Passengers intending to use some rail services in South Yorkshire, East Yorkshire and Lincolnshire are being warned to expect delays.
Vandalism of railway equipment at Conisbrough means fewer trains are currently able to run between Sheffield and Doncaster, meaning delays, changes and cancellations are expected.
Services between Sheffield and Adwick/Hull/Bridlington and between Lincoln Central and Doncaster are affected.
TransPennine Express services between Manchester Airport and Cleethorpes are also affected.
Problems are currently expected until at least 10:00, according to National Rail Enquiries.