In order to provide a basis for predicting track performance, an analytical model is necessary that will realistically represent the actual behavior of the track system subjected to vehicle loading conditions. The model should adequately characterize the three-dimensional nature of this problem; the various soil and ballast layers can be distinguished and be given proper material properties. In this paper a model is presented that incorporates both of these requirements with a feature which permits loss of contact between tie and ballast when the rail springs up. This model, named GEOTRACK, was developed primarily to characterize the geotechnical aspects of the track behavior. The predictions of this model are in good agreement with measured stresses, strains, and displacements from field experiments at the government test track in Pueblo, Colo.