I don't think there are major technical issues. The issue is the scale, which requires a construction effort probably spanning decades. So if they really do s

I don't think there are major technical issues. The issue is the scale, which requires a construction effort probably spanning decades. So if they really do start building it they'll likely start from one end and build it section by section until either it's complete or they give up. Even 1km out of the 170 will result in a very large building.