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41 Texture Construction Analysis--Analysis of the design/ The 1/12th octave band spectra in Figure 5-9 shows a rela- specified texture profile dimensions versus the actual/ tively close grouping among the newly constructed sections, as-constructed texture dimensions. with the exception of two transverse-tined sections (Sections 9 and 11). Section 11 (1-in. [25.4-mm] transverse tine) exhibited Spectral Analyses a significant tone at 1,000 Hz, which would be quite audible and contributes to the 104.2 dB(A) overall noise level. Section 9 Noise Spectrum Analysis (0.5-in. [12.7-mm] transverse tine) exhibited a predominant Noise spectra were developed using software that utilizes tone around 1,600 Hz and an overall noise level of 102.6 dB(A). Fourier transform to analyze the near-field SI noise data With measured texture depths for these two sections being very recorded over the full length of the individual test sections. similar, it can be seen that the closer tine spacing resulted in a Raw noise data were normalized for the ambient air temper- higher-pitched and overall reduced noise level. ature and barometric pressure from the time of testing and Figures 5-10 and 5-11 show SI noise spectra for the newly then post processed to create a 1/12th octave band spectrum, constructed longitudinal- and transverse-textured sections, instead of the typical 1/3rd octave spectra, to provide better respectively. resolution for defining the test sections. Figures 5-1 through 5-8 show the SI noise spectra of the Texture Spectrum Analysis existing test sections. The sections are presented in narrow- band 1/12th-octave spectrum to detect the presence of a tone The field testing results presented in Chapters 3 and 4 illus- or whine (highlighted by a prominent spike of 5 dB(A) dif- trate the effects of texture depth, direction, and orientation/ ference from one octave to the next). Nearly all the spectra bias on noise. However, texture wavelength properties also show a typical peak near 1,000 Hz followed by a low tonal play a key role in the generation of noise. The wavelength apex at about 1,500 Hz. As seen in Figure 5-5 for the Iowa sec- properties are obtained through power spectral density (PSD) tions, the longitudinal-tined section (Section IA-1003) and analysis that produces histograms of the contents or levels of the transverse-tined sections (Sections IA-1002, IA-8001, and texture observed for specific wavelength bands. Figure 5-12 IA-8002) show a definite high tonal spike near 1,500 Hz. Also, illustrates the typical PSD function. as Figure 5-8 shows, the transverse-tined section in Missouri Sandberg and Ejsmont (2002) have suggested that to reduce (Section MO-1001) contains a medium spike near 2,000 Hz. exterior noise effectively, texture in the 0.80 to 24 in. (20 to 10 5 10 0 95 Sound Intensity, dB(A) 90 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz AZ 1003 AZ 1004 Figure 5-1. SI noise spectra for test sections in Arizona.

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42 105 100 95 90 Sound Intensity, dB(A) 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz CA 1002 CA 1003 CA 1004 CA 1045 CA 1005 CA 1007 CA 1075 Figure 5-2. SI noise spectra for test sections in California. 10 5 10 0 95 90 Sound Intensity, dBA 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz CO 3001 CO 3002 CO 3003 CO 3004 CO 3005 CO 3006 Figure 5-3. SI noise spectra for test sections in Colorado.

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43 105 100 95 90 Sound Intensity, dB(A) 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz IL 4001 IL 5001 IL 8001 Figure 5-4. SI noise spectra for test sections in Illinois. 105 105 95 Sound Intensity, dB(A) 90 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz IA 1002 IA 1003 IA 1004 IA 1061 IA 1007 IA 2001 IA 2002 IA 8001 IA 8002 IA 9002 Figure 5-5. SI noise spectra for test sections in Iowa.

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44 105 100 95 90 Sound Intensity, dB(A) 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz KS 1002 KS 1004 KS 1005 KS 1006 KS 1007 KS 1008 KS 1010 KS 2001 KS 4001 Figure 5-6. SI noise spectra for test sections in Kansas. 105 100 95 Sound Intensity, dB(A) 90 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz MN 1001 MN 2003 MN 2004 MN 5001 MN 7001 MN 8001 Figure 5-7. SI noise spectra for test sections in Minnesota.

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45 105 100 95 Sound Intensity, dB(A) 90 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz MO 1001 ND 2001 ND 6001 WI 1001 NC 1001 TX 1001 MI 1001 Figure 5-8. SI noise spectra for test sections in Michigan, Missouri, North Carolina, North Dakota, Texas, and Wisconsin. 105 100 95 Sound Intensity, dB(A) 90 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz 1a--Heavy Turf Drag (orig) 1b--Heavy Turf Drag (mod) 2--No Pretexture + 0.75-in Long Tine 3--No Pretexture + Long Grind 5a--Std Turf Drag + 0.75-in Long Tine 5b--Heavy Turf Drag + 0.75-in Long Tine 6--Std Turf Drag + 0.75-in Shallow Long Tine 7--Burlap Drag + Long Groove 8--Std Turf Drag + Long Groove 9--Burlap Drag + 0.5-in Tran Tine (GA design) 10--Burlap Drag + Random Tran Tine 11--Burlap Drag + 1-in Tran Tine (ISTHA Std) 12--Std Turf Drag + Random Skewed Tine Figure 5-9. SI noise spectra for the newly constructed test sections.

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46 105 100 95 Sound Intensity, dB(A) 90 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz 2--No Pretexture + 0.75-in Long Tine 3--No Pretexture + Long Grind 5a--Std Turf Drag + 0.75-in Long Tine 5b--Heavy Turf Drag + 0.75-in Long Tine 6--Std Turf Drag + 0.75-in Shallow Long Tine 7--Burlap Drag + Long Groove 8--Std Turf Drag + Long Groove 1a--Heavy Turf Drag (orig) 1b--Heavy Turf Drag (mod) Figure 5-10. SI noise spectra for longitudinal textures test sections. 105 100 95 Sound Intensity, dB(A) 90 85 80 75 70 65 500 1000 1500 2000 2500 3000 3500 4000 Frequency, Hz 9--Burlap Drag + 0.5-in Tran Tine (GA design) 10--Burlap Drag + Random Tran Tine 11--Burlap Drag + 1-in Tran Tine (ISTHA Std) 12--Std Turf Drag + Random Skewed Tine Figure 5-11. SI noise spectra for transverse textures test sections.

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47 60 Spectrum Peak 50 Texture level [dB rel, 1 micro m rms] 40 30 A2 A1 20 10 Mega-texture range Macro-texture range 0 640.0 320.0 160.0 80.0 40.0 20.0 10.0 5.0 2.5 Texture Wavelength, mm Figure 5-12. Texture spectrum characteristics for low noise. 610 mm) wavelength range should be reduced, texture in the The texture profile level represented on the y-axis in Fig- 0.08 to 0.40 in. (2 to 10 mm) range should be increased, and ures 5-12 and 5-13 is expressed in decibels relative to a refer- the spectrum peak should occur at the lowest wavelengths pos- ence RMS value of 1 m (ISO, 2002). sible, as illustrated in Figure 5-12. Also, two measures derived To evaluate the significance of texture spectral parameters, from the texture spectrum (L4 and L63) reportedly are good pre- the profile data collected on the newly constructed sections dictors of pavementtire noise, as illustrated in Figure 5-13 (right wheelpath for each 528-ft [161-m] test segment) were (Sandberg and Ejsmont, 2002). L4 and L63 are defined as follows: processed using the MatLab PSD software program to obtain texture spectra for each section and compute the L4 and L63 L4--Profile level of the 0.16-in. (4-mm) octave band, rep- profile levels. Two other PSD parameters were also calculated. resented by an energetic average of the third-octave bands A1--Texture content for the desirable wavelength range of 0.12, 0.16, and 0.20 in. (3.15, 4, and 5 mm); it is associated 0.08 to 0.40 in. (2 to 10 mm). with high-frequency noise development. A2--Texture content for the undesirable wavelength range L63--Profile level of the 2.48-in. (63-mm) octave band rep- of 0.80 to 24 in. (20 to 610 mm). resented by an energetic average of the third-octave bands 2.0, 2.5, and 3.15 in. (50, 63, and 80 mm); it is associated The corresponding ratios of L4 /L63 and A1 /A2 were also with low-frequency noise development. computed and the locations of the spectrum peaks (in terms Figure 5-13. Texture spectrum profile levels.