So are the 2 notches near the top of the arch, something that was done intentionally when taller freight and superliners began using the route, or just random chunks that fell out in the last 89 years? It looks rather short in the picture, how much clearance would a tunnel like this have? Just curious.
Yes the tunnel is notched to allow for double stack container trains to operate it. And to answer another question, 100+ car trains routinely use the tunnel. There is a blower on the railroad east end of the 7+ mile long tunnel to keep the locomotives from stalling and the engine crews from choking to death while in the tunnel. Not many people know that there is a similar tunnel in northern Montana, called flathead tunnel. It is also 7+ miles long, and it also has blowers and doors on one end of the tunnel.