Essential upgrade work will begin this weekend inside one of the world’s oldest railway tunnels, located between Rochdale and Hebden Bridge.
Network Rail is replacing track through the 180-year-old Summit Tunnel on the Calder Valley line for nine days from Saturday 23 October as part of a £2M Great North Rail Project investment.
It was built between 1838 and 1841 as part of the Manchester and Leeds railway.
The essential work requires the full closure of the tracks.
Network Rail’s North West head of performance and customer relationship Karen Hornby said: “We appreciate passengers' patience while we carry out these vital improvements to Summit Tunnel as part of the Great North Rail Project. The work will mean fewer train delays on the Calder valley line and make tracks inside the Victorian-built structure fit for the 21st century.
“However, replacing track like this means we have no choice but to close the line for old sections to be ripped up and replaced with new. I’d urge anyone planning to travel over the nine-day railway closure to check National Rail Enquiries to they know exactly what to expect from their journeys.”
Northern regional director Chris Jackson said the work will provide "an even more reliable railway".
"We are sorry for any disruption during the improvements and our customers can be assured that both Northern and Network Rail will do everything possible to minimise the impact of the work and deliver alternatives that keep people on the move," he said.
Network Rail is also working in partnership with the Environment Agency to upgrade a culvert beneath the railway lines in Littleborough as part of a wider flood defence project in the area.
Environment Agency senior flood risk advisor Nick Pearson said: “Working in partnership with Network Rail as part of the proposed £56M Rochdale and Littleborough Flood Risk Management Scheme will make a huge difference to rail passengers, residents and the local economy.
“This project, one of the biggest flood alleviation schemes in the north of England, will play a crucial role in better protecting the community from the risk of flooding and we are pleased to see it progress.”