A sign tells the story of the tunnel's construction in 1932. It took workers three months to drill and blast their way through 600 feet of solid granite (granodiorite).
I remember when the walls of the tunnel were not yet coated with concrete. You could see the rough granite and water was constantly dripping through the rock, even in dry weather. In the winter it formed dramatic icicles. (It still does at the entrances.) This was when I was a child; the tunnel was lined with concrete in 1958.
The poster on the left side of the sign presents a message about what services are available in Shenandoah National Park during the winter. (Summary: just about everything is closed except picnic areas.)