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Why does everyone drive 10-15 miles above the speed limit?
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Why don’t we raise the speed limit if that’s how fast everyone wants to go?
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Why is traffic enforcement given to very expensive and ineffective police instead of cheaper and more automated traffic cameras?
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Why do we refuse to ever use ANY traffic calming measures? Yes, than you flashing digital sign for telling me I’m going 10 miles above the limit on this incredibly wide and straight and flat road with high curbs and perfect visibility.
It’s a serious confusion I have about how society is supposed to operate because it seems like a complete and total breakdown of logic and sense.
And, yes, I know there’s some thing people did long ago to set the speed limit at some percentile of what people were already traveling at, but that’s obviously a stupid way to do it and we did it anyway. So why?


This isn’t really unique to the US. In my country people also consider it their right to drive above the speed limit and hate the police for telling them they can’t do it…
Because then everyone would drive above that new limit instead. It’s a psychology thing. It’s not that everyone would rather go speed y than speed x, being above the speed limit is the very point to it. Otherwise you’d see different behaviors with different speed limits, but at least here, every speed limit sees the same behavior of people not respecting it by the same amount.
I’m not so sure about that. If the speed limit in my neighborhood was 80mph I don’t think I’d be going that fast much less above it. If the nearby interstate reduced the speed limit to 25mph I don’t think I’d naturally be driving it at 35-40mph as you state.
In my experience, it’s more a thing that I think many people disregard the speed limit for the most part and have a certain speed they feel is natural and comfortable for them to drive on a given road in a given situation.
Going through the neighborhood? Some people think 15mph, some think 25mph, some think 30mph. See some kids playing on the side of the road? Most people generally would slow down a bit. Roads are tight and narrow? Well now I have to be a bit more careful in this area so I need to slow down even further.
In my experience the psychology trick has everything to do with the road, what’s around it, the condition it’s in, etc, and less to do with the sign itself.
Well, I think both of you have a point. The problem with “most people would slow down” is that this means dead children because of those who don’t.
Speed limits to have a role to play, however much better than a sign is indeed to create roads that naturally make people drive slower. Countless streets in Europe have been redesigned according to that principle, the most systematically in the Netherlands. Why? Because it works and it saves lives.
The US requires roads to built in a way that the “natural speed” would be insanely high, even in purely residential areas.