§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

If the distance between the microphone location point and the microphone target point is—

Highway operations test

Stationary tests

Soft site

Hard site

Soft site

Hard site

35 mi/h or less

Above 35 mi/h

35 mi/h or less

Above 35 i/h

31 ft (9.5 m) or more but less than   35 ft (10.7 m)

87

91

89

93

89

91

35 ft (10.7 m) or more but less than 39 ft (11.9 m)

86

90

88

82

88

91

39 ft (11.9 m) or more but less than 43 ft (13.1 m)

85

89

87

81

87

89

43 ft (13.1 m) or more but less than 48 ft (14.6 m)

84

88

86

80

86

88

48 ft (14.6 m) or more but less than 58 ft (17.1 m)

83

87

85

89

85

87

58 ft (17.1 m) or more but less than 70 ft (21.3 m)

82

86

84

88

84

86

70 ft (21.3 m) or more but less than 83 ft (25.3 m)

81

85

83

87

83

85

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.

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