Imentioned in an earlier posting that 3rd Rocky tunnel (centered at 35.85881, -81.99896), was opened up, according to Goforth, in 1977. It was originally about 420′ long. As Butch Adkins commented, this was to widen the area to extend a siding track, not due to any instability of the ridge.
This, however, is the very sturdy 4th Rocky tunnel, just 179′ long. This southwest portal is at 35.863089, -81.990881. No visible date on the lintel. We were rather tired by the time we got to this tunnel, having walked from 2nd Rocky down past the remnants of 3rd Rocky. It was only about 2 miles, but, then it was 2 miles back.
Blogging the Railroad Tunnels 
Bob,
My understanding is that that the 3rd Rocky Tunnel was daylighted in the 70s so that the siding could be extended. Thanks, Butch
You’re correct. I’d forgotten that. There’s now a double track through that area. Thank you!