(a) Gage is measured between the heads of the rails at right-angles to the rails in a plane five-eighths of an inch below the top of the rail head.
(b) Gage shall be within the limits prescribed in the following table:
| Class of track | The gage must be at least - | But not more than - | The change of gage within 31 feet must not be greater than - |
|---|---|---|---|
| Class 6 track | 4′8″ | 4′91⁄4″ | 3⁄4″ |
| Class 7 track | 4′8″ | 4′91⁄4″ | 1⁄2″ |
| Class 8 track | 4′8″ | 4′91⁄4″ | 1⁄2″ |
| Class 9 track | 4′81⁄4″ | 4′91⁄4″ | 1⁄2″ |
[63 FR 34029, June 22, 1998, as amended at 78 FR 16104, Mar. 13, 2013]