49 C.F.R. § 236.303 Control circuits for signals, selection through circuit controller operated by switch points or by switch locking mechanism.
Title 49 - Transportation
The control circuit for each aspect with indication more favorable than “proceed at restricted speed” of power operated signal governing movements over switches, movable-point frogs and derails shall be selected through circuit controller operated directly by switch points or by switch locking mechanism, or through relay controlled by such circuit controller, for each switch, movable-point frog, and derail in the routes governed by such signal. Circuits shall be arranged so that such signal can display an aspect more favorable than “proceed at restricted speed,” only when each switch, movable-point frog, and derail in the route is in proper position.
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
§ 236.303 Control circuits for signals, selection through circuit controller operated by switch points or by switch locking mechanism.
