ILLI-PAVE (a stress-dependent, finite-element pavement model)-based procedures have been developed for flexible pavement analysis and design. Full-depth asphalt concrete (AC), AC granular base, and AC high-strength stabilized base (HSSB) type pavements can be considered. Pertinent ILLI-PAVE inputs are the moduli of the AC and stabilized base layers and ERi (the stress-dependent subgrade resilient modulus).

ILLI-PAVE data bases were used to develop direct plot procedures and algorithms for backcalculatirtg pavement layer and subgrade moduli from falling weight deflectometer (FWD) type nondestructive testing (NDT) data. FWD 9-kip surface deflection basin measurements (at 0, 12, 24, and 36-in. offsets) and AREA (a calculated deflection basin parameter) are the required plot and/or algorithm inputs.