Signal Systems of the Pennsylvania Railroad

Signal Systems of the Pennsylvania Railroad. . , Controlling the movement of trains, avoiding collisions, and ensuring the safety of railroad operations has always been the primary mission of railroad signal engineering. The Camden and Amboy Railroad contributed to the improved safety of the railroad when it introduced the first mechanically activated control system or "interlocking" in Trenton in 1870. The Pennsylvania Railroad, which obtained control of the Camden and Amboy Railroad in 1871, originally used semaphore signals. These signals used the position of a moveable arm to indicate stop (horizontal), caution (diagonal) or proceed (vertical)., Following the introduction of the electric track circuit in 1872, railroad began installing electrically activated signals across the country. After 1910, some railroads used color-light signals to indicate stop (red), caution (yellow), and proceed (green). Because the early color lights were not always easy to read, the Pennsylvania Railroad, in 1915, developed and installed the position-light signal system that used horizontal, diagonal, and vertical rows of three lights to represent stop, caution, and proceed., Controlling train movements over the Rancocas Creek SWing Span Bridge required four position-lights. One distant light signal was located at each approach to the bridge and one home (or near) light signal was placed adjacent to each end of the bridge to indicate if the swing span was in the opened or closed position and to ensure the safety of the trains as they crossed the Rancocas Creek., The position light signals and other antiquated signals were removed and replaced with state of the art signaling systems during construction of this light-rail line. The position-light signal at the center of this display is one of the two Rancocas Creek Bridge home signals. NJ Transit donated both distant signals to the Cape May Seashore Lines railroad, where they may be viewed as they continue to perform their historic function of controlling the movement of trains.