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.
A continuously growing album of photos that IMHO reveal the awesome and seldom-seen beauty of the railroad world from the dimming of day to dawn's early light! From dusk to dawn, trains roll on! (I'm still finding gems of sunset-to-sunrise surprises!)