I don't see the point in the smaller speedbump, I see some people take the ones on my road at 5mph, and then accelerate back up to 15-20mph in between, whereas I did a test at the weekend with my friend, and we could drive at a constant 45mph over them no problem. Less comfortable but there's no reason to actually slow down for them, considering it's a 30mph road. Long term effects are more concerning, though.