Railway traffic vibrations: generation and propagation - theoretical aspects

The interest in vibrations due to railway traffic is increasing in all developed countries, and it requires to develop both experimental and theoretical studies. In fact, innovative track can reduce the transmission of vibrations toward buildings and people, but also a better knowledge of the physical phenomenon can be useful to apply other methodologies, like a better control of contact surface characteristics. Theoretical mechanical models, based on the analysis of dynamic interaction between wheel and rail, and between track and formation soil, are the key tool to understand the phenomenon and evaluate interventions. In the paper, after a review of principles of vibration theory, two different calculation models are presented: the first one is a mathematical model for the analysis of dynamic loads caused by rail and wheel irregularities, the second one is useful to study the transmission of vibrations in the railway track and soil. The models, which can be used in sequence, are valid for various applications, in particular concerning the analysis of the role of different system components (wheels, rail, track) and their importance in the generation and propagation problems of railway vibrations.