Network Rail completes UK’s first low-carbon track renewal between Honor Oak Park and Forest Hill

Credit: Network Rail

Network Rail has successfully delivered the UK’s first low-carbon track renewal between Honor Oak Park and Forest Hill in south London, using a combination of green steel rail, low-carbon concrete sleepers, recycled ballast and renewable biofueled trains. This project marks a significant milestone in sustainable rail delivery and contributes to Network Rail’s net zero commitments.

Led by the Southern Renewals Enterprise (SRE), Network Rail’s integrated delivery team in the south of England, the project saw VolkerRail, SRE’s Track business partner, renew 1,150 yards of plain line track using innovative products developed by Network Rail Supply Chain Operations (SCO). The track was fully welded, stressed, and handed back at line speed, demonstrating that sustainability and operational excellence can be achieved simultaneously.

Materials account for a significant share of carbon emissions in track renewals, often up to 90 per cent, with steel rails, concrete sleepers and ballast being the main contributors. To address this, the project introduced multiple low-carbon innovations in a live operational environment. Green steel rail was produced using an electric arc furnace, achieving around 60 per cent lower carbon intensity than traditional blast furnace steel. Low-carbon concrete sleepers delivered an estimated 40 per cent reduction in embodied carbon, while recycled blended ballast achieved up to 13 per cent carbon savings by reducing the need for virgin aggregate. ISCC-certified renewable biofuel was used to power trains, and solar-powered welfare units reduced on-site diesel consumption.

This was the first time all three primary track components, rail, sleepers and ballast, achieved verified carbon reductions in a single renewal in the south of England, while also using HVO-fuelled trains. The combination of these innovations resulted in a 63 per cent reduction, equivalent to 581 tCO2e, compared with baseline materials and transport methods. This is the annual emissions of around 200 UK households.

Between April 2024 and April 2025, the SRE achieved a 10.2 per cent reduction in whole-life carbon against the baseline, demonstrating steady progress towards a more sustainable and future-proofed rail network. Beyond carbon savings, the project highlighted the importance of collaboration between SRE Track, Network Rail SCO, the Environment and Sustainability team, and partners across the supply chain.

Green steel and low-carbon sleepers are now in use across SRE projects, and the successful implementation of blended ballast in the south represents a key milestone in scaling low-carbon materials nationally. Further investment in these supply chains will continue this growth.

Dave Sutton, SRE Track’s Project Lead, said:

Liz Baldwin, SID director, added:

While challenges remain, such as scaling supply chains, ensuring biofuel sustainability and managing costs of low-carbon materials, the Honor Oak Park renewal offers a practical example of embedding sustainability into everyday rail operations. It provides a replicable model for future renewals and contributes to Network Rail’s alignment with the UK’s 2050 net zero target, striving towards a simpler, better and greener railway.