U.S. Code of Federal Regulations
Regulations most recently checked for updates: Aug 27, 2025
The guard check and guard face gages in frogs shall be within the limits prescribed in the following table:
Table 1 to § 299.333
| Track class | Guard check gage
The distance between the gauge line of a frog to the guard line 1 of its guard rail or guarding face, measured across the track at right angles to the gauge line, 2 may not be less than— | Guard face gage
The distance between the guard lines, 1 measured across the track at right angles to the gauge line, 2 may not be more than— |
|---|---|---|
| H0-H7 | 1,393 mm | 1,358 mm. |
1 A line along that side of the flangeway which is nearer to the center of the track and at the same elevation as the gage line.
2 A line 14 mm (0.55 inches) below the top of the center line of the head of the running rail, or corresponding location of the tread portion of the track structure.
