[15] During the state election campaign in March 2019, the Liberal/National coalition government announced a funding of $6.4 billion to the project and commitment to start construction earlier in 2020, if re-elected.

[6] The Clyde facility would be on the site of Sydney Speedway, which would be demolished, and would be accessed from the main tunnels via the former Carlingford railway line corridor.

The Rydalmere station option was confirmed scrapped due to the cost of extra 3 kilometres (1.9 mi) of tunneling and the increase in commuter travel times.

[6] The line connects a number of suburbs in Sydney's inner west that lacked heavy rail transportation, including Pyrmont and Five Dock.

[7] The project's western end serves a similar area to the Parramatta Light Rail, whose stage 1 alignment runs between Westmead and Carlingford.

[10][36] Stage 2 of the light rail project was initially deferred, then redesigned and truncated from Strathfield to Sydney Olympic Park via the suburbs to the north of the Parramatta River.

[6] Construction of the project is split into multiple parts, with separate contracts to build the tunnels, underground stations, rolling stock, signalling and electrical and mechanical systems.

[38] The contract for the Central Tunnelling Package was awarded to the Acciona Australia and Ferrovial joint venture (AF JV) in July 2021 at a cost of $1.96 billion.

[40] The contract for the Western Tunnelling Package was awarded to Gamuda and Laing O’Rourke joint venture (GALC JV) in March 2022 at a cost of $2.16 billion.

[42] In November 2022, the Eastern Tunnelling Package was awarded to the John Holland, CPB Contractors and Ghella Pty Ltd joint venture (JCG JV) at a cost of $1.63 billion.

[42] Media reports in 2021 suggested that difficulty in excavation and property acquisition in Sydney CBD for the Hunter Street station risked escalating costs on the project.

However, on 13 April 2023 the recently elected Premier of NSW Chris Minns announced a review of the project with the government presently examining the potential to include additional stations along the route in these suburbs.

Western FastRail was backed by a consortium led by businessman and former union leader Michael Easson, which included Dutch bank ABN AMRO and Australian construction company Leighton Holdings.

An unreleased government document leaked to The Daily Telegraph suggests that such a train would eliminate the need of around 18 million car trips per year, reducing between 34,000 and 45,000 tonnes of greenhouse gas emissions being put into the atmosphere.

The proposal was first made on 11 April 2002 when Col Gellatly, the state's top civil servant and director-general of the Department of Premier convened a meeting of Treasury secretary, John Pierce, the Transport NSW director-general, Michael Deegan, and the State Rail Authority chief executive, Howard Lacy.

Before them consortium leader Michael Easson made a presentation for a privately financed rail line linking Sydney's far west with the city.

There were 10 stations proposed for the Western FastRail:[58] The centrepiece of the scheme premier Morris Iemma announced in March 2008 was "Metro Link" with an underground rapid-transit, privately-operated, single-deck, automated trains.

[60] Rees' Sydney Metro project was cancelled in February 2010 by the government led by newly appointed premier Kristina Keneally.

Keneally said "We've listened to the community and made a tough decision," and pledging to reimburse tenderers and property owners for losses incurred as a result of the work that had occurred to that point.

Keneally announced a $50 billion transport plan to replace the metro project, including a new heavy rail line under the CBD.

[63] Keneally lost office just over a year later in the 2011 New South Wales state election, and the relief line was cancelled by the incoming government led by premier Barry O'Farrell.