It wouldn't work on any .ter, as you need to start out with a smooth enough fractal to allow for a smooth road. Build the terrain on either side up with additional fractals (or maybe a generated terrain or .ter). In fact I used a fractal setup shown in another recent thread about extreme settings. So it's all procedural. And as for the steepness; that's just a matter of hitting the right seed or decreasing the size differences in the fractal. I think this is a perlin PF with sizes 900/5000/90 or so, displaced 300m. If I use 200 instead of 90 the road smooths out of course.