Keywords: railway track dynamics, turnout design, track stiffness.

Turnouts represent very important elements of the railway infrastructure providing flexibility of the system by enabling railway trains to be guided from one track to another at a railway junction. Rail discontinuity in the turnout crossing results in high impact forces from passing vehicles, which makes turnouts sensitive to damage.

Recently, the increased damage of the crossing nose in turnouts where the wooden sleepers were replaced by the less elastic concrete ones has been observed in the Dutch railway network. It should be noted that the elastic properties of the turnout structure was not adjusted when replacing the sleepers. The goal of the research presented here was to investigate the causes of the increased damage to the crossing nose and to find solutions to reduce that damage.

The train and turnout interaction has been investigated in a number of research papers published recently [1,2,3,4,5]. Here the dynamic interaction between the railway vehicle and track structure has been analysed in time domain using the two-dimensional finite element model (DARTS_NL). A procedure for obtaining vertical rail geometry in crossing using visual images has been suggested. The rail geometry obtained was in good agreement with measurement results.

Using the models developed the BWG turnout 1:9 on ballast bed with and without under sleeper pads and ballast has been analysed. The results have shown that the geometrical properties of the wheel and global rail geometry strongly influence the dynamic forces. The elastic properties of the rail pads have the biggest influence on the wheel impact forces (so-called P₁). The effect of USP on the low frequency forces P₂ was much higher than on the P₁ forces. Therefore, the use of USP in combination with softer pads can be very attractive.

1

E. Kassa, C. Andersson, J.C.O. Nielsen, "Simulation of dynamic interaction between train and railway turnout", Vehicle System Dynamics, 44(3), 247-258, March 2006. doi:10.1080/00423110500233487

2

M. Wiest, W. Daves, F.D. Fischer, H. Ossberger, "Deformation and damage of a crossing nose due to wheels passages", Wear, 265, 1431-1438, 2008. doi:10.1016/j.wear.2008.01.033

3

C. Andersson, T. Dahlberg, "Load impacts at railway turnout crossing", Vehicle System Dynamics, 33, Suppl, 131-142, 2000.

4

A. Johansson, J.C.O. Nielsen, R. Bolmsvik, A. Karlström, "Under sleeper pads - Influence on dynamic train-track interaction", Wear, 265, 1479-1487, 2008. doi:10.1016/j.wear.2008.02.032

5

S. Alfi, S. Bruni, "Mathematical modelling of train-turnout interaction", Vehicle System Dynamics, 47(5), 551-574, 2009. doi:10.1080/00423110802245015

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