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Publication Number: FHWA-RD-03-040
Date: July 2002

Researcher's Guide to The LTPP Layer Thickness Data

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This guide describes sources of layer thickness information available in the LTPP database and provides recommendations on how to search for the most appropriate layer thickness data for different research purposes. In addition, topics related to layer thickness variability, within-section layer thickness variation, and the relationship between as-design and as-constructed layer thicknesses are discussed. The recommendations provided in this guide are based on assessment of the LTPP layer thickness data available in the LTPP data release 11.5 version NT3.0, obtained on June 8, 2001. For a detailed analysis of the LTPP layer thickness data, please refer to the report titled, Evaluation and Analysis of LTPP Pavement Layer Thickness Data [29].

Also note that information presented in this Guide about LTPP table structures, field names and descriptions, and code lists reflect the current LTPP database structure and may be changed in the future. For the updated information, the users should refer to the most recent IMS Quality Control Checks document [19].


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