FORCE-BASED ASSESSMENT OF RAIL WELDS

TU Delft developed new geometrical standards for rail welds on behalf of the Dutch Rail Infra Manager ProRail. Previous standards were based on the principle of maximum vertical and horizontal tolerances, as is worldwide common practice. However, this approach does not account for the geometrical shape of the weld. In this way, the relation with the dynamic wheel-rail contact forces and stresses is disregarded, whereas these forces determine the rate of track deterioration. In this paper a theoretical model is presented to translate dynamic wheel-rail contact forces into the 1st derivative of the weld geometry. Intervention values depending on the line section speed are presented. Measurement and simulation results show good correspondence with the theory. The new assessment method requires the application of digital straightedges instead of steel straightedges, in order to obtain the weld quality index according to the new standards. The governing algorithm is fast and easy to implement in a numerical code for the small processor of such a measuring device