A major extension of Sydney's metro rail project is on track, including the link to the city's new airport.
While always part of the NSW government's vision, the metro connection with the western Sydney aerotropolis is now a step closer to reality following the successful completion of other key sections of the network.
The government announced on Sunday it would undertake final business cases for four routes - Tallawong to St Marys, Westmead to the aerotropolis, Bankstown to Glenfield via Liverpool and Macarthur to the aerotropolis.
The process will help direct government spending and determine which line needs to be started first.
With Western Sydney International Airport due to open in 2026 the airport metro is being jointly-funded and delivered by the federal and state governments.
Premier Dominic Perrottet said in total the extension would add around 100 kilometres of track in Sydney's west to the ongoing Metro project.
"Sydney Metro is Australia's biggest public transport project and is already re-shaping this city and transforming how we move around," he said.
"These new lines will complete the missing links in the metro network in the west and connect our city like never before in what will be a major win for the people of western Sydney."
Infrastructure, cities and active transport minister Rob Stokes said the aerotropolis residential and business hub was turning paddocks into a thriving city around the future airport.
"Our ambition is to complete the Metro network that we started when we first came to government," he said.
"By starting this work now, we're putting the aerotropolis on a strong footing to be one of the most accessible cities in Australia for people on bikes, cars, planes or trains - connected to a new airport, active transport network and world-class metros and motorways."
Opposition leader Chris Minns said existing metro projects were already billions of dollars over budget, adding his party would release its own public transport plan for Western Sydney before the election.
"Many of the projects that were started by former premier Gladys Berejiklian are now wildly off the rails effectively," he said.
"Now Mr Perrottet is talking about the next iteration but he hasn't explained how and why the costs associated with Metro West and Southwest Metro have exploded."
At the start of this month the final track was laid connecting the new Sydney Metro City and Southwest line with the existing North West line at Chatswood, which Mr Perrottet described as a milestone.
Services from Chatswood to Sydenham are scheduled to commence in 2024, then on to Bankstown the following year.
