Annotated Literature Review for NCHRP Report 640 (2009)

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260 Table 125: Results of Friction Measurement Average Dynamic Friction Tester (DFT) Number (Standard Deviation) Mix 20 kph 40 kph 60 kph International Friction Index (F60) PFC 0.51 (0.03) 0.45 (0.03) 0.42 (0.03) 0.36 SMA 0.37 (0.01) 0.31 (0.01) 0.29 (0.01) 0.28 HMA 0.52 (0.01) 0.47 (0.01) 0.44 (0.01) 0.19 In terms of the IFI measurements, the PFC showed the highest friction, followed by the SMA and the HMA. Since these values are calculated from the mean profile depth, the trend is similar to the trend of the mean profile depth. Since no quantitative measurement was made for splash and spray, no results are given. However, based on visual evaluation, the authors indicate that sight condition for the driver was improved significantly (even when passing or passed by semi trailer trucks) with the use of the PFC, as compared to the SMA section. McDaniel and Thornton illustrate the better draining capabilities of the PFC section with the help of a figure showing a close-up view of the PFC and the HMA section, side by side. 1.69.8 Structural Design No information on structural design is given in this paper. 1.69.9 Limitations No information on limitations of the use of the PFC is given in this paper. 1.70 Scofield, L. and P. Donavan. “The Road To Quiet Neighborhoods In Arizona.” TRB 2005 Annual Meeting CD-ROM. Transportation Research Board. National Research Council. Washington, D.C. 2005. 1.70.1 General Scofield and Donavan describe the initial results of a ten-year $2 million program of research on producing quieter pavements in Arizona. The scope of this work to date consists of the determination of noise levels in existing roadway network, use of different types of tinings in new concrete pavements, the use of Asphalt Rubber Friction Course (ARFC), and the determination of noise levels in the new pavements using different techniques. The authors describe the background of the quieter pavement work in Arizona, and the resultant research program, which has been implemented through the use of different experimental pavements and tinings in the metropolitan Phoenix area. They describe the two main techniques used for determination of noise levels – the close proximity (CPX) method (using a trailer) and the sound intensity (SI) techniques (which can be used without a trailer). The results from these techniques compared well with each other, and were used for determination of noise levels in not only ARFC layers over concrete pavements, but also new concrete pavements tined in different ways.

261 Scofield and Donavan indicate that the 25 mm (one inch) ARFC over concrete pavements did produce the lowest noise levels, about 5 dB(A) less than random transverse tined concrete pavement (which produced the highest noise level). The ARFC was also found to have reduced the noise level by 5dB(A), on an average, at neighborhood residences. 1.70.2 Benefits of Permeable Asphalt Mixtures No benefit of permeable asphalt mixtures have been mentioned separately in this paper. 1.70.3 Materials and Design No information on materials and design has been provided in this paper. 1.70.4 Construction Practices Scofield and Donavan mention that traditionally 12.5 mm thick ARFCs have been placed over HMA pavements in Arizona, and as part of this new research program on producing quieter pavements, 25 mm thick ARFCs are being placed over concrete pavements. No other details of construction have been provided. Scofield and Donavan indicate techniques used for lowering of noise levels in existing pavement. These techniques include uniform longitudinal tinings, random transverse tinings and different diamond grinding techniques using different spacing between grinding blades, and difference in the amount of head pressure and beam length used in constructing the sections. 1.70.5 Maintenance Practices No information on maintenance practices has been provided in this paper. 1.70.6 Rehabilitation Practices Scofield and Donavan do not mention any specific rehabilitation activities to improve the condition of existing pavements 1.70.7 Performance Performance of the different types of surfaces, in terms of results from noise testing studies, has been provided in this paper. The authors give a detailed description of the different types of tests, data analysis and the amounts of noise reduction obtained from the different pavements. The authors present the results of their study in three different sections – development of a near field noise measurement system, determination of noise levels in existing pavements of different types but of similar ages, and the determination of noise levels in new concrete pavements with open surface and those with ARFC surfaces. Scofield and Donavan indicate that the AZ DOT have used both the CPX and the SI method (for near field noise measurement) and have decided to adopt the SI system because of its ability to measure noise without using a trailer. The authors describe the studies conducted to compare the results from these two test methods.

262 Initially, the CPX and SI methods were compared by conducting tests with a Goodyear Aqua Tread tire, at 60 mph on three roadway locations - SR 138 in California and sections of I-8 and I-10 in Arizona. The SI system was mounted on the driver side trailer wheel (in the CPX trailer) and leaving the CPX system mounted on the passenger side of the trailer. Five hundred foot long pavement segments were tested at each location. Data was reduced and averaged in terms of overall A-weighted level and 1/3 octave band level. Scofield and Donavan indicate that there was a good correlation between the two systems even though they measured different wheel path locations. In addition to obtaining A-weighted values, spectral comparisons of CPX and SI data were also made, and the results indicated a slight spectral shift between the CPX and SI results, particularly below a frequency of approximately 1600 Hz. Scofield and Donavan mention that to overcome the added time required to use the original SI system (made by GM, which required making two passes with the vehicle), I&R has developed a modified design which would allow both leading and trailing edge contact patch areas to be measured concurrently with one pass of the trailer. Although this would violate the draft ISO standards for close proximity measurements, Arizona DOT is working on developing a trailer which can be used for both CPX and SI measurement, to increase the speed and reduce the variability of data collection. Scofield and Donavan then provide results of field and laboratory tests conducted to independently evaluate the trailer modifications. From the field testing (which used a noise generator, a microphone and speaker), the authors conclude that most of the differences are due to experimental variations. In the laboratory testing, where the effect of isolation through an enclosure was evaluated, a 10dB(A) expected difference between tests conducted with open and closed door were not obtained, and the authors caution against the use of this system. In the third testing, the isolation of side-to-side tire noise when using two different tire types on the same axle, was evaluated, both in the field and in the laboratory. The laboratory testing consisted of mounting a speaker in place of the tire at one position and replacing the tire with a microphone at the other position. The results of this testing indicated the minimum 10 dB(A) separation requirement was met. To further verify the isolation of the side-to-side tire noise, on-road tests were conducted using an ASTM friction tire and a Goodyear Wrangler SUV type tire. The baseline testing was conducted using the friction tire on both sides. The far side Friction tire was then replaced with the Wrangler SUV type tire. The results indicated the 10 dB(A) requirement had been met. Scofield and Donavan indicate that three to twelve year old pavements constructed in similar environments as Phoenix were identified and tested using both the CPX and SI systems. These pavements had 12.5 mm thick ARFC surfaces over HMA pavements. No significant correlation between pavement age and overall noise level was found. The authors indicate that due to equipment problems, some of the older and quieter pavements did not get tested. Scofield and Donavan indicate that testing was conducted on existing concrete pavements prior to overlay with ARFC. Both longitudinal and random transverse tinings were

263 present in different sections of SR202. These sections were tested with controlled pass-by technique. For each of the roadside test locations, 32 vehicles representing three classes of vehicles were driven past each of the three points at approximately one-minute intervals for the passenger vehicles and two minute intervals for the medium and heavy trucks. Each of the passenger cars were driven by at 60 MPH and then again at 70 MPH Measurements were obtained at 25 ft and 50 ft from the centerline of the travel lane at all three-test locations. Scofield and Donavan mention that the results indicated that the uniform longitudinal texture produced approximately a 5 dB(A) reduction over ADOT’s standard uniform one inch transverse texture. It also produced approximately an 8-9 dB(A) reduction over the Wisconsin random transverse texturing. All three tining methods resulted in approximately a 2 dB(A) increase between 60 and 70 MPH at the 50 ft measurement location. Inside the test vehicle, it was found that the random traverse tined surface produced levels higher than either of the two other surfaces between about 200 and 800 hertz apparently due to the details of the tine spacing. The authors mention that the experience with random transverse tining of AZ DOT is different from Wisconsin DOT, as the tinings were of different nature – AZ DOT tinings had an upward (positive) tine of 5/32inch, whereas Wisconsin tines had typical depths of 2/32 to 3/32 inch. In addition to existing concrete section, Scofield and Donavan mention the testing of new concrete pavements, which had several different types of grindings. The four grinding techniques are essentially based upon altering the spacing between grinding blades, and in the amount of head pressure and beam length used in constructing the sections. Testing was conducted using the CPX method and using a Goodyear Aqua Tread tire at 60 mph. The noise levels in these experimental sections were found to be significantly lower than in pavements constructed with other concrete texturing methods. Scofield and Donavan point out that the current procedure of loudness measurement using the 1/3 octave analysis with A-weighting does not consider the tonal properties (spikes) that may exist. In a figure showing results of analysis conducted in two ways – using 1/3 octave and 1/24 octave, the authors illustrate that in the 1/3 octave spectrum, a tonal spike at approximately 1500-1600 Hz is not apparent, whereas in the other one, the tonal spike is readily apparent. The authors mention that this is important, since this tonal spike represents the “tire whine” associated with uniformly-tined PCCP and represents an important part of the annoyance factor. They illustrate that using 1/24 octave the benefit of using ARFC is more apparent - there is also a significant reduction in the spectrum in the range between 1000 and 2000hz, a range where hearing is quite sensitive. Overall, Scofield and Donavan mention that the ARFC produced the lowest noise level (91.8 dB(A)), followed by the Whisper Grinding (95.5 dB(A), the longitudinally tined PCCP (99.1 dB(A)), ADOT uniformly transverse tined PCC)P (102.5 dB(A)), and the random transverse tined PCCP (104.5 dB(A)). The ARFC was found to have reduced the noise level at residential neighborhoods by 5dB(A). The authors mention that the 25 mm thick ARFC layers do produce quieter pavements compared to the traditionally used 12.5