There'll be no train services on the North Wales Coast line for four weeks in the New Year, because of major engineering works.

Network Rail says over £25 million will be spent on a "once-in-a-generation" investment programme, which will see track work being carried out on track and other infrastructure across the region.

From Saturday 9th January, the line will be closed between Chester and Holyhead, while during the fourth week, the closure will be reduced to between Llandudno Junction and Holyhead until Saturday 6th February.

The initial closure will also affect the Conwy Valley line and services between Llandudno Junction and Holyhead.

Network Rail says it's been working with engineering works to reduce the closure on services east of Llandudno Junction but insists the closure must take place to allow work to be carried out "safely and efficiently".

January has been chosen for the closure as it is traditionally a quieter period for tourism in North Wales.

Emma Osborn, passenger strategy director at Network Rail Wales and Borders, said: "This is a once-in-a-generation investment in the North Wales Coast railway and a huge opportunity to renew and improve infrastructure right across this vital route."

"Investment on this scale inevitably means some temporary disruption while we carry out the work, and we recognise closing the railway will have an impact on customers and communities."

"But by bringing years’ worth of complex work together into one intensive programme, we can deliver it more safely and efficiently, while avoiding a prolonged series of disruptive weekend closures."

"The long-term benefits for passengers and freight customers will far outweigh this temporary disruption, with a safer, more reliable railway that is better equipped to support the increased number of services now running across North Wales."

"We’re working closely with Transport for Wales and Avanti West Coast to keep passengers moving and we thank everyone in advance for their patience while we deliver this major investment."

Locally, plans for the work include improving the track and drainage at Bodorgan Tunnel, replacing infrastructure dating back to 1972 in an effort to reduce the risk of flooding.

Work will also be carried out on four level crossings east at Bangor along with track and points improvements at Holyhead.

Other work will include:

• Renewing track through the Grade I-listed Conwy Tubular Railway Bridge, where the existing track dates back to 1978.
• Track renewal and ground improvements at Penmaenbach, where sections of track were last renewed in 1986.
• Platform improvements at Llandudno Junction.
• Around £1.4m of vegetation management across nine locations, alongside extensive maintenance throughout the route.
• Two new fully accessible footbridges at Prestatyn and Abergele, supporting the closure of four high-risk level crossings.

The work will be delivered by rail using 22 engineering trains and specialist on-track machinery, bringing in more than 3,000 concrete sleepers and 9,000 tonnes of ballast, while around 9,800 tonnes of spoil will be removed for recycling and reuse on future railway projects.

Replacement bus services will run throughout the closure with confirmation expected later in the autumn.

In May, new timetables were rolled out which saw Transport for Wales (TfW) services increase by 50%, with Holyhead now served by trains to and from Manchester Airport.

Network Rail says with more trains running, the closure will allow additional maintenance to be carried out and reduce the need for repeated weekend closures and further disruption for passengers, residents and businesses in the months and years ahead.

Colin Lea, planning director for Transport for Wales, said: "As we see passenger numbers and service frequencies across North Wales grow, working alongside our partners at Network Rail is essential to ensure our infrastructure can support that demand."

"Essential track maintenance, tunnel drainage, and new accessible footbridges will help deliver a more reliable service and better stations for the communities we serve."

"We know railway closures are disruptive to our passengers, and we appreciate their patience. We remain committed to keeping North Wales moving throughout January, and full details on alternative travel arrangements will be shared this Autumn."

Chris Liptrot, operations director at Avanti West Coast, added: "While Network Rail carries out these improvements, there will be changes to services on our North Wales route."

"We are working closely with Network Rail and our industry partners to ensure customers are kept informed about how their journeys may be affected."

"Once the timetable has been confirmed, customers planning to travel during this period are advised to check the Avanti West Coast and National Rail Enquiries websites for the latest travel information."