30/10/2026
From GWR
We wanted to make you aware of upcoming railway upgrade work in the Thames Valley which will affect all journeys to and from London Paddington in November and over the Christmas period.
Dolphin Junction in Slough carries more than 400 trains and 10,000 passengers every day, making it critical to the railway network in the Thames Valley and beyond. On Saturday 28 and Sunday 29 November, and between Sunday 27 December and Sunday 3 January, we’ll be replacing the eastern side of the junction, installing track in a new layout using state-of-the-art components to support more reliable journeys to and from London Paddington.
During these periods, we’ll be keeping people moving, but passengers should plan ahead, allow extra time and check journey planners before travelling. When London Paddington is unavailable, passengers will still be able to get where they need to go, with alternative routes via London Euston, London Waterloo and London Marylebone, alongside TfL services across London and the Thames Valley. However, we are encouraging all passengers to plan ahead, allow extra time and check journey planners before travelling. Full details are available at GWR.com/Upgrade.
The majority of GWR services will start and finish at Reading, with long-distance services from South Wales and the West of England (Bristol area) diverted to London Euston. GWR’s Thames Valley branch line services will continue to operate, with the exception of the Greenford branch. Connections to central London will also be available via SWR services to London Waterloo and Chiltern Railways services to London Marylebone respectively.
Elizabeth line and Heathrow Express services are also affected, starting again from New Year’s Eve. GWR services to and from London Paddington will resume as normal from Monday 4 January.
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.
Given the scale of the work, we would appreciate any help you can give to share this information with your networks, particularly the alternative routes available. Further information can be found at GWR.com/Upgrade and nationalrail.co.uk/dolphinjunction.
Upgrades to Dolphin Junction near Slough will affect journeys to and from London Paddington on 28 and 29 November, and at Christmas 2026
