A comparative study on measured vs. Predicted pavement responses from falling weight deflectometer (FWD) measurements

Falling weight deflectometer (FWD) drops were applied on the entire 24 test sections, and the resulting surface deflections were measured simultaneously using FWD geophones. The MODULUS 4.0 backcalculation program developed by the Texas Transportation Institute (TTI) was used to backcalculate the asphalt concrete layer moduli values of each test section. then the backcalculated moduli values were entered into a forward calculation program, WES-5, with known pavement layer thicknesses, assumed Poisson's ratio, and the magnitude and geometry of FWD loading to calculate the surface and depth deflections. The surface and depth deflections were used to calculate the average vertical strains of different layers at the centerline of loading. In the validation process, the comparisons between the measured and predicted pavement responses were made.