The best "traffic calming" device I've encountered is a thing called "speed tables." A neighborhood in Alexandria where a friend of mine lives has them. Basically, they're a shallow ramp up to a bit less than the height of a speed bump, a flat surface (with some round bumps, I think) for three or four feet, and then a ramp down. They seem to work remarkably well for making it so you can comfortably drive at the speed limit (25 mph there) but not faster. (Unless you have some idiot in an SUV in front of you who, despite the fact that they've bought a vehicle that pretends to be able to go off-road, still slows down to 5 mph for any obstruction, grrrrr...)
Ah! One of my big beefs with most "vertical" traffic-calming devices is that they seem designed to make people slow down below the posted speed. One that makes it possible to drive at the posted speed comfortably but not faster sounds like a win on that score. (My other big beef has to do with most being bicycle-unfriendly. I've got scars from a speed bump that the paint had worn off of that I encountered just before dusk in college.)
A couple blocks from here they installed another "lateral" traffic calming device a few months ago. A really tiny traffic circle. Yeah, it means people can't fly through the intersection any more. It also means trucks can't fit through there (which may have been the point -- I don't know which route trucks were taking to the Safeway down thataway). But I'm not sure fire engines fit through there either, and that's in the Arson Zone of SW Baltimore! Furthermore, it's made the intersection more dangerous, between the folks who just don't understand how to drive a traffic circle (including the bit about yielding to cars already in the circle), and the ones who want to turn left but don't notice that the tiny little thing is a circle and not just a funny island (thus going the wrong direction around it). I've had several near misses there since the circle went in; none at all before then.
Traffic Calming
Re: Traffic Calming
A couple blocks from here they installed another "lateral" traffic calming device a few months ago. A really tiny traffic circle. Yeah, it means people can't fly through the intersection any more. It also means trucks can't fit through there (which may have been the point -- I don't know which route trucks were taking to the Safeway down thataway). But I'm not sure fire engines fit through there either, and that's in the Arson Zone of SW Baltimore! Furthermore, it's made the intersection more dangerous, between the folks who just don't understand how to drive a traffic circle (including the bit about yielding to cars already in the circle), and the ones who want to turn left but don't notice that the tiny little thing is a circle and not just a funny island (thus going the wrong direction around it). I've had several near misses there since the circle went in; none at all before then.