: Does it matter that there are always big signs warning that backing up at a toll booth is illegal?

And then, as she's about to utter her pronouncement, I add a final twist: Does it make a difference whether the driver was clueless until the last moment or simply too impatient to wait in a long line?

My wife's answers, based on her estimable knowledge of the road, match my own take on the ethics of the situation.

First, a waiting driver has no obligation to let another driver cut into line in front of her. She earned the place she occupies fairly, and is not obligated to give it up to another driver simply because that driver has placed himself in an awkward position.

That said, because the cutting driver cannot legally back up at the toll booth, it could present a traffic hazard not to let him cut into line. The driver may have been heading to a booth that registered scanning devices and not have realized until the last minute that he was in the wrong lane. If he doesn't get out of that lane, he could be in the way of other cars, especially if other drivers make the same mistake and the line to cut builds up.

Because safety is an issue, despite the absence of any ethical obligation to give way, the right thing to do is to let him cut into line in front of you. Fairness to the drivers who have waited patiently behind you comes into play, but safety trumps patience in this scenario.

The situation is different in a grocery store, where there is no meaningful safety consideration. There it's wrong to let a person cut in front of you when there are people waiting behind you, unless they too give their OK.

My wife and I agree that it does make a difference whether the driver was clueless or simply too impatient, at least in terms of how we feel about yielding, but that, by the time he's up there waiting to cut into line, the safest course is still to let him in. One incivility should not breed another, particularly when safety is at stake.

And, my wife adds, it wouldn't kill you to turn off your windshield wipers when it's raining, so that the toll collectors don't get soaked.