I like driving on the I-5—and it’s not just because I end up liking the things I do often enough (I’ve been visiting my parents more often since I, ah hem, learned to drive long distance, rather than flying; ‘turns out the hours saved in flying between Norcal and Socal are minimal, and I’ve recently driven on the I-5, attending the nEDM collaboration meeting). It’s because, well, because I like analyzing the two-lane system that is the I-5 (for most of the way).

It’s a simple system with just enough complexity to make it interesting—while making the problems tractable (I believe it was Prof. Commins who pointed out that 3 Nobel prizes have been awarded for works on two-level systems). There is an interesting dynamic there. Here’s a couple:

Generally, there are at least 3 different types of cars and drivers on the I-5: the trucks (which go at the speed limit of 55 mph but usually around 60 to 65 mph), the … lawful drivers (who either drive at the speed limit of 70 mph or just above), and the speedsters (go at 100 mph, that’s usually the top of the range most of the day). But there are only 2 lanes, with the right lane being occupied by trucks. Because of this, the following dynamic develops. The careful, lawful drivers tend to take the left lane and stay there—so those who drive (and want to drive) fast are more often found on the right lane, trying to pass the cars on the left in-between the trucks. Never mind the driver’s ed class that teaches if you are getting passed from the right, you should change lane to the right!

Sometimes, there are constructions, and the two lanes merge into one lane for a bit. Before the point of merge, do you know which lane moves faster? It’s the right lane, the lane with trucks. I’ve hit this traffic jam a couple times last year while visiting my parents, and I had it reasoned out this way: at the point of merger, the cars in two lanes alternate in merging into one lane—after all, that’s the courteous thing to do. However, while the truck gets counted as one car in that accounting, physically, they are much longer than other cars, so, right lane simply ends up moving more meters per merger—sometimes I wonder why the cars in the left lane stay in the left lane.

Anyways. I admit I’m a bit of an aggressive—and fast—driver (I’m a safe driver; no ticket—that I didn’t fight successfully in court—or accident in 10 years of driving). And I’ve found that in weaving between the traffics, the key is in figuring out the intent of the driver, as quickly as possible. I mean, all cars on the I-5 (that are not trucks) can go at 70 mph like the speed limit says, or at 80, 90, or even 100 mph. What limits the speed is how much the driver is willing to step on the pedal. Where this matters is this: you are in a row of 3 cars, just passing a truck on the right, and the car in front of you changes the lane to the right after passing the truck—do you follow that car, or do you stay in the left lane, which is the ironically slow lane? The problem here is that there are two equally valid reason for the car in front of you to switch the lane to the right—he perceived the cars behind him wanted to go faster and yielded at the earliest chance; or he thought that the cars in front of him were to slow and wanted to pass them.

Although this hasn’t been right 100% of the time, I’ve found that the cars that don’t accelerate immediately after switching lane belong to the former—and I’m better off staying in the left lane, at least until we pass that car, because a driver wanting to drive faster will start accelerating immediately when he has a clear space to accelerate.

Anyways. I don’t want to go on and on—but I just like driving on the I-5—although I think I’ve started getting the hang of the wider freeways with 4 or more lanes; one thing I’ve found when hitting a moderate traffic: switch to the right lane as necessary; never decelerate to a complete stop (unless you want to get stuck in the lane, unable to switch because the cars in the other lane are coming too fast).