The delivery of Queensland's $4.4 billion train fleet has been cast into doubt again amid revelations of similar delays overseas.

The rollout of the fleet — built in a Bombardier plant in India —is still months away after it was halted by the State Government in March when significant design issues were discovered.

The fleet was ordered in January 2014, under the previous Newman government, which said at the time they were coming in at half the price the previous government had paid for its rollingstock.

It was supposed to begin rolling out by the end of 2016, but on-track testing uncovered problems with braking, air-conditioning, ventilation, sightlines for train drivers, and disability access.

Bombardier, a Canadian based transport company, has come under fire for two separate delayed public transport projects in its home country amid significant financial problems.

One project involves the botched delivery of more than 200 new streetcars for the city of Toronto, with several missed deadlines in the last five years.

The other contract relates to dozens of new light rail vehicles ordered by the Government for a separate cross-town line on Toronto's outskirts.

Bombardier missed several deadlines in the delivery of more than 200 new streetcars for the city of Toronto ( Supplied: Toronto Transit Commission )

Significant concerns about quality: Ontario minister

Last week the Ontario Transportation Minister Steven Del Duca announced a new deal with Bombardier's competitor to deliver additional light rail vehicles in case Bombardier failed to deliver its fleet for the cross-town line.

"Over the past several months, Metrolinx has had significant concerns regarding Bombardier's ability to deliver quality vehicles according to the contract schedule," he said in a statement.

"The stakes are too high to sit idly by without a viable alternative."

The matter has now gone to court, as Bombardier tries to hang onto the $770 million contract.

Bombardier, one of the largest transportation businesses in the world, is set to receive $370 million from the Canadian Government in the form of an interest-free loan.

Last year, Canadian media reported CEO Alain Bellemare said the company was considering bankruptcy in 2015.

He now says the business is improving.

Jackie Trad confident issues will be resolved

Despite the developments, Queensland Minister for Transport Jackie Trad said she still believed Queensland's fleet would get on track.

"I have confidence the issues are being worked through as quickly as possible so we can have safe reliable trains on our network this year," she said.

In a statement issued by Qtectic, a spokesperson said delays were not uncommon in new train projects.

"The first new-generation rollingstock trains are due to be on the network later this year, and the Department of Transport and Main Roads, Queensland Rail and Qtectic are working around the clock to ensure that the trains enter passenger service as soon as possible, without compromising safety," it said.

"Consortium member Bombardier has a long record of constructing high-quality trains throughout the world.

"For all new train projects, especially of this size and complexity, it is not uncommon to experience some delays as issues are identified during testing and rectified accordingly."

Next Generation Rollingstock tests have revealed a range of problems ( Supplied: Transport and Main Roads )

Contract 'should gone to Australian company'

Fifteen of the 75 trains have already arrived in Queensland but cannot be commissioned until they undergo modification.

Rail, Tram and Bus Union state secretary Owen Doogan said the manufacturing should never have been awarded to an offshore company.

"We have a history of reliability of manufacturing in this country," he said.

"We should be building our trains and all rollingstock in Australia and we will certainly not renege from that position."

The Opposition's Scott Emerson, who was transport minister when the deal Bombardier contract was signed, said it was up to the new Government to ensure the trains were operational.

"This project continues to seem to have problems after problems," he said.

"The problems weren't there when we left office. This project was on track when we left office."