Speed Zone indicators in pavement

Idea first posted in GlobalIdeasBank. Just like the rumble strips that get you to slow down as you get closer to the border or an airport, only the rumbling is specific to speeds required by law. The faster, the higher pitch, the slower the lower pitch. Cuts in the road would be good alternative to reapplying layers of cement. Could be done with slightly different grooves of pavement as well, in alternating patterns to indicate speeds. Could be done with road turtles as well, or simply raised paint.