Type G Signal
This is a straight build of a (mostly) unmodified Showcase Miniatures kit. I'm awfully glad I'm not building a large layout where I'd need bunches of these things; building just one was more than enough frustration for me. In particular, threading the LED wires down the mast brought me right to the very brink of insanity and taking the better part of an afternoon. The only modification I made was to mount the mast atop a relay cabinet in order to replicate a real signal near where I used to live. Details I added include an extension of the concrete footing beyond the relay cabinet, and anchor brackets for the bottom of the ladder, again per the prototype.
The signal is controlled manually with a center-off toggle switch, which is wired with a relay so that the center position illuminates the yellow signal. Note that the diagram has three resistors: the different color LEDs have different current requirements, so a separate resistor for each LED evens out the brightness.