Municipalities do not do much to slow traffic. The might put up a slower speed limit sign, and post traffic copes - but the cynic who says this is about revenue not slowing traffic has a good point. There are plenty of real ways to slow traffic known in traffic engineering circles, but they are rarely implemented.
You are not in Southern California then. Traffic circles and road humps are quite endemic.
This is sufficiently common that I could use road humps as a proxy for "Am I going the correct direction?" back before nav systems. Maybe you weren't going the completely right direction, but a road hump (or traffic circle) meant you were on a road sufficiently useful that it needed a traffic calming measure.
Cities with winter have extra considerations, though.
