Google earth works if there is topo data. Plus a road usually will not follow the incline of a hill that's why we have switchbacks.

Yeah a hill looks vertical but the actual road not so much. If I am not mistaken, Peru or Bolivia one of those countries have really long steep roads. They are also not paved. I think there is Canton street in Pittsburg s considered the steepest street that is paved. It really is. Visited it last year on a trip there. It it is short but I imagine keeling over if you don't do it right.