49 C.F.R. Subpart A—General Provisions
Title 49 - Transportation
(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. The rules in this part are effective on October 15, 1975. (a) Statutory definitions. All terms defined in the Noise Control Act of 1972 (Pub. L. 92–574, 86 Stat. 1234) are used as they are defined in that Act. (b) Definitions in standards. All terms defined in §202.10 of the Interstate Motor Carrier Noise Emission Standards, 40 CFR 202.10, are used as they are defined in that section. (c) Additional definitions. (1) Hard test site means any test site having the ground surface covered with concrete, asphalt, packed dirt, gravel, or similar reflective material for more than (2) Soft test site means any test site having the ground surface covered with grass, other ground cover, or similar absorptive material for (3) Ground cover means any of various low, dense-growing plants, such as ivy, myrtle, low weeds, or brush. (4) Traffic railing means any longitudinal highway traffic barrier system installed along the side or median of a highway. For the purpose of this part, a traffic railing must have at least 35 percent of its vertical height, from the ground surface to the top of the railing, open to free space in order to qualify as an acceptable object within a noise measurement test site. Further, for the purposes of this part, posts or other discrete supports shall be ignored when ascertaining open free space. (5) Relatively flat when used to describe a noise measurement site means a site which does not contain significant concave curvatures or slope reversals that may result in the focusing of sound waves toward the microphone location point. Motor vehicle noise emissions, when measured according to the rules of this part, shall not exceed the values specified in Table 1. [40 FR 42437, Sept. 12, 1975, as amended at 54 FR 50385, Dec. 6, 1989] (a) Measurement tolerances will be allowed to take into account the effects of the following factors: (1) The consensus standard practice of reporting filed sound level measurements to the nearest whole decibel. (2) Variations resulting from commercial instrument tolerances. (3) Variations resulting from the topography of the noise measurement site. (4) Variations resulting from atmospheric conditions such as wind, ambient temperature, and atmospheric pressure. (5) Variations resulting from reflected sound from small objects allowed within the test site. (6) The interpretation of the effects of the above cited factors by enforcement personnel. (b) Measurement tolerances shall not exceed 2 decibels for a given measurement.
Title 49: Transportation
PART 325—COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS
Subpart A—General Provisions
§ 325.1 Scope of the rules in this part.
§ 325.3 Effective date.
§ 325.5 Definitions.
§ 325.7 Allowable noise levels.
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.
§ 325.9 Measurement tolerances.
