Roads are in a state of constant form of deterioration, due to factors such as climate and heavy traffic loads and are therefore constructed to have a certain lifetime before being maintained. To minimize the cost of construction and rehabilitation, robust models for predicting their performance are needed. The aim of this project is to develop prediction models for flexible pavement structures for initiation and propagation of fatigue cracks in the bound layers, and rutting for the whole structure. The models are based on observations from the Swedish Long Term Pavement Performance (LTPP) database. The intention is to use them for planning maintenance activities; as a part of a pavement management system (PMS). A statistical approach is used for the modeling where both cracking and rutting are related to traffic data, climate conditions, the subgrade characteristics as well as the pavement structure. This paper will present validated models, linking climate, environment, construction methods, material and traffic with road distress