South Wales electrification

Work to electrify the South Wales Mainline – an important rail route linking major towns and cities – is well underway.

We are electrifying the line between London and Cardiff – a major part of our Railway Upgrade Plan. This will result in the introduction of bi-mode trains – trains that can run on electric and diesel – providing extra seats and faster services for thousands of passengers and a quieter and greener environment for lineside neighbours.

The South Wales Mainline runs from the Severn Tunnel in Monmouthshire, through Newport, Cardiff, Bridgend, Port Talbot, Neath and Swansea.

Severn Tunnel upgrade

We’ve carried out significant work on the Severn Tunnel to prepare it for when the South Wales Mainline is electrified.


Our work in Cardiff continues to progress. A number of bridges in Cardiff are currently being reconstructed as they are too low to accommodate the overhead line equipment which will power the new trains. Work in Cardiff began in 2015 and will continue until late 2018.

Splott Road Bridge

We are currently working to reconstruct Splott Road Bridge in Splott. For more information on our work to this bridge, please view our Splott Road Bridge FAQs document.

From 13 August until 4 September 2017 Splott Road Bridge will be closed to all traffic to allow us to demolish and reconstruct the eastern side of the bridge. There will be no pedestrian access over the bridge between;

20.00hrs on 19 August – 11.00hrs on 20 August 2017

07.00hrs on 22 August – 19.00hrs on 22 August 2017

07.00hrs on 23 August – 00.01hrs on 25 August 2017

23.00hrs on 2 September – 16.00hrs on 3 September 2017

During these times there will be a minibus service, with wheelchair access, available to transport members of the public from one side to the other.

The second phase of the reconstruction will commence in early 2018.

Adamsdown Footbridge

The footbridge is currently too low however it does not require reconstruction. The footbridge will be jacked in order to raise it to the appropriate clearance level.

The footbridge is closed from 22.00hrs on Saturdays until 07.00hrs on Sunday throughout August 2017. The footbridge will also be completely closed during August Bank Holiday 2017.

Mardy Road Bridge

This bridge is currently under reconstruction, with the demolition of the bridge expected in October 2017. Mardy Road Bridge closed to all traffic in March and will reopen in Summer 2018. Please click here for more information. 

Mardy Road Bridge FAQS

Newport station

To electrify the South Wales Mainline, we’ve been carrying out essential work on the platforms at Newport station throughout 2016, and this will continue into early 2017.

Platforms will remain open, but bridges on the railway nearby will also need to be rebuilt to accommodate the overhead lines that power electric trains, and this will require the temporary closures of roads and footpaths.

Ongoing work includes:

  • preparing the platforms and canopies for masts and overhead electric wires
  • removing the redundant footbridge over Christmas 2016
  • Bridge Street is due to reopen in December 2016
  • upcoming work to the Newport Tunnels, west of the station, in 2017
  • jacking and raising Tunnel Terrace footbridge in 2017 once Bridge Street has reopened
  • working on the two closed bridges in Marshfield (Hawse Lane and Heol Las) until 2018, when they are due to reopen
  • tiling work through Newport and along the South Wales Mainline until 2018.

See the bridge works we’re carrying out around Newport (PDF)

Please check National Rail Enquiries before you travel, for changes to night-time and early-morning train services.


As part of our plan to electrify the South Wales Mainline, a number of bridges in Monmouthshire will need to be rebuilt as they are too low to accommodate the overhead lines that power the trains. We began work at the eastern end of the South Wales Mainline, in Monmouthshire, in spring 2015.

See the bridge works we’re carrying out in Monmouthshire (PDF)