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| REPORT |
| This report is an archived publication and may contain dated technical, contact, and link information |
 |
| Publication Number: FHWA-HRT-13-090 Date: April 2016 |
Publication Number: FHWA-HRT-13-090 Date: April 2016 |
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The Mechanistic-Empirical Pavement Design Guide (MEPDG), Interim Edition: A Manual of Practice requires detailed axle loading information in the form of normalized axle load spectra (NALS), number of axles per truck class and axle group types, and axle spacing inputs as part of traffic loading inputs.(1) These data are obtained from weigh-in-motion (WIM) sites.
The objectives of this project were to evaluate the applicability of the existing MEPDG global traffic loading defaults and to use research-quality WIM data from the Long-Term Pavement Performance (LTPP) Specific Pavement Study (SPS) Traffic Data Collection pooled fund study to revise and improve the global default axle loading values.(2) This report provides an assessment of the original MEPDG axle loading defaults, describes WIM data selection criteria, including data reliability assessment, presents findings from the LTPP SPS traffic pooled fund study traffic data review, describes a methodology to generate new MEPDG traffic loading defaults, and provides a description of the new traffic loading defaults and recommendations for their use.
The report also discusses a sensitivity analysis of MEPDG pavement performance models to NALS. Significant differences found in the MEPDG outcomes support the need for axle loading characterization beyond a simple default value for heavy trucks that dominate vehicle class distributions, especially for class 9 trucks. The effect of WIM accuracy on axle weight measurements, NALS estimates, and the associated MEPDG outcomes was also investigated.
Mark Swanlund
Acting Director, Office of Infrastructure
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 the use of the information contained in this document. This report does not constitute a standard, specification, or regulation.
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Technical Report Documentation Page
| 1. Report No.
FHWA-HRT-13-090 |
2. Government Accession No. | 3 Recipient's Catalog No. | ||
| 4. Title and Subtitle
MEPDG Traffic Loading Defaults Derived from Traffic Pooled Fund Study |
5. Report Date April 2016 |
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| 6. Performing Organization Code | ||||
| 7. Author(s)
O.I. Selezneva, M. Ayres, M. Hallenbeck, A. Ramachandran, H. Shirazi, and H. Von Quintus |
8. Performing Organization Report No. |
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9. Performing Organization Name and Address Applied Research Associates, Inc. |
10. Work Unit No. (TRAIS) |
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| 11. Contract or Grant No.
DTFH61-02-C-00138 |
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| 12. Sponsoring Agency Name and Address
Office of Infrastructure Research and Development |
13. Type of Report and Period Covered
Final Report |
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14. Sponsoring Agency Code |
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| 15. Supplementary Notes
The Contracting Officer's Representative (COR) was Larry Wiser, HRDI-30, Long-Term Pavement Performance Data Analysis Contract. |
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| 16. Abstract
As part of traffic loading inputs, the Mechanistic-Empirical Pavement Design Guide (MEPDG), Interim Edition: A Manual of Practice requires detailed axle loading information in the form of normalized axle load spectra (NALS), number of axle per truck class and axle group types, and axle spacing inputs.(1) These data are obtained from weigh-in-motion (WIM) sites. The objective of this project was to evaluate the applicability of the existing MEPDG global traffic loading defaults and to use research-quality WIM data from the Long-Term Pavement Performance (LTPP) Specific Pavement Studies (SPS) Traffic Data Collection pooled fund study to revise and improve the global default axle loading values.(2) This report provides an assessment of the original MEPDG axle loading defaults, describes WIM data selection criteria, including data reliability assessment, presents findings from the LTPP SPS traffic pooled fund study traffic data review, describes a methodology to generate new MEPDG traffic loading defaults, and provides a description of the new traffic loading defaults and recommendations for their use. The report also discusses a sensitivity analysis of MEPDG pavement performance models to NALS. Significant differences found in the MEPDG outcomes support the need for axle loading characterization beyond a simple default value for heavy trucks that dominate vehicle class distributions, especially for class 9 trucks. The effect of WIM accuracy on axle weight measurements, NALS estimates, and the associated MEPDG outcomes was also investigated. It was found that drift in WIM system calibration leading to over 5 percent bias in mean error between true and WIM-measured axle weight could lead to significant differences in MEPDG design outcomes. In addition, two new statistical parameters were developed in this study: (1) a summary statistic used to describe traffic loads for comparison and grouping of similar NALS called the relative pavement performance impact factor and (2) a parameter used to quantify errors associated with NALS and to assess NALS reliability called the pooled weighted load error. |
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| 17. Key Words
Long-term performance, Traffic pooled fund study, Mechanistic-Empirical Pavement Design Guide, Weigh-in-motion, Load spectra |
18. Distribution Statement
No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161. |
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19. Security Classification Unclassified |
20. Security Classification Unclassified |
21. No. of Pages 206 |
22. Price | |
| Form DOT F 1700.7 (8-72) | Reproduction of completed page authorized |
SI* (Modern Metric) Conversion Factors
CHAPTER 2-REVIEW OF MEPDG TRAFFIC LOADING DEFAULTS
CHAPTER 3-SUMMARY OF IMPROVEMENTS IN LTPP TRAFFIC DATA SINCE ORIGINAL MEPDG DEFAULTS
CHAPTER 4-IMPORTANCE OF AXLE LOADS FOR PAVEMENT DESIGN USING THE MEPDG
CHAPTER 5-METHODOLOGY FOR ESTIMATING RELIABILITY OF TRAFFIC LOADING DATA
CHAPTER 6-ANALYSIS OF AXLE LOAD SPECTRA VARIABILITY USING SPS TPF WIM DATA
CHAPTER 8-METHODOLOGY FOR DEVELOPMENT OF MEPDG TRAFFIC LOADING DEFAULTS USING LTPP SPS TPF DATA
CHAPTER 9-MEPDG SENSITIVITY TO DIFFERENT AXLE LOAD SPECTRA CLUSTERS
CHAPTER 10-DESCRIPTION OF THE NEW MEPDG TRAFFIC LOADING DEFAULTS FOR LTPP SITES
CHAPTER 11-SUMMARY OF FINDINGS AND RECOMMENDATIONS
APPENDIX A-RESULTS OF MONTHLY AXLE LOAD TEMPORAL CONSISTENCY AND OUTLIER ANALYSIS
APPENDIX B-EVALUATION OF ATYPICAL APC COEFFICIENTS
APPENDIX D-DATABASE CD AND DATA DICTIONARY
| AADTT | average annual daily truck traffic | |
| AASHTO | American Association of State Highway and Transportation Officials | |
| AC | asphalt concrete | |
| APC | axle per class | |
| AVC | automatic vehicle classification | |
| CF | confidence factor | |
| CL | confidence level | |
| DOW | day of the week | |
| ESAL | equivalent single-axle load | |
| ETG | expert task group | |
| FHWA | Federal Highway Administration | |
| GP | load cluster group | |
| GPS | General Pavement Studies | |
| GVW | gross vehicle weight | |
| HMA | hot mix asphalt | |
| IRI | International Roughness Index | |
| JPCP | jointed plain concrete pavement | |
| LTAS | Long-Term Pavement Performance Traffic Analysis Software | |
| LTPP | Long-Term Pavement Performance | |
| MEPDG | Mechanistic-Empirical Pavement Design Guide | |
| M.P. | Milepost | |
| NALS | normalized axle load spectra | |
| NCHRP | National Cooperative Highway Research Program | |
| PCC | portland cement concrete | |
| PLUG | Pavement Loading User Guide | |
| PWLE | pooled weighted load error | |
| PVR | per vehicle record | |
| QA | quality assurance | |
| QC | quality control | |
| RANALS | representative annual normalized axle load spectra | |
| RI | rural interstate | |
| ROPA | rural other principal arterial | |
| RPPIF | relative pavement performance impact factor | |
| SDR | Standard Data Release | |
| SHRP | Strategic Highway Research Program | |
| SPS | Specific Pavement Studies | |
| TPF | transportation pooled fund | |
| TTC | truck traffic classification | |
| VCD | vehicle class distribution | |
| WIM | weigh-in-motion |
