This paper describes the modifications done to a Finite Element Model (DEFPAV) and its incorporation into a backcalculation computer program capable of being run on a Personal Computer. The results from this are verified against those from well established programs found in the literature. The modified model was also verified against the in-situ stress measurements obtained from two recently constructed pavement sections instrumented with stress gauges. The surface deflection measurements were taken using two non-destructive testing (NDT) devices, the Falling Weight Deflectometer (FWD) and the Deflectograph.