The role of stiffness variation in switches and crossings: Comparison of vehicle–track interaction models with field measurements. (November 2020)

• Record Type: Journal Article
• Authors: Grossoni, Ilaria; Le Pen, Louis M; Jorge, Pedro; Bezin, Yann; Watson, Geoff VR; Kostovasilis, Dimitrios; Powrie, William
• Is Part Of: Proceedings of the Institution of Mechanical Engineers. Volume 234:Number 10(2020)
• Page Start: 1184
• Page End: 1197
• Publication Date: 2020-11
• Subjects: Switches and crossings (S&Cs) -- switch panel -- crossing panel -- trackbed stiffness -- composite track stiffness -- field measurements -- geophones -- vehicle–track interaction -- finite element approach -- multibody system approach -- under sleeper pad; Railroads -- Periodicals; Personal rapid transit -- Periodicals; 625.1
• DOI: 10.1177/0954409719892146
• Languages: English
• ISSNs: 0954-4097

Abstract

The performance of switches and crossings 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 switches and crossings, 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 the performance of switches and crossings. Field measurements of bearer displacement were carried out using geophones at a switch and crossing equipped with under sleeper pads. The vehicle–switch and crossing interaction was modelled using a multi-body system and finite element method. The trackbed stiffness along the whole of the switch and crossing 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. Under sleeper pads are shown to reduce absolute maximum loads, but may increase the variation in deflection.