Here it is, the north portal of the Highline tunnel near Cawood KY at 36.78308, -83.24311. It’s one of three tunnels between Cawood and Smith KY (where Hagan tunnel’s north portal is). This one is a little over 1,200′ and curved, so you can’t see the other end from here. Note the lack of facing, indicating that the rock here is strong. The line is active. And, as you see from the mile marker, 251 miles from somewhere.