Premier Gladys Berejiklian said the new line - most of which will run through tunnels - would bust congestion and more than double the rail capacity between Parramatta and Sydney’s CBD. "This crucial project will reduce the journey between Parramatta and the city to around 20 minutes with trains running every two minutes," she said. The travel time for a journey from the CBD to Olympic Park will be 14 minutes. Of the 116 properties to be acquired for the project, 23 are residential and 93 commercial businesses. The Bays Precinct will be the first site on which work will start because that is where tunnelling will commence. Tunnel boring machines are expected to start digging the line in 2022.

Labor leader Jodi McKay said the new timeline for completion of the project by 2030 represented a "major broken promise" by the government, which had planned to complete it in 2028. "The tunnel boring machines are running a year late, the project at least two years late – and there is a massive funding black hole," she said. But Transport Minister Andrew Constance said it could be completed earlier than 2030, saying: "We are setting a realistic expectation and, as always, this government will set about bettering it". Sydney Business Chamber's western Sydney director David Borger said it was great news that Metro West had finally been locked in but it was "unfortunate that the timeline [for completion of the line] seems to have slipped by two years since the election" in March.

"We hope [the project] can be sped up again. It is absolutely critical that we get this new 25-kilometre tunnel in place as soon as we can," he said. Loading The government has yet to make a final decision on building metro stations at Pyrmont in the inner city, or Rydalmere, east of Parramatta, which have been dubbed "optional stations". It is also finalising the site of the station in Sydney’s CBD, which is expected to be under Hunter Street, linking Wynyard and Martin Place. A turn-back site for trains will be needed in the central city. While that could be built at the CBD station, the government has not ruled out Zetland in the inner south as the site of a turn-back or a station.

So far, the Berejiklian government has committed $6.4 billion to Metro West over a four-year period. It declined to put a cost on the entire project, citing the need to retain "competitive tension" in the bidding process for contracts to build the project. A large stabling yard and operations centre for the single-deck, driverless metro trains will be built at the Clyde and Rosehill industrial estate bounded by James Ruse Drive, the M4 motorway and Unwin and Shirley streets. Metro West is effectively the third stage of the city’s metro rail network. The first stage known as Metro Northwest from Rouse Hill to Chatswood opened in May, and the second stage under Sydney Harbour and on to the CBD and Sydenham and Bankstown is due to be completed in 2024. An artist's impression of Westmead metro train station. Credit:NSW Government

Sydney Metro West station locations Westmead: The eastern side of Hawkesbury Road, south of the existing Westmead station. The new station will have one entrance on Hawkesbury Road. Parramatta: On the block bound by George, Macquarie, Church and Smith streets with an entrance on Horwood Place. Sydney Olympic Park: To the south of the existing train station. It will sit to the east of Olympic Boulevard with the main station entrances between Herb Elliot Avenue and Figtree Drive, and off Dawn Fraser Avenue. North Strathfield: Adjacent to the existing train station. New metro platforms will sit alongside the existing station and entry to the station would be from a new entrance on Queen Street.