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Mechanistic pavement design procedures based on elastic layer theory require characterization of all pavement layer materials including subgrade soil. This paper discusses the subgrade stiffness obtained from a new compaction device called the Intelligent Compaction (IC) roller on highway embankment projects in Kansas. Three test sections on two routes were compacted using a single, smooth steel drum Bomag Variocontrol (BVC) intelligent roller that compacts and at the same time, measures stiffness values of the compacted soil. Traditional compaction control measurements like density testing, in-situ moisture content, soil stiffness measurements using Geogage, surface deflection tests using Light Falling Weight Deflectometer (LFWD) and Falling Weight Deflectometer (FWD), and penetration tests using a Dynamic Cone Penetrometer (DCP), were also done. The results show that the IC roller was able to identify the locations of lower soil stiffness in the spatial direction. In general, IC roller stiffness showed sensitive to the field moisture content. No universal correlation was observed among the IC roller stiffness, Geogage stiffness, backcalculated subgrade soil moduli from the LFWD and FWD deflection data, and th