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Modelling of the shape of railway transition curves from the point of view of passenger comfort

Zboiński Krzysztof, Woźnica Piotr, Bolzhelarskyi Yaroslav

Archives of Transport

2021

Vol. 60, iss. 4

205--217

In the past, railway transition curves were not used. Instead of it, a simple connection of the straight track and circular arc was applied. Nowadays, such simplicity is not allowed due to the increasing vehicle operating velocities. It is mainly visible in the high-speed train lines, where long curves are used. The article aims to develop a new shape of railway transition curves for which passenger travel comfort will be as high as possible. Considerations in this paper concern the polynomials of 9th- and 11th-degrees, which were adopted to the mathematical model of the mentioned shape of curves. The study's authors applied a 2-axle rail vehicle model combined with mathematically understood optimisation methods. The advanced vehicle model can better assign the dynamical properties of railway transition curves to freight and passenger vehicles. The mentioned model was adopted to simulate rail vehicle movement in both cases of the shape of transition curves and the shape of circular arc (for comparison of the results). Passenger comfort, described by European Standard EN 12299, was used as the assessment criterion. The work showed that the method using the 2-axle railway vehicle model combined with mathematically understood optimisation works correctly, and the optimisation of the transition curve shape is possible. The current study showed that the 3rd-degree parabola (the shape of the curve traditionally used in railway engineering) is not always the optimum shape. In many cases (especially for the long curves), the optimum shape of curves is between the standard transition curves and the linear curvature of the 3rd-degree parabola. The new shapes of the railway transition curves obtained when the passenger comfort is taken into account result in new railway transition curves shapes. In the authors' opinion, the results presented in the current work are a novelty in optimisation and the properties assessment of railway transition curves.

Tests of dynamic impact from trains on noise barriers

Olaszek Piotr, Sakowski Artur, Twardosz Ewa, Nurek Paweł

Roads and Bridges - Drogi i Mosty

2020

Vol. 19, no. 4

247--265

The article presents an investigation on the dynamic impact from passing trains on noise barriers. The effect was an investigation along two railway line sections: on the first section the barriers were located less than 3.8 m from the track axis and considerable distress of the barriers was observed; on the second section barriers of the same type were located 4.6 m from the track axis and no distress was noted. A method for determination of displacement occurring under aerodynamic loading is presented, based on measurement of vibration acceleration and calculation of double integral. The obtained results are compared with measurements from an interferometric radar. Parameters for analysis and assessment of the magnitude of dynamic impact from passing trains are proposed. The results of the analyses performed on the two railway line sections are compared. The article also presents laboratory tests of an undamaged noise barrier panel. Conclusions are formulated regarding the use of noise barriers susceptible to fatigue due to alternating positive and negative aerodynamic pressure peaks.

Tematem artykułu są oddziaływania dynamiczne przejeżdżających pociągów na ekrany przeciwhałasowe. Badania oddziaływania pociągów przeprowadzono na dwóch odcinkach: pierwszym, gdzie ekrany znajdowały się w odległości poniżej 3,8 m od osi toru i występowały liczne uszkodzenia ekranów oraz na drugim, gdzie ekrany tego samego typu znajdowały się w odległości 4,6 m od osi toru i nie występowały żadne uszkodzenia ekranów. Opisano metodę wyznaczania przemieszczeń powstałych podczas oddziaływania obciążeń aerodynamicznych poprzez pomiar przyspieszeń drgań i podwójne całkowanie. Uzyskane wyniki badań porównano z otrzymanymi na podstawie pomiarów przeprowadzonych z zastosowaniem radaru interferencyjnego. Zaproponowano parametry, które będą wykorzystywane przy analizie i ocenie wielkości oddziaływań dynamicznych, których źródłem są przejeżdżające pociągi. Zestawiono wyniki analizy oddziaływań pociągów na dwóch odcinkach linii kolejowej. Przedstawiono także badania laboratoryjne nieuszkodzonego panelu ekranu przeciwhałasowego. Sformułowano wnioski związane ze stosowaniem ekranów podatnych na oddziaływania zmęczeniowe pików nadciśnienia i podciśnienia.