Callahan is a common name in this area.  There’s a Callahan Avenue in Appalachia and a Callahan Creek that’s near here.  I assume that is the origin of the name of this tunnel.
Anyway, this is the other tunnel on that old (1890) Fremont branch of the L&N line that ran from Appalachia to Big Stone Gap.  It’s been unused since 1986 or so.

This is Callahan’s Nose tunnel from the Appalachia side:

 

 

 

 

 

 

 

 

The short, 135′ tunnel is centered at 36.884670, -82.786329.
This is the south face.  The overpassing track is active N&S.

 

 

 

 

 

 

 

 

I took these when I was more interested in the pleasant hike from Appalachia to Big Stone Gap than I was the tunnels, but I took one picture because I was surprised at the brick interior of this tunnel (below).  I suspected that it showed that the tunnel was an older one and, surprise, I was right.  Bricking was an earlier technique of shoring up a tunnel.  After the turn of the century, they generally used concrete to ensure the integrity of a tunnel.  Enlarge the picture and you can clearly see the brick.