Network Rail says the UK's first low-carbon track renewal has taken place between Honor Oak Park and Forest Hill in south London.

In total 1,150 yards of plain line track have been replaced on a stretch of railway line using a range of low carbon, sustainable materials - a UK first that will help Network Rail contribute to its net zero commitment

The railway has successfully delivered the UK’s first low-carbon track renewal combining green steel rail, low-carbon concrete, recycled ballast and renewable biofueled trains to cut emissions without compromising performance.

Led by the Southern Renewals Enterprise (SRE) – Network Rail’s integrated delivery team in the south of England – the project saw VolkerRail, the SRE’s Track business partner, renew  plain line track using innovative new products developed by Network Rail Supply Chain Operations (SCO).

Materials account for a significant share of the overall carbon footprint in track renewals, as much as 90%. The key contributors are steel rails, concrete sleepers and ballast, all traditionally produced through carbon-intensive processes.

The project team worked with Network Rail SCO to deliver the renewal using:

• Green steel rail produced using an electric arc furnace, achieving around 60% lower carbon intensity compared with traditional blast furnace steel.
• Low-carbon concrete sleepers, designed to deliver an estimated 40% reduction in embodied carbon.
• Recycled blended ballast, achieving up to 13% carbon savings by reducing the need for virgin aggregate.
• ISCC-certified renewable biofuel (commonly referred to as HVO).
• Solar-powered welfare units, reducing the need for diesel generators and cutting on-site emissions.

This project marks the first time all three primary track components - rail, sleepers and ballast - have achieved verified carbon reductions on a single renewal in the South of England, while also using HVO-fuelled trains.

The combination of these innovations resulted in 63% (581 tCO2e) avoided in carbon emissions compared with baseline materials and transport methods – the annual emissions of around 200 UK households.

Across the first year of the programme, April 2024 to April 2025, the SRE achieved a 10.2% reduction in whole-life carbon against the baseline.

Green steel and low-carbon sleepers are now in use across SRE projects, and the successful use 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: “This project shows what’s possible when innovation and teamwork come together. It’s the first of many greener renewals we plan to deliver - helping us move steadily toward Network Rail’s net zero goals.”