Network Rail is carrying out a major upgrade in the Severn Tunnel and Bristol area which is set to transform rail links between South Wales and England.

This vital project will see Network Rail and contractors ARQ complete the transformation of the Severn Tunnel’s overhead power system, designed specifically to withstand the tunnel’s harsh, corrosive environment - making it more resilient, reducing the frequency of maintenance and helping to minimise disruption for passengers.

The work will take place around the clock from Saturday 23 May until the early hours of Tuesday 9 June, with the railway closed between Newport and Bristol Parkway during this time.

Running beneath the Severn Estuary, the 4.35-mile Severn Tunnel is one of the toughest environments on the UK rail network, where moisture and saltwater accelerate wear on equipment.

Since electrification, the overhead power system has been prone to corrosion and electrical wear, leading to more frequent maintenance.

To address this, Network Rail’s Wales and Borders team has developed and successfully trialled an innovative new system. It uses a single 7km copper contact wire supported at regular intervals by modified bridge arms, to eliminate previous corrosion issues and improve performance.

Engineers will now install this system along the full length of the tunnel - using a world-first approach on this scale - to create a more resilient railway and reduce the need for frequent maintenance.

Alongside the tunnel work, Network Rail will also carry out improvements in the Bristol area, including upgrades to the railway serving the new Bristol Brabazon station on the former Filton airfield site. The station is due to open in the autumn and will bring passenger services back to the Henbury line for the first time since 1964.

Nia Watkins, regional asset manager at Network Rail Wales and Borders route, said: “Running beneath the Severn Estuary, the 4.35-mile Severn Tunnel is one of the most challenging environments on the UK rail network, making this work essential to maintain safe, reliable services and support its long-term future.

“Using an innovative solution developed by our teams at Network Rail, this complex and highly coordinated upgrade is being delivered at a world-first scale across the tunnel’s full length - making the railway more resilient and reducing the risk of future disruption for passengers and freight.”