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Friday 8 May 2026

Innovative Severn Tunnel upgrade to transform key rail link between South Wales and England

Region & Route:

Wales & Western: Wales & Borders

Passengers are advised to plan ahead as Network Rail carry out major upgrade in the Severn Tunnel and Bristol area, with replacement buses and diversionary routes in place to keep people moving from late May to early June.

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.

The new system

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.

The programme of work involves:

• Replacing 838 bridge arms that support the overhead electric wires in the Severn Tunnel
• Renewing 9,000 metres of overhead wiring in the Severn Tunnel
• Carrying out track and infrastructure upgrades, and drainage works in the Bristol and Patchway areas.

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.

“Alongside this, we’re also renewing track that will serve the new Bristol Brabazon station, which will bring passenger services back to the Henbury and Portishead lines for the first time in over 60 years, supporting local communities and economic growth. The station is due to open later this year and will bring passenger services back to the Henbury line for the first time since 1964."

“We recognise this work requires the temporary closure of the railway between Newport and Bristol Parkway, and we’re grateful to passengers and local communities for their patience while we carry out these important upgrades.”

Travel information

The railway will be closed between Newport and Bristol Parkway from Saturday 23 May until the end of Monday 8 June, reopening on the morning of Tuesday 9 June.

• Replacement bus services will run between Newport and Bristol Parkway
• Some trains will operate between London and South Wales via Gloucester (except Sunday 24 May)
• A reduced service will run between London Paddington and Bristol Parkway
• On Sunday 24 May, trains will not divert via Gloucester, with services operating only between Paddington and Bristol Parkway, and Newport and Swansea

Passengers are strongly advised to check before they travel and allow extra time for their journeys.

Marcus Deegan, GWR's Station Manager at Bristol Parkway, said: “We know that bus replacement services are a significant ask of passengers, and we're genuinely grateful for their patience while this vital work is completed.

“This investment to improve and maintain the Severn Tunnel will make a real difference to the reliability and resilience of the route for many years ahead.

“The wider work taking place will also allow us to introduce train services to Bristol Brabazon later this year, and in time to Portishead and Pill - reconnecting people to rail and providing a vital economic catalyst across the area.

“Our team at Bristol Parkway is on hand to help customers navigate their options, and we've worked hard to put in place replacement services that keep people moving. The most important thing anyone can do is check their journey in advance at GWR.com and allow a little extra time.”

As part of GWR's Growing Places research, stations across the South West are projected to contribute £14 billion pounds in economic value and 238,000 of new jobs by 2036.