Quantifying complex track stiffness response

Research Project, 2017 – 2020

In most (high-speed, HS) line infrastructure, very strict alignment and stiffness variations are prescribed. These perhaps result in overly costly track configurations being pre-scribed to prevent additional maintenance issues resulting from track degradation down the line. At present the complete system of railway head, sleepers, subgrade (slab), embankment and subsoil are not considered in setting these guide lines. Something that will be addressed in this project.

Trafikverket requires adequate design guidelines for regular and HS railway systems that ensure trouble free low maintenance operation of their track with smooth transitions, that incorporate short term dynamic loading considerations (e.g. vibrations from a single bogie) and accumulated effects over long-term loading (e.g. 60 yrs. operational life). The main issue is to establish the bounds of permissible stiffness distributions along & below the track, this includes track alignment, during its life-time that minimises construction and maintenance costs. Here, ‘stiffness’ refers to the evolving track-subgrade-soil system. The project aims to use a combination of quasi-static and dynamic numerical analyses to establish a generalised guideline, in terms of a maximum allowable variation in track compliance (rather than alignment alone), to fulfil the operational needs of a railway track.