[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: 49CFR325.1] [Page 7-8] TITLE 49--TRANSPORTATION DEPARTMENT OF TRANSPORTATION PART 325_COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS --Table of Contents Subpart A_General Provisions Sec. 325.1 Scope of the rules in this part. Subpart A_General Provisions Sec. 325.1 Scope of the rules in this part. 325.3 Effective date. 325.5 Definitions. 325.7 Allowable noise levels. 325.9 Measurement tolerances. Subpart B_Administrative Provisions 325.11 Issuance, amendment, and revocation of the rules in this part. 325.13 Inspection and examination of motor vehicles. Subpart C_Instrumentation 325.21 Scope of the rules in this subpart. 325.23 Type of measurement systems which may be used. 325.25 Calibration of measurement systems. 325.27 Use of a windscreen. Subpart D_Measurement of Noise Emissions; Highway Operations 325.31 Scope of the rules in this subpart. 325.33 Site characteristics; highway operations. 325.35 Ambient conditions; highway operations. 325.37 Location and operation of sound level measurement system; highway operations. 325.39 Measurement procedure; highway operations. Subpart E_Measurement of Noise Emissions; Stationary Test 325.51 Scope of the rules in this subpart. 325.53 Site characteristics; stationary test. 325.55 Ambient conditions; stationary test. 325.57 Location and operation of sound level measurement systems; stationary test. 325.59 Measurement procedure; stationary test. Subpart F_Correction Factors 325.71 Scope of the rules in this subpart. 325.73 Microphone distance correction factors. 325.75 Ground surface correction factors. 325.77 Computation of open site requirements--nonstandard sites. 325.79 Application of correction factors. [[Page 8]] Subpart G_Exhaust Systems and Tires 325.91 Exhaust systems. 325.93 Tires. Authority: 42 U.S.C. 4917; 49 U.S.C. 301; 49 CFR 1.73. Source: 40 FR 42437, Sept. 12, 1975, unless otherwise noted. Editorial Note: Nomenclature changes to part 325 appear at 66 FR 49869, Oct. 1, 2001. (a) The rules in this part prescribe procedures for inspection, surveillance, and measurement of motor vehicles and motor vehicle equipment operated by motor carriers to determine whether those vehicles and that equipment conform to the Interstate Motor Carrier Noise Emission Standards of the Environmental Protection Agency, 40 CFR part 202. (b) Except as provided in paragraph (c) of this section, the rules in this part apply to motor carriers engaged in interstate commerce. The rules apply at any time or under any condition of highway grade, load, acceleration or deceleration. (c) The rules in this part do not apply to-- (1) A motor vehicle that has a Gross Vehicle Weight Rating (GVWR) of 10,000 pounds (4,536 kg.) or less; (2) A combination of motor vehicles that has a Gross Combination Weight Rating (GCWR) of 10,000 pounds (4,536 kg.) or less; (3) The sound generated by a warning device, such as a horn or siren, installed in a motor vehicle, unless such device is intentionally sounded in order to preclude an otherwise valid noise emission measurement; (4) An emergency motor vehicle, such as a fire engine, an ambulance, a police van, or a rescue van, when it is responding to an emergency call; (5) A snow plow in operation; or (6) The sound generated by auxiliary equipment which is normally operated only when the motor vehicle on which it is installed is stopped or is operating at a speed of 5 miles per hour (8 kph) or less, unless such device is intentionally operated at speeds greater than 5 mph (8 kph) in order to preclude an otherwise valid noise measurement. Examples of that type of auxiliary equipment include, but are not limited to, cranes, asphalt, spreaders, ditch diggers, liquid or slurry pumps, auxiliary air compressors, welders, and trash compactors.