Network Rail will undertake major upgrades to the Severn Tunnel this month.
Network Rail and contractor ARQ will complete the transformation of the overhead power system, designed to withstand the tunnel’s harsh, corrosive environment. The upgrade will improve resilience, reduce maintenance and help to minimise disruption to passengers.
The work will take place around the clock from May 23 to June 9. The railway will be closed between Newport and Bristol Parkway during this time.
Network Rail says the 7km tunnel, which runs beneath the Severn Estuary, connecting South Gloucestershire in England to Monmouthshire in Wales, 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 a system that 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 install the system along the full length of the tunnel, using a world-first approach on this scale.
The programme of work involves replacing 838 bridge arms that support the overhead electric wires; renewing 9km of overhead wiring; and carrying out track and infrastructure upgrades, and drainage works in the Bristol and Patchway areas.
Nia Watkins, regional msset Manager at Network Rail Wales and Borders route, said the work was essential to maintain safe, reliable services and support the tunnel’s long-term future.
“Using an innovative solution developed by our teams at Network Rail, this complex and highly co-ordinated 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.
“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.”
