§ 1045. Measurement Procedures for Vehicles in Use.
13 CA ADC § 1045Barclays Official California Code of Regulations
13 CCR § 1045
§ 1045. Measurement Procedures for Vehicles in Use.
Noise from vehicles in use shall be measured as follows:
(1) Primary Location. The microphone shall be located at a height not less than 0.6 m (2 ft), not more than 1.8 m (6 ft) above the plane of the roadway surface, and not less than 1.1 m (3.5 ft) above the surface upon which the microphone stands. The preferred microphone height on a flat surface is 1.2 m (4 ft).
(A) When the microphone boom is used, the microphone shall be located 0.41 m ± 7.6 cm (16 in. ± 3 in.) above the highest point of the vehicle within an area bounded by the windshield, the tops of left and right front windows, and the rear of the driver's seat. The vehicle upon which the microphone is mounted shall be positioned so that its longitudinal axis is perpendicular to the center of the lane of travel. The height of the microphone above the plane of the roadway surface shall not exceed 2.4 m (8 ft). A correction factor of -2dB(A) shall be applied to the recorded sound level.
(B) When the sound level meter with microphone attached is held by a person sitting astride an open motorcycle, the motorcycle shall be positioned parallel to the center of the lane of travel. The microphone shall be pointed toward the traffic and project beyond the windshield if the motorcycle is so equipped. The microphone shall be within the height requirements specified in preceding subsection (a)(1). A correction factor of -1dB(A) shall be applied to the recorded sound level.
Distance from microphone to center of lane of travel | Sound level correction factor, dB(A)* |
7.9-8.8 m (26-29 ft) n | -6 |
8.8-9.8 m (29-32 ft) | -5 |
9.8-10.7 m (32-35 ft) | -4 |
10.7-11.9 m (35-39 ft) | -3 |
11.9-13.1 m (39-43 ft) | -2 |
13.1-14.6 m (43-48 ft) | -1 |
14.6-17.7 m (48-58 ft) | 0 |
17.7-21.3 m (58-70 ft) | +1 |
21.3-25.3 m (70-83 ft) | +2 |
25.3-30.2 m (83-99 ft) | +3 |
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* If the distance from microphone to center of lane of travel falls on the midpoint between distance ranges given in the table, the larger correction factor shall be used.
** These distances are not applicable to measurements of heavy trucks with a gross vehicle weight rating (GVWR) of over 4,537 kg (10,000 lb) operated by motor carriers engaged in interstate commerce and governed by the Federal Bureau of Motor Carrier Safety regulations.
(2) Modified Sites. Modified measuring sites shall meet the specifications shown in Figure 1, except the dimensions may range from 7.9 to 30.2 m (26 to 99 ft). The radii of the minimum clear area shall be the distance between the microphone and the microphone target point. Sound level readings taken at such sites shall be corrected as provided in preceding subsection (b). The site shall be free of large sound-reflecting objects, with the following exceptions:
4. Any object on the side of the vehicle path opposite the microphone with a width measured parallel to the vehicle path not exceeding 1.0 m (3.1 ft) regardless of height, and not slanting toward the roadway. If objects exceeding 1.0 m (3.1 ft) in width (such as parked vehicles) are on the side of the vehicle path opposite the microphone, a correction factor of -2 dB(A) shall be applied to the recorded sound level.
(1) Vehicle Location: The vehicle shall be parked on a measuring site meeting the requirements of preceding subsection (c). The centerline of the vehicle shall be on the center of the lane of travel as shown in Figure 1. The vehicle shall be positioned so the exhaust system outlet is within 1.0 m (3.3 ft) of the microphone target point measured along the center of the lane of travel.
(2) Auxiliary Equipment. Auxiliary equipment used only when the vehicle is stationary or operating at a speed of 8 km/h (5 mph) or less shall be turned off. Such equipment includes but is not limited to cranes, asphalt spreaders, ditch diggers, slurry pumps, auxiliary air compressors, welders, and trash compactors.
(3) Engine Cooling Fans. If the engine cooling fan automatically disengages or reduces speed in response to reduced engine cooling loads, the engine shall be run at high idle, or any other speed the operator may choose, for sufficient time but not more than 10 min to permit the fan to operate at reduced speed during the noise test.
(4) Engine Operation. With the transmission in neutral and the clutch engaged, the engine shall be rapidly accelerated from idle to its maximum governed speed with wide open throttle. After the engine speed has stabilized, the engine shall be returned to idle. This procedure shall be repeated until the maximum sound level readings are within 2 dB(A) of each other, disregarding unrelated peaks due to extraneous ambient sound.
(5) Sound Level Measurement. The recorded sound level for the stationary vehicle shall be the numerical average of the highest 2 or more readings within 2 dB(A) of each other. This level shall not exceed 88 dB(A) on a measurement site with concrete, asphalt, packed dirt, gravel or similar reflective material for more than one-half the distance between the microphone and the microphone target point. The level shall not exceed 86 dB(A) on a measuring site with grass, other ground cover, or similar absorptive material for more than one-half the distance from the microphone target point.
Credits
Note: Authority cited and Reference: Sections 23130, 23130.5 and 27207, Vehicle Code.
History
1. Repealer and new section filed 7-1-83; effective thirtieth day thereafter (Register 83, No. 27).
2. Amendment of subsection (a) filed 11-20-84; effective thirtieth day thereafter (Register 84, No. 47).
This database is current through 5/10/24 Register 2024, No. 19.
Cal. Admin. Code tit. 13, § 1045, 13 CA ADC § 1045
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