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Licentiatavhandling (sammanfattning) Göteborg : Chalmers tekniska högskola, 2024

Railway switches are essential for ensuring efficient train operations, and efforts to improve their safety standards have driven the introduction of socalled switch rail control contact (TKK in Swedish) sensors in Sweden. These sensors monitor the gap between the switch and stock rail, complementing the function of the drives. Such gaps can be a result of undetected foreign objects such as ballast stones or ice, that are stuck between the switch and stock rail. According to statistics from the Swedish Transport Administration (Trafikverket), faults in TKKs due to component failure, snow and foreign object interference, account for a substantial portion of the total faults occurring in switches for a year. This results in increased maintenance and operational costs. Therefore, the aim of the thesis is to evaluate the necessity of these sensors by performing simulations of switch operations and derailment risk to provide input to a technical risk analysis of derailments in switches. For assessing the derailment risk in scenarios of interfering foreign object, field measurements, finite element (FE) and multibody simulations (MBS) are carried out. Two physical measurement campaigns were performed to obtain the deformation pattern of the switch rail in the presence of a foreign object. These measurements are used to validate the numerical models.