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The dimensioning of the locking device of a switch is made essentially as a function of the applied loads during the switch rails movement or considering a false route. The phenomena related to the vibrations induced by the track are therefore normally not taken into account. Such vibrations are particularly accentuated by the ballast bed deconsolidation in the sleeper panel supporting the locking device. Unfortunately, there is no specific technical reference in order to control these aspects, even though the most frequent cause of locking device components failures is relied to the vertical oscillations induced by the trains, rather than to the effort to commute the switch rails. In this study, the results of a field investigation carried out at two levels of ballast tamping are reported and discussed. It is found that the ballast compaction plays a fundamental role for the component to be prone to the early attainment of critical mechanical conditions. Procedures for the monitoring of the stability and efficiency of the ballast bed to ensure the required reliability of the locking device are also envisaged. [ABSTRACT FROM AUTHOR]

In the present paper the design and construction choices of a test field for the ballast lateral resistance measurement, in order to produce data useful for the development of a numerical model able to simulate the service critical conditions of a continuous welded rail track, are described. Some construction details described herein allow to better understand the methodological approach followed in the design of experiments, the tests management philosophy as well as of the accuracy achieved in their implementation. [ABSTRACT FROM AUTHOR]

Several studies have been carried out until now by various Research Agencies and Railway Administrations to quantify the effects of the track-bed geometrical characteristics on the transverse strength of the track. Unfortunately, not all the possible scenarios in terms of track components, track-bed cross profile, operating conditions etc. have been investigated and not all the relevant variables have been directly measured. Therefore data available from the literature have different degrees of reliability. With the aim of enlarging the knowledge on the track stability and covering much of the possible relevant scenarios, an experimental research program has been developed in the framework of a cooperation between RFI, Italcertifer and DII. In order to perform the investigation under quite general conditions and to reduce the experimentation costs, n. 28 significant scenarios have been identified and reproduced on as many independent track segments. By applying on each track segment a transversal load, the strength of the ballast-sleeper interface has been determined. The results relative to the first four scenarios are presented in terms of applied load vs. lateral track displacement diagrams and in more synthetic numerical tables. [ABSTRACT FROM AUTHOR]