The guard check and guard face gages in frogs shall be within the limits prescribed in the following table -
| Class of track |
Guard check gage The distance between the gage 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 gage line 2, may not be less than - |
Guard face gage The distance between guard lines 1, measured across the track at right angles to the gage line 2, may not be more than - |
| Class 1 track |
4′6 1/8″ |
4′ 5 1/4″ |
| Class 2 track |
4′6 1/4″ |
4′ 5 1/8″ |
| Class 3 and 4 track |
4′ 6 3/8″ |
4′5 1/8″ |
| Class 5 track |
4′6 1/2″ |
4′ 5″ |
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 5/8 inch 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.