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Everyone has their own pet theory of how people should behave in traffic. The problem isn't even that most of them are wrong -- most of them are "correct" in the sense that, if everyone behaved in this way, traffic jams would be less common and have shorter durations.

The problem is that you don't know which theories other drivers have, so you don't know how they will react to different situations. If you don't know how other drivers will react, you need to drive conservatively -- which usually means slowing down.

Take a construction merge down to a single lane. It might be the case that it's best to use both lanes up to the merge, so that the traffic jam takes up less space. It might be the case that it's best to merge as soon as you figure out what's going on, to provide more time for the merge negotiation and reduce the risk of accidents at the merge point.

In reality, it doesn't matter either way. If I try to use both lanes, I don't know that I'll be allowed to merge at the lane closure. If I merge early, I don't know if someone is going to use the now-unoccupied lane to zoom up and cut someone off, making both lanes slower and more accident-prone. I can't do either one and confidently say that I've made the correct choice, because I don't know how other drivers will react. What I do is just pick one, and slow down when something unexpected happens.

This article also generalizes some things incorrectly (it seems based mainly on German data, presumably because they have better infrastructure for measuring such). For example, I live in the northeastern U.S. We are notoriously bad drivers up here, even among other east coasters. Here, a two-second following distance at 65MPH is almost unheard of -- actually, a two-second front-to-rear distance probably qualifies as a "large space", as some people here seem to think such a space can fit multiple vehicles. That's about 100ft or 30m, so I suppose it technically can, but it is not safe.

I can react to this either by leaving a very large space (5-6 seconds seems sufficiently large that people get impatient and leave before it fills up) or by leaving a small space (.75-1.25 seconds is the largest I can leave and have a good chance of nobody trying to use it). The former is much safer, so that's what I do.

The key is that, over a period of about two minutes, I need to maintain this following distance relative to the same vehicle. Usually this is fine: at most three cars tend to use that space at a time, and if anything they're more likely to tailgate the vehicle I'm following than to stay back near me. Occasionally I need to slow down in a situation where many vehicles fill that space, or someone moves in and immediately slows down. This is the exception, rather than the rule.

Yes, I know this behavior can cause traffic jams under certain conditions and with certain other drivers -- but so could the alternative, under other conditions. Given the choice between two bad options, I optimize for my personal safety.



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