Merging on highway can be efficient and polite

When you think about economics and mergers, you probably think about merging two companies into one, a la Boeing and McDonnell Douglas. But lately I’ve been thinking about the kind of merging that involves traffic lanes and honking. Such thoughts usually come after I’ve courteously merged early into a single lane – just like the equally courteous driver in front of me – and I’m left wondering why some clown is rocketing past me in the empty lane and jumping the queue.

Drivers around here are notoriously polite. Still, that one queue jumper somehow cancels the goodwill generated by 100 more courteous folks. It’s time to redefine our local merging customs.

Suppose we were designing a computer system to drive everyone’s car. With no human drivers, questions of politeness wouldn’t matter, so we’d go for pure efficiency. In other words, we’d do whatever made the greatest use of our limited road space.

When the roads are empty, it makes sense to merge early – just as soon as there’s open space. But what about when the roads are crowded, so that merging two lanes into one means creating a slow spot?

The efficient merge point is all the way at the head of the line, at the point where the two lanes actually begin to join into one. When we all merge early, the last few hundred yards of one lane go to waste. The space in that lane is there for us to use: We should use it! If efficiency was all we cared about, we should drive all the way to the end of the disappearing lane before merging.

But please don’t change your merging habit yet! What counts with traffic rules – as with many customs – is not so much the particular rule, but that we have a shared understanding of what the rules are. It’s far more critical that we all agree on where to merge than it is that the merge point be perfectly efficient. In the Northwest, our custom is that we merge early.

It would be nice to change our informal, local understanding so that both lanes continue to the actual merge point. Not only would we make better use of scarce highway space, but we’d eliminate the irritation caused by queue-jumpers because there wouldn’t be any queue to jump.

Unfortunately, social convention isn’t the kind of thing that any one person can change. And surely we don’t want to discourage courtesy on the highways. More generally, “Northwest nice” is a precious commodity. The issue is not to have less politeness – rather, the goal is to change our unspoken agreement about what customs constitute polite behavior to behavior that’s a little more functional.

Here’s something that might do the trick. How about identifying the dozen or so worst merge spots in the state and putting up two signs at each of them? The first sign should say something to the effect of “Lane ends soon – don’t merge yet.” The second sign, at the merge point, reads “Merge now.”

Once the transportation department puts up signs, it signals to everyone that we should drive up to the front and that delaying the merge to the last minute has become the polite thing to do. Life on the highways will be a tad more efficient and, having eliminated the irritation caused by queue-jumpers, a touch more relaxed as well.

Dick Startz is Castor Professor of Economics at the University of Washington. He can be reached at econcol@u.washington.edu.