Regulations last checked for updates: Feb 07, 2026

Title 49 - Transportation last revised: Feb 03, 2026
All TitlesTitle 49Chapter IIPart 299Subpart C - Subpart C—Track Safety Standards
View all text of Subpart C [§ 299.301 - § 299.357]
§ 299.333 - Frog guard rails and guard faces; gauge.

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-H71,393 mm1,358 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.

authority: 49 U.S.C. 20103,20107,20133,20141,20302,20306,20701,21301,21304; 28 U.S.C. 2461,note; and 49 CFR 1.89
source: 85 FR 69731, Nov. 3, 2020, unless otherwise noted.
cite as: 49 CFR 299.333
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