SELECTION OF FLEXIBLE BACKCALCULATION SOFTWARE FOR THE MINNESOTA ROAD RESEARCH PROJECT

This report presents the results of an evaluation process of several different flexible pavement backcalculation programs. The objective of this study was to compare the performance of the candidate programs in terms of useability and accuracy of backcalculation results. This was accomplished by evaluating the selected programs using both field and simulated data. The results of the analysis were used as the basis for selecting a program for routine analysis of Mn/ROAD pavement deflection data. In situ pavement strains were measured during falling-weight deflectometer tests. The measured strains were then compared to backcalculated strain values from each program. In addition to the field tests, a series of hypothetical pavement structures with a range of prescribed layer thicknesses and moduli were analyzed to obtain surface deflection data. These surface deflections were then used as input for each program involved in the study. The output from each program was compared to the expected values.