Assessment of pavement foundation layer in situ using mechanistic parameters such as stress-dependent resilient modulus can provide a validation of the input parameters assumed during pavement design. In this paper, results from a recent field study on the Illinois Tollway Elgin O'Hare Expressway construction project is presented. The project involved developing geospatially referenced validated intelligent compaction (VIC) measurements through a field calibration process using automated cyclic plate load testing, which produced coefficient of determination (R2) values of >0.9. The VIC measurements were obtained using an instrumented smooth drum vibratory roller that was programmed to output stress-dependent resilient modulus (Mr). VIC-Mr on a compacted subgrade and the overlaid granular layer are presented in this paper. The VIC maps and field observations revealed the compaction layers and pavement foundation materials to be highly non-uniform and to have built-in low stiffness "soft" areas and high spatial variability that are not necessarily addressed with conventional quality control (QC)/quality assurance (QA) observation and spot testing. The VIC maps on the unbound subbase layer showed reflections of the "soft" and "stiff" areas in the underlying subgrade.