Analytical evaluation of the dynamic impact forces acting on railway tracks due to track and wheel roughness

Railway track and train wheel irregularities may cause the train to transfer a dynamic force to the track that is higher than its own static force. When the transferred forces exceed certain limit values, results such as damage to the rail and rail fasteners, cracks in the sleepers and wear on the ballast layer may occur. As a result of all these damages, the drainage ability and the vertical carrying capacity of the track structure decrease and high track maintenance requirements cause increased costs. These damages reduce the sustainability of the structure and may pose serious risks to the structural safety of the track in the future. Therefore, dynamic impact forces must be estimated realistically and practically, and design and maintenance planning must be made in accordance with these estimates. This work concludes an ongoing research initiative by presenting a set of coupled equations that can predict the peak value of dynamic impact forces due to track and wheel irregularities. It also examines the effect of axle spacing on dynamic impact forces and provides a set of generalized functions that show the apparent track stiffness values experienced depending on the axle spacing in two- or three-axle bogies. It has been observed that the findings of the equations proposed in this study are in high compatibility with the finite element analysis and field test results in the literature for dynamic impact forces due to track transitions to bridges, tunnels and culverts where both the track stiffness and profile may change, discontinuity locations such as turnout zones, rail joints and rail corrugations. In order to use the relevant method in a practical way, ALLTRACK v3 desktop software has been developed, which detects irregularities by applying Wavelet Transform on raw track profile data, estimates dynamic impact forces and examines the relationship between track parameters.