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The influence of worn and nominal rail profiles on railway vehicle motion and dynamics

Zboiński Krzysztof, Kukulski Jacek, Gołofit-Stawińska Milena, Woźnica Piotr

Archives of Civil Engineering

2025

Vol. 71, nr 2

177--192

In this study the rail wear influence on safety of rail vehicle motion is assessed. The profile measurements for the nominal rail head and for the slightly worn and heavily worn rail heads were performed. Then, these measured real values were entered into a computer program designed to study the motion (dynamics) of rail vehicles. The studied model of passenger vehicle moved in simulations along a track consisting of straight and curved sections with transition curve between them at two velocities. After obtaining the simulation results, they were compared for different stages of the rail wear process based on profile measurement results and the suitability of the track was assessed, too. The aim of present paper was to show that extension of the traditional approach with the simulation studies of vehicle motion and dynamics leads to different and much more precise information about the need of the rails replacement. The proposed idea and approach in the current work is original and not used in practice by the track infrastructure operators.

W pracy oceniono wpływ zużycia szyn na bezpieczeństwo ruchu pojazdów szynowych. Wykonano pomiary profili dla nominalnej główki szyny oraz dla lekko i mocno zużytej główki szyny. Następnie te zmierzone wartości rzeczywiste wprowadzono do programu komputerowego przeznaczonego do badania ruchu (dynamiki) pojazdów szynowych. Badany model pojazdu pasażerskiego poruszał się w symulacjach po torze składającym się z odcinków prostych i zakrzywionych z krzywą przejściową między nimi przy dwóch prędkościach. Po uzyskaniu wyników symulacji porównano je dla różnych etapów procesu zużywania się szyn na podstawie wyników pomiarów profilu oraz oceniono przydatność toru. Celem niniejszego artykułu było wykazanie, że rozszerzenie tradycyjnego podejścia o badania symulacyjne ruchu i dynamiki pojazdów prowadzi do uzyskania odmiennej i znacznie dokładniejszej informacji o potrzebie wymiany szyn. Zaproponowana koncepcja i podejście jest oryginalne i nie jest stosowane w praktyce przez zarządców infrastruktury szynowej. Można go zatem traktować jako nowość i pewien wkład autorów w problematykę i metodykę utrzymania torów.

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.