Passengers are facing rail chaos this Christmas as train bosses embark on one of the biggest investments ever on the London to Brighton mainline.

The £80 million works will see more than 150 engineers take to the line between Christmas Day and January 2.

The three main focus points will be at London Victoria, Gatwick and the junction between Redhill and Purley.

Train bosses are warning of disruption throughout the period and have advised passengers to check for the latest information before they travel.

Tim Robinson, Network Rail’s route managing director, said: “These three upgrades have been carefully planned to take place at the same time over Christmas and the New Year to keep disruption to a minimum.

“If we had carried out the work at weekends, there would have been up to 15 months of weekend disruption, affecting many more passengers for a much longer amount of time.”

Work at Gatwick will see a new platform, nearly a mile of track, a 50m long footbridge and signalling system installed.

Disruption will see the Gatwick Express cancelled between December 25 and January 1 while Southern services between London Bridge and Gatwick will stop at East Grinstead, with buses continuing the rest of the way to the airport.

First Capital Connect services will also avoid the airport during the period, adding an extra 70 to 90 minutes to passengers’ journeys.

There will also be new signalling installed between London Victoria and Battersea. Work at 70 locations will see 12 signals put up followed by separate tests for each.

A major junction replacement between Redhill and Purley will see workers along the route across the week followed by 48 hours of testing.

David Scorey, Southern’s performance director, said: “This vital work will improve the performance of our railway and so ultimately benefit passengers.

“But we appreciate this will be disruptive for those travelling at Christmas and so we are giving as much warning as possible to allow people to plan their journeys.

“Our advice is travel, but do check before you travel and allow extra time for your journey.”

Keith Jipps, First Capital Connect’s customer service director, said: “Our passengers must allow 70 to 90 minutes longer to complete their journey during this work, which is especially important if catching a flight.”

For up-to-minute information visit www.nationalrail.co.uk.