Transport Minister Stirling Hinchliffe has again found himself apologising to rail commuters for disruptions to train services.

The trouble started at 6:00am after a track fault at Yeronga and a broken down train at Kuraby.

Queensland Rail (QR) maintenance crews doing rail repairs were pouring a molten metal mixture into a sand mould, which then failed.

From about 7:00am there were 60-minute delays on the Airport line and inbound from Beenleigh, Gold Coast, as well as a 30-minute delay on the Ferny Grove Line.

An overhead power issue at South Bank and another separate train break down then caused 30-minute delays in both directions on the Beenleigh, Ferny Grove, Gold Coast, Springfield, Cleveland, Doomben, Shorncliffe and Airport lines.

Mr Hinchliffe conceded QR should have done better in letting people know of the impending delays.

"Today we've had a confluence … of infrastructure mishaps and misfires that have caused a poor level of service delivery," he said.

Mr Hinchliffe promised to refund all commuters who used the rail network between 6:00am and midday.

The refund is expected to occur before Christmas and cost Translink more than $300,000.

"It's not acceptable that people have not had the notice to be able to make changes to their arrangements and as a consequence potentially been late for work, been late for appointments, been late for studies," Mr Hinchliffe said.

"These are matters that we take very seriously and we regret very sincerely the impact that this had on our customers this morning.

"I think a very serious lesson has been learnt by how this wasn't as communicated as well."

Emoji tweet no laughing matter

Queensland Rail is investigating how this tweet was sent. ( Twitter )

Amid the chaos, Queensland Rail tweeted a picture of a laughing emoji, causing further embarrassment for the minister.

It was deleted about 15 minutes later.

Mr Hinchliffe blamed the tweet on "some sort of breach" of the communications system, which was being investigated.

"I can assure you there's no one within the organisation that I'm aware of that would think this is funny," he said.

Earlier, Premier Annastacia Palaszczuk said QR needed to explain any track maintenance issues.

"I do believe that Queensland Rail should have been more proactive in letting people know about the issue," she said.

"It's up for them to come out and explain it and I believe that they should have been more forthcoming with their explanation to commuters this morning and frankly it's not good enough."

Opposition leader Tim Nicholls slammed the delays as "yet another Queensland Rail Train fail".

"We haven't seen a rail fail like this in terms of track maintenance or whatever excuse is being put forward certainly since Annastacia Palaszczuk was last Transport Minister," he said.

"It certainly seems that this is a Government and Transport Minister that can't walk and chew gum at at the same time when it comes to trains."