A closer look at a Pennsylvania Railroad signal bridge in Wooster, Ohio. The Pennsy's distinctive position light signals came in a huge variety of configurations, with the upper set of lights framed by round or semi-rectangular backplates and the lower set with or without backplates, with anywhere from one to nine individual bulbs and a corresponding variety of meanings. Seeing those brilliant yellow lamps (carefully designed for maximum fog penetration) forming strange unearthly heiroglyphics in the darkness was an unforgettable experience.
