1、Standard Method of Test for Measurement of Tire/Pavement Noise Using the On-Board Sound Intensity (OBSI) Method AASHTO Designation: T 360-161 Release: Group 1 (April 2016) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 200
2、01 TS-5a T 360-1 AASHTO Standard Method of Test for Measurement of Tire/Pavement Noise Using the On-Board Sound Intensity (OBSI) Method AASHTO Designation: T 360-161Release: Group 1 (April 2016) 1. SCOPE 1.1. This test method describes the procedures for measuring tire/pavement noise using the on-bo
3、ard sound intensity (OBSI) method and the procedures for verification of the measurement system. The test method provides an objective measure of the acoustic power per unit area at points near the tire/pavement interface. 1.2. The OBSI measurement method described herein permits tire/pavement noise
4、 to be measured in isolation of other noise sources allowing the noise performance of pavements to be compared. 1.3. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its use. It is the respo
5、nsibility of the user of this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: TP 98, Determining the Influence of Road Surfaces on Vehicle Noise Using the
6、Statistical Isolated Pass-By (SIP) Method TP 99, Determining the Influence of Road Surfaces on Traffic Noise Using the Continuous-Flow Traffic Time-Integrated Method (CTIM) 2.2. ASTM Standards: D2240, Standard Test Method for Rubber PropertyDurometer Hardness F2493, Standard Specification for P225/6
7、0R16 97S Radial Standard Reference Test Tire 2.3. ANSI Standards: S1.1, Acoustical Terminology S1.9, Instruments for the Measurement of Sound Intensity S1.11, Specification for Octave-Band and Fractional-Octave-Band Analog and Digital Filters S1.40, American National Standard Specifications and Veri
8、fication Procedures for Sound Calibrators S1.42, American National Standard Design Response of Weighting Networks for Acoustical Measurements 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a T 360-
9、2 AASHTO 2.4. Other: Donavan, P. R. and D. M. Lodico, Measuring Tire-Pavement Noise at the Source, NCHRP Report, Project 1-44(1), National Cooperative Highway Research Program, Transportation Research Board, Washington, 2011. Available at http:/onlinepubs.trb.org/onlinepubs/nchrp/docs/nchrp01-44(01)
10、_FR.pdf. 3. TERMINOLOGY 3.1. arithmetic averaging of levelsaveraging levels by summing the levels and dividing by the number of samples in the average. Use the following equation to arithmetically average a set of N levels, Li. 11NA avg iiLLN=3.2. coherencea measure of the linear dependency of two s
11、ignals with a value of 0 being no dependency, and a value of 1 being prefect linear dependence. Mathematically, it is the magnitude of the cross-spectrum between two signals squared divided by the product of the auto spectrum of both signals. 3.3. energy averaging of levelsaveraging levels by first
12、transforming the levels to energy quantities, averaging the energy quantities, and then converting back to a level. Use the following equation to energy average a set of N levels, Li. ( )( )/10101110 10iNLE avgiL LogN= 3.4. measurement periodthe time it takes the test vehicle to traverse the distanc
13、e of the test section. 3.5. on-board sound intensity (OBSI) methoda measurement procedure to evaluate the tire/pavement noise component resulting from the interaction of an ASTM F2493, Standard Reference Test Tire (SRTT) on a pavement surface. Sound intensity is measured at positions located on a mo
14、ving vehicle near the tire/pavement interface. 3.6. overall on-board sound intensity (OBSI) levelthe tire/pavement sound intensity level corresponding to the energy sum of the A-weighted sound intensity within the one-third octave bands ranging from 400 to 5000 Hz. ( )( )5000/101040010 10iLiOverall
15、Sound Intensity Level Log= where: Li= the A-weighted intensity level in the one-third octave band with center frequency i. 3.7. powertrain noisethe noise from the vehicle engine, exhaust system, air intake, fans, transmission, differential, and axles. 3.8. pressure-intensity index (PI index)defined
16、by the arithmetic average of the sound pressure levels (SPL) of both microphones on the probe minus the sound intensity level (IL), as given by the following equation: PI = SPLavg IL. The PI index for each one-third octave band is calculated using the sound pressure levels and intensity level corres
17、ponding to that one-third octave band. Note 1Since it represents a difference in level, the units for the PI index shall be reported in dB rather than dBA. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable la
18、w.TS-5a T 360-3 AASHTO 3.9. reference temperaturean ambient air temperature of 68F (20C). 3.10. sound intensityaverage rate of sound energy transmitted in a specified direction at a point through a unit area normal to this direction at the point. Units are watt per square meter (W/m2). As such, it i
19、s a vector quantity with magnitude and direction. The direction can be associated with the direction of sound propagation or the direction of the orientation of a probe for measuring sound intensity. (Reference ANSI S1.1, Acoustical Terminology.) 3.11. sound intensity level (IL)ten times the logarit
20、hm to the base 10 of the ratio of the intensity of a given sound in a stated direction to the reference sound intensity of 1 pW/m2(1 1012W/m2). Units are decibels. (Reference ANSI S1.1, Acoustical Terminology.) 3.12. sound pressure level (SPL)ten times the logarithm to the base 10 of the ratio of th
21、e time-mean-square pressure of a sound, in a stated frequency band, to the square of the reference sound pressure of 20 Pa (20 106Pa). Units are decibels. (Reference ANSI S1.1, Acoustical Terminology.) 3.13. standard reference test tire (SRTT)16-in. (P225/60R16) standard tire as defined in ASTM F249
22、3. 3.14. systemfor this standard, refers to the entire system used to measure the sound intensity using the on-board method by means of equipment including matched microphone pairs, preamplifiers, cables, sound analyzers (computational system), probe holders, and associated items mounted on the test
23、 vehicle or test trailer. 3.15. test runa single measurement over a test section. 3.16. test sectiona 440 10 ft (134 3 m) length of pavement over which a sound intensity measurement is made. 3.17. tire/pavement noisethe sound generated as a tire traverses a specific length of pavement. 3.18. vehicle
24、 noisethe total noise from a vehicle, including a combination of noise generated by tire/road interaction (tire/pavement noise), air turbulence, and the powertrain. 4. SUMMARY OF TEST METHOD 4.1. The test method describes the measurement of sound intensity in close proximity to the tire/pavement int
25、erface. 4.2. Results are reported as overall A-weighted sound intensity levels, and as A-weighted one-third octave band levels. 4.3. General system requirement, equipment, and installation requirements that are used for these measurements are described in Annex A, Sections A2, A3, and A4. 5. SIGNIFI
26、CANCE AND USE 5.1. This test method provides an objective means for the on-board measurement of sound intensity of noise generated at the tire/pavement interface at defined points near the tire. 5.2. Using this method, measurements can be made to compare different pavements. 2016 by the American Ass
27、ociation of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a T 360-4 AASHTO 5.3. Complementing this test method are wayside methods including TP 98 for the determination of noise from isolated vehicle pass-by events, and TP 99 for th
28、e determination of continuous-flow traffic noise. 6. PROCEDURE 6.1. Selection of Test Section: 6.1.1. Pavement SurfaceThe test section shall have the same nominal material and surfacing for its length and width of the path to be tested. The test section shall be dry and free of debris to the extent
29、practical. 6.1.2. Geometry and GradeThe test section should be a tangent (straight) section of the roadway. Horizontal curves should be avoided when possible, as should steep downgrades due to the potential for brake usage. Roadway geometry and approximate grade should be noted. 6.1.3. Wheel PathTes
30、ting should be conducted with the test tire positioned in the normally trafficked wheel path. If testing is conducted outside of this path (for example, center of lane measurements), the location of the selected path shall be documented and reported. 6.1.4. Reflective SurfacesThere should be no acou
31、stically reflective surfaces within 20 in (0.5 m) of the center of the wheel path along the length of the test section. If measurements must be made with an object(s) nearby, the location and nature of the object(s) should be documented. 6.2. Measurement LocationsMeasurements shall be made alongside
32、 both the leading edge and trailing edge of the SRTT contact patch on the side of the vehicle opposite of the driver (see Annex A4 and Figure A4.1). Figure A4.1 includes the specified locations for the microphone probes during measurement. 6.3. Test Vehicle Operating Conditions: 6.3.1. Standard Test
33、 Speed60 mph (97 km/h) shall be used unless conditions do not permit, or the test purpose requires a different speed. If a speed other than the standard test speed of 60 mph (97 km/h) is used, the speed shall be clearly designated in the reporting of all sound intensity levels. Alternative standard
34、test speeds shall be the highest achievable speed from one of the following: 45, 35, and 25 mph (72, 56, and 40 km/h, respectively). The length of the test section shall be that defined in Section 3.1.16, regardless of test speed. Corrections to sound levels as a function of test speed shall not be
35、applied beyond the tolerance of the test speed. Data shall not be valid if brakes are applied during the measurement period. 6.3.2. Test Speed VariationDuring the test, the vehicle shall travel with constant speed 1 mph (1.6 km/h) over the test section in an appropriate gear setting. Note 2Use of cr
36、uise control is allowed to assist in maintaining constant vehicle speed. 6.3.3. Tire InflationCold tires shall be inflated to 30 2 psi (207 14 kPa). 6.3.4. Tire InspectionRemove small stones from the tread grooves prior to test runs. The test tire shall not have uneven or excess tread wear and/or da
37、mage relative to the appearance of a new SRTT. Refer to Annex A, Section A2.2, for additional test tire requirements. 6.4. VerificationAt the beginning of the measurements, and following all warm-up procedures specified by the manufacturer, the sound level measurement system shall be verified using
38、an acoustic calibrator or piston phone. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a T 360-5 AASHTO 6.4.1. At a minimum, initial verification (acoustical calibration) shall be conducted no more
39、 than 1 h before and final verification no more than 1 h after the test period. Additional verification shall be conducted during the course of the measurements so that the maximum period between verification checks does not exceed 4 h. 6.4.2. The measurement system shall be adjusted for accuracy ac
40、cording to the manufacturers instructions. The results of all measurement system accuracy checks shall be recorded in the test report. If the results of any two subsequent verification checks during the measurement period differ by more than 0.5 dB, the testing between those checks shall be consider
41、ed invalid. 6.4.3. The sound calibration device shall meet Class 1 requirements of ANSI S1.40. (Note that some calibrators require correction for environmental conditions. The manufacturers specifications should be consulted.) The microphones and calibrator shall be calibrated in accordance with the
42、 manufacturers specifications and ANSI S1.9 and S1.40, respectively. 6.5. Measurement Period StartThe measurement period should begin when the test tire is within 10 ft (3 m) of the beginning of the test section. The tolerance allowed at the beginning of the test section shall not include a nominall
43、y different pavement. For the entire duration of the measurement period, the test tire shall be on pavement of the same nominal type. If needed, optical sensors and roadside reflective markers can provide capability to start the measurement within the recommended distance tolerance. 6.6. Averaging T
44、imeThe measurement defining a test section shall be an energy average over the measurement period. For the standard test speed of 60 mph (97 km/h) and the test section of 440 10 ft (134 3 m) length, this corresponds to an averaging time of 5.0 0.1 s. Slower test speeds will result in longer averagin
45、g times. Note 3The alternate standard test speeds have the following corresponding averaging times: 45 mph (72 km/h): 6.7 0.2 s 35 mph (56 km/h): 8.6 0.2 s 25 mph (40 km/h): 12.0 0.3 s 6.7. Prevention of System OverloadsThe measurements shall not include overloaded signals. To minimize the risk of o
46、verload to the recording system, the signals should be A-weighted prior to digitization. 6.8. Valid Test RunThe measurement over a test section must meet the following conditions to be considered a valid test run: 6.8.1. The PI index shall be in conformance with the minimum and maximum levels in Tab
47、le 1. Any test run in which these criteria are not satisfied shall be considered invalid and not used in any averages of the test runs. 2016 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-5a T 360-6 AASH
48、TO Table 1PI Index Requirements for each One-Third Octave Band One-Third Octave Band Center Frequency (Hz) Minimum PI Index (dB) Maximum PI Index (dB) 400 1.0 5.0 500 1.0 4.5 630 1.0 3.5 800 1.0 2.5 1000 1.0 2.5 1250 1.0 3.0 1600 1.0 3.0 2000 1.0 3.0 2500 1.0 3.5 3150 1.0 4.0 4000 1.0 4.5 5000 1.0 5
49、.0 6.8.2. The direction of the sound intensity vector (sound power flow per unit area) must be positive (sound energy propagating away from the tire) for each one-third octave band with a center frequency between 400 and 5000 Hz. Any test run in which these criteria are not satisfied shall be considered invalid and not used in any averages of the test runs. 6.8.3. The coherence of sound pressure between the two microphones of each sound intensity prob
