Wear 271 (2011) 158–167 Contents lists available at ScienceDirect Wear journal homepage: www.elsevier.com/locate/wear Combatting RCF on switch points by tuning elastic track properties V.L. Markine a,∗ , M.J.M.M. Steenbergen a , I.Y. Shevtsov b a Section of Road and Railway Engineering, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Stevinweg 1, 2628 CN, Delft, The Netherlands b ProRail, Utrecht, The Netherlands article info Article history: Received 1 September 2010 Accepted 3 October 2010 Available online 16 October 2010 Keywords: Railway track dynamics Turnout design Track stiffness abstract A railway switch (turnout) is a very important element of the railway infrastructure. Due to the discon- tinuity in the rail geometry high dynamic amplification of the wheel loads occurs in the crossing nose. These dynamic forces can severely damage the turnout structure. Especially the high-frequency impact loads (the so-called P 1 forces) are responsible for RCF damage on the crossing nose. In the present study the relationship between the elastic properties of the turnout supporting structure (such as the rail pads, under sleeper pads and ballast mats) and the occurrence of RCF damage on the crossing point has been investigated. The RCF damage can be reduced by decreasing the high-frequency dynamic forces in the crossing nose. The dynamic interaction between the railway vehicle and track structure has been analysed numerically using DARTS NL software (TU Delft). The performance of the turnout has been assessed using numerical simulations in which a railway vehicle (the ICE locomotive) was running through the turnout at 140 km/h. In this simulation only the vertical dynamic forces in the crossing point have been considered: lateral behaviour was disregarded. The results of the parameter analysis have demonstrated that by varying the elastic properties of the supporting track structure the forces on the crossing point can be significantly reduced. It was also shown that by varying substructure elasticity the dynamic forces on other track components such as sleepers and ballast can be reduced as well. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Switches (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. Due to the discontinuity in the rail geom- etry introduced in the crossing nose, the turnouts experience high impact loads from passing vehicles, which makes them sensitive to several types of damage. Statistical evidence shows that failures in switches and crossings cause major operational disturbances in a railway network. Switches have a number of contact problems originating from disturbed vehicle motion and high impact loads introduced by the track discontinuities at turnouts. A number of research papers on damage in turnouts have been published recently [1–5]. In Ref. [5] the relationship between velocity of a vehicle passing through the turnout and the maximum vertical impact forces in the crossing were analysed. The effects of high resilience under-sleeper mats on track stability and ground-borne noise in railway switches were ∗ Corresponding author. Fax: +31 152783443. E-mail address: v.l.markine@tudelft.nl (V.L. Markine). investigated in [4]. In Ref. [1] two alternative multibody system models for analysis of the dynamic interaction between a train and a standard turnout were presented and compared. Cyclic defor- mations in the crossing nose of a railway turnout due to repeated wheel passages using a finite element model were studied in [3]. The presented research concerns only damage of a crossing nose. This type of damage usually originates from high impact loads, the so-called P 1 forces, caused by the contact point jump on a wheel tread at the transition from the wing rail to the crossing nose. The P 1 and P 2 wheel forces are typical for the wheel behaviour in the presence of short-waves irregularities [6] such as dipped rail joints as it schematically shown in Fig. 1. These forces act in different frequency regions and therefore affect different components of the track structure. Such cyclic high-frequency impact loads (P 1 ) cause very local plastic deformation and work hardening in the rail, until the material reaches the ratchetting regime with crack initiation and propagation. This process manifests itself as severe rolling contact fatigue (RCF) damage of the crossing nose (Fig. 2). The abovemen- tioned process has significant impact on the life span of the turnout structure, essentially influenced by service conditions (type of traf- fic, vehicles speed, traffic frequency, climatic conditions) and track 0043-1648/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.wear.2010.10.031