49 C.F.R. § 236.305 Approach or time locking.
Title 49 - Transportation
Approach or time locking shall be provided in connection with signals displaying aspects with indications more favorable than “proceed at restricted speed.”
Title 49: Transportation
PART 236—RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES
Subpart C—Interlocking
Standards
§ 236.305 Approach or time locking.