The West Coast Main Line, which connects the two countries and extends to Birmingham, Manchester, Liverpool, Edinburgh, and Glasgow will undergo works to renew more than 150 miles of overhead wires installed in the 1970s.
Engineers will also renew an estimated 140 miles of track and 2000 signal units.
However, The Times has reported Network Rail will close sections of the essential line for two week blocks every year for up to 10 years.
According to transport planning documents and industry insiders, the line will be shut for three blocks of two weeks in 2026, 2027 and 2028.
READ MORE: BBC host’s plans to develop Loch Lomond island given green light
Another set of works are reportedly expected up until 2035, but this has not been scheduled yet.
Stations affected include Warrington Bank Quay, Wigan, Preston, Lancaster, Oxenholme, Penrith, and Carlisle.
Avanti West Coast, which operates services between London and Scotland, has said it is too early to say the full impact on its timetable.
When asked about the reported plans, Chris Coleman, Network Rail industry programme director for the north, said: “Trilink is an industry-wide programme bringing digital signalling to the West Coast Main Line (north), as well as renewing track and overhead line equipment that are reaching the end of their life.
“Disruptive access will be required to deliver this work, which we will consult and agree with the wider industry over the coming months. The programme is at a very early stage of development and work to refine the delivery programme and confirm the costs is underway.”
Speaking at a Rail Freight Group convention in Scotland in May 2024, David Gordon, principal programme sponsor of Trilink, said: “The programme is 140 miles long, from Warrington all the way through to the Scottish border and slightly beyond.”
“What we will be doing is renewing life-expired infrastructure,” he said, reported Rail Freight. “We have identified that there is actually an opportunity to bring in a substantial degree of efficiency with regard to the infrastructure that we retain and eventually to the timetable offering we can give to the passenger and freight operating companies.”
Passengers are expected to switch from trains to planes between Scotland and London amid the delays, it has been reported.
Stuart Patrick, chief executive of Glasgow Chamber of Commerce, said: “This is a demonstration of how bad we are at long-term investment in infrastructure — when you get to the point when you have to replace things that are 50 years old.”