On roads around the world, how are safe speed limits decided and what factors go into making those decisions?

Question

On roads around the world, how are safe speed limits decided and what factors go into making those decisions?

In: 3

Answer 1

It’s supposed to be based on visibility and stopping distance. For example, if someone randomly pulls out of a driveway in front of you, you should be driving at a speed slow enough to stop before you hit them, starting from the time you see them. And it works the other way around, the person pulling out of the driveway should have enough of a time buffer to safely pull out, depending on how far they can see you from.

For highways the visibility is usually much better, which results in higher speed limits, but there’s still curves that may limit visibility. And at the extreme end, the curvature of the earth limits visibility.