> There is an entire very technical industry for this sort of thing. The industry being technical does nothing to prevent it's general rules from being dictate

> There is an entire very technical industry for this sort of thing. The industry being technical does nothing to prevent it's general rules from being dictated by politics. If an engineer does a study that shows no significant increase in injury by increasing the speed limit 10 MPH, I find it highly unlikely the city or state is going to approve it based on those findings.