According to the director of the rail project, a $18 billion metro train line that would transport commuters between a new station cut out of sandstone at Barangaroo and North Sydney in three minutes will be finished in 2024, expanding Sydney's CBD northward.

The underground station at Barangaroo is nearing completion as the first autonomous train is scheduled to cross Sydney Harbour as part of testing next year. In honour of the station's proximity to Observatory Hill and Barangaroo Headland Park, workers are adding a sandstone exterior to the station's walls. They are also building screen doors on the platforms for the future metro rail line, high-voltage cables, equipment, and systems.

The new station will have an above-ground entrance with escalators and lifts in Nawi Cove, a new inlet created from the old container wharf, in order to minimise disruption to the region around the headland.

Hugh Lawson, Project Director for Sydney Metro City and Southwest, stated that the three-minute trip to North Sydney on single-deck metro trains would aid in overcoming the harbour's inherent obstruction, while the new Barangaroo station will ease congestion at existing CBD stations.

“It makes it one extended CBD rather than two separated by the harbour,” he said. “It really brings North Sydney into the CBD and shortens those journey times. Heading the other way, [it will be] only about 13 minutes to Sydenham all the way through the rest of the CBD.”

In contrast, the current Sydney Trains double-deck service takes around six minutes to get from North Sydney to Wynyard station. Through a well-liked underground corridor that debuted in 2016, Wynyard gives access to train services for the southern part of the Barangaroo precinct.

Early City and Southwest line plans did not include a Barangaroo station; however, the government made a commitment to it in 2015 when it permitted the construction of larger buildings on the 5.2-hectare Barangaroo Central site, the final of the precinct's three portions.

The City and Southwest line leaves Barangaroo and travels south under the CBD before continuing to Sydenham and its final stop at Bankstown in the west.

The Barangaroo station location, which is perched on the edge of the bay, is up to 30 metres below ground level and created significant construction difficulties due to water pressure. Prior to covering it with a waterproof membrane, the company responsible for tunnelling the rail line had to build a substantial concrete wall around the enormous hole created for the station.

“A lot of the supporting structure [had to be built] inside the primary structure … to just basically hold the box open, so it didn’t try and collapse in on itself,” Lawson said. “We had to drill anchors and poles into the ground to stop the box lifting because we created this buoyant-like structure.”

The station has the sole crossover—tracks that cross in an X-shape on the route between Chatswood and Sydenham due to a massive cavern made by a machine used to tunnel under the port. The crossover will provide the metro line with a relief valve to help sustain services by allowing trains to be turned around in the event of a line operating issue.

The 22-hectare precinct's headland, as well as the surrounding Walsh Bay Arts Precinct and the Rocks, will have easier access to public transportation thanks to the Barangaroo station. Currently, it is challenging to use public transportation to reach the northern part of Barangaroo.

“What you’ll see is people being able to come from both the south and southwest but also from the north and exit into the city in a very different place,” Sydney Metro chief executive Peter Regan said. “That’s opened up a whole new catchment for the railway.”

Philip Thalis, an architect and former councillor for the City of Sydney, concurred that the new station would greatly improve access to Barangaroo and the surrounding districts for a larger segment of the greater Sydney population.

“That whole northwestern quadrant is a dead spot in the city, and the metro station is a huge improvement. It means that the arts space at Walsh Bay immediately becomes part of the broader city because it is a long way to walk to get to at the moment from the city,” said Thalis, whose team won an international design competition in 2006 for the waterfront site.

In order to blend in with the parks and northern headland, Barangaroo station building director Claire Moore said a canopy covering a bank of escalators and a pavillion for the elevators to the station below were "deliberately understated" structures.

Vital equipment rooms are located on floors above ground level at other new stations along the railway. At Barangaroo, though, everything is underground.

“It is like an iceberg,” Moore said of the underground station. “The majority of what the customer sees is a very small part of the station itself. Everything else is back-of-house – power, station management room, operation rooms, staff meal rooms.”

Despite the fact that the multibillion-dollar rail project's opening is only two years away, Sydney Metro has yet to specify a specific date for when the first train will be tested on the line under the harbour to Barangaroo. Sydney Metro blames the pandemic and labour unrest for the delay in construction.

“There’s a whole load of things impacting the project at the moment that potentially could delay that,” Lawson said. “You’ll see the stations looking complete [next year] but we’ll be heavily into the testing and commissioning of the railway phase. We can see the end in sight, but we still have to deliver a huge amount of work to get that.”