For roads I use a simple terrain.  I create the terrain's bumpmap and texture in Paint Shop Pro.  I make the main shader map first, then I save it.  Next I change the image to a greyscale and use adjust  brightness and contrast so the surface level point is at 50% grey.  I then save this as the bumpmap.  Use the terrain shader for the color, then use the bumpmap as a displacement map.  If you do it right, you should end up with a smooth road surface amidst the mountains.