49 C.F.R. § 236.10 Electric locks, force drop type; where required.
Title 49 - Transportation
Electric locks on new installations and new electric locks applied to existing installations shall be of the forced drop type.
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 A—Rules and Instructions: All Systems
General
§ 236.10 Electric locks, force drop type; where required.