Brotherhood of Railroad Signalmen
The Brotherhood of Railroad Signalmen (BRS) is a United States labor union representing workers responsible for the installation, maintenance, and repair of railroad signaling and traffic control systems. These systems include wayside signals, interlockings, and highway-rail grade crossing warning devices that are critical to the safe and efficient operation of rail transportation networks.
Source: Wikipedia — Brotherhood of Railroad Signalmen (CC BY-SA 4.0)