Its a tunnel. The Frankfort station is just behind me on the other side of the tracks, It's still there. This is a very scenic line, I;m surprised that R J Corman doesn't run a Dinner train on it.
Yep, this tunnel is why this line never saw more traffic in later years. It will not clear auto racks, and because ther are city streets and residences over top it was not deemed worth the cost to raise the roof.