An irregular geometry of the track can influence the safe passage of railway traffic. Therefore, maintenance activities on railways are mostly directed towards the correction of track geometry. It has been shown that unevenly supported and unsupported sleepers make major contributions to the effect of track geometry deterioration. In addition, irregular sleeper support conditions can contribute to ballast fouling, thus reducing its service life. Therefore, assessing the support conditions of the sleepers in a railway track is essential. This paper reviews methods that can be used for this purpose. Then, we propose a method for the assessment of sleeper support conditions and present results obtained in field investigations. The proposed method is based on sampling of the micro-tremor on sleepers and interpretation of obtained data. The obtained results prove that the proposed method is reliable and therefore usable in practice.
The analysis of track behaviour under vertical load is traditionally based on the presumption that the stresses and deformations in track elements can be determined by the application of the Winkler’s Hypothesis. The rail is considered a beam on a continuous elastic foundation. The basis of the hypothesis is a presumption about the proportionality between the load and deflection. However, it is empirically known that the track and track foundation elements in a real environment during the railway exploitation behave neither linearly, nor completely elastically. Moreover, there is a problem with unevenness of the track stiffness along the track. This paper analyses the track stiffness from the aspect of its influence on the quality of the vertical track geometry. The paper analyses optimum stiffness. Optimum stiffness is conditioned by the single stiffness of all the elements of the superstructure and substructure as well as by their mutual compatibility.
This article presents results obtained in the research conducted on railway infrastructure in Serbia, which aimed at prediction of substructure condition based on the analysis of track quality. It presents the results of seismic tomography application as non-destructive procedure for assessment of railway substructure condition. Track geometry quality was assessed according to analysis of longitudinal level data, which was recorded during regular track geometry inspections. Track section for application of seismic tomography was chosen on the basis of analysed track geometry data recorded during the regular track geometry inspections in 2006, 2008, 2009, 2012, 2013 and 2014. Tomographic imaging of railway platform on Test Section enabled the creation of two-dimensional finite element model, which was used for determination of propagation speed of seismic P-waves. Seismic tomography on Test Section, which is the part of the international railway line Belgrade–Vrbnica, was performed in 2014. Obtained tomographic image was discussed and compared to track geometry data recorded during the regular track geometry inspections.
This paper analyses the stresses in continuous welded rails on bridges including the aspect of fatigue of rail steel. Furthermore, it examines the possibility to avoid rail expansion joints, while simultaneously exploiting the permissible stress capacity of the rail profile 60E1. Accordingly, general application of permissible values of pressure and tensilestresses prescribed in the current European standards was critically analysed. Paper includes specific application aspects of the prescribed stress values for railway bridges in Serbia. General algorithm for reducing the stresses due to the vehicle/track/bridge interaction, which is presented in this paper, was developed by the authors.This algorithm includes all essential parameters of the bridge structure and railway superstructure, as well as the influence of climate conditions and railway route design.
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