Engineers are again working overnight to try and get metro trains running between two stations on the Sunderland to Newcastle Metro line.
Trains between Brockley Whinns and Pelaw have been replaced by buses since Tuesday because of a fault with an underground power cable.
The work is the responsibility of Network Rail and teams are due to be working tonight to replace it.
The damaged section was found on Wednesday night but cannot be repaired and the whole cable has to be replaced.
A spokeswoman for Network Rail said engineers were expected to work on rectifying the issue during the night.