Rail commuters have been caught in delays stretching as long as an hour, after a signalling issue blocked half of the available lines at Eagle Junction.
Queensland Rail discovered the issue shortly after 6.30am.
About 40 minutes later Translink warned all northern lines except Ferny Grove were experiencing delays, including the Airport, Caboolture, Doomben, Redcliffe Peninsula, Shorncliffe, and Sunshine Coast lines.
By 7.30am, Queensland Rail said the delays could be as long as 60 minutes.
Engineers were on-site correcting the fault, which left two of four tracks closed, but the rail authority could not provide an estimate of when the services would run as usual.
The delays affected trains travelling north and south through the major rail station.