New research has shown that a world-first system of rubber shock absorbers made from recycled tyres can significantly protect railway tracks from damage, addressing the dual challenges of high maintenance costs and national tyre waste.
The technology was validated over a two-year period by a collaborative team from the University of Technology Sydney (UTS), Sydney Trains, Transport for NSW, and industry partners EcoFlex and Bridgestone, following extensive monitoring at a live Sydney Trains freight line in Chullora.
Researchers installed track sections with the rubber underlay alongside conventional track sections for a direct comparison, monitoring vibration, track settlement, and ballast degradation under real-world conditions.
The results, detailed in the research paper " Effects of Rubber-Intermixed Ballast on Train Loading Response Through Field Monitoring in Western Sydney " and published in the Canadian Geotechnical Journal, confirmed the sections with the rubber underlay showed significantly less degradation and greater stability.
The patented technology involves placing the tyre cells in a specific layout made from recycled tyres infilled with waste materials such as spent ballast and coal wash. Recycled rubber grids cast from worn out conveyor belts from mining sites are also placed directly beneath the rail track's primary load-bearing layer, known as ballast.
The technology addresses a long-standing engineering challenge: the high cost of maintaining conventional tracks.
"The rubber-based underlay effectively protects the ballast preventing it from being pulverised and extending the life of the entire track structure," said UTS researcher Distinguished Professor Buddhima Indraratna, the original inventor of this technique, and Director of the UTS Transport Research Centre.
"Additionally, the underlay controls the way the train load is distributed to the deeper, softer and often wet soil beneath the track, preventing unacceptable soil settlement and weakening of the overlying track.
"This translates directly to lower maintenance costs, fewer track closures for the public, and improved network reliability."
Dr Richard Kelly, Chief Technical Principal for Geotechnical Engineering at SMEC Australia and an advisor on the project, said: "If widely adopted by railway asset owners, this will save Australian rail industry millions of dollars annually by reducing the demand for freshly quarried rock for ballast that is very expensive and not carbon friendly."
The project provides a powerful solution for the over 50 million end-of-life tyres Australia generates annually.
"Finding sustainable, onshore uses for this material is a national priority, and at the same time, we need to reduce our reliance on finite quarried materials," said Professor Cholachat Rujikiatkamjorn from the UTS Transport Research Centre.
"We have proven we can turn a significant waste stream into a high-value asset that makes our critical infrastructure more resilient and advances the circular economy."
Building on this success, the research team will now expand the work through a newly announced $740,000 Australian Research Council Linkage Project grant. This next phase will test the technology in more demanding locations, such as at bridge approaches and junctions, where abrupt changes in track stiffness create high-impact zones prone to rapid degradation.
