A model-based approach for joint estimation of track irregularities and track support modulus from trackside measurements in railway turnouts

The paper proposes a model-based approach for the concomitant estimation of track modulus, track irregularity, and dynamic loading by combining an analytical model of a beam on an elastic foundation with vibration data collected by a trackside measurement system. The model is empirically extended to incorporate the effects of dynamic wheel/rail interaction forces when both short wavelength defects (in the rail surface) and medium-long wavelength track irregularities (e.g. hanging sleepers, differential ballast settlement) are present. The power spectral density of the rail vertical acceleration is then exploited in combination with the extended model to estimate track parameters using least squares. The proposed method is validated on vibration data collected in a turnout of the Danish railway infrastructure over a period of 2.5 years. The obtained results show that changes over time in track modulus and track irregularities, and consequently in dynamic wheel/rail contact forces, can be efficiently monitored from trackside measurements.