EVALUATION AND ANALYSIS OF LTPP PAVEMENT LAYER THICKNESS DATA

In 2001, the Federal Highway Administration sponsored a study to review pavement layer thickness data for Long Term Pavement Performance (LTPP) sites. The main objective of the study was to assess the quality and completeness of pavement layering information and layer thickness data and to provide recommendations for improvement. In the course of the study, layer thickness data available in the LTPP database were examined for quality and completeness using Levels A to E data. Following the data completeness evaluation, pavement layering data were evaluated to determine the consistency of material type and thickness data between different data sources. In addition, layer thickness variability indicators, within-section material type consistency, and material type and thickness reasonableness were evaluated. In the cases where there were inconsistencies in the data, the data were reviewed and reported to the LTPP data managers along with recommendations for data anomaly resolution. In addition, the layer thickness data from Specific Pavement Studies (SPS) experiments were analyzed to determine characteristics of within-section layer thickness variation. The analysis included layers with different material and functional types. Descriptive statistics such as mean, standard deviation, skewness, and kurtosis were computed for each section. The statistical analysis results for 1,034 SPS layers indicated that 84% of all layer thickness variations within LTPP sections follow a normal distribution. The extent of differences between as-designed (inventory) and as-constructed (measured) layer thickness data was also investigated for the SPS sections. The results of analysis indicate that about 60% of all section/layers have mean thicknesses within 6.35 mm (0.25 in.) of the target thickness. For a tolerance level of 25.4 mm (1 in.), this percentage is above 90 for most layer types and target thickness values. For the same layer and material type, the mean constructed layer thicknesses tend to be above the designed value for the thinner layers and below the designed value for the thicker layers. One important product from this study is the Researcher's Guide to LTPP Layer Thickness Data. The main purpose of this guide is to provide guidance for the selection of layer material type and thickness data from the LTPP database. The guide also contains a discussion about within-section layer thickness variability and comparison between as-designed and as-constructed layer thickness. The guide is available as a separate publication.

• Record URL:
  http://www.fhwa.dot.gov/publications/research/infrastructure/pavements/ltpp/reports/03041/
• Record URL:
  http://www.fhwa.dot.gov/publications/research/infrastructure/pavements/ltpp/reports/03041/03041.pdf
• 
• Corporate Authors:

  Applied Research Associates, Incorporated

  ERES Division, 9030 Red Branch Road, Suite 210
  Columbia, MD  United States  21045

  Federal Highway Administration

  Turner-Fairbank Highway Research Center, 6300 Georgetown Pike
  McLean, VA  United States  22101
• Authors:
  • Selezneva, O I
  • Jiang, Y J
  • Mladenovic, G
• Publication Date: 2004-1

Language

• English

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: 159 p.

Subject/Index Terms

• TRT Terms: Data quality; Databases; Guides to information; Materials; Pavement layers; Statistical analysis; Thickness; Variables
• Identifier Terms: Long-Term Pavement Performance Program; Specific Pavement Studies (LTPP)
• Subject Areas: Data and Information Technology; Design; Highways; Materials; Pavements; I22: Design of Pavements, Railways and Guideways; I23: Properties of Road Surfaces;

Filing Info

• Accession Number: 00969859
• Record Type: Publication
• Report/Paper Numbers: FHWA-RD-03-041,, Final Report
• Contract Numbers: DTFH61-96-C-00003
• Files: TRIS, USDOT
• Created Date: Feb 12 2004 12:00AM