Rail speed limits in the United States

Speed restrictions are based on a number of factors including curvature, signaling, track condition, and the presence of grade crossings.

This rule, issued in 1947 and effective by the end of 1951, was a response to a serious 1946 crash in Naperville, Illinois, involving two trains.

In the Maryland crash, the signal panel had been partially disabled, including a muted whistle and a missing light bulb.

[5] After several extensions, the Federal Railroad Administration (FRA) announced on December 29, 2020, that PTC was operating on all required freight and passenger rail routes.

In the United States, the Federal Railroad Administration has developed a system of classification for track quality.

Track superelevation is usually limited to 6 inches (150 mm), and is often lower on routes with slow heavy freight trains in order to reduce wear on the inner rail.