Services on the Mandurah line are currently cancelled from Rockingham to Mandurah due to a technical issue.
Trains will continue to run from Mandurah to Rockingham; however these services will be delayed.
Buses are being organised to run from Rockingham Station to Mandurah Station.
The Joondalup Line is also expected to experience delays.
A Transperth spokesperson asked passengers to allow extra travelling time and be aware that delayed trains may not connect with timetabled bus and train services.
They said they hope to have the disruption fixed as soon as possible and thank passengers for their patience.