Paul R. Donavan

Measuring Tire–Pavement Noise at the Source

This report presents a suggested procedure for measuring the tire–pavement noise at the source. The procedure uses the on-board sound intensity (OBSI) method that was found to be the preferred approach for measuring tire–pavement noise at the source. Although the research presented in this report provided a basis for the recently introduced provisional Standard Test Method for the Measurement of Tire/Pavement Noise Using the On-Board Sound Intensity (OBSI) Method (AASHTO Designation TP076-08), the procedure includes some modifications to the provisional standard. The content of the report will be of immediate interest to state engineers and others concerned with pavement design and construction and the noise impacts on nearby communities.

Assessment of tire/pavement interaction noise under vehicle passby test conditions using sound intensity measurement methods

Over the past several years, sound intensity measurement methods have become an increasing valuable tool in isolating tire/pavement interaction noise when a vehicle is tested under full throttle acceleration conditions such as the ISO 362 R15 procedure. Several investigations have been conducted and reported which demonstrate the relationship between ‘‘on‐board’’ sound intensity measured close to a tire contact patch and the sound pressure level measured by a stationary microphone 7.5 m away from the line of travel of the vehicle. Using these relationships, the contribution of tire/pavement noise can be assessed relative to other noise sources associated with a vehicle under acceleration as measured at 7.5 m. In this application, it has been determined that some tires can produce significantly higher noise levels under the torque of acceleration than under cruise conditions. Sound intensity has also been used to separate sound propagation from sound generation effects in the assessment of test surfaces su...

Investigations of Effects of Porous Pavement on Traffic Noise and Traffic Noise Prediction

The U.S. Department of Transportations FHWA Traffic Noise Model (TNM) is currently missing the effect of sound-absorbing pavements on predicted noise levels, in regard to both a reduction in source level and a reduction of sound through propagation. In TNM, a single effective flow resistivity value representing acoustically hard ground is used in sound propagation and ground reflection algorithms. With acoustically hard ground, most of the sound from vehicles is reflected. For porous pavements (those with more than 15% interconnected air voids), sound incident on the pavement is partially absorbed and thus potentially reduces the noise level for receivers along the roadway relative to that for a non porous surface. Results of investigations indicate that the sound absorption produced by porous pavements will have an effect on both measured and predicted traffic noise levels. The work shows that more accurate TNM-predicted sound levels can be achieved by properly accounting for the sound absorption of pavement, the effect of sound-absorbing pavement is not insubstantial, and predictions can be made as to the effect of sound-absorbing pavement by using modeling or measurement techniques, or both.

Evaluating Pavement Strategies and Barriers for Noise Mitigation

This report presents a methodology for evaluating feasibility, reasonableness, effectiveness, acoustic longevity, and economic features of pavement strategies and barriers for noise mitigation. The methodology uses life-cycle cost analysis (LCCA) to examine the economic features of mitigation alternatives, the FHWA Traffic Noise Model (TNM®) to integrate the noise reduction performance of pavements and barriers, and on-board sound intensity (OBSI) measurements as an input to the prediction model. This approach provides a rational basis for evaluating alternatives for noise mitigation. The appendixes, which provide elaborations and detail on several aspects of the research, are not included with the print version of the report, but are available on the Transportation Research Boards website.The material contained in the report will be of immediate interest to state engineers and others concerned with pavement design and construction and the noise impact on nearby communities.

Tire Noise Generation and Propagation over Porous and Nonporous Asphalt Pavements

Acoustic measurements were made on several asphalt test pavements at the National Center for Asphalt Technology test track, including five porous pavements. Onboard sound intensity (OBSI) measurements were taken to quantify the tire–pavement noise source strength as a function of pavement parameters. The OBSI results fell into three pavement groupings based on spectral shape. More than other parameters, these groupings were determined by whether the pavement was porous or not and whether it was new or older. The OBSI results also indicated that single-layer porous pavements were particularly effective at reducing tire–pavement noise source strength at frequencies above 1,250 Hz for designs 18 to 33 mm thick. For a thicker, double-layer porous pavement, source strength reductions extended down to 630 Hz. Porous pavements were also found to be effective in reducing the source strength of the tire–pavement interaction by reducing some tire noise mechanisms and by reducing the sound power level of the source through local sound absorption. Testing was also conducted to evaluate the additional attenuation for sound propagating over porous, sound-absorbing pavements compared with nonporous pavements. From the propagation measurements, all porous pavements produced additional sound attenuation over that produced by the nonporous pavements. The additional attenuation also increased with distance from the source.

Acoustic Beamforming: Mapping Sources of Truck Noise

This report documents the use of the acoustic beamforming technique to pinpoint and measure noise levels from heavy truck traffic. The system uses an elliptical array of more than 70 microphones and data acquisition software to measure noise levels from a variety of noise sources on large trucks—including the engine, tires, mufflers, and exhaust pipes. The results validate the feasibility of beamforming technology, offer new insight into the distribution of truck noise sources, and provide valuable input to the design and testing of quieter pavements and noise barrier systems. This report will be of interest to anyone concerned with understanding and mitigating highway noise levels.

Effect of Porous Pavement on Wayside Traffic Noise Levels

In 2011, pavement on an eight-lane portion of U.S. Highway 101 in San Rafael and Novato, California, was rehabilitated with the application of an open-graded asphalt concrete (OGAC) overlay as part of a larger project to improve the traffic flow along the 101 corridor. Residents in the area of rehabilitation had periodically complained to the local transportation agency about traffic noise. For an understanding of the noise reduction expected after the application of the new OGAC, wayside traffic noise levels and onboard sound intensity (OBSI) levels were measured at two sites: the site where the new pavement was to be placed and a nearby site that had received new OGAC 1 year earlier. The results indicated that a reduction of 7.8 dB in OBSI tire–pavement noise should be expected, along with a reduction of 7.8 to 8.4 dB in wayside traffic noise. The measurements were repeated after the OGAC application; OBSI reductions of 7.1 dB were found, and reductions of 10.5 and 11.2 dB were found for the wayside levels measured 60 ft from the highway. The comparison of results from previous studies of sound propagation over porous pavements led to the conclusion that this additional reduction in the wayside levels of 3.4 and 4.1 dB compared with the tire–pavement source levels was attributable to the sound absorption provided by the porous pavement.

Effects of Aging on Tire-Pavement Noise Generation for Concrete Pavements of Different Textures

Between 2003 and 2010, research on the changes in tire–pavement noise generation over time was conducted on 11 textures applied to portland cement concrete. The initial textures included longitudinal tining, burlap drag, and longitudinal broom. Additional texturing was applied to these surfaces in the form of longitudinal grooving of varying depth and spacing and diamond grinding with varying spacer dimensions, as well as a combination of the two. Since their application, these sections have been routinely monitored for tire noise performance with the onboard sound intensity method. As originally measured in June 2003, the range in level between the surfaces was relatively small at 2.7 dB. At 5 years, the range is slightly smaller at 2.3 dB. During the total 71/2 years of the study, the overall noise performance increased at an average rate of about 0.10 dB per year. The study has shown that for different frequency ranges the change in noise level has displayed some variation; the lower-frequency levels have decreased for some pavements with time, while the higher-frequency levels have increased at a rate higher than the overall levels for all pavements. For the higher frequencies, findings suggested that the increased noise was due to polishing of the surfaces. For the lower frequencies, the reduction in noise level was less pronounced with more variability between textures. For the ground surfaces, some evidence was found that indicated that the reduction might be linked to some loss of larger-scale texture as the surfaces were worn down.

Quieting of Portland cement concrete highway surfaces with texture modifications

In recent years, various types of asphalt surfaces have become identified as ‘‘quiet pavements’’ due to their ability to reduce tire/pavement noise and, ultimately, traffic noise. Often lost in this perception is the fact that substantial reductions in tire/pavement noise can also be made by texture modifications to existing Portland Cement Concrete (PCC) or by novel constructions. PCC surfaces have been found to span a range of as much as 16 dB. As a result, there is the potential to achieve large noise reductions depending on the existing and final surfaces. In California, grinding of bridge decks and elevated structures has been found to reduce tire/pavement source levels 3 to 10 dB with comparable reductions in wayside measurements. In Arizona, grinding of PCC has reduced source levels up to 9 dB relative to some transversely tined surfaces. Measurements conducted in Europe using the same measurement methodology indicated a range of 11 dB including more novel porous PCC surfaces. In this paper, measur...

The role of acoustic tube resonances in the radiation of sound from circumferentially ribbed truck tires

While in contact with the pavement surface, the grooves of circumferentially ribbed tires form tubes open at both the leading and trailing edges of the tire contact patch. These tubes efficiently radiale sound at the fundamental resonant frequency, corresponding to an acoustic wavelength equal to one half of the tube length, and at the higher harmonic frequencies. This behavior was studied with acoustic intensity measurements made alongside a moving straight rib (HCR) truck tire using the technique described in a previous presentation [L. J. Oswald and P. R. Donavan, J. Acoust. Soc. Am. Suppl. 1, 67, S71 (1980)]. These data show a 3 to 7 dB reduction from 500 to 2500 Hz in the narrow‐band acoustic intensity spectrum when the resonant‐tube radiation is eliminated with open cell foam placed in the grooves. Further, consistent with the dipolelike radiation from the tube ends occurring at the odd‐numbered tube harmonics, distinct nulls in the acoustic intensity were measured alongside the center of the contac...