An accurate, rapid, and reliable methodology for identifying material properties of pavements modeled as layered viscoelastic halfspaces subjected to dynamic excitation is developed. The methodology is based on the forward model of system identification. The Modulus of elasticity of each layer, the damping in each layer, and the slope of the creep curve for the top layer are selected as the parameters to be identified. The validity and accuracy of the proposed methodology is demonstrated by several numerical experiments involving simulated changes in the selected pavement parameters. Iterative procedures developed to solve nonlinear problems which arise in estimating the pavement parameters are presented.

The methodology developed in the accompanying paper is verified using Falling-Weight Def1ectometer (FWD) data from in-service highways. The procedure to transform Falling-Height Deflectometer data from the time domain to the frequency domain and its analysis In the frequency domain is presented. Frequency response curves based on back-calculated parameters obtained by other Independent methods, parameters identified using the proposed methodology, and the actual Falling-Weight Deflectometer data collected from the field, are compared to demonstrate the validity of the approach.