Deterioration Models for Managing Flexible Pavements

The deterioration of pavements, in terms of roughness, rutting, and cracking, is a complex process. An incremental-recursive method is needed to model this process because of the influence of time and aging and the interaction between different types of distress. A number of deterioration models are presented that may be used with the mechanistic-empirical method to model the gradual deterioration of pavements as a function of loading, climate, and aging. Comparisons of measured and calculated stresses, strains, and deflections have shown that the simple combination of Odemark’s transformation with Boussinesq’s equations (modified for nonlinearity) results in an agreement between measured and calculated values that is as good as that obtained with the finite element method. Linear elastic methods normally result in rather poor agreement. A program called Performance and Economic Rating System (PERS) is presented in which the simple mechanistic method is combined with deterioration models using the critical stresses or strains in the pavement materials to predict deterioration. With this model it is possible to consider all of the elements that are believed to be essential for pavement deterioration, including seasonal variations, aging, and interaction between different modes of distress. The program may be used on the project as well as on the network level and uses historical data for verification and modification of the models to fit the particular conditions of the network considered.