[Code of Federal Regulations] [Title 49, Volume 4] [Revised as of October 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR236.22] [Page 506] TITLE 49--TRANSPORTATION CHAPTER II--FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 236--RULES, STANDARDS, AND INSTRUCTIONS GOVERNING THE INSTALLATION, INSPECTION, MAINTENANCE, AND REPAIR OF SIGNAL AND TRAIN CONTROL SYSTEMS, DEVICES, AND APPLIANCES--Table of Contents Subpart A--Rules and Instructions: All Systems Sec. 236.22 Semaphore signal arm; clearance to other objects. At least one-half inch clearance shall be provided between semaphore signal arm, and any object that may interfere with its operation.