Signalling problems at Eaglescliffe causing delays of up to 30 minutes on First Transpennine Express between Northallerton and Middlesbrough.
Also causing delays of up to 30 minutes on Grand Central Trains between Northallerton and Sunderland, and on Northern Rail between Darlington and Saltburn.
There is currently no estimate for when a normal service will resume.
More top news
Highways England wants to hear the views of local people about their proposals. The public have until January 6, 2017 to respond.
With a little help from Santa, the 5-year-old turned on Durham County Hall's christmas lights
Looking back on a turbulent year: Paul Brand and guests discuss Brexit, Trump - and hopes for 2017.