Media centre

Wednesday 14 Oct 2026

Passengers advised to plan ahead as £27.8m Dolphin Junction upgrade takes place to improve journeys on route to London Paddington

Region & Route:

Wales & Western: Great Western

• Passengers travelling between London Paddington and the Thames Valley are set to benefit from a £27.8 million upgrade to one of the busiest and most important junctions on the Great Western Main Line

 

• Initial closure of lines to and from London Paddington on 28 and 29 November will be followed by the main phase of work between Christmas Day and Sunday 3 January (inclusive)

 

• Customers will still be able to get to where they need to go, with alternative routes available, but journeys may take longer than usual.

Network Rail is upgrading Dolphin Junction in Slough, replacing ageing points, improving the track layout and upgrading overhead line equipment to deliver more reliable journeys for the millions of people who travel through the area each year. New track will also be installed, alongside a deep clean of Paddington station.

To carry out the work, there will be an initial closure of the lines to and from London Paddington on Saturday 28 and Sunday 29 November, followed by the main phase of work between Christmas and New Year as part of a wider programme of engineering upgrades across the Thames Valley.

To keep customers moving, GWR services will start and finish at Reading, or will operate via a diversionary route to London Euston. Connections via Waterloo and Marylebone are also available. Elizabeth Line and Heathrow Express customers are also advised to check before travelling.

Elizabeth Line and Heathrow Express services will begin returning from New Year's Eve, with GWR services resuming access to Paddington from Monday 4 January.

Ross Mahoney, project director for Network Rail’s Great Western route, said:

"Dolphin Junction is one of the busiest and most important parts of the Great Western Main Line, carrying thousands of passengers every day between London, the Thames Valley, the South West and Wales.

"This investment will replace ageing equipment with modern technology and improve the track layout, helping trains move through the junction more smoothly and efficiently. This will mean less congestion and more reliable journeys for passengers across the route.

"We've worked closely with train operators to keep people moving throughout these closures, but there will be changes to services while the work is carried out. Passengers travelling over the weekend of 28 and 29 November and during the Christmas and New Year period should plan ahead and check before they travel."

"We know this work will cause disruption in the short term, and we'd like to thank passengers and freight customers for their patience. Once complete, these upgrades will help create a more dependable railway, supporting better performance and smoother journeys for years to come."

GWR Operations Director Richard Rowland said:

“Our priority over Christmas is making sure customers can still get where they need to go.

"Although trains won’t run into London Paddington for a short period, we’ve worked closely with Network Rail and our industry partners to put alternative routes in place, including GWR services from London Euston, and connections via Waterloo and Marylebone.

“This does however mean some journeys may take longer than usual; so we ask anyone travelling to or from London during this period to plan ahead and check before they travel. Our teams will be on hand to help customers along the way. Once complete, the upgrade will enable trains to move through the junction more smoothly, helping to reduce congestion and improve performance across the route.”

Every day, around 400 passenger trains carrying more than 100,000 passengers pass through the junction, making it one of the busiest pieces of railway infrastructure on the Great Western Main Line.

The work builds on recent investment through the Thames Valley Performance Improvement Programme, which has already delivered performance improvements across the Great Western route. The Dolphin Junction upgrade is the next step in creating a more reliable railway between London Paddington, the Thames Valley, the South West and Wales.

The November weekend closure will help engineers complete preparatory work ahead of the main Christmas and New Year programme, reducing overall disruption and helping the scheme to be delivered as efficiently as possible.

Journey planners are now up to date with travel information through to 4 January, allowing passengers to plan their Christmas and New Year journeys in advance.

Further information on GWR services impacted by this work can be found at: Planned Engineering Work and Disruption | Great Western Railway

For service information for all rail operators, visit Dolphin Junction upgrade 2026 | National Rail.

ENDS