Combining wavelet analysis of track irregularities and vehicle dynamics simulations to assess derailment risks

Abstract

Guaranteeing operational safety is mandatory for railways worldwide. As track deteriorates, its geometry deviates from ideal conditions (e.g. perfectly aligned and levelled), which creates undesired vibration and oscillations to the vehicle, increasing dynamic loads and derailment risk. Although current standards establish nominal limits for the track geometry, such point-wise comparisons may overlook relevant track features that can lead to unsafe conditions. The proposed investigation is a contribution to the study of the response of the rail vehicle to the track quality, aimed at identifying track irregularities that produce high track forces and unsafe vehicle responses. To fulfil this aim, Wavelet Analysis is combined with Vehicle Dynamics Simulations to evaluate how the track irregularities, filtered in various wavelength ranges and reconstructed with different wavelets and coefficients' amplitudes, impact vehicle safety in terms of the Nadal safety criterion Y/Q. The simulations demonstrate that defects occurring in some scales/frequencies are more harmful than others, and the similarity between the geometric defects and the shape of the wavelets may be used to identify track locations that require maintenance. These findings suggest that it is possible to create ‘stamps’ of track irregularities that can be used by infrastructure managers to improve their maintenance strategies.

Keywords:

• Railway track maintenance
• wavelet analysis
• vehicle dynamics simulations
• design of experiments
• Nadal's criterion

Acknowledgements

We thank the anonymous reviewers for critically reading the manuscript and suggesting substantial improvements.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Foundation for Science and Technology (FCT), through IDMEC, under LAETA, project UIDB/50022/2020. The first author would also like to acknowledge the support of the Brazilian National Council for Scientific and Technological Development (CNPq) [grant 203130/2015-4]. The second author expresses his gratitude to the Portuguese Foundation for Science and Technology (FCT) through grant PD/BD/128138/2016.