Study of radiative characteristics of a completed partial discharge

The work is devoted to the study of the optical and electrical characteristics of a completed partial discharge burning in the presence of an electrolyte (1.5% NaCl solution). The possibility of using optical sensors that are part of smartphones such as Xiaomi for research is shown. The dependence of the radiation intensity of the completed partial discharge on the value of the ballast resistance in the discharge circuit and the material of the grounded electrode (anode) is studied. The dependence of the breakdown voltage on the size of the discharge gap is also studied. It is shown that it has a nonlinear character at a significantly lower (up to 20 times) breakdown voltage in comparison with the case of the absence of an electrolyte.

INFLUENCE OF THE BALLAST RESISTANCE ON THE STABILITY OF CONTINUOUS WELDED RAIL

The article is about the issue of the influence of ballast resistance on the stability of the Continuous Welded Rail. The ballast resistance affects both the longitudinal and transverse displacements. It depends on the quality of the ballast, the degree of its compaction and contamination. The article contains an analysis of the impact of ballast resistance on the track based on the Finite Difference Method. The calculations showed that the resistance value directly affects the allowable critical force and the maximum temperature rise in the rail that does not endanger the safety of railway traffic.

Optimisation of bitumen emulsion properties for ballast stabilisation

Ballasted track, while providing economical and practical advantages, is associated with high costs and material consumption due to frequent maintenance. More sustainable alternatives to conventional ballasted trackbeds should therefore aim at extending its durability, particularly considering ongoing increases in traffic speed and loads. In this regard, the authors have investigated a solution consisting of bitumen stabilised ballast (BSB), designed to be used for new trackbeds as well as in reinforcing existing ones. This study presents the idea behind the technology and then focuses on a specific part of its development: the optimisation of bitumen emulsion properties and dosage in relation to ballast field conditions. Results showed that overall bitumen stabilisation improved ballast resistance to permanent deformation by enhancing stiffness and damping properties. Scenarios with higher dosage of bitumen emulsion, higher viscosity, quicker setting behaviour, and harder base bitumen seem to represent the most desirable conditions to achieve enhanced in-field performance.

On the ballast–sleeper interaction in the longitudinal and lateral directions

In service, railway tracks must withstand the transverse and longitudinal forces that are caused by running vehicles and thermal loads. The mechanical design that adopts any of the track models available in the technical literature requires that the strength of the track is fully characterised. In this paper, the results of an experimental research activity on the sleeper–ballast resistance along the lateral and the longitudinal directions are reported and discussed. In particular, the work is aimed at identifying the strength contributions offered by the base, the ballast between the sleepers, and the ballast shoulder to the global resistance of the track in the horizontal plane. These quantities were experimentally determined by means of an ad hoc system designed by the authors. Field tests were carried out on a series of track sections that were built to simulate scenarios in which the ballast was removed from the crib and/or the shoulder. The results of this study indicate that the strength percent contributions from the crib, the sleeper base, and the shoulder are, respectively, equal to about 50%, 25%, and 25% in the lateral direction, and 60%, 30%, and 10% in the longitudinal direction. Moreover, the comparison of the acquired data with literature results reveals that a detailed knowledge about the testing conditions and the activated ballast failure mechanisms is needed in order to correctly use the test data for the design purpose.

Analysis of structure importance of compensation capacitor in jointless track circuit

This paper models the input signal amplitude of the main track and the small track of the adjacent jointless track circuit (JTC) when JTC is idle and the track circuit reader(TCR) received signal amplitude when JTC is occupied, based on the work mechanism of JTC and TCR. Based on the models, the relative impact of compensation capacitor on signal amplitude is obtained by simulation. The paper further proposes a calculation method for structure importance of compensation capacitors. Experimental results indicate that the rankings of structure importance are not affected by ballast resistance of JTC in this method. The results also show that the compensation capacitors closer to the receiving end are more important than those closer to the sending end. In addition, C2, C6, and C3 closer to receiving end are the most important and should be paid close attention during maintenance. The second, the first and the fifth capacitor from the sending end, have less impact on the JTC and TCR signal. This paper is helpful to determine the maintenance priority of each capacitor, optimize the maintenance strategy, and make better use of JTC.

Application limits for continuously welded rails on temporary bridge decks

The possibility of omitting rail expansion devices from the track configuration, when continuously welded rail is continued over temporary bridge decks, is investigated in detail. More specifically, the related rail track to temporary bridge interaction phenomena are analysed using finite element modelling. A first parametric analysis assesses the additional rail stresses due to moving trainloads and temperature variations, based on stipulations provided in the unit identification code 774-3R. In addition the model is expanded to a more complex structure that is able to simulate the buckling behaviour of the rail track using non-linear methods. Using this model, a second parametric study is performed in which only thermal loading is considered. This allows for determining the parameters, which are predominant in determining the critical buckling temperature of the rails, and for assessing the magnitude of the safety margin necessary, when it comes to thermal buckling of the rails and the temporary bridges. It can be concluded that, depending on the magnitude of two main factors, the lateral ballast resistance and the amplitude of the initial track misalignment, a considerable reduction of the track stability might arise. Therefore, a minimal characteristic lateral ballast resistance of 4 kN is recommended along with a maximal allowable misalignment amplitude of 7 mm has to be prescribed when thermal track buckling has to be considered in the design.

STUDY OF METHODS OF IMPROVING THE RELIABILITY OF THE INSTRUMENT IS FUNCTIONING TONAL TRACK CIRCUITS WHEN THE RESISTANCE OF THE BALLAST

Based on the general principles of automatic control systems are considered options for the structureof tonal track circuit equipment with automatic correction tracking generator output voltage depending on the ballast resistance. For further development, a system of automatic control of the output voltage of thegenerator with the stabilization of its prescribed value. The prescribed value is set in accordance with the results of measurements of the insulation resistance (ballast).