Severn Tunnel reopens after £23m upgrade designed to improve Wales-England rail link

Mark Mansfield

Train services are once again running through the Severn Tunnel after engineers completed a £23 million upgrade aimed at improving reliability on one of the most important rail connections between Wales and England.

The 16-day closure allowed Network Rail and its contractors to carry out what has been described as a world-first engineering solution inside the 4.35-mile tunnel beneath the Severn Estuary.

Around 250 engineers worked around the clock from May 23 to complete the project, with the route reopening to passengers on Tuesday.

The Severn Tunnel, which opened in 1886, is a vital transport link connecting south Wales with Bristol and London, carrying both passenger and freight services.

However, its unique environment, with saltwater seepage, high moisture levels and corrosive conditions, has caused persistent problems for railway infrastructure since the route was electrified.

Network Rail said the harsh conditions accelerate a process known as bi-metallic corrosion, where different metals deteriorate rapidly when exposed to wet, salty conditions.

To tackle the problem, engineers developed a new overhead line system specifically designed for the tunnel. The scheme involved replacing 838 support arms, installing 14,000 metres of new wiring and more than seven kilometres of continuous copper contact wire, while removing ageing equipment throughout the tunnel.

The new system was first tested on the Cardiff-bound line last year before being rolled out across the entire tunnel during the latest closure.

Nick Millington, Route Director for Network Rail Wales and Borders, said the project represented years of planning and innovation.

“The Severn Tunnel is one of the most challenging environments anywhere on the UK rail network, so completing this upgrade is a significant achievement for everyone involved,” he said.

“We’ve now delivered a world-first engineering solution at scale, designed specifically to withstand the uniquely harsh conditions inside the tunnel.

“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.”

The closure was also used to carry out additional rail improvements around Bristol, including drainage works to tackle flooding issues, more than 1.5 kilometres of track renewals, and progress on the new Bristol Brabazon station, which is expected to open later this year.