Pragmatic rulemaking for large numbers of people also needs to take into account the fact that the rule will naturally be viewed as a loose guideline by some people, and even as a thing to be defied for its own sake by others. Setting the limit stricter than the actual desired behavior can push average behavior closer to the target.
> Setting the limit stricter than the actual desired behavior can push average behavior closer to the target.
Absolutely not, at least in the context of speed limits. Where I live, most of the speed limits are at least 15mph lower than they should be (why is a 6 lane road 30mph???), so you get:
* people who follow the speed limit exactly: 30mph
* people who follow the speed limit the road was designed for: 45mph
* people who see the limit as a "limit:" 25mph
It's a mess. Roads need to be designed to the desired speed limit. Don't make a 6-lane straight road 30mph; people unfamiliar with the area will assume the speed limit's 50% higher than it is, and people from the area will feel like they're going incredibly slow.
In short, it should be uncomfortable to go >= 20mph over by design if you want people to follow your speed limits.
