Many of Australia’s railway bridges are based on the open deck system, where timber transoms are fixed directly to the bridge superstructure, and the resilient, damping qualities of ballast are absent. Timber has been used successfully in this application for over 100 years, however, the declining availability of suitable hardwood and restrictions on timber treatment has created the demand for new bridge transom technologies. The absence of ballast on these structures requires that new technologies have similar stiffness and behavioural properties to timber, to ensure continued compatibility with existing bridge and track components. Fibre composites are an appropriate alternative because they can be tuned to match the desirable properties of hardwood. With the support of University of Southern Queensland, Austrak has been developing a suitable fibre composite product technology that has similar structural properties to hardwood timber and a design life of 50 years. In contrast to other composite technologies used in timber replacement applications, Austrak’s design utilises multiaxial fibre reinforced laminates as the primary structural elements. This approach allows Austrak to customise the structural design to meet performance criteria, whilst conserving material usage.
A key feature of this new design is the utilisation of recycled fibreglass material in the transom core, which forms the bulk of this product. Waste fibreglass currently has very few secondary uses, so this application represents a significant step towards diverting existing waste. Additionally, in the next 3 – 5 years many of Australia’s first wind farm turbines will be decommissioned, introducing another large waste stream associated with the fibreglass blades used in these wind turbines. This presentation will address the key challenges associated with developing a fibre composite transom, including the structural design, the utilisation of recycled fibreglass materials, product testing, and the process of Type Approving new products in Australian rail networks.