[Code of Federal Regulations] [Title 49, Volume 5] [Revised as of October 1, 2005] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR325.7] [Page 9] TITLE 49--TRANSPORTATION DEPARTMENT OF TRANSPORTATION PART 325_COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS --Table of Contents Subpart A_General Provisions Sec. 325.7 Allowable noise levels. Motor vehicle noise emissions, when measured according to the rules of this part, shall not exceed the values specified in Table 1. Table 1--Maximum Permissible Sound Level Readings (Decibel (A)) \1, 2\ ---------------------------------------------------------------------------------------------------------------- Highway operation test Stationary tests ------------------------------------------------------------------- Soft site Hard Site -------------------------------------------- 35 mi/h Above 35 35 mi/h Above 35 Soft site Hard site or less mi/h or less mi/h ---------------------------------------------------------------------------------------------------------------- If the distance between the microphone location point and the microphone target point is-- 31 ft ( 9.5m) or more but less than 35 87 91 89 93 89 91 ft (10.7m)............................. 35 ft (10.7m) or more but less than 39 86 90 88 92 88 90 ft (11.9m)............................. 39 ft (11.9m) or more but less than 43 85 89 87 91 87 89 ft (13.1m)............................. 43 ft (13.1m) or more but less than 48 84 88 86 90 86 88 ft (14.6m)............................. 48 ft (14.6m) or more but less than 58 83 87 85 89 85 87 ft (17.1m)............................. 58 ft (17.1m) or more but less than 70 82 86 84 88 84 86 ft (21.3m)............................. 70 ft (21.3m) or more but less than 83 81 85 83 87 83 85 ft (25.3m)............................. ---------------------------------------------------------------------------------------------------------------- \1\ The speeds shown refer to measurements taken at sites having speed limits as indicated. These speed limits do not necessarily have to be posted. \2\ This table is based on motor carrier noise emission requirements specified in 40 CFR 202.20 and 40 CFR 202.21. [40 FR 42437, Sept. 12, 1975, as amended at 54 FR 50385, Dec. 6, 1989]