49 CFR §236.408
Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
Route locking shall be provided where switches are power-operated. Route locking shall be effective when the first pair of wheels of a locomotive or car passes a point not more than 13 feet in advance of the signal governing its movement, measured from the center of the signal mast or, if there is no mast, from the center of the signal.