Railway track transitions, where abrupt changes between different track sections lead to differential settlement and increased maintenance costs, pose a significant challenge. This often results in considerable track damage and elevated maintenance expenses. In Thailand, the early stages of the high-speed rail project integrate a slab track system from China with conventional ballasted tracks at multiple junctions, underscoring the importance of effectively managing these transition zones. Despite the potential benefits of Under Sleeper Pads (USPs) in ballasted tracks and Under Slab Mats (USMs) in slab tracks for reducing track vibration, impact load, and differential settlement, their usage is not widespread. This paper presents a 3D train-track-soil finite element model that incorporates both USPs and USMs, considering strain-rate effects, to analyze railway track transitions. The model evaluates various pad types across different track locations and train speeds. The results show that USPs can significantly reduce ballast degradation, while USMs help maintain overall track stiffness. The results also show that the combination of USPs and USMs effectively manages track stiffness gradients, achieving a normalized gradient between 0.04 and 0.20, compared to 1.00 in the baseline case. Although the combined use of USPs and USMs offers a promising solution for managing track transitions, careful selection are crucial to avoid potential issues. This research provides a comprehensive framework for understanding and improving the performance of railway track transition zones using resilient materials. It suggests further studies to evaluate the broader applicability of these methods in minimizing track disturbances across various environmental conditions.

Buckle initiation devices, such as sleepers and distributed buoyancy modules, are typically adopted to initiate lateral buckles at pre-determined locations to release thermal expansion in a controlled manner to ensure pipeline integrity. For pipelines installed by S-lay, sleepers are desired as it is difficult for buoyancy modules to pass over the stinger rollers. If the thermal cyclic fatigue is critical in the pipeline design, pipeline lateral buckling designs may result in small sleeper spacing. As such, buckle reliability of conventional sleepers may be inadequate in some cases. In this paper, lateral buckling mitigation with sleepers is investigated using finite element (FE) models for a water injection pipeline. Sensitivity analyses are performed on key input parameters including single and dual sleepers, lower bound and upper bound friction factors between sleeper and pipeline, berm effects on soil lateral resistances, and sleeper heights. Based on the sensitivity study results, a mitigation solution combining sleepers and mattresses under the pipeline touch down zones is proposed and evaluated. It is found that sleepers combined with reduced touch down point lateral friction can reduce the maximum longitudinal strain and thermal fatigue damage by more than 50% as compared to using sleepers alone as mitigation. Therefore, this design adds a new option to allow increases in the sleeper spacing and improved reliability of buckle initiation.