Layer Moduli Backcalculation Procedure: Software Selection: Fid-Bau Portal

Layer Moduli Backcalculation Procedure: Software Selection

Deflection basin measurements for the purpose of structural capacity evaluation are a key component of the Strategic Highway Research Program's (SHRP's) Long-Term Pavement Performance monitoring program. In the near term, SHRP will apply a backcalculation procedure to these deflection measurements in order to estimate the in situ elastic moduli of the pavement layer materials. Because a standard or generally accepted method for evaluating the structural capacity of flexible pavements from deflection data does not presently exist, a study was undertaken by SHRP to develop a layer moduli backcalculation procedure for use in the initial analysis of the SHRP deflection data. This procedure covers not only the software but also the rules, guidelines, and criteria used in applying the program. As part of this study, a literature review was undertaken to develop a listing of available backcalculation software. Using deflection data and other pertinent information obtained from SHRP pavement test sections, the selected software was exercised by a group of evaluators which included the program developers. Backcalculation results were evaluated on the basis of reasonableness, robustness, and stability, goodness of fit, and general suitability for SHRP's purposes. This report discusses the process SHRP followed in selecting software and developing a backcalculation procedure, and presents the outcome of the software evaluation portion of the study.