10. Sustainable Transport Infrastructure Adopting Energy-Absorbing Waste Materials

Ballasted rail tracks are the most common type of transportation infrastructure. However, ballast progressively degrades under dynamic loads and impact loads. The degree of degradation will be accelerated due to the increasing demand for higher-speed passenger trains and heavier axle load freight transportation. It is therefore those novel technical methods are adopted to enhance track conditions. Over the past two decades, many studies have been conducted by the researchers of Transport Research Centre (TRC) at the University of Technology Sydney (UTS) to investigate the ability of recycled rubber mats/pads, as well as waste tyre cells and granulated rubber to improve the stability and longevity of rail track. This paper presents an overview of these novel methods and materials used in recent studies based on large scale laboratory tests (i.e. cubical triaxial tests and drop hammer impact tests) and numerical modelling. Moreover, in an effort to put theory into practice, the performance of under ballast shock mats placed at ballast-bridge deck interfaces has been investigated in field tests carried out at Singleton (near Newcastle, Australia). The test results and the numerical modelling show that rubber inclusions will greatly improve overall track performance.