The article describes the main damages of box girder viaducts constructed in Lithuania and discusses the reasons for their occurrence. Several viaducts are examined in more detail with regard to their design data and experimental results. Using finite element software “Midas Civil” the distribution of the main stresses was determined in the box and reduced girders of the Pareizgupis viaduct caused by symmetrical and asymmetrical loads. The widths of flexural cracks in the Pareizgupis viaduct are analyzed evaluating the behaviour of prestressed reinforcement suffered from corrosion. The above mentioned program was used to calculate the deflection of viaduct when damage of reinforcement is estimated. The paper examines the possibility to evaluate viaduct durability using the probability methods based on the initial investigation data.