The Use of Strain Attenuating Tie Pads and Its Influence on the Rail Seat Load in Heavy-Haul Railroads

Abstract

In Greece, during the 1980’s, 60% of the twin-block concrete ties designed for 200 km/h, which were laid on a track with maximum operational speed of 140 km/h, presented serious cracks. The existing theories, in the French, German and American bibliographies, could not justify the appearance of these cracks since the calculated actions on the rail seat of the ties were much lower than the limit values of the regulations. This paper presents a model for the determination of the load acting on the rail seat of the ties in relation to the fluctuation of the substructure stiffness coefficient. The basic parameters influencing the estimation of the rail seat load — considering the most adverse conditions of a railway network — are investigated, and a methodology for calculating the load undertaken by each rail seat is presented. Numerical applications on twin-block and monoblock ties are presented, including the use of strain attenuating tie pads with high resilient fastenings. Finally, an application for the heavy-haul rail transport is presented, for the case of a track equipped with W24 fastening, Zw700WIC pad, rail 140RE type and concrete sleepers.

Track Maintenance of Heavy Haul Railways with Resilient versus Stiff Fastenings

“…Q total is derived in Equation 5, and β is given by where E is the modulus of elasticity, and I is the moment of inertia of the rail. Equation 2 is transformed into where A stat is the static coefficient of the sleeper's reaction and is given in Equation 6, as described by Giannakos (12).…”

“…For more details about these methods as well as about the methods in the German and French literature the interested reader is referred to Giannakos (12).…”

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

“…where Q total is the total load acting on track, static and dynamic, without any relation to probability of occurrence, and k in lb/in. 2 is the rail support modulus derived by the relation p = k ? w = k ?…”

“…This situation changed with the development of high-speed railways. In modern high-speed railways the necessity for achieving very low life-cycle costs and, consequently, low operating and maintenance costs, led to a very well compacted substructure, almost undeflected, with 100% modified Proctor or 105% Proctor compaction (2). Applications of excellent quality substructure are encountered in the French network with the operation of TGV (high-speed train, in French) and also in research projects of the International Union of Railways [see Optimum Adaptation of the Conventional Track to Future Traffic (3)].…”

Design Loads on Railway Substructure: Sensitivity Analysis of the Influence of the Fastening Stiffness

“…3. The method was calibrated to for the calculation of loads on ballastless track systems and the results were verified against measurements on Slab Track (Giannakos, 2010a). The results of the method were also presented for lines with Heavy Haul traffic that are typical in the United States (Giannakos, 2011).…”