Sydney Metro Western Sydney Airport

Sydney Metro Western Sydney Airport, previously known as Sydney Metro Greater West, is a rapid transit rail project currently under-construction in Greater Western Sydney. The project involves the construction of a 23 km line as part of the Sydney Metro system. The line will operate between St Marys, where the line will connect to the Main Western railway line, and Badgerys Creek Aerotropolis at Bradfield via the Western Sydney Airport. It is intended to provide public transport for the upcoming Western Sydney Airport. Construction of the line started in December 2022 and is expected to be completed in late 2026 in time for the opening of the airport.

The line will form Stage 1 of the proposed North South Rail Line, which would see the line extended north to Schofields to connect to the Richmond railway line, and south to the Main Southern railway line at Macarthur.

Route
Six stations have been proposed for the line.
 * St Marys (interchange with T1 Western Line)
 * Orchard Hills
 * Luddenham
 * Airport Business Park
 * Airport Terminal
 * Bradfield

The Sydney Metro Trains Facility and the Operations Control Centre will be located at Orchard Hills, and services facilities will be located at Claremont Meadows and Bringelly.

The line is proposed to run via twin tunnels between St Marys and Orchard Hills stations and between the Airport Terminal and Bradfield stations. Tunnel boring machines were planned to be launched from Orchard Hills and the Airport Business Park. The section from Oran Park to Macarthur in the proposed southern extension would also run via tunnels.

Planning
In 2014, the Federal Government under then Prime Minister Tony Abbott initially had no plans to build a rail line. However, it indicated provision for a railway line would be included in the development that may include preparing tunnels under the runway as part of the runway construction and preparing the underground space for a station. It was considered likely the rail connection to the airport would consist of an extension to the South West Rail Link from Leppington. In 2015, then Prime Minister Malcolm Turnbull indicated that the airport would need both road and rail links to the Sydney CBD. In November 2015, a scoping study into rail investment to service Western Sydney and the Western Sydney Airport was announced. The study was jointly managed by the NSW and the Commonwealth governments. A discussion paper, released in September 2016, proposed various options that could provide a rail link to the airport, listed below:

The final report, released in March 2018, proposed that two lines would ultimately service the airport: a "North-South Link" from Schofields to Macarthur and an "East-West Link" from Parramatta to the "Badgerys Creek Aerotropolis", an area south of the airport. The East-West Link would likely form an extension of the already-announced Sydney Metro West. An extension of the South West Rail Link to the Badgerys Creek Aerotropolis was also proposed. Interchanging with the North-South Link or East-West Link would be required to access the airport itself.

Later in March 2018, the federal and state governments signed the Western Sydney City Deal and announced the development of stage 1 of the North South Rail Link as part of the deal. Between 2019 and May 2020, the stage 1 of the North-South Link is referred to as "Sydney Metro Greater West" by the Sydney Metro agency. The project update on 1 June 2020 confirmed the name of the line to be "Sydney Metro – Western Sydney Airport".

Prior to June 2020, the only stations proposed were at St Marys, Western Sydney Airport and Aerotropolis. The proposed six stations of Stage 1 were confirmed in June 2020 and the exact locations of the stations were confirmed in September 2020.

In October 2020, the project's Environmental Impact Statement (EIS) was released to the public for exhibition. Since the work would be carried out within the airport boundary, federal planning approval was also required. State planning approval was granted in July 2021, and federal planning approval was granted in September 2021.

Funding
In the 2019-2020 federal budget in April 2019, the federal government announced a contribution of $3.5 billion to deliver stage 1 of the rail link. This funding also includes $50 million towards the business case process for the North-South Rail Link and $61 million for the Elizabeth Drive overpass.

In the 2019–2020 New South Wales state budget in June 2019, the state government announced an investment of $2.0 billion to commence the construction of stage 1 for the next 4 years.

In June 2020, the federal and state governments announced a further $3.5 billion contribution to push the construction date earlier to late 2020. Designs were modified to include an additional six kilometres of tunnelling. As of June 2020, the project has a price tag of A$11 billion.

Construction
In March 2021, three consortia (Acciona, a joint venture of John Holland and Gamuda, CPB and Ghella) were shortlisted to deliver tunnelling works for the project. The station box and tunnelling contract was awarded to CPB and Ghella in December 2021. In September 2023, a tunnel boring machine, one of four tunnel boring machines, had completed the first 1.26 km section of its 5.5 km tunnel. Tunnelling is expected to be complete in late 2024, with track laying and station fitout to occur afterwards.

A second major contract for surface and civil alignment works was awarded to CPB and United Infrastructure in March 2022.

A third major contract was the Stations, Systems, Trains, Operations and Maintenance (SSTOM) package for the construction of the stations and operation of the line. In October 2021, three consortia were shortlisted:
 * Bradfield Metro, comprising John Laing, Keolis Downer, FCC Construction Australia and Hitachi Rail STS
 * Parklife Metro, comprising Plenary Group, Webuild, RATP Dev and four Siemens Mobility companies
 * WestGo, comprising CIMIC Group (Pacific Partnerships, CPB, UGL Engineering and UGL Rail), two Acciona companies, DIF Management Australia, ComfortDelGro Transit and Coleman Rail Pty Ltd

The SSTOM package was awarded to Parklife Metro in December 2022.

Operations
Being awarded the SSTOM package, Parklife Metro will operate and maintain the line for 15 years after it becomes operational. Siemens will deliver 12 automated 3-car Siemens Inspiro trains to run on the line.