In the photo below, the last car of a freight train passes under the signal bridge.  Once the tracks are realigned, the signal for Track 1 automatically turns green and the trio of Union Pacific 6-axle HO locomotives move onto the now-clear main line.  Trackside signals reflect the status of the track ahead, virtually eliminating derailments and collisions. The custom 3-track signal bridge and signal lighting circuits were designed, assembled and installed by Custom Signal Systems.