How is Falling Weight Deflectometer (FWD) data used in pavement evaluation?

FWD drops calibrated weight on pavement, measuring deflection basin at multiple offsets from load. Analysis: (1) Backcalculation - iteratively adjust layer moduli until calculated deflections match measured using layered elastic or plate theory, (2) Structural indices - SCI (surface curvature), BDI (base damage), BCI (base curvature) indicate layer conditions, (3) Remaining life estimation from calculated strains and transfer functions, (4) Overlay design using effective structural number or layer coefficients. Temperature corrections applied to asphalt moduli. Data collected at regular intervals (every 100-500m) for network evaluation.