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  • § 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.
  • § 325.11
    Issuance, amendment, and revocation of the rules in this part.
  • § 325.13
    Inspection and examination of motor vehicles.
  • § 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.
  • § 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.
  • § 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.
  • § 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.
  • § 325.91
    Exhaust systems.
  • § 325.93
    Tires.

Part 325
COMPLIANCE WITH INTERSTATE MOTOR CARRIER NOISE EMISSION STANDARDS

§ 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

DistanceHighway Operation TestStationay Test
 Soft siteHard siteSoft siteHard site
35 mi/h or lessAbove 35 mi/h35 mi/h or lessAbove 35 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 ft (10.7m)879189938991
35 ft (10.7m) or more but less than 39 ft (11.9m)869088928890
39 ft (11.9m) or more but less than 43 ft (13.1m)858987918789
43 ft (13.1m) or more but less than 48 ft (14.6m)848886908688
48 ft (14.6m) or more but less than 58 ft (17.1m)838785898587
58 ft (17.1m) or more but less than 70 ft (21.3m)828684888486
70 ft (21.3m) or more but less than 83 ft (25.3m)818583878385

1The speeds shown refer to measurements taken at sites having speed limits as indicated. These speed limits do not necessarily have to be posted.

2This table is based on motor carrier noise emission requirements specified in 40 CFR 202.20 and 40 CFR 202.21.

 

Citation:

[40 FR 42437, Sept. 12, 1975, as amended at 54 FR 50385, Dec. 6, 1989]