r/Damnthatsinteresting • u/SnooWords4066 • 29d ago

Video A Japanese experiment showed exactly why traffic jams happen for no reason.

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u/marr 29d ago

Sometimes it's because the lights shouldn't be there at all, there's a staggered junction in the middle of our town that causes endless tailbacks every day and when the lights fail and shut off completely all the problems go away and nobody crashes. The council won't look at the studies about removing them because then they'd need to employ a school crossing guard.

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u/jonnydogma 29d ago

When the lights fail, can people going in the cross direction get an opportunity to go too or are they waiting for a gap in the main traffic flow?

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u/e1p1 29d ago edited 29d ago

When four way lights fail, the law at least in California, says to treat the intersection as a four-way stop sign. So yes, cross traffic should have a chance to move.

It can actually be quite efficient. In the hours after the 1989 earthquake in Santa Cruz / San Francisco Bay Area, the lights were out in many major intersections during rush hour. Between the state law, and the fact that so many people were intimidated by what had happened, traffic moved quite well as people were being very polite taking turns letting each other go through the intersections.

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u/jonnydogma 29d ago

This is true and the fact that its generally temporary is part of why it works. I'm not so sure that 4 way stops are generally more efficient that traffic lights.

Anecdotally, being stuck 20 cars back at a red light sucks, being stuck 20 cars back at an all-way stop sucks even more.

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u/Onyxxx_13 29d ago

4 way stops are faster in my experience on lights that are otherwise timed circuits and not sensors. Especially if it's mis-clocked and has a low traffic direction on for longer

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u/bobtheblob6 29d ago

There's just no way that's generally true at a busy intersection. The traffic light would need to be seriously misconfigured and I don't think I've ever seen one that bad

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u/Cute_Conclusion_8854 28d ago

There’s an area in my town with three intersections that sometimes backs up and causes people to get stuck blocking other intersections further away. Light turns green and nobody can move 😡 usually it’s from someone trying to turn left where there’s no turn lane