A Norfolk Southern double-stack intermodal knocks down the signals in Duluth, Georgia, a few seconds shy of 1:30 AM. My camera was able to capture all three aspects on the right-hand block signal. The signal tower was built by NS predecessor Southern Railway, and is likely six decades old by now. This is an old photo from 2010, and if memory serves, the locos on point were a pair of big GEs, most likely Dash 9s.

This is a big part of railfanning for me - watching the green signal and waiting in anticipation for the train to pass. My favorite experience of them all is one like this--late at night, when all is dead quiet until you hear that horn miles out. The blows become louder and louder, and soon enough you see the headlights come around the curve. The train is upon the signal in seconds and he 'knocks down' the aspect to red again as his engines pass by. The hunt begins anew when the aspect changes to green once more.