Current Investigations into the Effects of Texture on IRI RPUG Jareer Abdel-Qader, Emmanuel Fernando, Roger Walker

Transcription

1 Current Investigations into the Effects of Texture on IRI RPUG 28 Jareer Abdel-Qader, Emmanuel Fernando, Roger Walker

2 Study Objectives Emmanuel s Presentation confirmed texture effects on IRI in both Laboratory studies as well as pavements with textured surfaces. Part of his research effort was focused on guide lines to account for the effects of surface texture on IRI Abdel-Qader/Fernando/Walker 2

3 Study Objectives cont. Also noted in his presentation was that the Texas roughness statistic NSI was insensitive to texture. NSI insensitivity to texture was later confirmed in studies conducted by the Texas Smoothness Initiative (TSI) The current presentation focuses on why does texture affect IRI and how can the effect be minimized. Abdel-Qader/Fernando/Walker 3

4 Current Solutions To Reduce Effects of Texture on IRI Current methods to minimize affects of texture on IRI are based around new lasers with wider footprints, line lasers, etc., and bridging filters Why are these methods used? What frequencies compose texture and why is IRI affected by these frequencies? Abdel-Qader/Fernando/Walker 4

5 Why is The Effect of Texture on IRI Different For NSI? Review the characteristics of IRI. What are the characteristics of texture that is causing the higher IRI readings? Abdel-Qader/Fernando/Walker 5

6 Review the characteristics of IRI. Investigate the Quarter Car Model Frequency Response of IRI Abdel-Qader/Fernando/Walker 6

7 Investigating the Quarter Car Model From Little Book of Profiling Abdel-Qader/Fernando/Walker 7

8 IRI Definition IRI 1 L L /V z s z u dt where L : Profile Length V : Speed,( 8km / h or : 49. 7mph) Abdel-Qader/Fernando/Walker 8

9 9 State-Space Equations Used for Computing Quarter Car Model m / k k,. m / m, m / k k,. m / c c where, / k c / ) / k ( k c / / k c k c k z z z z u y u, s s s u s t s s T u u s s D C B A x D Cx B Ax x

10 Quarter Car Simulation Model Abdel-Qader/Fernando/Walker 1

11 Quarter-Car Displacement Response Abdel-Qader/Fernando/Walker 11

12 Quarter-Car Displacement Response Need to take this out to 1-2 as this is high freq texture range Abdel-Qader/Fernando/Walker 12

13 White Noise What are the primary range of frequencies in texture? Texture often referred to as bandlimited white noise. The spectral density of white noise or a random signal has a flat power spectral density. Used Matlab to generate white noise with noise magnitude equal to that of the grade 3 over 3 texture specimen. Abdel-Qader/Fernando/Walker 13

14 White Noise Superimposed on Base Plate Abdel-Qader/Fernando/Walker 14

15 Plate Used to Hold Texture Specimens Abdel-Qader/Fernando/Walker 15

16 Plate With Textured Biscuit Sand Patch Areas Abdel-Qader/Fernando/Walker 16

17 Time Plot of Laser Readings Abdel-Qader/Fernando/Walker 17

18 IRI values Profile IRI (in/mi) Plate 3. Textured Plate 1-36 Plate + White Noise 12.8 Abdel-Qader/Fernando/Walker 18

19 Power Spectrum of Plate With and Without Texture and White Noise Wobble Filter Effects Abdel-Qader/Fernando/Walker 19

20 IRI values Profile IRI (in/mi) Plate 3. Textured Plate 12.7 Plate + White Noise 12.8 Abdel-Qader/Fernando/Walker 2

21 Quarter-Car Displacement Response Texture Effects in Sample Abdel-Qader/Fernando/Walker 21

22 Power Spectrum of SH36 Texture Measurements So where do you filter to take out texture but leave profile? Abdel-Qader/Fernando/Walker 22

23 Model Selected PSI 5e αp where: αp α P 1 1 α 2 P 2... α 8 P 8 PSR' ln PSR 5 2 i, P i Coefficient and Power Component for i = 1 to 8 meters Abdel-Qader/Fernando/Walker 23

24 So What Filter Bridging Algorithm Laser Type? So what filter to use that doesn t also take out profile? Is reduction in Profile frequencies really causing the reduction of IRI? Small amplitude band-limited white noise causes IRI increase of 8 to 1 inches per mile. Continue investigations of textured road sections and Concrete with tining Abdel-Qader/Fernando/Walker 24

25 Thank You Abdel-Qader/Fernando/Walker 25