The document describes a ladder logic program for controlling a traffic light system. The system has two switches: one to run the system according to one of two modes (normal or flashing), and another to select the mode. In normal mode, lights are green for 5 seconds and red for 5 seconds, with 1 second for yellow. In flashing mode, lights flash on and off independently. The ladder logic program uses timers, switches, and coils to control the lights according to the two modes.