Interesting concept that will need some major testing for vehicle braking distances but I guess that could lead to a new type of tyre.
Much consideration of other utilities would have to be applied, covering over Gas, Water and drainage services could cause major headaches when it comes maintenance. It's not like you could dig a whole in a Solar Panel Road.
I suppose if your road structures are made wide enough other services could be installed outside of the roads stress area's but undoubtedly they will cross at some point.
If you are building a new town or highway, with careful planing these problems could be largely overcome at the onset.
Replacing existing highways might prove costly so the long term costs of maintenance will need studying thoroughly.
The city engineers are just going to love Scott Brusaw but as for the guys who paint the white lines, well they might not be so keen................
Ever lost a raffle ticket? then wished it wouldn't win?[b]