Track and Ground Vibrations from Trains Running on Conventional Ballasted Track

Abstract

This theoretical analysis predicts how spectra of track and ground vibrations from passing trains depend upon axle spacings in vehicles and sleeper spacings in track. At any measuring point on the surface of the ground, vibrations caused by trains running on conventional ballasted track are the combined effect of vibration waves propagating from every sleeper. The character of these vibrations is initially determined by the character of the vibration input that the train applies to each sleeper, but this is substantially modified by what happens as the resulting vibration waves propagate to the measuring point and superpose there. Propagation and superposition strongly modulate the input spectrum from trains, emphasizing vibrations at some frequencies in the measured response while minimizing vibrations at others. The shape of the final predicted spectrum depends upon the interrelationship of sleeper spacing and axle spacings, so it may be possible through careful choice of these dimensions to reduce the unwanted effects of train-induced vibrations—for example by minimizing excitation at known resonant frequencies of sensitive line-side structures. The predictions of the theory now await checking by experiment.