There are delays on Sydney trains today with services around the city running up to 20 minutes late.
It is understood that the cause of the delays stems from a train needing mechanical repairs at Central station earlier.
This has altered the stopping patterns of some services .
Commuters are advised to allow extra travel time and to listen to announcements.
Affected services include the T3 Bankstown Line, T2 Inner West and Leppington Line, T8 Airport Line and T1 North Shore Northern & Western Line.