Modern Signaling on the Reading Railroad

A description of one railroad´s signal system limits most of the detail to the type of signals and interlockings standard on that particular road, however, there are many features of inter-locking and signal control that are common to most modern signal systems. These features are described briefly in the paper. Following a brief description of the earliest forms of signaling employed on The Reading Railroad, this paper describes the Reading´s most recent installation of 100 cycle alternating current color light signaling. The 100 cycle frequency was first used in the continuous coded train control territory, where a distinctive frequency was required to eliminate any possibility of foreign inductive interference, and was later adopted for use in electrified territory, as the range between the 100-cycle signal frequency and the 25-cycle electrification frequency permitted the use of frequency selective track relays. The main features of the Reading´s loop and code systems of continuous automatic train control and those of the automatic signaling and power interlockings are described in this paper.