kitty2 wrote:
Depends on the road and the purpose of that road, asphalt with motorways/highways, sand or clay on the country side and stones with pavement and some roads surfaces have signs on it (white lines, right of way etc).
It also depends on the country and the temperature range the road surface will be exposed to. To answer "tarmac" as some have done is also technically dodgy as generally true tarmac is not used, it's normally some sort of asphalt or bituminous macadam for a flexible road pavement.
But whatever the technical accuracy of the above, the road surface per se is the top of that material. I suppose you could argue for white lining, but as that is bonded to the material below, it becomes part of that surface. So, I'd suggest that the correct answer would be that which the road surface is designed to take, namely vehicle tyres or water.