A safety system mandated by Congress after the 2008 Chatsworth collision that automatically enforces speed limits, prevents train-to-train collisions, and enforces temporary speed restrictions, overriding human error. PTC uses GPS, wireless communications, and digital track maps to monitor and control train movements in real time. All Class I railroads completed PTC implementation by the 2020 deadline.
A wayside device that conveys authority and speed information to train crews by displaying light aspects or physical positions. Signals are the fundamental mechanism for maintaining safe train separation in a signaled territory. Signal aspects are governed by rulebooks that define what each combination of lights means.
The U.S. Department of Transportation agency responsible for railroad safety regulation and enforcement, including track standards, equipment inspection, operating rules, and hazardous materials transportation. The FRA conducts safety inspections, investigates accidents, and issues emergency orders when immediate safety threats exist. It also administers federal rail investment programs.
One or more locomotives placed mid-train or at the rear of a train and controlled remotely from the lead unit to provide additional tractive effort and improve brake handling on long or heavy trains. DPUs reduce in-train forces (slack action) and allow railroads to run longer trains than would otherwise be practical. They are standard on heavy-haul coal and grain unit trains.
The network of trackside sensing systems that monitor trains as they pass, including hot box detectors, dragging equipment detectors, wheel impact load detectors, and machine vision systems. Data from wayside detectors is transmitted in real time to dispatching centers and maintenance systems. Wayside detection is a foundational layer of railroad safety and car health monitoring.
The use of Global Positioning System receivers installed on locomotives or railcars to provide continuous real-time location data independent of wayside AEI readers. GPS tracking is standard on locomotives and is increasingly deployed on railcars and intermodal containers for enhanced visibility. It provides location data in areas between AEI readers and within yards.