Sydney trains returning to normal after lengthy delays

Commuters faced lengthy delays on Sydney's train system tonight following a series of mechanical issues.

Trains are now running back on schedule across the network after urgent signal repairs at Ashfield and a mechanical issue with a train at Bondi Junction.

"Services are now returning to normal following urgent signal equipment repairs at Ashfield earlier. Thank you for your patience," Sydney Trains tweeted.

Commuters had earlier been warned to allow extra travel time and buses had replaced a number of lines.