Trains to and from Barnstaple will be halted for two weeks later this month.
Network Rail will be upgrading the Tarka Line track between Barnstaple and Crediton from Saturday, October 26 until Friday, November 8.
The work is being carried out in order to provide a smoother and more comfortable journey, and to improve reliability on the route.
No trains will run in either direction between Crediton and Barnstaple, with a rail replacement bus service put in place.
Great Western Railway has issued travel advice to passengers urging them to check the times of buses before they travel as bus times will be different to train times.
They are also advised to allow more time for their journeys, with the bus route taking longer than the usual train.
As well as the replacement bus service, Stagecoach South West buses will accept valid rail tickets on its 5B and 155 services from Barnstaple to Exeter.
Travel is also permitted on the 5A, 5C, 6 and 6A services.