You can also align the shapes to the terrain, and give it a little vertical offset, so that it doesn't sink into the terrain. This process can benefit from some manual cleanup after import. Just select the move tool, and grab road nodes and/or segments and adjust them up and down until it looks clean.
Can't really get this 100% right. I upscaled terrain resolution and its better but still off. In the graphics engine I am using I smooth it out a little further but doesn't look quite right for a ground level view.