US lawFederal (United States)RegulationsTitle 49 CFR — TransportationChapter II — FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATIONPart 236 — RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCESSubpart C — Interlocking236.38449 C.F.R. § 236.384Cross protection.Last amended: 2017Year: 2026Length: 17 wordsOfficial source Cite as 49 C.F.R. § 236.384 (2026)Cross protection shall be tested at least once every six months. [49 FR 3385, Jan. 26, 1984]Previous49 C.F.R. § 236.383Next49 C.F.R. § 236.386