The development of a new road design method in Sweden

Abstract

Since 1998, Sweden has been conducting a strategy for developing a new model for road design, including implementation of ethis model. Today a new model for calculation of stress and strain is ready. It can do calculations for asphalt pavement with viscous elasticity and unbound material with non-linear elasticity. In spring 2005, the model is to be supplemented by calculation modules for permanent deformations in bituminous bound layers and in unbound layers, based on the theories behind the new AASHTO “Design Guide”. Implementing this model has involved three years of continuous training of new road designers in Western Sweden, with participation of consultants and contractors. During the winter and spring of 2004/05 six different projects were chosen to demonstrate the new model. Road quality is to be improved by “active design” on site. Unbound material is to be tested by triaxial tests, and there are to be calculations of future permanent deformations. The results are to be used in deciding pavement thicknesses for different parts of the road. Road pavement optimizationroad in this way will save a lot of money. A better
design method and relating test methods should also make it possible to avoid most of the problems of early failure of roads.