Train is a coming: Sydney metro gets a green light

Sydney metro line
Commuters will be able to catch trains under Sydney's iconic harbour for the first time from Monday. -AAP Image

Sydney's driverless train network is ready to leave the platform, sparing the government further blushes after its opening was previously delayed.

Commuters will be able to catch the trains under Sydney's iconic harbour for the first time from Monday after a regulator signed off on the delayed opening of the new line.

The state Labor government was left red-faced when it was forced to push back the targeted August 4 opening date for the $21 billion addition to Sydney's metro network, Australia's most expensive public transport project.

Transport Minister Jo Haylen had previously refused to nominate a new date when she announced services would not begin as targeted.

NSW Transport Minister Jo Haylen has said multiple factors contributed to the delayed opening. (Dan Himbrechts/AAP PHOTOS)

But the government confirmed on Thursday evening it would launch its new network on Monday.

Eleven days after the initial scheduled launch, the Office of the National Rail Safety Regulator on Thursday confirmed it had finished its safety assessment and approved the publicly owned, privately run metro line to operate.

Ms Haylen in July said multiple factors had contributed to the delay.

"One of those of course is the incident that occurred on the northwest, as well as industrial action," she said.

Problems on the existing northwest section of the Sydney line, beginning at Tallawong left passengers stuck for hours.

The Fire Brigade Employees Union also imposed a temporary ban on emergency management exercises on the metro amid a stoush over pay.

The union on Wednesday warned the line was still not ready to open after a firefighter received an electric shock during a training exercise earlier in August.

"What if this occurred during an actual incident such as a fire?" the union's secretary Leighton Drury said.

"This could have devastating consequences for not only firefighters but the general public." 

The city metro project, planned and commenced under the former coalition government, has been hit with a series of cost overruns since it was approved in early 2017.

The final bill for the Sydney Metro City and Southwest line is expected to be about $21.5 billion, up $9 billion on its initial price tag.

It forms part of a wider rollout of metro services across the city that combine to constitute the nation's biggest public transport project.

A Sydney Metro West line will connect the city centre with Parramatta, while a third project will connect St Marys in western Sydney to the region's new airport.