Speed bumps are counter productive IMHO. They may cause a driver to slow down but they focus his mind on the road 30 feet in front of the car to the exclusion of everything else.
They put speed bumps on a bit of road I use to get to work. Now, this road is rather well to do but unfortunately has become one of the main arteries into a town. Lots of influential residents, I'd imagine, who don't like the level of traffic. It's a 30 limit but a long straight road and it's easy to let your speed creep up.
They've tried speed bumps, then ripped them up. Then they tried chicanes, but approaching drivers used to accelerate to get round before the guy coming the other way. 2 Guys decide to try the same trick and there's a head-on. So, they've now ripped them up.
Meanwhile the surface is shocking, it's all you can do to keep the car in a straight line. They've spent hundreds of thousands of pounds experimenting with schemes that don't work and now, seemingly, there's nothing left in the coffers to ensure that it at least has a safe surface.
Kevin