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.

Upcoming Piling Work

Saturday 29 September - Friday 17 November

  • Between Rogiet and Llandevenny (Monmouthshire County Council)
  • Between Liswerry and Maindee (Newport City Council)
  • Between Newport Station and Duffryn (Newport City Council)
  • Between Rumney and Cardiff Central Station (Cardiff City Council)

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 have been working to reconstruct Splott Road bridge as part of our work to electrify the Mainline, throughout 2017 and early 2018. To electrify the railway we needed to ensure that we had sufficient clearance levels for overhead line equipment (OLE). Splott Road bridge was too low to accommodate the new OLE. At 119 years old, it was also nearing the end of its working life, so we have had to demolish and rebuild it. The demolition and rebuilding of Splott Road bridge was undertaken in two parts, in an unusual feat of engineering. One half of the bridge was demolished and rebuilt, and the other half a year later. We wanted to keep the road open as long as possible, so apart from one short full closure in 2017, and one in early 2018, the road has been open to traffic while works have been taking place. Over three weeks in February 2018, we closed the road to traffic for the essential second half of Splott Road bridge works. We had to demolish the western side of the bridge this year, and build a new half to match the eastern side that we constructed last year. The road was reopened to traffic and pedestrians early in the morning on 27 February as planned. The western half of the bridge was successfully reconstructed during this period, which included a 50 hour closure of the railway over a weekend. During this time, the four span bridge was removed, and replaced with new beams to create a new raised three span bridge to cater for the running of Intercity Express Trains. We will now complete the bridge works including installing parapets, utilities works and preparing the road for full re-opening later this year.

Image 1: Contractors working on the demolition of the western half of Splott Road bridge

Image 2: Crane in place ready for the demolition of Splott Road bridge

Image 3: Digger next to the railway track on the site of the demolished bridge

Newport station

To electrify the South Wales Mainline, we have been carrying out essential work on the platforms at Newport station since 2016, and this is expected to continue throughout 2018. Passengers are reminded that platforms will remain open during our work.

Ongoing station work includes:

  • preparing the platforms and canopies for posts and overhead electric wires (OLE)
  • removal of the redundant footbridge over the platforms
  • 75% of the canopy reductions and 90% of OLE foundations have been completed. The remaining canopy reductions and OLD foundations will be completed throughout 2018.


  • upcoming work to the Newport Tunnels, west of the station, in 2018
  • Tunnel Terrace footbridge reopened on 28 February 2018
  • Hawse Lane and Green Lane road bridges are due to reopen in early 2018
  • piling and post installation for OLE will continue through Newport and along the South Wales Mainline throughout 2018.


We have now completed our work to the bridges in Monmouthshire which required reconstruction. Our piling work and post installation work will continue through Monmouthshire in 2018.

The new Tunnel Terrace footbridge
Tunnel Terrace footbridge was reopened in February 2018