Direct Analysis Methods for Falling Weight Deflectometer Deflection Data

Two direct methods of analyzing falling weight deflectometer deflection data are presented. One method, which involves dividing the deflection 1828.8 mm (72 in.) away from the load plate by the deflection underneath the load plate, relates directly to the ratio between the pavement modulus and subgrade modulus for a two-layer system. The other method described in the paper gives a qualitative evaluation of the stiffness of the base material as it relates to the pavement surface. Examples of using these methods are described and compared with results from the Modulus Version 5.0 computer program developed by the Texas Transportation Institute.