For several years, the compaction quality of embankments has been controlled by the dry bulk density and water content. However, the quality assessment is time consuming and merely a point measurement. We are developing a method that measures the mechanical properties of soil by observing the soil - wheel interaction behavior. In this study, we have proposed a method for estimating the subgrade reaction modulus of the soil by towing a wheel on the ground surface. This paper describes the theoretical basic concept of this method and discusses its validity with the results obtained from a laboratory model experiment.