Metro users faced rush-hour delays after a points failure led to trains being halted on a Wearside route.
The service between Park Lane and South Hylton was suspended after a points failure on the track.
Network Rail engineers are en route to repair the fault, which occurred shortly after 5pm today.
A Metro spokesman said: "Network Rail engineers are en route and we'll update with more info soon.
"We apologise for any inconvenience."
Trains were back up and running at about 6pm today, with delays of up to 15 minutes.