There will be severe disruption to train services between London and Gatwick Airport, Brighton, Littlehampton and Eastbourne over the weekend of Saturday 20 and Sunday 21 January.

The disruption is because Network Rail engineers will be renewing 1,500m of track, including the sleepers and ballast, and refurbishing three sets on the Brighton Main Line between Gatwick Airport and Purley.

Journeys will take considerably longer than normal, so plenty of additional time should be allowed for using a train to Gatwick Airport to catch a flight.

There will be no through trains on the main line between London and Gatwick, two trains per hour between Three Bridges and Brighton, and services from Littlehampton and Eastbourne towards London will terminate at Three Bridges where a replacement bus service will run to East Grinstead to connect with trains to London.

Between London and Gatwick two trains per hour will run between London Victoria and Gatwick Airport via Horsham which will take about 80 minutes, or travel by train from London Bridge to East Grinstead where a special replacement bus service will operate to and from Gatwick Airport.

There will be very few replacement buses operating to or from intermediate stations between Gatwick Airport and East Croydon.

Lucy McAuliffe, Network Rail’s Sussex route director, said: “We’re really pleased to see further investment being made in improving the reliability of the Brighton Main Line, a key commuter route that needs constant work to keep it running.

“Over the weekend of the 20 and 21 January, we’ll be taking all lines out of use between Gatwick and Purley to tackle a host of maintenance work, including renewing track at a major railway junction near Coulsdon.

“We understand it’s frustrating for passengers in the short term when we divert trains, but this is a rare chance for us to undertake major work on such a busy section of track that will help us run a more reliable railway in the long term.

“I really appreciate everyone’s patience and urge passengers using Southern, Thameslink and Gatwick Express services to plan ahead and check before they travel over the weekend.

Jenny Saunders, customer services director for Southern and Thameslink, said: “We’re sorry for the inconvenience to passengers during Network Rail’s essential maintenance to keep this busy part of the network in good shape. While we’ve arranged alternatives to help our customers get where they need to be, several routes are affected and many journeys will take considerably longer than normal, so please check your routes and times on a journey planner, or the Southern or Thameslink website, well ahead of your journey, and allow plenty of extra time.”

Alterations to Southern Railway services planned for Saturday, 20 and Sunday, 21 January can be found here, and changes to Thameslink services can be found here.

Summary of changes:

Gatwick Express

• Gatwick Express services will not run.

Southern

• No trains between Purley and Gatwick Airport or Reigate.
• A direct service will run between London Victoria and Gatwick Airport via Horsham, calling at Clapham Junction, Horsham and Three Bridges. Journeys between London Victoria and Gatwick Airport will take around 80 minutes.
• A reduced number of trains will run between London Victoria and East Croydon.
• Trains between Littlehampton, Eastbourne, Hastings, Ore and London will start/terminate at Three Bridges.
• No trains will run between Redhill and Tonbridge.
• Extra trains will run between London Bridge and East Grinstead.
• Passengers using the Arun Valley line from Bognor Regis or Portsmouth should change at Horsham onto the diverted London service.

Thameslink

• No trains between East Croydon and Gatwick Airport and no through services from London to the airport.
• A limited service will run between Brighton and Three Bridges, and between Horsham and Gatwick Airport.

Buses will replace trains between:

• East Grinstead and Gatwick Airport
• East Grinstead and Three Bridges
• Gatwick Airport and Redhill
• Redhill and Tonbridge
• Redhill and Reigate
• Redhill and East Croydon
• Dorking and Horsham (Saturday only)