This paper analyses the stresses in continuous welded rails on bridges including the aspect of fatigue of rail steel. Furthermore, it examines the possibility to avoid rail expansion joints, while simultaneously exploiting the permissible stress capacity of the rail profile 60E1. Accordingly, general application of permissible values of pressure and tensilestresses prescribed in the current European standards was critically analysed. Paper includes specific application aspects of the prescribed stress values for railway bridges in Serbia. General algorithm for reducing the stresses due to the vehicle/track/bridge interaction, which is presented in this paper, was developed by the authors. This algorithm includes all essential parameters of the bridge structure and railway superstructure, as well as the influence of climate conditions and railway route design.

Additional temperature stresses in continuously welded rails (CWRs) are caused by track/bridge interaction (TBI) due to thermal actions. Exceeding permissible stresses in CWRs on the bridge can lead to track buckling or rail cracking, compromising the safety of railway traffic. The main aim of the conducted study is to determine the effects of the key parameters such as rail cross-sectional area, track longitudinal resistance, bridge expansion length, and longitudinal stiffness of the fixed bridge support on the reduction of additional temperature stresses in CWRs on steel truss railway bridges. To quantify the effects of these parameters, two steel railway bridges with CWRs and the maximum expansion lengths according to UIC Code 774-3 were analyzed: (1) simply supported truss bridge with expansion length of 60 m and (2) continuous truss bridge with expansion lengths of 2 × 60 m. According to the obtained results, the track longitudinal resistance had the most significant impact on additional temperature stresses in CWRs, leading to their reduction of up to 72%. The bridge expansion length and the rail cross-sectional area led to reductions of up to 25% and up to 18%, respectively. Considering the deformation criteria of TBI, the longitudinal stiffness of the fixed bridge support had a minor effect on the reduction of additional temperature stresses in CWRs.

The analysis of the dynamic interaction between the train, track, and bridge is crucial for ensuring the performance of railway infrastructure and the safety of railway traffic, especially on high-speed rail systems. This paper examines the key requirements for analyzing the dynamic interaction between the train, track, and bridge, with particular emphasis on the guidelines outlined in UIC Code 776-2. The analysis includes the structural strength of the bridge, passenger comfort, and the overall safety of railway traffic, ensuring a comprehensive evaluation of the entire railway system. Specifically, the paper examines the impact of continuously welded rails, which are widely used in modern railways due to their improved performance and reduced maintenance needs. The dynamic behavior of the train, track, and bridge is analyzed to confirm the structural integrity of the system, mitigate vibrations, and enhance passenger comfort. UIC Code 776-2 serves as a key reference for understanding the design and performance requirements for analyzing train-track-bridge dynamic interaction, guaranteeing that safety standards are met while optimizing efficiency. By evaluating the dynamic performance of the train, track, and bridge components, potential risks can be assessed, and strategies can be developed to mitigate them. This research contributes to the development of more resilient railway systems, ensuring the safety of both passengers and infrastructure.