Thousands of commuters in South Tyneside faced delays on the Tyne and Wear Metro after thieves took off with cable.
Police have issued an appeal for information.
It happened in the South Drive area of Hebburn during Tuesday night.
Thieves made away with a substantial amount of cable, causing a fault in the system.
As a result, significant travel disruption has been caused across South Tyneside with trains between Pelaw and South Shields cancelled as engineers carry out repairs.
Enquiries are ongoing and police are now urging anybody with information about the theft to come forward and help with the investigation.
Sergeant Tim Hand, of Northumbria Police’s Metro Unit, said:
Nexus are offering a £1,000 cash reward for information leading to the conviction of the people or persons responsible for the cable theft.