Rail weld geometry and assessment concepts

Worldwide, metallurgical rail welds are being geometrically assessed by the principle of vertical deviations satisfying given tolerances, measured with steel straightedges or occasionally with digital/electronic straightedges. In this approach, the geometrical shape of the weld in longitudinal direction has no real influence, although it has a direct relation with the dynamic wheel-rail interaction forces, which are responsible for track deterioration. In this article, different new assessment methods for rail welds are proposed and evaluated in practice, after which a choice is made for the best method. This is done in line with the situation in the Netherlands, where the chosen new method was recently introduced and standardized (2005). The proposed method is based on a limitation of the gradient of the discrete measurement signal, implying a limitation of the wheel-rail dynamic contact force.