49 C.F.R. § 236.728 Circuit, trap.
Title 49 - Transportation
A term applied to a circuit used where it is desirable to provide a track circuit but where it is impracticable to maintain a track circuit.
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 G—Definitions
§ 236.728 Circuit, trap.