Network Rail warns of Christmas disruption as £27.8m works start

Festive rail journeys into London are set for significant disruption this year, as Network Rail begins a £27.8 million upgrade of Dolphin Junction near Slough, prompting Christmas and New Year closures on the key route to London Paddington.

Major junction upgrade targets bottleneck west of London

According to information published on Network Rail’s media centre, the £27.8 million project focuses on Dolphin Junction, a critical part of the Great Western Main Line just east of Slough. The work includes replacing life‑expired points, reconfiguring the track layout and upgrading overhead power lines used by Elizabeth line and intercity services.

Publicly available project details describe Dolphin Junction as a long‑standing bottleneck for trains running between Reading, Heathrow Airport and London Paddington. Modernising the layout is expected to allow more reliable movements through the area and reduce the risk of signal and points failures that have caused delays for years.

Network Rail’s published material frames the upgrade as part of a broader programme of investment across the Thames Valley, timed for periods when passenger numbers are lower so that fewer people are affected. However, the scale and timing of the works mean that Christmas leisure and family travel plans for many passengers will still be heavily impacted.

Rail industry coverage indicates that the Dolphin Junction scheme is one of the largest single pieces of infrastructure work planned on the Western route over this festive period, alongside other Christmas renewals and maintenance across Britain’s main lines.

Key dates: closures, diversions and reduced services

Network Rail information shows that the upgrade begins with an initial blockade of lines to and from London Paddington on Saturday 28 and Sunday 29 November 2026, when preparatory work will take place. This early phase is designed to set up the railway for the full closure that follows over Christmas.

The main phase of engineering work is scheduled between Christmas and New Year, coinciding with the annual nationwide shutdown on Christmas Day and Boxing Day. During this period all main lines between Slough and London Paddington are expected to be closed, with long‑distance and regional services diverted or curtailed.

National Rail Enquiries’ engineering pages state that Great Western Railway services which normally run into London Paddington will instead start and finish at Reading or be diverted to operate into London Euston for several days during the closure. This will increase journey times and require passengers to use alternative London terminals and Underground connections.

Published timetables indicate that Elizabeth line and Heathrow Express services are planned to return in stages around New Year’s Eve, with Great Western Railway intercity services resuming normal access to Paddington in early January once testing and handback of the upgraded infrastructure are complete.

Impact on GWR, Elizabeth line and Heathrow routes

The closure of the Paddington approach affects a wide range of services, from local commuter trains to airport links and long‑distance intercity routes. Information on the National Rail and train‑operator websites shows that Great Western Railway services between South Wales, the West Country, the Cotswolds and London will either terminate at Reading or be routed via diversionary lines into London Euston during the works.

Elizabeth line services that normally run through central London to Paddington and beyond will be altered, with reduced frequencies or revised terminating points at the western end of the route on the days when the lines between Slough and Paddington are closed. Precise service levels are being confirmed closer to the time, and passengers are being advised to check journey planners before travelling.

Heathrow Express operations are also directly affected because they rely on the same fast lines into Paddington. Public information indicates that services will be suspended on the days when Paddington is closed, with travellers advised to allow additional time and consider alternative routes to Heathrow, including the Elizabeth line where it is running or coach links from central London.

The combination of changed stopping patterns, altered London terminals and temporary bus links at some intermediate stations is expected to make journeys more complex than usual, particularly for those carrying luggage or travelling with children over the festive break.

Network‑wide festive works add to Christmas disruption

The Dolphin Junction project forms part of a wider programme of Christmas engineering works across Britain’s rail network. Network Rail’s national seasonal overview highlights parallel schemes on the East Coast Main Line around Doncaster, West Coast Main Line upgrades between Euston and Rugby, and work at key urban hubs including Birmingham New Street and routes in the North and Midlands.

These projects are intended to deliver long‑term reliability benefits, but taken together they mean that rail disruption over the Christmas and New Year period will extend well beyond the Thames Valley. Published advice from industry bodies repeatedly urges passengers to check for changes if they plan to use long‑distance routes between 24 December and the first week of January.

In previous years, rail investment programmes over Christmas have occasionally overran into working days, leading to additional short‑notice disruption. Parliamentary reports and historic service updates underline why planners now emphasise contingency and communication when large blockades are scheduled for the festive period.

Travellers connecting between different regions, or relying on onward local rail and bus services, are being encouraged to build extra time into their itineraries in case of crowding, extended interchange times or weather‑related delays on top of the planned engineering work.

Advice for festive travellers planning around the works

Publicly available guidance from Network Rail, National Rail Enquiries and individual train companies emphasises a few consistent messages for people heading to or from London over Christmas. Passengers are advised to use online journey planners before buying tickets, as timetables have been altered to reflect diversions, bus replacements and changed London terminals.

Where possible, industry information suggests considering travel on days outside the peak Christmas getaway period or avoiding connections that rely on tight interchange times. Those who must travel on affected dates are encouraged to allow significant extra time, particularly when connecting between Paddington‑diverted services at Euston and other onward routes.

Passengers with reduced mobility or heavy luggage are also advised to check in advance how diversions and replacement transport will affect step‑free access and assistance arrangements, since some temporary routes and bus interchanges may be more challenging than regular station facilities.

With the £27.8 million Dolphin Junction upgrade scheduled to continue through the heart of the festive season, rail users heading into and out of London are being told, in public notices and operator updates, to plan carefully and stay alert to late‑running or further timetable changes as the work gets under way.