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Wednesday 18 Mar 2026

Major rail upgrade plans submitted to help unlock new railway stations

Region & Route:

Wales & Western: Wales & Borders

Passengers are closer to benefitting from improved rail services, better connectivity and new stations as Network Rail submits a full business case for major railway upgrades between Cardiff Central and Severn Tunnel Junction. 

This March, Network Rail Wales and Borders formally submitted the full business case for the South Wales Relief Line Upgrade (SWRLU) - a key infrastructure project designed to increase the speed and performance of relief lines and unlock the capacity needed for future passenger services. 

The upgrades will play a vital role in supporting plans for new stations across the region, improving performance and unlocking better rail access for communities along the South Wales Main Line. 

The proposals, submitted to the UK Government Department for Transport, include infrastructure improvements across 27 miles of track, with refurbishment and renewal works, as well as increasing speeds on the Up and Down relief lines from 40mph to up to 100mph, where feasible. 

Subject to full business case approval, this work will allow for future increased line speeds on the relief lines that run alongside the main lines between Cardiff Central and Severn Tunnel Junction. While these lines are currently used primarily by freight services, the improvements would enable them to accommodate passenger services, without adding time to journeys, creating additional capacity and improved reliability and performance across this vital section of railway. The work will also allow freight trains to run faster, improving overall network efficiency. 

This infrastructure work is a critical step in enabling the proposed development of up to six new stations in South East Wales - including Cardiff East, Newport West, Somerton, Llanwern, Magor & Undy, as well as Cardiff Parkway - which aim to improve local connectivity and make it easier for communities to access rail travel. 

Nick Millington, route director for Network Rail Wales and Borders, said, “The South Wales Relief Line Upgrade is a vital step towards delivering better rail services for communities and businesses across South East Wales. By increasing the speed and capability of the relief lines between Cardiff and Severn Tunnel Junction, we can create the capacity needed to support new passenger services and unlock the proposed new stations along this route. 

“We’re proud to be working closely with Transport for Wales to enable improved connectivity, support sustainable travel and make it easier for people to access the railway in the future.” 

Vernon Everitt, Chair of Transport for Wales, said, "Progressing the Relief Line Upgrade is a major step in our ambition to bring new stations to South East Wales. 

"By increasing line speeds, we unlock the capacity needed to make those stations a reality and open up new regional and cross-border services for communities at Cardiff East, Newport West, Somerton, Llanwern, and Magor and Undy.  

"We're delighted to be working alongside Network Rail to make this vision a reality." 

Project context and future plans

The SWRLU scheme forms part of a wider programme of investment in the Wales and Borders railway and builds on the UK Government’s recent commitment to progressing rail improvements in the region. 

This commitment includes the proposed ‘Burns stations’, recommended through Lord Burns’ review into reducing congestion on the M4. The review identified the opportunity for new stations between Cardiff and Severn Tunnel Junction to improve connectivity across South East Wales and provide a more sustainable alternative to car travel for local communities and businesses. 

Both Network Rail and Transport for Wales are working together to continue the development of this scheme and its business case, focusing in the next year on site surveys and design work as the programme progresses towards the next stages of approval. 

Network Rail will lead the delivery of the rail infrastructure upgrades, including track, signalling and associated works, while Transport for Wales will continue progressing plans for the new stations integrated transport interchanges, and we will work collaboratively on the new station proposals. 

Subject to approval of the overall business case, the programme will continue to progress through design and development stages before moving towards delivery.