Possible money made in an ambitious plan to move key train lines below ground in downtown Salt Lake City is emerging in a new study. The economic study by Utah State University reveals the move could generate as much as $12.3 billion. The money comes from moving more than four miles of railroad lines over a full city block and having them run below ground, making it easier to connect with public transit downtown, and redeveloping 50 to 70 acres in the heart of Salt Lake City, currently taken up by the tracks.