A four-day railway closure affecting trains in Sussex starts tomorrow.
There will be no trains west of Eastbourne via Lewes as far as Brighton, Seaford and Haywards Heath, from Thursday (November 28), to Sunday (December 1).
The closure is due to a major upgrade of the line between Lewes and Seaford.
It is the final phase of work on a £25m project to upgrade the old signalling system on the line with modern, more reliable technology.
Dan Athol, programme director for Network Rail, said: “This is a much-needed upgrade to some of the oldest signalling in the country, with new state-of-the-art equipment providing passengers with more reliable journeys for many years to come.
“I’d like to thank people for their patience while we complete the upgrade in November.
“There is never a good time to close the railway and the alternatives would have meant impacting services over several weekends in the summer.
“Following our recent discussions with local stakeholders, we know this would have been unacceptable to the leisure and tourism industry here on the south coast.
“We continue to work closely with our colleagues at Southern, ensuring people are fully aware of the closures and the alternative travel options available to them.”
The upgrade will see signalling control of the Lewes, Newhaven and Seaford areas moved to Network Rail’s state-of-the-art route operating centre at Three Bridges, meaning that the signal boxes at Lewes, Newhaven Town and Newhaven Harbour will close.
The final commissioning, when the current system will be disconnected, and the new one switched on – can only be carried out with a closure of the railway.
The project also aims to reduce the impact of service disruption by allowing more trains to use the diversionary route for London-Brighton services via Lewes.
Network Rail says the improvement will give the Southern the flexibility to move three times as many passengers on the route when there is disruption on the Brighton Main Line between Brighton and Keymer Junction.
The signalling works will also support a rail link for the new aggregates facility at Newhaven Marine, helping to take hundreds of heavy goods vehicles off local roads, Network Rail said.
Track, switches and crossings at Southerham junction, where trains switch track for Lewes, Eastbourne or Seaford, have already been renewed as part of the project.
Keith Jipps, infrastructure director for Southern’s parent company Govia Thameslink Railway, said: “This major investment will improve the reliability of signalling and therefore our services for passengers travelling on one of our key Southern routes. Updated bus and train times for the closure period are now available at nationalrail.co.uk and we advise passengers to check before you travel.”