Keywords: railway track dynamics, track transition, track stiffness.

A great problem in spanish high speed railways remains track transitions between the embankment and structure. Such a transition introduces a discontinuity in the vertical stiffness of the rail which results in an increase in the dynamic forces and the deterioration of track geometry as a result of track settlement on the embankment side. The track maintenance costs in the transition zones consequently increase.

In the last ten years a number of studies have been performed on this topic [1,2,3,4]. In order to improve the performance of the transition zone various approaches have been suggested. The common solution was to create a smooth variation in support stiffness between the free track and the substructure by either increasing the stiffness of the track system within the transition zone or reducing the support stiffness of the substructure [1,2,3,4,5]. In some approaches new materials such as expanded polystyrene (EPS) have been used in order to prevent track settlement [6]. Track transitions are one of the most delicate areas of the track. Rolling stock significantly damages the track structure in these areas. The displacements and settlements are produced as the stiffness changes from one area to another.

The dynamic train-track interaction in transition zones with high and low vertical stiffness has been analysed numerically using the finite element software DARTS_NL (developed at TU Delft). A high-speed vehicle moving on a track that consists of a slab and ballasted track has been modelled. The train travelling in both directions has been simulated. The simulation results have shown a good correlation with reality.

The effects of six different track design modifications on reduction of the dynamic forces have been studied using the developed models. The modifications comprise of application of additional rails and sleepers with variable length in the transition zone as well as combination of these two modifications. The results have shown that the sleeper displacements and stresses in ballast within the transition zone can be significantly reduced by these modifications. The combined track modification with extra long sleepers in combination with double rails has demonstrated the best performance.

1

C.D. Sasaoka, D. Davies, "Implementing track transition solutions for heavy axle load service", In AREMA 2005, 2005.

2

A. Lundqvist, R. Larsson, T. Dahlberg, "Influence of railway track stiffness variations on wheel/rail contact force", In Track for high-speed railways, FEUP, 2006.

3

R.D. Frohling, H. Sheffel, W. Ebersohn, "The vertical dynamic response of a rail vehicle caused by track stiffness variations along the track", In Proceedings of the 14th IAVSD Symposium, International Association for Vehicle System Dynamics, Praha, Czech Republic, 2005. doi:10.1080/00423119608969194

4

H. Hunt, "Settlement of railway track near bridge abutments", Proc. Inst. Civ. Engng Transp., 123(1), 6873, 1997. doi:10.1680/itran.1997.29182

5

A.D. Kerr, L.A. Bathurst, "Pads ease track transitions", Railw. Track Struct., 5764, 2000.

6

C. Esveld, V. Markine, M. Duškov, "Feasibility of EPS as a lightweight sub-base material in railway track structures", EPS GEOFOAM 2001, 3rd International Conference, Salt Lake City, Utah, USA, December 10-12, 2001.

purchase the full-text of this paper (price £20)

go to the previous paper
go to the next paper
return to the table of contents
return to the book description
purchase this book (price £130 +P&P)