The best way to slow down motorists is a 3d speed bump. Not a 3d illusion of a speed bump - an actual speed bump. They have speed bumps littering the side streets in certain areas of Queens and Brooklyn. If you don't slow down, and take care, these large speed bumps will simply wreck your car - and they are much easier to install than these 3-d paintings.
That's not true, my car scrapes on them at practically any speed.
People with slightly higher cars than mine scrape because they try to brake, forcing their suspension to compress, then go over the bump.
There's so much ceremony to going over a speed bump that I think plenty of people not going that fast are inconvenienced. whether that inconvience is worth the net benefit is a separate issue.
Same hear, Nissan 350Z scrapes most speed bumps even going as slow as is possible.
Also, they don't work for a lot of cars - I see lots of cars (presumably without stiff suspension) fly over the things at quite high speed. It seems that at certain high speeds, if you straddle them just right, you don't have to slow down at all.
Yup, on cars with soft suspensions you can actually get more clearance by speeding up right as you reach the speed bump, since weight transfer will push the front end of the car up
Austin has some speed bumps that I didn't notice on my first visit. It felt like the transmission had dropped out of my rental. After that I was as careful as can be to watch out for them. Austin also has a nice concept of "Don't block the box" for their intersections. In my neck of the Midwest, people always wait in the intersection, and it slows down traffic immensely. You get a green signal, then have to wait for the three cars in the intersection to move...
Some of them are pretty awful, making the whole car shudder even when you creep across slower-than-idle. (This is typically the ones that look more like a 2x4 than a hump)
Well made speed bumps are like that, but it's full of badly made ones (too narrow or too high) that make your car jump and wreck your suspension even when going at half the speed limit.
