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38 Figure 4-20. ASTM SRTT and Goodyear Aquatred III test tire. Figure 4-19. SI vertical dual-probe configuration. Locked-wheel friction testing was also performed at two different times: in early September and in mid October. In the first round of testing, both ribbed (ASTM E 501) and smooth adjustments were made and formal testing commenced. The (ASTM E 524) test tires were used, with three tests performed dual-probe/SRTT test method reduced by half the number of per tire at both the lane center and the right wheelpath. In the runs required to average the front and rear SI measurements second round of testing, only ribbed tire testing of the lane and increased mechanical reliability. In addition, the reduced center and right wheelpath was performed. vibration of the probe bracket resulted in less variability in the data. In the case of far-field CPB tests, the setup was placed at Texture, Friction, 300 ft (91.5 m) from the start instead of 508 ft (155 m). Also, and Noise Test Results because the outside shoulders were largely incomplete during testing, it was decided that CPB measurements would be This section summarizes the results of the texture, friction, obtained by setting up the noise equipment on the inside shoul- and noise tests conducted on the test sections. The results are der and driving the test segment with the Aquatred III tires provided in terms of the key outputs from the various tests mounted on the left side of the vehicle closest to the micro- and other extrapolated indices. phone. Thus the 25-ft (7.6-m) offset distance prescribed in the Table 4-4 lists the mean texture values for each test sec- pass-by test was maintained and no correlation was needed for tion, based on measurements from both the right wheelpath differing tire types, since the Aquatred tire was used for the and the lane center, the mean micro-texture and friction existing test sections and the new Tollway sections. In addition, values measured for each section, and the mean noise levels, to eliminate background noise, CPB testing was conducted dur- as measured at the pavementtire interface, in the vehicle ing periods when there was no construction traffic, usually after interior, and at the side of the road. (Detailed results are the end of the work shift or on weekends. presented in Appendix D.)

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Table 4-4. Texture, friction, and noise test data. High-speed Profiler1 CT Meter1 DF Tester1 Locked-Wheel1 SI INT CPB Sect MPD, EMTD, MPD, MTD, NOISE, NOISE, NOISE, No. Texture Description mm mm mm mm TR DFT(20)2 F(60)2 FN40S/FN40R F(60)3 DB(A)1 DB(A)1 DB(A) 1a Long Heavy Turf Drag4 0.40 0.52 N/A N/A N/ A 45.6 23.1 ------ / 45.4 ------ / 31.8 101.55 69.50 #N/A 1b Long Heavy Turf Drag (mod)4 0.32 0.46 0.28 0.36 1.96 32.7 19.9 24.1 / 48.5 24.7 / 30.8 101.79 69.10 79.3 2 Long Tine (0.75-in. spacing, 0.125-in. depth), no 0.71 0.75 0.60 0.66 1.10 36.0 23.9 33.2 / 46.3 32.1 / 29.8 103.23 69.50 79.5 pretexture 3 Long DG (no jacks), 0.235-in. spacing (0.11-in. spacers) 0.35 0.48 0.65 0.71 2.41 48.3 22.8 ------ / 53.1 ------ / 34.1 100.48 67.60 77.5 5a Long Tine (0.75-in. spacing, 0.125-in. depth), turf drag 0.55 0.65 0.51 0.58 1.19 33. 3 21.1 35.0 / 48.7 37.8 / 32.7 102.35 71.10 77.6 5b Long Tine (0.75-in. spacing, 0.125-in. depth), heavy turf 1.22 1.20 1.02 1.06 1.25 42.9 30.8 44.2 / 47.5 41.8 / 31.8 105.31 72.00 82.4 drag 6 Long Tine (0.75-in. spacing, 0.075-in. depth), turf drag 0.54 0.63 0.49 0.56 1.23 34. 1 21.2 34.0 / 45.9 34.1 / 31.7 102.20 68.40 78.7 7 Long Groove (0.75-in. spacing, 0.25-in. depth), burlap 1.04 1.05 1.02 1.06 0.74 44.8 30.5 ------ / 46.8 ------ / 30.4 101.69 68.10 79.1 drag 8 Long Groove (0.75-in. spacing, 0.25-in. depth), turf drag 0.98 0.98 1.22 1.25 0.78 53.6 34.6 ------ / 57.1 ------ / 35.6 102.47 68.00 78.3 9 Tran Tine (0.5-in. spacing, 0.125-in. depth), burlap drag 0.48 0.59 0.48 0.55 1.41 42.4 23.6 ------ / 46.0 ------ / 29.7 102.63 67.70 80.7 (GA design) 10 Tran Tine (variable spacing, 0.125-in. depth), burlap 0.62 0.70 0.62 0.68 1.36 36.8 23.4 37.3 / 60.0 36.9 / 40.5 102.85 68.80 81.2 drag 11 Tran Tine (1.0-in. spacing, 0.125-in. depth), burlap drag 0.50 0.60 0.44 0.51 1.10 34.3 20.9 35.1 / 49.6 31.8 / 32.1 104.07 69.30 80.3 (old ISTHA std) 12 Tran Skew Tine (variable spacing, 0.125-in. depth), turf 0.64 0.71 0.58 0.65 1.28 36.9 23.5 ------ / 45.4 ------ / 31.8 102.69 67.80 80.1 drag (new ISTHA std) 1 Mean values based on right wheelpath and lane center measurements. 2 Values substantially lower than expected. 3 Smooth-Tire Friction Number, unless otherwise noted. 4 Sand patch tests conducted on heavy turf drag textures (after hardening of the PCC) yielded average MTD values of 0.023 in. (0.6 mm) for Sect 1a and 0.03 in. (0.76 mm) for Sect 1b. NA=Not available