A better understanding of stability of turnouts in continuous welded rail track

Continuous Welded Rail (CWR) has been acknowledged as the greatest technical achievement in railway technology since the second half of last century. However, by eliminating rail joints and gaps between rail sections, the ambient temperature change during the year from severe cold winter to hot summer, high thermal stress exist and change within the welded rails. In some circumstances, if the CWR structure is combined with poor track maintenance, it may cause problems such as track buckling, broken rails, or derailment. As part of ARTC’s North-South Corridor Strategy some new concrete-bearer turnouts have been installed to connect the new passing loops and strengthen the Main South Line (Sydney to Albury) during the last two years. These concrete bearer turnouts include Vossloh Cogifer and VAE. Same as the old turnouts, almost all the turnouts on the main line are welded within the adjacent CWR tracks, which has significantly integrated the track structure and decreased the maintenance cost. However, regarding the turnouts which are welded into CWR track, especially for the turnouts which are directly connected to long welded rails (located outside of stations), they are usually under very high thermal stress which is transferred by the CWR in the longitudinal direction. In this scenario, both the stability and functionality of turnouts may be problematic. In this paper we review and analyse the turnout defects related to the high longitudinal stress. In addition, further analysis and explanation of the defects and some data calculations including non-linear finite element models were utilised for this study. Moreover, based on the in-field inspection, analysis, and numerical studies, some findings are presented and recommendations for maintaining the stability of turnouts in CWR track given.