Why can't they just install more speed-bumps? Scientifically calibrated so that they only cause damage to cars going beyond an acceptable speed for the particular intersection in question. I used to live somewhere hoons would regularly speed by; a speed-bump was built, and it put an end to such speeding almost instantaneously as all the hoons had their vehicles' suspension destroyed.
- Given the variety of suspension systems in cars (and available aftermarket options), trying to make a speed bump targeting one speed (or even a relatively narrow range of speeds) would be pretty difficult unless you want to limit all traffic to 10-15 mph
- Speedbumps on major thoroughfares can cause problems for emergency vehicles
- (from personal experience) riding over a speed bump (certainly ones that haven't been well-maintained) on a bicycle is not fun
- they make snowplowing more difficult (but not impossible)