David Propes, left, and Richard Hensen, operate the massive excavation machine, "Harriet," as it digs beneath the limestone floor of Biscayne Bay Tuesday, March 13, 2012 in Miami. The $1-billion Port of Miami Tunnel is expected to be completed by May, 2014. It will connect the port with Watson Island. (AP Photo/El Nuevo Herald, Roberto Koltun)