Speed limits in the United States (rail)

Rail speed limits in the United States are regulated by the Federal Railroad Administration. Railroads also implement their own limits and enforce speed limits. Speed restrictions are based on a number of factors including curvature, signaling, track condition, the physical condition of a train, and the presence of grade crossings. Like road speed limits in the United States, speed limits for rail tracks and the trains that run on them use miles per hour (mph).

Federal regulators limit the speed of trains with respect to the signaling method used. Passenger trains are limited to 59 mph and freight trains to 49 mph on track without block signal systems. (See dark territory.) Trains without "an automatic cab signal, automatic train stop or automatic train control system "may not exceed 79 mph." The order was issued in 1947 (effective 31 Dec 1951) by the Interstate Commerce Commission following a severe 1946 crash in Naperville, Illinois involving two Chicago, Burlington & Quincy Railroad trains. Following the 1987 Chase, Maryland train collision, freight trains operating in enhanced-speed corridors have been required to have locomotive speed limiters to forcibly slow trains rather than simply alerting the operator with in-cab signals. The signal panel in the Maryland crash had been partially disabled, with a muted whistle and a missing light bulb.