The light at the end of the tunnel is, in fact, an approaching train: In less than a second, a westbound will emerge from the darkness of Cascade Tunnel into the gloom of a twilit evening. The heat contained in the exhaust gases which pour out of the tunnel with and after each train is evident from the amount of snow that has been melted off the tracks outside the portal.
An ongoing/growing album of photos that IMHO reveal the awesome, but seldom seen beauty of railroads because most of us don't go out after sundown or before sunrise. From dusk to dawn, lights are on! (And I continue to find new "Lights In The Night"!)