Use of falling weight deflectometer data to determine the effective structural number of full-depth asphalt pavements for structural condition assessment

The effective structural number (SNeff) determined from the falling weight deflectometer (FWD) has been widely used for pavement structural evaluations. In Indiana, the AASHTO 1993 method is currently used to determine SNeff, but it was found to be inaccurate for full-depth asphalt pavements. Thus, this study developed an enhanced model to more accurately estimate SNeff of full-depth asphalt pavements. The AASHTO 1993 method and the Rohde model tend to overestimate the SNeff, and the Rohde model was calibrated using the FWD deflection thresholds. Since the calibrated Rohde model requires an interpolation procedure sometimes resulting in negative deflections, a more practical method was developed using an FWD database generated by finite element analyses. New model provides SNeff values nearly identical to the calibrated Rohde model without the problem of negative deflections. Therefore, this enhanced SNeff prediction model is recommended for evaluating the structural conditions of full-depth asphalt pavements.