Combatting RCF on switch points by tuning elastic track properties

A railway switch (turnout) is a very important element of the railway infrastructure. Due to the discontinuity 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 P1 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.