The Economics of Traffic

The Economics of Traffic

The other day I was stuck in traffic coming down 26 into downtown Portland. There are 3 lanes, and immediately after my favorite tunnel in the whole world, they split. The left lane heads north, and it's usually not too backed up. The middle lane heads into downtown Portland, and it's usually the fastest lane. The thrice-cursed, deeply-dreaded right lane heads south, and it's almost always the lane I need to be in.
So, one of my biggest pet peeves has long been people who crowd into the faster-moving lane to get ahead of everyone else, then cut back in near their exit. I'll call 'em SJDs... Selfish Jerk Drivers. That's more polite than the words I generally think of when I see them. Anyway, cutting ahead via the faster lane is the road equivalent to going to the front of the line at a theater and cutting in front of someone, with the defense, "They're stupid to stand there and wait. Smart people don't wait behind all the stupid people." But in a theater line you aren't protected from the social disapproval of cutting in line. In a car you only have 3 or 4 seconds of potential eye-contact with the people you're cutting in front of.

I make the drive into Portland from Beaverton a lot. *sigh* An awful lot. When I have to do it during trafficky times I get lots of time to contemplate the ethics and efficiencies of traffic. I recently discovered some things that I hadn't realized before.
There are two societal goals in traffic. One is to get as many vehicles through the choke-points as efficiently as possible. (I'll refer to all vehicles as "cars" from here on out 'cause it's shorter to type.)
The other goal is to not force some drivers to pay a disproportionate "stuck in traffic" tax. That's what cutting in line does, by the way... the SJD gets through quickly by giving his Stuck Time to everyone he cuts in front of. This seems like a minor burden... he saves ten minutes of waiting and each person he cuts in front of only increases their wait time by a few seconds. Problem is, there are dozens of them, so the sum Stuck Time stays the same. And the more SJDs who cut in line, the more all those waiting folks' Stuck Time skyrockets. It's super-frustrating to watch car after car cut in front of your line after you've been sitting in the right lane for the last mile (it's No Lane Change for about half a mile, but the Selfish Jerk Drivers ignore that).
So, should all drivers sit in the slow lane when they know they're gonna have to be in that lane eventually? I used to think so, but then I analyzed further! Yeah, I know, not so exciting. It's a long, boring drive. I can't imagine this is interesting to anyone who isn't actually stuck in traffic.

The whole traffic problem is created by choke-points. Too many cars need to get through a choke-point, and that backs things up.

So, if you can avoid a choke-point, go for it! If you have a way to bypass the part where everyone has to slow down and wait, you're helping the situation without simply discarding your Stuck Time onto someone who isn't as inconsiderate as you are. In the case of 26-into-Portland, there's a good way to do this. Take the center lane, and instead of flying your SJD colors at the road-split, stay center. You can then get back into the same lane you were in after a few turns, and you aren't contributing to the choke-point, you're sailing past it. Yay!
Unfortunately, that's really the only ethical way to help out. :( If you have to take the choke-point, your most ethical choice is to get into the correct lane quickly and accept your Stuck Time so that all the cars you pass don't inherit it from you.
I've read studies talking about how it's more efficient to wait to merge until the last second, which makes sense in theory but doesn't really work that way in practice, 'cause the SJDs rush to the front and then cut in.
Because I deal with this so frequently, it's a big issue for me. If I'm in a car that speeds ahead and then cuts into traffic, I become most irate with the driver. If I don't absolutely have to get somewhere quickly, I'll make them drop me off and I'll find my own way to where I'm going, rather than be a passenger in a SJD car. If I was at a theater and a buddy dragged me to the front of the line with him while he cut, I'd refuse to participate. Being a passenger in a SJD car makes it harder to refuse, but it's important to me so I make a big deal of it.
If you've actually read through this (what's wrong with you, anyway? This is super-boring!) then you're now aware of the impact of pulling a SJD around me. It drastically lowers my opinion of people when they do it. :)

(Facebook Note from 4/09/2009)