Railway sidings are operated at speeds much lower than those used on national railway lines; a typical speed is 6 km/h. In\udestablishing reference values for maintenance of railway infrastructure in terms of the geometry for such operating conditions, it is\udnoted that both national and European regulations do not provide specific information regarding railway sidings.\udThe overall objective of the research is, therefore, the definition of possible reference values for track geometry, based on those\udadopted by European rail networks (European and national standards), which can guarantee the appropriate security level for low\udspeed operation typical of railway sidings connected to the national network.\udThe basic principle in defining these values is the maximization of technical-economic efficiency and the maintenance of the\udacceptability of the risk associated to railway operation. The research results can therefore provide useful information about the\udcost-effective management of maintenance and safe operation for railway sidings.\udFor this purpose, the approach was inspired to that of Regulation 402/2013, which defines at European level a common safety\udmethod for risk analysis. Quantification of probabilities and damages should be based on simulation models because the available\udstatistics do not allow significant results to be inferred. However, the research sector has not yet produced a consolidated modelling.\udFor these reasons, and since it is not possible to quantify probabilities reliably, the proposals resulting from this research are based\udon the identification of situations where it can be shown that the hazard probability remains unchanged.\udThe approach used to formulate possible reference values valid outside of national networks (railway sidings) is based on an\udunderstanding of the underlying principles of the codes of good practice, on the formulation of hypotheses conform to the same\udprinciples, and the proposals about mitigative measures of risk associated to the use of different reference values, such as to keep\udthe risk of the railway within the limits of acceptability, acting conservatively so as to keep unchanged, or reduce, the probability\udof hazardous events.The assessment parameters, object of the first phase of the research referred to in this work and used here as an example, are\udlongitudinal level and alignment of railway track. In the case of vehicles running at low speed, the study was conducted by varying\udthe magnitude of the reference values by using values that belong to external intervals with respect to those in accordance with\udEuropean and national codes of good practice, examining the corresponding effects on the physical quantities related to safety. The\udeffects of their variations on the wheel-rail interaction forces were studied using a simple dynamic model (with one degree of\udfreedom) and a random generated excitation given by track defectiveness and the corresponding random response in terms of\udvertical and lateral contact forces (Q and Y).
展开▼
