Effect of Rail Irregularities and Rail Pad on Track Vibration and Noise

This paper focuses on the effect of short and long wavelength track irregularities and rail pads on train induced vibration and noise using a train-track interaction model. An Indian rail vehicle is modelled as a spring-mass-damper system, and a ballasted track structure is modelled as an infinite rail resting on the viscoelastic foundation. Long-wavelength track irregularity is obtained from measured field data; however, short-wavelength track irregularity is generated using Sato track spectrum. It is observed that vibration and noise levels are not only higher for short-wavelength compared to long-wavelength but also exceed the limits imposed by the Indian Railway standards. Thus, track properties are modified by varying stiffness and damping of rail pads to reduce vibration and noise levels. The stiffer pads reduced vibration level in the range of 7dB–24dB and noise level in the range of 8dBA–14dBA; hence, stiffer pads are recommended for the ballasted track. Moreover, track properties for short-wavelength also keep vibration and noise levels within the permissible limit for long-wavelength. Thus, modification of track properties based on only short-wavelength irregularity is required.