Determination of inspection intervals for welded rail joints on a regional network

One of the most frequent and dangerous failure modes in continuous welded rails is fatigue crack propagation terminated by brittle fracture. Due to the brittleness of the weld material and the scatter in its mechanical properties, a probabilistic approach is necessary. The paper deals with surface cracks at the foot base of aluminothermic welded rails, developing a probabilistic methodology for determining the day by day prospective failure probability. The model used is based on weld material characterization, simulation of fatigue crack growth and day-by-day failure probability calculation using the Monte Carlo method. The model is then adopted to assess the time dependent safety margin during fatigue crack propagation and to understand which variables are really influencing the failure probability. Finally, the results are compared to the standard rail classification method, considering the real traffic condition in several railway lines.