Severn Tunnel Upgrade

Region, Route & Location: Wales and Western | Wales and Borders | Severn Tunnel

Network Rail delivered a £23 million world-first upgrade to the Severn Tunnel’s overhead line equipment and power supply. The tunnel is one of the most challenging environments on the UK rail network, with its combination of saltwater and moisture accelerating corrosion and wear of overhead line equipment (OLE).

The upgrade introduced a new, simplified OLE solution using modified bridge arms and a continuous copper contact wire designed to withstand the tunnel’s harsh conditions. As part of the work, 838 overhead line support arms were replaced, 14,000 metres of new wiring was installed, and more than 7 km of single copper contact wire was installed to help improve reliability.

The project demonstrates how innovative engineering can support a greener railway by reducing environmental impact, improving reliability and making better use of resources. The simplified design uses fewer components and was designed to improve the resilience and lifecycle of the infrastructure. Keeping assets performing effectively for longer supports circular economy principles, reducing the need for further maintenance and replacement materials.

“Investing in innovative solutions like this helps us build a more resilient and reliable railway for the future. By reducing the impact of corrosion and the need for maintenance, this new system will help keep passengers and freight moving on a route that plays a crucial role in connecting communities, supporting businesses and driving economic growth on both sides of the border.”

Nick Millington, Wales and Borders Route Director