49 C.F.R. § 213.9 – Classes of track: operating speed limits.

(a) Except as provided in paragraph (b) of this section and §§ 213.57(b), 213.59(a), 213.113(a), and 213.137(b) and (c), the following maximum allowable operating speeds apply -
[In miles per hour]Over track that meets all of the requirements prescribed in this part for - The maximum allowable operating speed for freight trains is - The maximum allowable operating speed for passenger trains is - Excepted track10N/A Class 1 track1015 Class 2 track2530 Class 3 track4060 Class 4 track6080 Class 5 track8090
(b) If a segment of track does not meet all of the requirements for its intended class, it is reclassified to the next lowest class of track for which it does meet all of the requirements of this part. However, if the segment of track does not at least meet the requirements for Class 1 track, operations may continue at Class 1 speeds for a period of not more than 30 days without bringing the track into compliance, under the authority of a person designated under § 213.7(a), who has at least one year of supervisory experience in railroad track maintenance, after that person determines that operations may safely continue and subject to any limiting conditions specified by such person.