Rail passengers in the Central trains area are being warned to expect serious disruption over the next 10 days.
Major engineering works will affect services between Nottingham, Leicester and Peterborough.
Buses are replacing services between Nottingham, Grantham, Peterborough, Ely, Thetford and Norwich.
The work is now underway and is due to go on until 1 June. All passengers are advised to check journey details and allow extra time for their trips.
For those wanting to travel between Nottingham and Cambridge, an express bus service has been laid on.
Buses will also replace services between Birmingham New Street and Stansted Airport.