William Brandon, Network Rail’s project manager, said: “This is a vital project which will improve journeys for passengers for decades to come.
He added: “We appreciate passengers’ patience while this work is completed, and I would urge anyone planning to travel in this period to check National Rail Enquiries in advance.”
Chris Liptrot, operations director at Avanti West Coast, said it would operate an amended timetable.
“Some journeys between the north-west, Carlisle, and Scotland will involve changes onto a shuttle service as well as rail replacement buses,” he added.
“We strongly advise customers to plan ahead and check their journey before travelling.”