Rut prediction, whether stemming from deformation in asphalt orsoil, has always been a particularly difficult area for the pavementengineer. This paper centres around a predictive technique forsoils and granular materials and presents two examples where thetechnique has been used and appears to be a sufllciently accuratetool for achieving meaningful results. One example is of traffickingat a laboratory scale, the other relates to airfield pavementdesign. The derivation of the model itself is described and themeans of obtaining model parameters discussed. Finally its rolein pavement design is examined and recommendations made for itsuse.