In recent years there has been a considerable awareness among soil engineers concerned with highway and airport construction of the need for studies of the behavior of soil under repeated loading. Studies conducted by the State of California Division of Highways (1)³ for example, have shown that highway pavements may fail by fatigue as a result of the repreated reversals of stress to which they are subjected by highway traffic and that the danger of such failures occurring depends on the resilient or elastic deformation of the subgrade on which the pavement is constructed. Furthermore, the wide variations in the predictions of the various state highway departments concerning the number of load repetitions required to cause failure of the pavement of the Western Assn. State Highway Officials (WASHO) test road (2) has indicated the lack of reliable information on this aspect of soil behavior.