Obviously this would be a great addition. Of course its would be mainly for racing side of the game, and would solve many problems with cheats, just like the tyre walls. Also these are used in real circuits across the world and its a shame these are not in the game. I have noticed though that rumble stripes, as there called usually, are used perminantly on one of the tracks. So if these are already in the game surely they could be edited.
So i agree with the idea, as it has so many pluses for all sorts of LFS uses and not just racing! 10/10!