Switches and crossings (S&C) form an important asset of modern day railways. Current Decision Support Systems for track maintenance and renewal however do not provide help on maintenance and renewal management of S&C, due to the lack of understanding of the degradation and deterioration processes of S&C often combined with an unsuitable way of data collection. This project will focus on understanding and modelling the degradation and deterioration processes of complete S&C and its components (ballast, sleepers, rail, frogs/crossings, sliding chairs, half set of switches etc) on geometrical scale and with regard to material deterioration. In close cooperation with the Swiss Federal Railways (SBB) and – if possible – other networks through the International Union of Railways (UIC), information will be gathered on S&C deterioration in combination with information on the trains which run over the S&C, the number of settings, axle loads, speeds, quality of the subsoil etc. The end product will consist of models and a computer tool which allow future prediction of maintenance and renewal needs of S&C on network, regional and local scale.