A world-first system of shock absorbers made from recycled tyres has been shown to be effective in protecting railway tracks from damage.
The new technology was tested 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.
Researchers installed track sections with a rubber underlay made from tyres alongside conventional track sections for a direct comparison, monitoring vibration, track settlement, and ballast degradation at a live Sydney Trains freight line in Chullora.
The results showed that the sections with the rubber underlay showed “significantly less degradation and greater stability”.
To make the shock absorbers, tyre cells are placed 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 ballast.
The technology addresses a long-standing engineering challenge: the high cost of maintaining conventional tracks.
UTS researcher Distinguished Professor Buddhima Indraratna, the original inventor of this technique, and Director of the UTS Transport Research Centre, said the rubber-based underlay effectively protects the ballast, preventing it from being pulverised and extending the life of the entire track structure.
“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 this 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 also provides a novel way to address tyre waste – with over 50 million end-of-life tyres generated in Australia each year.
“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,” said Professor Cholachat Rujikiatkamjorn from the UTS Transport Research Centre.
The research team will now expand its work through a $740,000 Australian Research Council Linkage Project grant, testing the technology in more challenging locations – such as at bridge approaches and junctions, where abrupt changes in track stiffness create high-impact zones prone to rapid degradation.
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