The aim of this paper is to demonstrate the possibilities of estimating the track condition using axle-boxes and car-bodies motions described by acceleration signals. In the paper, the results presented indicate the condition of tracks obtained from the preliminary investigation on the test track. Furthermore, the results from the supervised runs (on Polish Railway Lines) of Electric Multiple Unit (EMU-ED74) with the prototype of track quality monitoring system installed on-board are described. As Track Quality Indicator (TQI) algorithm, used in the mentioned prototype, a modified Karhunen–Loève transformation is used in preliminary preparation of acceleration signals. The transformation is used to extract the principal dynamics from measurement data. Obtained results are compared to other methods of evaluating the geometrical track quality, namely methods, which apply the synthetic coefficient Jsynth and five parameters of defectiveness W5. The results from the investigation showed that track condition estimation is possible with acceptable accuracy for in-service use and for defining cost-effective maintenance strategies.

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Die Bestimmung kritischer Parameter für die Stabilität hybrider Systeme mit fortschreitenden Wellen steht in Verbindung mit der Analyse der Bewegungen eines Balkens unter einer bewegten und oszillierenden Kraft. Untersucht werden die Schwingungen eines unendlich langen Timoshenko‐Balkens auf elastischer Bettung unter der Wirkung einer harmonisch zeitveränderlichen und mit konstanter Geschwindigkeit längs des Balkens bewegten Kraft. Die Lösung wird für den gesamten Frequenz‐Geschwindigkeitsbereich der Kraft angegeben. Die Ergebnisse für einen Bernoulli‐Euler‐Balken folgen als Grenzfall aus denen des Timoshenko‐Balkens.

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The paper is devoted to the study of dynamical behaviour of railway tracks as continuous systems (rails) supported by periodically spaced sleepers and subjected to moving concentrated loads. Several cases of dynamical problems, where elastically supported beams are excited by a moving concentrated force, are considered. In particular, the study is focused on interactions with structure periodic in the space. Results on one-dimensional structures are extended to the case of a two-dimensional system. The problems of stopping bands, passing bands, and mistuning are also mentioned.

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