Trains between Machynlleth and Pwllheli in North Wales will be disrupted for 13 weeks from Saturday, 2 September until Friday, 1 December when Network Rail engineers will complete the final stage in the multi-million-pound refurbishment of Barmouth Viaduct.

The viaduct is Grade II* listed so the metallic parts of the bridge will be replaced and restored on a like-for-like basis to maintain the integrity of the 154-year-old structure.

Among the work to be carried out is the removal of two old metallic spans, each weighing 160 tonnes. Because of the complexities and challenges of the task, a trial removal was recently carried out in readiness for the real thing this Autumn.

To carry out the trial, a purpose-built mock railway track was laid just outside Barmouth, and 15 engineers tested a cantilever and jack system that will be used when the real span is lifted onto the viaduct. Because of the weight of the span, 16 jacks of from 20 to 100 tonnes capacity were required, as well as six rail trailers to carry out the technical move.

Network Rail and contractors Alun Griffiths are now preparing for the final move when two metallic spans will be lifted onto the viaduct and carried by rail to the northern end of the bridge. This will take two days, and once it is positioned, the old span will be removed, piece by piece, onto a pontoon in the Mawddach Estuary.

As well as work on the viaduct, 130 metres of track will be relaid on the northern end of the viaduct and track will be upgraded at Dovey Junction.

The work will require closure of the bridge for two consecutive periods:

• Saturday, 2 September to Friday, 24 November, when the metal sections of the bridge will be refurbished.
• Saturday 25 November to Saturday 2/Sunday 3 December, when the track will be relaid.

During the closure, Transport for Wales will operate a combination of bus replacements and train services along the Cambrian Coast line, and passengers should check at tfw.wales for travel advice.

To allow engineers to have full access to the viaduct during the work, the footpath across the viaduct will be closed from today, Thursday, 31 August until Friday 24 November.

To minimise disruption to local residents, the work has been carried out in stages, including for three months at the end of 2021 and remaining open during the October half term and Christmas period last year.

Nick Millington, route director for Network Rail Wales & Borders, said: “We’re delighted to begin the final, and most visually exciting, stage of our multi-million-pound restoration of Barmouth Viaduct, with our focus now on restoring the metallic elements on a like-for-like basis.

“A huge part of this phase of work has been planning the replacement of the 160-tonne metal spans, a feat of engineering that has involved months of preparation to develop a unique delivery and installation system. We have also worked closely with our partners at Natural Resources Wales to ensure we’re doing everything we can to protect the delicate ecology of the Mawddach Estuary.

“As the railway and footpath across the viaduct will need to be closed for the duration of our work to ensure everyone’s safety, I would like to thank everyone for their patience as we carry out this vital work, which will protect this important and iconic rail link for years to come.”

Colin Lea, Planning and Performance Director at Transport for Wales, said: “This investment in one of the most iconic railway bridges in the world by our partners Network Rail will secure the future of the Cambrian Coast line for decades to come.

“This vital improvement work to replace the metallic spans does mean train services will need to be replaced with road transport until early December, and customers should check journey times before they travel.”