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Publication Number: FHWA-RD-01-166
Date: November 2003

Structural Factors for Flexible Pavements—Initial Evaluation of The SPS-1 Experiment Final Report

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Foreword

This report documents a study undertaken to conduct a detailed review of the Long-Term Pavement Performance (LTPP) Special Pavements Study–1 (SPS-1) experiment to determine to what extent it will provide the necessary data to ensure that the objectives and expectations from this experiment are attained.  The SPS-1 experiment entitled Strategic Study of Structural Factors for Flexible Pavements is one of the key experiments of the LTPP program. Its goal is to develop improved methodologies and strategies for the construction of flexible pavements.  The review concentrated on the core experimental test sections with secondary emphasis on the supplemental test sections that were built by the individual agencies for each SPS-1 project. 

As a result of this work, the data availability and completeness for the SPS-1 experiment are fairly complete with two exceptions.  The two critical elements or parameters found to have significant deficiencies are the traffic and materials test data.  These data deficiencies need to be addressed before a comprehensive analysis of the SPS-1 experiment is conducted.  The majority of the SPS-1 data that have been collected are at level E.

This report will be of interest to highway agency engineers involved in the collection, processing, and analysis of SPS-1 data to improve the design procedures and standards for constructing hot-mix asphalt-surfaced pavements.

T. Paul Teng, P.E.
Director, Office of Infrastructure
Research and Development

NOTICE

This document is disseminated under the sponsorship of the U.S. Department of Transportation in the interest of information exchange.  The U.S. Government assumes no liability for its contents or use thereof.  This report does not constitute a standard, specification, or regulation.

The U.S. Government does not endorse products or manufacturers.  Trade or manufacturers’ names appear herein only because they are considered essential to the objective of this document.

Technical Report Documentation Page

1. Report No.
FHWA-RD-01-166

2. Government Accession No.

3. Recipient's Catalog No.

4. Title and Subtitle
 Structural Factors for Flexible Pavements—Initial Evaluation of the SPS-1 Experiment

5. Report Date

6. Performing Organization Code

7. Author(s)
Harold L. Von Quintus and Amy  L. Simpson

8. Performing Organization Report No.

9. Performing Organization Name and Address
Fugro-BRE, Inc.
8613 Cross Park Drive
Austin, TX 78754

10. Work Unit No. (TRAIS)
C6B

11. Contract or Grant No.
DTFH61-96-C-00003

12. Sponsoring Agency Name and Address|Office of Engineering Research and Development
Federal Highway Administration
6300 Georgetown Pike
McLean, VA  22101-2296

13. Type of Report and Period Covered
Final Report
Oct 1999 to April 2000

14. Sponsoring Agency Code

15. Supplementary Notes
Work was conducted as part of the LTPP Data Analysis Technical Support Contract.
Contracting Officer’s Technical Representative (COTR): Cheryl Allen Richter, HRDI-13   

16. Abstract

The SPS-1 experiment entitled Strategic Study of Structural Factors for Flexible Pavements is one of the key experiments of the LTPP program.  The objective of this experiment is to determine the relative influence and long-term effectiveness of hot mix asphalt (HMA) design features (including surface and base thickness, base type, and drainage condition) and site conditions (traffic, subgrade type, and climatic factors) on performance.  This report documents the first comprehensive review and evaluation of the SPS-1 experiment.  Eighteen SPS-1 projects have been constructed and each site includes 12 core test sections and some sites also include supplemental sections. A total of 248 test sections are included in the SPS-1 experiment.

The data for the SPS-1 experiment are fairly complete with two exceptions:  the traffic and materials test data.  However, a significant amount of some types of data is still missing, especially the distress data.  These data deficiencies need to be addressed before a comprehensive analysis of the SPS-1 experiment is conducted.  The majority of the SPS-1 data that has been collected is at level E.  

Required experimental design factors were compared with the actual constructed values.  A large majority of SPS-1 sections follow the experiment design and can be characterized as good to excellent.  Two projects are relatively new, and the data processing and materials testing are currently underway.  The evaluation and detailed review have highlighted several significant problems that will clearly limit the results that can be obtained from the SPS-1 experiment.  Specifically, these include the missing traffic and materials test data.  These data must be collected in order for the SPS-1 experiment to meet the expectations for calibrating and validating mechanistic models.  The performance trends and effects of several design features and site conditions were noted and documented.

17. Key Words
Design factors, experimental design, HMAC, LTPP, performance trends, SPS-1

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

19. Security Classification (of this report)
Unclassified

20. Security Classification (of this page)
Unclassified

21. No. of Pages
200

22. Price

Form DOT F1700.7 (8-72)                     Reproduction of completed page authorized


SI* (Modern Metric) Conversion Factors


TABLE OF CONTENTS

Section 
  1. INTRODUCTION
  2. GENERAL OVERVIEW OF EXPERIMENT
  3. PROJECT REQUIREMENTS
  4. EXPERIMENT ASSESSMENT—DATA AVAILABILITY AND COMPLETENESS
  5. ANALYSIS OF EARLY PERFORMANCE OBSERVATIONS
  6. SUMMARY AND CONCLUSIONS

Section 

APPENDIX A.—SPS-1 PROJECT SUMMARIES


APPENDIX B.—SUMMARY OF CONSTRUCTION DATA
REFERENCES


LIST OF FIGURES

Figure

  1. Location of the SPS-1 projects
  2. LTPP data collection and data movement flowchart
  3. Thickness histograms for the thin HMA layer (102 mm) from tables SPS1_LAYER  (construction data) and TST_L05B
  4. Thickness histograms for the thick HMA layer (178 mm) from tables SPS1_LAYER (construction data) and TST_L05B
  5. Thickness histograms for the thin ATB layer (102 mm) from tables SPS1_LAYER (construction data) and TST_L05B
  6. Thickness histograms for the thick ATB layer (203 mm) from tables SPS1_LAYER (construction data) and TST_L05B
  7. Thickness histograms for the PATB layer from tables SPS1_LAYER (construction data) and TST_L05B
  8. Thickness histograms for the 102-mm DGAB layer from tables SPS1_LAYER  (construction data) and TST_L05B
  9. Thickness histograms for the 203-mm DGAB layer from tables SPS1_LAYER (construction data) and TST_L05B
  10. Thickness histograms for the 305-mm DGAB layer from tables SPS1_LAYER  (construction data) and TST_L05B
  11. Histogram of air voids measured on the HMA surface layer
  12. Histogram of air voids measured on the HMA binder layer
  13. Histogram of air voids measured on the ATB layer
  14. Histogram of the material passing the number 4 sieve, PATB layer
  15. Histogram of material passing the number 200 sieve, PATB layer
  16. Histogram of material passing the number 200 sieve, HMA surface layer
  17. Histogram of material passing the number 200 sieve, ATB layer
  18. Area of fatigue cracking measured over time comparing test sections with and without permeable base layers for all SPS-1 projects combined
  19. Total length of transverse cracks measured over time comparing test sections with and without permeable base layers for all SPS-1 projects combined
  20. IRI values measured over time comparing test sections with and without permeable  base layers for all SPS-1 projects combined
  21. Rut depths measured over time comparing test sections with and without permeable  base layers for all SPS-1 projects combined
  22. Longitudinal cracking in the wheel paths measured on different dates for the core test sections of the Alabama project
  23. Longitudinal cracking outside the wheel paths measured on different dates for the core test sections of the Alabama project
  24. Transverse cracking measured on different dates for the core test sections of the Alabama project
  25. Graphical illustration of the average amount of fatigue cracking observed on each of the projects, as of January 2000
  26. Percentage of the core test sections that exceed an IRI value of 1.2 m/km
  27. Percentage of the core test sections that exceed 8 mm of rutting
  28. Percentage of test sections that exceed an IRI value of 1.2 m/km
  29. Percentage of core test sections that have fatigue cracking

 

LIST OF TABLES

Table 

  1. Factorial for the SPS-1 experimental design and the sites/projects originally nominated for each cell within the experiment
  2. Supplemental sections constructed on SPS-1 projects
  3. Final factorial for the SPS-1 experiment design
  4. Required testing for the SPS-1 experiment
  5. Summary of SPS-1 data elements and their importance to experimental expectations
  6. SPS-1 project site information and report availability
  7. SPS-1 subgrade classification
  8. Summary of key factor values for the SPS-1 projects
  9. Summary of materials testing on the subgrade soils
  10. Summary of materials testing on the unbound aggregate base materials
  11. Summary of materials testing on the permeable asphalt treated base mixtures
  12. Summary of materials testing on the asphalt treated base mixtures
  13. Summary of materials testing on the HMA mixtures
  14. Summary of materials testing completed by material type for the core test sections,  percent complete
  15. Summary of climatic and traffic data for the SPS-1 project sites
  16. Summary of the minimum number of distress and other performance indicator measurements made at each project site
  17. Summary of the average time interval between the different performance indicator surveys   
  18. Summary of Level E dynamic load response data for the Ohio SPS-1 project
  19. Summary of the overall construction difficulties and deviations, and the adequacy code for the projects included in the SPS-1 experiment
  20. Percentage of the SPS-1 core test sections with distress magnitudes exceeding  the value noted
  21. Summary of the average area of fatigue cracking observed at each project
  22. Summary of p-values from a one-way ANOVA to determine the effect of experimental factors on selected performance indicators
  23. Average performance differences of the test sections between the different soil types included in the SPS-1 experiment
  24. Average performance differences of the test sections between the different  types of base layers included in the SPS-1 experiment
  25. Average performance differences of the test sections between the different drainage conditions included in the SPS-1 experiment
  26. Average performance differences of the test sections between the different HMA layer thickness included in the SPS-1 experiment
  27. Summary of missing or limited data for the SPS-1 experiment
  28. Deficiencies and action items for each SPS-1 project
  29. Identification of future research studies from the SPS-1 experiment—initial analysis of the individual factorial cells and companion projects
  30. Identification of future research studies from the SPS-1 experiment—overall effect of the main experimental factors on performance
  31. Identification of future research studies from the SPS-1 experiment—benefits of drainage
  32. Identification of future research studies from the SPS-1 experiment—effect of thickness variations on performance
  33. Identification of future research studies from the SPS-1 experiment—effect of base material type on pavement performance
  34. Identification of future research studies from the SPS-1 experiment—effect of seasonal changes on pavement response and material responses related to performance
  35. Identification of future research studies from the SPS-1 experiment—effect of soil type and stiffness on pavement performance
  36. Identification of future research studies from the SPS-1 experiment—effect of base condition on pavement performance
  37. Identification of future research studies from the SPS-1 experiment—effect of HMA properties on pavement performance
  38. Identification of future research studies from the SPS-1 experiment—quantification of remaining life of cracked or damaged HMA layers
  39. Identification of future research studies from the SPS-1 experiment—identify those properties and conditions most conducive to the development of surface initiated fatigue cracks
  40. Identification of future research studies from the SPS-1 experiment—applicability of the subgrade protection criteria for use in design of flexible pavements
  41. Identification of future research studies from the SPS-1 experiment—confirm the C-values or differences between laboratory measured resilient modulus and back calculated elastic layer modulus
  42. Identification of future research studies from the SPS-1 experiment—mechanistic analysis of the SPS-1 sites
  43. Summary of key project monitoring data for the Alabama SPS-1
  44. Summary of available materials testing data on the Alabama SPS-1
  45. Summary of key project monitoring data for the Arizona SPS-1
  46. Summary of available materials testing data on the Arizona SPS-1
  47. Summary of key project monitoring data for the Arkansas SPS-1
  48. Summary of available materials testing data on the Arkansas SPS-1
  49. Summary of key project monitoring data for the Delaware SPS-1
  50. Summary of available materials testing data on the Delaware SPS-1
  51. Summary of key project monitoring data for the Florida SPS-1
  52. Summary of available materials testing data on the Florida SPS-1
  53. Summary of key project monitoring data for the Iowa SPS-1
  54. Summary of available materials testing data on the Iowa SPS-1
  55. Summary of key project monitoring data for the Kansas SPS-1
  56. Summary of available materials testing data on the Kansas SPS-1
  57. Summary of key project monitoring data for the Louisiana SPS-1
  58. Summary of available materials testing data on the Louisiana SPS-1
  59. Summary of key project monitoring data for the Michigan SPS-1
  60. Summary of available materials testing data on the Michigan SPS-1
  61. Summary of key project monitoring data for the Montana SPS-1
  62. Summary of available materials testing data on the Montana SPS-1
  63. Summary of key project monitoring data for the Nebraska SPS-1
  64. Summary of available materials testing data on the Nebraska SPS-1
  65. Summary of key project monitoring data for the Nevada SPS-1
  66. Summary of available materials testing data on the Nevada SPS-1
  67. Summary of key project monitoring data for the New Mexico SPS-1
  68. Summary of available materials testing data on the New Mexico SPS-1
  69. Summary of key project monitoring data for the Ohio SPS-1
  70. Summary of available materials testing data on the Ohio SPS-1
  71. Summary of key project monitoring data for the Oklahoma SPS-1
  72. Summary of available materials testing data on the Oklahoma SPS-1
  73. Summary of key project monitoring data for the Texas SPS-1
  74. Summary of available materials testing data on the Texas SPS-1
  75. Summary of key project monitoring data for the Virginia SPS-1
  76. Summary of available materials testing data on the Virginia SPS-1
  77. Summary of key project monitoring data for the Wisconsin SPS-1
  78. Summary of available materials testing data on the Wisconsin SPS-1

ABBREVIATIONS

AASHTO—American Association of State Highway and Transportation Officials

AC—Asphalt Concrete

ANOVA—Analysis of Variance

AGG—Aggregate bases, identical to dense graded aggregate base

ATB—Asphalt Treated Base

AVC—Automated Vehicle Classification

AWS—Automated Weather Stations

DGAB—Dense Graded Aggregate Base, identical to aggregate base

ESAL—Equivalent Single Axle Load

FHWA—Federal Highway Administration

FWD—Falling Weight Deflectometer

GPS—Global Positioning System

HMA—Hot-Mix Asphalt

HMAC—Hot-Mix Asphalt Concrete

IMS—Information Management System

IRI—International Roughness Index

LTPP—Long-Term Pavement Performance

NAA—National Aggregate Association

NCHRP—National Cooperative Highway Research Program

NIMS—National Information Management System

NOAA—National Oceanic and Atmospheric Association

PATB—Permeable Asphalt Treated Base mixtures

QC/QA—Quality Control/Quality Assurance
RCO—Regional Coordination Office

RIMS—Regional Information Management System

SHA—State Highway Agency

SHRP—Strategic Highway Research Program

SPS—Special Pavement Studies

WIM—Weigh-in-Motion

SPS-1 Project Name Abbreviations

AL—Alabama

AR—Arkansas

AZ—Arizona

DE—Delaware

FL—Florida

IA—Iowa

KS—Kansas

LA—Louisiana

MI—Michigan

MT—Montana

NM—New Mexico

NE—Nebraska

OH—Ohio

OK—Oklahoma

TX—Texas

VA—Virginia

WI—Wisconsin