The role of stiffness variation in switches and crossings: comparison of vehicle-track interaction models with field measurements

Abstract

The performance of Switches and Crossings (S&Cs) compared with plain line is complicated by the presence of movable parts, changing rail geometry and non-uniformities in the composite and/or trackbed stiffness. These features lead to complex vehicle-track interactions and higher maintenance costs. The trackbed stiffness is the least well controlled engineering property. A greater variability in trackbed stiffness leads to higher differential trackbed settlement and associated poorer track quality. At S&C changes in trackbed stiffness are exacerbated by changing rail properties which also contribute to changes in the overall composite track stiffness. This work focuses on the role of variations in stiffness on S&C performance. Field measurements of bearer displacement were carried out using geophones at an S&C equipped with Under Sleeper Pads (USPs). Vehicle-S&C interaction was modelled using a multi-body system and finite element method. The trackbed stiffness along the whole of the S&C was inferred using the measurements of track deflections in an iterative back-calculation taking account of changing rail properties. It is shown that not including the variation in trackbed/composite stiffness leads to significant under/overestimates of the wheel-rail contact forces. USPs are shown to reduce absolute maximum loads, but may increase the variation in deflection.

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Identifiers

ORCID for Louis Le Pen: orcid.org/0000-0002-4362-3895

ORCID for Geoff Watson: orcid.org/0000-0003-3074-5196

ORCID for William Powrie: orcid.org/0000-0002-2271-0826

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