The main railway line between Taunton and Tiverton is to be closed for three weeks in the new year for repairs. It means passengers will have to travel by coach while the work takes place.
Network Rail is to spend £15 million upgrading the line and repairing Whiteball tunnel, which was built in Victorian times. It says it will also carry out flood prevention work.
About three miles of track is to be upgraded so that trains can travel at the higher speed of 80mph.
Replacement coach services are planned along with extra car parking. The closure will take place between 18 January and 10 February.
Network Rail says the work is necessary: