Better late than never. If this tunnel was right off of the upper switchback track that heads for mount Pisgah it was most likely not a coal mine but it was actually the Hacklebarney tunnel. This tunnel is west of mount Pisgah, there used to be a small trestle on the switchback to get over the rock face that the tunnel is driven into. It is still wide open with some water draining from it. If I am correct this was one of the first tunnels in the southern coal fields and may have been used to search for uranium in the Pisgah mountain.