Effects of rubber-intermixed ballast on train loading response through field monitoring in Western Sydney

The use of waste tyres in transportation infrastructure promotes environmentally sustainable engineering practices and reduces the cost of transportation and disposal. Laboratory testing has shown that a Rubber Intermixed Ballast System (RIBS) has significant advantages over conventional ballast. This study extends the evaluation of RIBS via a fully instrumented field trial near Western Sydney to assess its compatibility and efficiency under real-life conditions. The trial revealed a beneficial redistribution of stress along the depth of the track, despite an initial increase in deformation during construction and stabilizing the track in the initial loading phases. The measured acceleration response indicated a reduction of ground vibrations in the RIBS track, while the reduced particle breakage suggested its lifespan would exceed that of conventional ballast. Finite element modelling (FEM) of the RIBS track, calibrated with large-scale triaxial tests and field data, was carried out under moving wheel loads to compare its performance with a conventional ballasted track. The FEM simulations highlighted the differences in vertical stress and track settlement at varying train speeds. These findings indicate that RIBS support a circular economy and also offer a sustainable approach to stabilizing ballasted tracks by enhancing their longevity and reducing their maintenance costs.