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 complete list of equipment making up a train, including locomotives and each railcar in order, with car numbers, commodities, weights, and destinations. A consist document (also called a train list) travels with the train and is transmitted electronically ahead of arrival. Consists are essential for safety planning and crew briefings.
An electronic device attached to the rear coupler of the last car in a train that monitors rear brake pipe pressure, provides a flashing rear marker light, and communicates wirelessly with the locomotive. The EOT replaced the traditional caboose and enables emergency brake applications from the rear of the train. FRA requires EOT devices on all freight trains over a specified length.
The pneumatic braking system used on all North American freight cars, based on George Westinghouse's fail-safe design in which brakes apply automatically if air pressure is lost. The system uses a continuous brake pipe running the length of the train, fed by a locomotive compressor. FRA regulations govern brake testing requirements before each departure.
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.