[Code of Federal Regulations] [Title 49, Volume 4] [Revised as of October 1, 2005] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR222.53] [Page 283] TITLE 49--TRANSPORTATION CHAPTER II--FEDERAL RAILROAD ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 222_USE OF LOCOMOTIVE HORNS AT PUBLIC HIGHWAY-RAIL GRADE CROSSINGS --Table of Contents Subpart C_Exceptions to the Use of the Locomotive Horn Sec. 222.53 What are the requirements for supplementary and alternative safety measures? (a) Approved SSMs are listed in appendix A of this part. With the exception of permanent crossing closures, approved SSMs can qualify for quiet zone risk reduction credit in the manner specified in appendix A of this part. (b) Additional ASMs that may be included in a request for FRA approval of a quiet zone under Sec. 222.39(b) of this part are listed in appendix B of this part. Modified SSMs can qualify for quiet zone risk reduction credit in the manner specified in appendix B of this part. (c) The following do not, individually or in combination, constitute SSMs or ASMs: Standard traffic control device arrangements such as reflectorized crossbucks, STOP signs, flashing lights, or flashing lights with gates that do not completely block travel over the line of railroad, or traffic signals.