Lawson said everything had been “scaled up” at the new Martin Place station in terms of the size of the passages,escalators and concourse,which had presented major engineering challenges during construction as contractors had to work above,below and between existing rail tunnels.

“We had to work so close to the operating Sydney Trains lines without disrupting them significantly. That was very difficult,” he said. “There was a huge amount of excavation required under people’s feet.”

Almost half a century after the last rail line under Sydney’s CBD opened,Transport Minister Jo Haylen said the new station at Martin Place would provide commuters with an “incredible interchange” between multiple transport modes right in the heart of the CBD.

Testing on the Metro City and Southwest line ramped up last weekend when 33 of the 45 driverless trains in the fleet completed at least one return journey between Sydenham and Tallawong,near Rouse Hill in the city’s northwest.

“We are entering the home stretch of this city-shaping project and it’s exciting to see our biggest weekend of testing go off without a hitch,” Haylen said.

Since testing and commissioning started last April,more than 7500 hours of a total 11,000 hours required for testing have been completed.

The main section of Metro City and Southwest between Chatswood and Sydenham has to open before a 13-kilometre stretch of the Bankstown line can be closed to commuters in the third quarter of this year to allow workers to complete the conversion of the track to metro train standards. The Bankstown line conversion is the final part of the project.

Asked whether the conversion would,in fact,start this year,Haylen said the Bankstown line would not be closed until there was a high level of service reliability on the main section of the new metro line. “Our plan is to progress with the timeline we have outlined,” she said.

The rail project,which also includes new stations at Waterloo,Barangaroo,North Sydney and Crows Nest,has beendogged by cost blowouts and challenges converting the 128-year-old line between Sydenham and Bankstown into one capable of carrying driverless trains. The government estimates the conversion will cost anextra $1 billion,pushing up the bill for the entire project to $21.6 billion – almost double the price tag last decade.

The looming opening of the main section of the new line comes as former senior Sydney Metro chief executive Tim Parker has been selected as the inaugural chief executive of the federal government’s high-speed rail authority. He resigned as Sydney Metro’s head of project delivery last month.

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