Theoretical modelling of wheel-rail noise generation

The major source of noise from railways, particularly at high speeds, emanates from the wheel—rail region. This wheel—rail rolling noise is generally attributed to structural vibrations of the wheels and rails, excited from the contact patch area. The main excitation is caused by the wheel and rail surface roughness (undulations), which introduce a relative vibration between the wheel and rail. A linear mathematical model of wheel—rail interaction has been developed which incorporates detailed predictions of the vibration properties of the wheel, the rail and the contact area. Results of this model give good agreement with experimental results as long as the roughness levels are not too severe. Models of the noise radiation from the wheel and rail vibrations have also been developed, from which it is apparent that the vibrations of both the wheel and rail are significant sources of noise and that the vibrations of both components need to be reduced if significant reduction in noise is to be achieved.