This thesis explores the use of Axle Box Accelerations (ABA) in passenger trains as a means to monitor and assess the structural health of railway turnouts, particularly the crossings. The increasing demand for higher capacity, speed, and axle loads, coupled with reduced maintenance time, has put a strain on the reliability of these sensitive components. The study focuses on the fixed crossing, a vulnerable component due to its discontinuity that can cause large impact forces leading to potential failure and disruptions.

The research aims to develop an assessment method to determine crossing health using ABA measurements from two retrofitted intercity trains. The crossing, formed by the wing rails and a crossing nose, presents a discontinuity that disturbs wheel motion and generates impact forces. The study acknowledges the challenges related to data quality, quantity, and processing due to the random nature of measurements and conditions. Despite these challenges, the research leverages the Law of Large Numbers and the Central Limit Theorem to overcome frequency-limited measurements.

The proposed assessment method is validated against geometry metrics derived from train-borne laser measurements. However, the current approach does not establish a reliable relationship between the impact angle and wear levels, making it unsuitable for monitoring wear levels of crossings. Nevertheless, a strong correlation was found between the kinematic wheel dip angle, mean and standard deviation of vertical impact, indicating that a larger mean or standard deviation suggests a more degraded vertical geometry. This finding is in agreement with prior research based on wayside measurements and underscores the potential of in-service passenger train ABA for assessing the structural health of turnout crossings.

This Bachelor’s thesis presents a comprehensive study of the static wheel/rail contact problem using Finite Element Analysis (FEA) with a parametric modeling approach. The work begins with a historical overview of the wheel/rail contact problem, highlighting the critical phenomena that occur at the wheel-rail interface. The thesis then delves into the Hertzian contact theory, providing a theoretical foundation for the subsequent modeling of the wheel-rail contact problem using FEA. A detailed description of the Finite Element Model (FEM) macro is provided, explaining the process of modeling the wheel/rail contact problem. The study concludes that FEA is a powerful tool for analyzing the wheel/rail contact problem, and the parametric modeling approach offers adaptability for future improvements and easy adjustments. The thesis underscores the importance of validation against analytical solutions to ensure the accuracy of the FEM model. As a future direction, the thesis recommends further research to apply different loads, explore relative positions of wheel and rail, and investigate different contact elements for modeling real-world contact behavior. This work serves as a stepping stone towards future research and a more comprehensive understanding of the wheel/rail contact problem.