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Publication Number: FHWA-HRT-05-054
Date: September 2005

Quantification of Smoothness Index Differences Related To Long-Term Pavement Performance Equipment Type

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Foreword

The main objective of this project is to quantify and resolve the differences in the longitudinal profile and roughness indices that are attributable to the different profiling equipment that have been used in the LTPP program. The Long-Term Pavement Performance (LTPP) program was designed as a 20-year study of pavement performance. A major data collection effort at LTPP test sections is the collection of longitudinal profile data using inertial profilers. Three types of inertial profilers have been used since the inception of the LTPP program: (1) K.J. Law Engineers DNC 690 incandescent profilers, (2) K.J. Law Engineers T-6600 infrared-system profilers, and (3) ICC laser profilers. The following analyses were performed for this research project: (1) investigate data collection characteristics and compare profile data collected by the different inertial profilers, (2) compare International Roughness Index (IRI) values obtained by the different inertial profilers, (3) investigate factors that contribute to differences in IRI for data obtained from profilers and Dipstick®, and (4) identify problems with equipment functionality and current data collection and processing procedures. The analysis indicated good agreement of IRI values among the different inertial profilers that have been used in the LTPP program.

Steve Chase,
Acting Director,
Office of Infrastructure Research and Development

Notice

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Technical Report Documentation Page

1. Report No.

FHWA–HRT–05–054

2. Government Accession No.

3. Recipient's Catalog No.

4. Title and Subtitle

Quantification of Smoothness Index Differences Related To Long-Term Pavement Performance Equipment Type

5. Report Date

September 2005

6. Performing Organization Code

7. Author(s)

R.W. Perera and S.D. Kohn

8. Performing Organization Report No.

9. Performing Organization Name and Address

Soil and Materials Engineers, Inc.
43980 Plymouth Oaks Blvd.
Plymouth, MI 48170

10. Work Unit No. (TRAIS)

11. Contract or Grant No.

DTFH61-96-C-00030

12. Sponsoring Agency's Name and Address

Office of Infrastructure Research, Development, and Technology
Office of Infrastructure R&D
Federal Highway Administration
6300 Georgetown Pike
McLean, VA 22101

13. Type of Report and Period Covered

Final Report
January–December 2004

14. Sponsoring Agency's Code

15. Supplementary Notes

Contracting Officer's Technical Representative (COTR): Larry Wiser, HRDI-13.
This research was conducted in collaboration with the University of Michigan Transportation Research
Institute (UMTRI) through participation and contributions from Steven Karamihas. Work was
performed as a subcontract to Construction Technology Laboratories, Inc. (CTL), Columbia, MD.
Dr. Shiraz Tayabji served as the project manager for the CTL contract.

16. Abstract

The Long-Term Pavement Performance (LTPP) program was designed as a 20-year study of pavement performance. A major data collection effort at LTPP test sections is the collection of longitudinal profile data using inertial profilers. Three types of inertial profilers have been used since the inception of the LTPP program: (1) K.J. Law Engineers DNC 690 incandescent profilers, (2) K.J. Law Engineers T-6600 infrared-system profilers, and (3) International Cybernetics Corporation (ICC) laser profilers. The following analyses were performed for this research project: (1) investigate data collection characteristics and compare profile data collected by the different inertial profilers, (2) compare International Roughness Index (IRI) values obtained by the different inertial profilers, (3) investigate factors that contribute to differences in IRI for data obtained from profilers and Dipstick®, and (4) identify problems with equipment functionality and current data collection and processing procedures. The analyses indicated good agreement of IRI values among the different inertial profilers that have been used in the LTPP program.

17. Key Words

IRI, inertial profilers, Dipstick, pavement data collection, pavement profile, profile measurement, profiler, LTPP.

18. Distribution Statement

No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

157

22. Price

Form DOT F 1700.7 (8–72) Reproduction of completed page authorized

 

SI* (Modern Metric) Conversion Factors

Table of Contents

  1. INTRODUCTION
  2. PROFILING DEVICES USED IN THE LTPP PROGRAM
  3. PROFILER COMPARISON STUDIES
  4. ANALYTICAL PROCEDURES
  5. DATA COLLECTION CHARACTERISTICS AND COMPARISON OF DATA COLLECTED BY LTPP'S PROFILERS
  6. DIFFERENCES BETWEEN DIPSTICK AND PROFILER IRI
  7. OTHER FINDINGS FROM ANALYSIS OF THE DATA
  8. CONCLUSIONS AND RECOMMENDATIONS

APPENDIX A. LTPP PROFILER COMPARISON STUDIES

APPENDIX B. PROFILER VERIFICATION STUDIES

REFERENCES

List of Figures

  1. LTPP regions
  2. K.J. Law Engineers DNC 690 profiler with a motor-home body
  3. K.J. Law Engineers DNC 690 profiler housed in a van
  4. K.J. Law Engineers T-6600 profiler
  5. ICC MDR 4086L3 profiler
  6. Height-sensor footprints
  7. Schematic view of Dipstick
  8. Roughness of a roadway expressed in 10-m (33-ft) segments
  9. Example of a roughness profile
  10. IRI obtained from two repeat runs
  11. Roughness profiles at 10-m (33-ft) base length for two runs
  12. Example of a PSD plot
  13. Profile recorded by a profiler
  14. Profile after being subjected to a 5-m (16-ft) high-pass filter
  15. Profile after being subjected to a 10-m (33-ft) low-pass filter
  16. Profile after being subjected to a band-pass filter
  17. Three IRI filtered profiles with an average correlation greater than 0.995
  18. Three IRI filtered profiles with an average correlation of 0.84.(21)
  19. PSD plot of data collected by the K.J. Law Engineers DNC 690 profiler
  20. PSD plot of data collected by the K.J. Law Engineers T-6600 profiler
  21. PSD plot of data collected by the ICC profiler
  22. Data collected by the North Central K.J. Law Engineers DNC 690 and T-6600 profilers at the smooth AC site during the 1996 verification test
  23. Data collected by the North Central K.J. Law Engineers DNC 690 and T-6600 profilers at the rough AC site during the 1996 verification test
  24. PSD plot of data collected by the K.J. Law Engineers DNC 690 and T-6600 profilers
  25. PSD plots of K.J. Law Engineers DNC 690 profiler data and ProQual-processed T-6600 profiler data
  26. Relationship between IRI from the K.J. Law Engineers DNC 690 and T-6600 profilers
  27. Differences in IRI between the K.J. Law Engineers DNC 690 and T-6600 profilers: All regions
  28. Differences in IRI between the K.J. Law Engineers DNC 690 and T-6600 profilers: North Atlantic region
  29. Differences in IRI between the K.J. Law Engineers DNC 690 and T-6600 profilers: North Central region
  30. Differences in IRI between the K.J. Law Engineers DNC 690 and T-6600 profilers: Southern region
  31. Differences in IRI between the K.J. Law Engineers DNC 690 and T-6600 profilers: Western region
  32. Comparison of ICC and K.J. Law Engineers profiles: Western site 320209
  33. Comparison of ICC and K.J. Law Engineers profiles: Western site 069107
  34. Response of the IRI filter
  35. PSD plot of 25-mm (1-inch) data collected by the North Central ICC and K.J. Law Engineers profilers at the chip-seal section during the 2002 verification test
  36. Closeup view of 25-mm (1-inch) profile data collected by North Central ICC and K.J. Law Engineers profilers on a chip-seal pavement
  37. Readings taken over a joint by the two profilers
  38. Profile data obtained by the ICC and K.J. Law Engineers profilers at a concrete site
  39. Relationship between IRI from the K.J. Law Engineers and ICC profilers
  40. Differences in IRI between the K.J. Law Engineers and ICC profilers
  41. Differences in IRI between the K.J. Law Engineers and ICC profilers: North Atlantic region
  42. Differences in IRI between the K.J. Law Engineers and ICC profilers: North Central region
  43. Differences in IRI between the K.J. Law Engineers and ICC profilers: Southern region
  44. Differences in IRI between the K.J. Law Engineers and ICC profilers: Western region
  45. Profile distortion caused by the application of a moving average onto data collected over a fault
  46. Profile distortion caused by the application of a moving average onto data collected over a patched crack
  47. Profile distortion caused by the application of a moving average onto data collected over a crack
  48. Application of a moving average onto data collected for a concrete pavement
  49. Application of a moving average onto a profile containing a sharp upward feature
  50. The 25-mm (1-inch) data and 150-mm (5.9-inch) averaged data from a smooth AC section
  51. Offset profile plot of 25-mm (1-inch) data and averaged 150-mm (5.9-inch) data collected from a smooth AC pavement
  52. Dipstick response to a sinusoid with a wavelength equal to the footpad spacing of Dipstick
  53. Gain plot of Dipstick
  54. An example of aliasing
  55. Roughness profiles for nine runs that show good agreement
  56. Roughness profiles for two profile runs that show variations
  57. Roughness profiles along the left wheelpath for three profilers
  58. Measurement of cracks by a profiler and Dipstick
  59. Measurement of a downward feature by a profiler and Dipstick
  60. Illustration of artificial profile used by ProQual for computing IRI
  61. Left-wheelpath 10-m (33-ft) base-length roughness profiles for profiler and Dipstick at site 5
  62. Left-wheelpath profiles for profiler and Dipstick at site 5
  63. Right-wheelpath profiles for profiler and Dipstick at site 1
  64. Roughness profiles for a profiler and Dipstick showing good agreement in roughness distribution
  65. Roughness profiles for a profiler and Dipstick showing moderate agreement in roughness distribution
  66. Roughness profiles for the case with the lowest cross correlation
  67. Roughness profiles for the case with the highest cross correlation
  68. Overlaid right-sensor profiles of the K.J. Law Engineers DNC 690 profiler
  69. Overlaid right-sensor profiles of the K.J. Law Engineers T-6600 profiler
  70. Overlaid right-sensor profiles from the K.J. Law Engineers DNC 690 and T-6600 profilers
  71. Right-sensor profile data collected by the Western and North Central profilers
  72. PSD plots of the right-sensor data collected by the North Central and Western profilers at site 2
  73. PSD plot of the left-sensor profile data from the North Atlantic profiler
  74. PSD plots of 25-mm (1-inch) right-sensor data from the North Central and Western profilers
  75. PSD plots of ProQual-processed right-sensor data from the North Central and Western profilers

LIST OF TABLES

  1. GPS experiments
  2. SPS experiments
  3. Changes in IRI caused by lateral variations in the longitudinal path
  4. IRI values from the 1996 verification test
  5. Results of cross correlation between the K.J. Law Engineers DNC 690 and T-6600 profilers
  6. Standard deviations of filtered elevation values
  7. Results of cross correlation between the K.J. Law Engineers T-6600 and ICC profilers
  8. IRI values for Dipstick data computed using ProQual and RoadRuf
  9. Results of cross-correlation analysis: Left wheelpath
  10. Results of cross-correlation analysis: Right wheelpath
  11. Cross correlation of IRI for North Atlantic and Western profilers
  12. Differences between the K.J. Law Engineers DNC 690 profiler IRI and Dipstick IRI
  13. Differences between the K.J. Law Engineers T-6600 profiler IRI and Dipstick IRI
  14. Differences between the ICC profiler IRI and Dipstick IRI
  15. IRI values computed using ProQual and RoadRuf
  16. Comparison of the IRI from the 25-mm (1-inch) data with the IRI from ProQual
  17. IRI values along the left wheelpath (1991)
  18. IRI values along the right wheelpath (1991)
  19. Differences between profiler IRI and Dipstick IRI: Left wheelpath (1991)
  20. Differences between profiler IRI and Dipstick IRI: Right wheelpath (1991)
  21. Standard deviations of IRI for 80-km/h (50-mi/h) runs: Left wheelpath (1991)
  22. Standard deviations of IRI for 80-km/h (50-mi/h) runs: Right wheelpath (1991)
  23. IRI values along the left wheelpath (1992)
  24. IRI values along the right wheelpath (1992)
  25. Differences between profiler IRI and Dipstick IRI: Left wheelpath (1992)
  26. Differences between profiler IRI and Dipstick IRI: Right wheelpath (1992)
  27. Standard deviations of IRI for 80-km/h (50-mi/h) runs: Left wheelpath (1992)
  28. Standard deviations of IRI for 80-km/h (50-mi/h) runs: Right wheelpath (1992)
  29. IRI values along the left wheelpath (1998)
  30. IRI values along the right wheelpath (1998)
  31. Differences between the profiler IRI and Dipstick IRI: Left wheelpath (1998)
  32. Differences between the profiler IRI and Dipstick IRI: Right wheelpath (1998)
  33. Standard deviations of IRI: Left wheelpath (1998)
  34. Standard deviations of IRI: Right wheelpath (1998)
  35. IRI values along the left wheelpath (2000)
  36. IRI values along the right wheelpath (2000)
  37. Differences between the profiler IRI and the walking profiler IRI (2000)
  38. Standard deviations of IRI: Left wheelpath (2000)
  39. Standard deviations of IRI: Right wheelpath (2000)
  40. IRI values along the left wheelpath (2003)
  41. IRI values along the right wheelpath (2003)
  42. Differences between the profiler IRI and Dipstick IRI: Left wheelpath (2003)
  43. Differences between the profiler IRI and Dipstick IRI: Right wheelpath (2003)
  44. Standard deviations of IRI: Left wheelpath (2003)
  45. Standard deviations of IRI: Right wheelpath (2003)
  46. Profiler IRI for 80-km/h (50-mi/h) runs and Dipstick IRI: North Atlantic region
  47. Differences between the profiler IRI and the Dipstick IRI: North Atlantic region
  48. Profiler IRI for 80-km/h (50-mi/h) runs and Dipstick IRI: North Central region
  49. Differences between the profiler IRI and the Dipstick IRI: North Central region
  50. Profiler IRI for 80-km/h (50-mi/h) runs and Dipstick IRI: Southern region
  51. Differences between the profiler IRI and the Dipstick IRI: Southern region
  52. Profiler IRI for 80-km/h (50-mi/h) runs and Dipstick IRI: Western region
  53. Differences between the profiler IRI and the Dipstick IRI: Western region
  54. IRI values obtained from the 2002 verification study

Acronyms and Abbreviations

AC Asphalt Concrete
ANOVA Analysis of Variance
ARRB Australian Road Research Board
DMI Distance Measuring Instrument
DOT Department of Transportation
FHWA Federal Highway Administration
GPS General Pavement Studies
ICC International Cybernetics Corporation
IRI International Roughness Index
LTPP Long-Term Pavement Performance
Mn/DOT Minnesota Department of Transportation
Mn/ROAD Minnesota Road Research Project
NCHRP National Cooperative Highway Research Program
PCC Portland Cement Concrete
PSD Power Spectral Density
RMSVA Root Mean Square Vertical Acceleration
RN Ride Number
RSC Regional Support Contractor
SHRP Strategic Highway Research Program
SPS Specific Pavement Studies
TxDOT Texas Department of Transportation
UMTRI University of Michigan Transportation Research Institute

FHWA-HRT-05-054

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