Speed sensitive road humps sound expensive. All it needs is to modify the shape to a gentle sine curve, instead of a sharp steep slope on each side of the hump.
The latter are most common and hated, the former are rare and quite OK at a moderate speed.
Moreover, even the horrible kind are not consistent. I could quote you some which are really vicious at any speed.
So spare us yet more cost on fiddling with roads instead of real improvement, please.
John Gray (M), Warwickshire, jericgray@hotmail. com.