Comparison of Magnitude of Actions on Track in High-Speed and Heavy-Haul Railroads

In modern high-speed railways the necessity for achieving low life-cycle costs has led to a well-compacted—almost undeflected—substructure. Applications of excellent quality substructure are encountered in the French network with the operation of high-speed trains (TGV in French) and also in research projects of the International Union of Railways. The countervailing need for increased elasticity in the track's structure is satisfied by the development of the highly resilient fastenings with soft pads. There is a long-standing discussion about whether these soft pads promote a sufficient life cycle for heavy-haul railways as well, as in the case of the U.S. railways. In this paper a parametric investigation using a theoretical approach is performed to estimate the actions on track support points (ties) in high-speed and heavy-haul lines with four methods found in the international literature; parameter values, mainly coefficients of stiffness, derived from measurements on the track are used. Because the life cycle of the pads and the clips of the fastenings are dependent on the actions exerted on each tie per passing axle and the number of axle passes, this investigation leads to significant ascertainments for comparing the actions on the track in both cases.