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.
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The study was carried out in conjunction with researchers at Newcastle University.