The mass driver is capable of being rotated, so when I built it, I also made a road around it. The problem is, when I upgraded it to a galactic freight (which is not a rotatable building) the orientation changed back. Now I have it crossing the road, and I can't access the road to remove it, and I'm afraid any attempt to remove it will also destroy my galactic freight. I have not done any more testing, but I would assume it will cross on top of any other structure.