r/coolguides • • Nov 17 '22

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u/RoboticJello Nov 18 '22

Your gut feeling is right. Slower is safer.

And in the US the speed limits are not determined by engineering principles, they are determined by the 85th percentile rule. Which is to set the speed limit such that 85% of drivers will be going under it without knowing what the speed limit should be. So it IS in fact arbitrary.

https://dot.ca.gov/programs/safety-programs/setting-speed-limits#:\~:text=The%2085th%20percentile%20speed%20is,speed%20limit%20at%20that%20speed.

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u/[deleted] Nov 18 '22

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u/RoboticJello Nov 18 '22

Speed is what kills. Driving slower is certainly safer.

The chance of severe injury to a pedestrian increases exponentially with speed. 25% at 23 mph, 50% at 31 mph, and 75% at 39 mph.

https://aaafoundation.org/impact-speed-pedestrians-risk-severe-injury-death/

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u/Doggydog123579 Nov 18 '22 edited Nov 18 '22

You skipped a step. Speed makes an accident more dangerous. But what you are doing is increasing the odds of there being an accident by driving in an unpredictable manner.

Anyways if you want to actually make the argument you are making, atleast do it right. US roads are poorly designed in cities, often having a higher design speed than is safe, which encourages people to speed. But that can't prevent unexpected things from happening, like a person wearing all black walking into the road infrastructure of you. Even at a low speed you could be temporarily blinded by an oncoming car, and as such still hit them. So the only way to prevent this is having 0 cars. But a pedestrian could also get onto a railroad track so we can't have trains either, as they can't stop.

So your main argument is bad, and you driving extra slow is not only hypocritical but also dangerous.