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REPORT
This report is an archived publication and may contain dated technical, contact, and link information
Publication Number:  FHWA-HRT-13-091    Date:  November 2014
Publication Number: FHWA-HRT-13-091
Date: November 2014

 

Verification, Refinement, and Applicability of Long-Term Pavement Performance Vehicle Classification Rules

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FOREWORD

The Long-Term Pavement Performance (LTPP) program has developed and deployed a set of rules that apply vehicle axle spacing and weight data obtained with weigh-in-motion systems to classify vehicles. These vehicle classification rules are being used across the country at the test sites included in the LTPP Specific Pavement Studies Traffic Data Collection Pooled-Fund Study, TPF-5(004). This report examines the performance of the LTPP vehicle classification rules and the implications of their use in the development and application of default values as input for the American Association of State Highway and Transportation Officials Mechanistic-Empirical Pavement Design Guide (MEPDG).

Part I examines how the LTPP classification rules differ from classification rules used by many States, evaluates the accuracy of the LTPP rules across truck types and at different locations across the country, and evaluates the magnitude of the error that may be introduced in estimation of traffic-loading inputs for pavement design. Part II evaluates the sensitivity of the MEPDG pavement design models to the errors introduced by the use of these traffic-loading inputs. Part III describes the minor changes recommended to the LTPP vehicle classification rules to improve the classification accuracy for the many types of vehicles using the highway system. The results of field tests using the revised vehicle classification rules are also reported.

This report will be of interest to pavement engineering professionals who must perform analyses using traffic data that are not collected at the specific location for which the pavement analyses are being performed. It describes the statistical reliability of using data from other States and regions when using such data is necessary.

 

Jorge E. Pagán-Ortiz
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 the use of the information contained in this document.

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

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

Technical Report Documentation Page

1. Report No.

FHWA-HRT-13-091

2. Government Accession No.

3. Recipient’s Catalog No.

4. Title and Subtitle

Verification, Refinement, and Applicability of Long-Term Pavement Performance Vehicle Classification Rules

5. Report Date

November 2014

6. Performing Organization Code:

7. Author(s)

M.E. Hallenbeck, O.I. Selezneva, and R. Quinley

8. Performing Organization Report No.

9. Performing Organization Name and Address

Applied Research Associates, Inc.

7184 Troy Hill Drive, Suite N

Elkridge, Maryland 21075-7056

10. Work Unit No.

11. Contract or Grant No.

DTFH61-02-C-00138

12. Sponsoring Agency Name and Address

Office of Infrastructure Research & Development

Federal Highway Administration

6300 Georgetown Pike

McLean, VA 22101-2296

13. Type of Report and Period Covered

Final Report

14. Sponsoring Agency Code

15. Supplementary Notes

Contracting Officer’s Technical Representative: Debbie Walker, HRDI

16. Abstract

The Long-Term Pavement Performance (LTPP) project has developed and deployed a set of rules for converting axle spacing and weight data into estimates of a vehicle’s classification. These rules are being used at Transportation Pooled Fund Study (TPF) weigh-in-motion (WIM) sites across the country. This report examines the performance of those rules and the implications of their use for the development and application of default values for use within the Mechanistic-Empirical Pavement Design Guide. The report is divided into three parts. In part I, the report examines 1) how the LTPP rules differ from classification rules used by many States, 2) the performance of the LTPP rules in terms of their accuracy across truck types and at different LTPP WIM sites across the country, and 3) the size of the error that can be introduced into the estimation of traffic loading inputs for pavement design when load spectra developed from the LTPP TPF sites using these rules are combined with truck volume data collected using State-specific classification rule sets. Part II of this report examines the sensitivity of the pavement design models to the errors introduced by the use of these traffic loading inputs. Based on the results of these sensitivity tests, recommendations are made about the use of load spectra computed using Specific Pavement Studies TPF WIM data. Part III of this report describes minor changes to the LTPP classification rules recommended to improve their performance. Finally, the results of field tests of the recommended revised classification rules are presented.

17. Key Words

Traffic loading, pavement design, long-term pavement performance

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

158

22. Price

Form DOT F 1700.7 (8-72)

Reproduction of completed page authorized

SI* (Modern Metric) Conversion Factors

Table of Content

Chapter 1. Introduction.

Project Background.

Report Overview.

PART I. COMPARISON OF LTPP VEHICLE CLASSIFICATION Rules WITH Rules Used By OTHER STATES

Chapter 2. Introduction to Vehicle Classification

Current FHWA 13-Category Rule Set

State Implementations of Vehicle Classification Rules

The LTPP Vehicle Classification Rules

Chapter 3. Findings From Comparison of the State and LTPP Vehicle Classification Rules

Differences in Vehicle Classification Rules

The Effects of Different Classification Rule sets on Traffic Loading Parameters

Summary of Findings

Chapter 4. Evaluation of Likely Errors in the Total Traffic Loading Estimate When Using Load Spectra Computed With the LTPP Class Rule set And Truck Volumes From State-Specific Rule sets

Analysis Purpose

Methodology for Testing the Applicability of LTPP WIM Rule set

Analysis of Expected Errors in Total Traffic Loading

Conclusions and Recommendations

PART II: SENSITIVITY OF PAVEMENT DESIGN MODELS TO DIFFERENCES IN VEHICLE CLASSIFICATION RULE SETS

Objectives

Organization of Part II

Chapter 5. Sensitivity of Pavement Design Models to Differences in Selected Vehicle Classification Rule sets

Analysis Approach

Analysis Execution

Discussion of Findings From MEPDG Analysis

Discussion of Findings From AASHTO 93 Analysis

Conclusions

Chapter 6. Sensitivity of Pavement Design Models to Differences in Classification of Class 5 and Class 8 Vehicles

Background

Analysis Objective

Analysis Approach

Analysis Execution

Discussion of Findings From MEPDG Analysis

Discussion of Findings from AASHTO 93 Analysis

Conclusions

Disclaimer

Chapter 7. Summary and Conclusions of Pavement Sensitivity Tests

Part III: Recommended Changes to the LTPP Classification Rule set

Chapter 8. LTPP Vehicle Classification Rule set Evaluation and Recommended Modifications

Recommended Class 7 Rules

Recommended Additional Class 10 Rules

Recommended Additional Class 13 Rules

Chapter 9. Results From Field Testing of the Refined Vehicle Classification Rule set07

Pennsylvania Data

Maryland Data

Tennessee Data

Chapter 10. Summary Conclusions and Recommendations

Vehicle Class Rule set Comparison

Nature and Size of Loading Errors RESULTING FROM Use of Different Classification Rule sets

Sensitivity of the MEPDG Pavement Design Models

Disclaimer

Refinement of the LTPP WIM Rule set

Appendix A. Vehicle Classification Rule sets

Appendix B. Load Spectra Tables for High and Low Traffic Scenarios

References

 

List of Figures

 

List of Tables

 

ACRONYMS AND ABBREVIATIONS

AADTT

Annual Average Daily Truck Traffic

AASHTO

American Association of State Highway and Transportation Officials

AC

Asphalt Concrete

AVC

Automatic Vehicle Classification

Caltrans

California Department of Transportation

ESAL

Equivalent Single-Axle Load

ETG

Expert Task Group

FHWA

Federal Highway Administration

GPS

General Pavement Studies

GVW

Gross Vehicle Weight

HMA

Hot Mix Asphalt

IRI

International Roughness Index

LTPP

Long-Term Pavement Performance

MEPDG

Mechanistic Empirical Pavement Design Guide

NALS

Normalized Axle Load Spectra

NCHRP

National Cooperative Highway Research Program

PCC

Portland Cement Concrete

PSI

Present Serviceability Index

RI

Rural Interstate

ROPA

Rural Other Principal Arterial

SPS

Specific Pavement Studies

SUV

Sport Utility Vehicle

TPF

Transportation Pooled Fund Study

TRB

Transportation Research Board

TTC

Truck Traffic Classification

VCD

Vehicle Class Distribution

WIM

Weigh in Motion

 

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