49 CFR § 223.9
Requirements for new or rebuilt equipment
November 18, 2020
(a) Locomotives, including yard locomotives, built or rebuilt after June 30, 1980, must be equipped with certified glazing in all locomotive cab windows.
(b) Cabooses, including yard cabooses, built or rebuilt after June 30, 1980, must be equipped with certified glazing in all windows.
(c) Passenger cars, including self-propelled passenger cars, built or rebuilt after June 30, 1980, must be equipped with certified glazing in all windows and at least four emergency windows.
[44 FR 77352, Dec. 31, 1979, as amended at 45 FR 49271, July 24, 1980; 63 FR 24675, May 4, 1998; 73 FR 6399, Feb. 1, 2008]