Network Rail is undertaking a £27.8 million engineering upgrade at Dolphin Junction in Slough that will cause significant disruption to rail services from November 28, 2026, through January 3, 2027. The works target one of the busiest routes on the Great Western Main Line, used daily by over 400 trains and 100,000 passengers.
November 28-29 Service Changes
The first phase of the upgrade will take place over the weekend of November 28-29. During this time, Great Western Railway (GWR) will suspend all services to and from London Paddington. The Elizabeth line west of Paddington will run a reduced service between Reading and Maidenhead only,
with no operation between Maidenhead and Abbey Wood or between Heathrow Airport and Shenfield. Heathrow Express services to and from the airport will be completely halted over the weekend.
Replacement buses will serve affected segments including between Ealing Broadway and Slough, Slough and Burnham, and Taplow and Maidenhead. GWR branch line services to Windsor & Eton Central, Maidenhead to Marlow, and Twyford to Henley-on-Thames will remain operational.
South Western Railway (SWR) will operate a special fast direct GWR train service linking Reading and Guildford, facilitating connections with SWR trains to London Waterloo. Chiltern Railways services between London Marylebone and High
Wycombe, Oxford, and Banbury will continue as usual.
Christmas and New Year Rail Disruptions
No national rail passenger services will operate on Christmas Day, December 25, with most routes also closed on Boxing Day, December 26. From December 27 to 30, Elizabeth line services are suspended between Paddington and Reading; GWR services between Paddington and Slough will also be suspended.
Passengers can travel via the London Underground from Paddington to Ealing Broadway, where replacement buses will run onward to Slough. GWR connections to and from Reading will be available at Slough. Elizabeth line and Heathrow Express trains will not serve Heathrow Airport between December 27 and
30, with services resuming on December 31. During this period, the Piccadilly line will provide the sole rail link to Heathrow Airport.
SWR will maintain train services from London Waterloo to Reading and Windsor & Eton Riverside throughout the Christmas period. Services may be exceptionally busy on December 28 due to an international rugby match at Twickenham Stadium.
Between December 31 and January 3, Elizabeth line trains will not run between Hayes & Harlington and Reading, with replacement buses operating on this stretch. Passengers can interchange at Slough or Maidenhead for connections to GWR services. Branch line services between Slough
and Windsor & Eton Central, Maidenhead and Marlow, and Twyford and Henley-on-Thames will continue to operate.
Passenger Advice and Alternative Connections
Passengers traveling to or from Heathrow Airport during disruption periods must rely on alternative routes such as the Piccadilly line when Elizabeth line and Heathrow Express services are suspended. Travelers should allow additional time for journeys and confirm service details ahead of travel dates.
Transport for London (TfL) staff will be available at affected stations including Iver to assist passengers. Passengers are advised to change trains at terminals including Maidenhead, Slough, Boston Manor, and Ealing Broadway for onward connections during service suspensions.
Network Rail’s Upgrade Objectives
Ross Mahoney,
Network Rail’s Great Western route project director, said the upgrade replaces ageing infrastructure with modern technology, improving track layout and train flow to reduce congestion and increase reliability. The engineering work includes replacing the eastern part of Dolphin Junction, installing new track, upgrading overhead lines, and deep cleaning London Paddington station.
Mahoney stated: “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.” He added that despite short-term disruptions, the improvements will lead to smoother, more reliable
journeys in the long term.
Timing and Context of Works
The engineering works are scheduled to take place during the quieter Christmas and holiday periods to minimize passenger impact. The project is part of ongoing efforts to modernize and maintain UK rail infrastructure on a key route serving London Paddington, Heathrow Airport, and beyond.
Following the main upgrade phases, further work is planned to affect Paddington services on January 10, 2027. Updated journey planners are available at GWR.com/Upgrade and nationalrail.co.uk/dolphinjunction.
