1. (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.

2. (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]