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 G — Definitions236.80449 C.F.R. § 236.804Signal, block.Last amended: 2017Year: 2026Length: 14 wordsOfficial source Cite as 49 C.F.R. § 236.804 (2026)A roadway signal operated either automatically or manually at the entrance to a block.Previous49 C.F.R. § 236.803Next49 C.F.R. § 236.805