Experimental Study on the Elastic Support in a Discrete Rail Fastening System Used in Ballastless Tram Track Structures

This paper presents an experimental study on the elastic support in a discrete rail fastening system used in a ballastless tram track structure. The study focuses on the elastic support of the anchor element, specifically the Pm49 baseplate. These elements significantly influence environmental pollution along tram routes, such as vibration (at low frequencies) or noise (at high frequencies), as well as static and dynamic rail deflections. The authors outline a methodology for identifying the static and dynamic characteristics of the discrete elastic support in laboratory conditions. The procedure follows the European standard EN 13146-9 for track category A (tramway), as classified according to the European standard EN 13481-5. The study analyzes how the thickness and density of the tested materials affect stiffness. Additionally, it examines the correlation between parameters identified easily on-site (thickness, Shore hardness and density) and laboratory-determined parameters (static and dynamic stiffness), which are costly and time-consuming to measure. The research confirms that prototype prefabricated vibration isolation baseplate pads made of styrene butadiene rubber (SBR) granules, recycled from end-of-life car tires, can achieve equivalent basic static and dynamic parameters, compared to underlays made of two-component polyurethane (PU) resin. This aligns with the strategy of promoting sustainable materials in construction. The innovative and prefabricated SBR rubber baseplate pads can also be used in repair and maintenance works (regardless of weather conditions), as they enable the quick launch of tram traffic. The results of the research included in this article can be used by other scientists, recycled rubber producers, tram track designers or construction site engineers.