In 2022, a childcare worker and a linesman bought a house-and-land package in Marsden Park, a new suburb spreading across Sydney's north-west toward the site of the new Western Sydney International Airport. The sales pitch showed a metro station minutes from the terminal, timed to open with the airport's first flights. Four years on, the airport is on schedule: Western Sydney International is due to open for passengers in October 2026 (approx.). The metro line built to serve it is not. In January 2026 the NSW Government confirmed a free interim bus, not the roughly $11 billion (approx.) Sydney Metro — Western Sydney Airport line, would carry the airport's first passengers between St Marys and the terminal, because the rail line will not open until at least mid-to-late 2027 (NSW Government / Transport for NSW, Sydney Metro — Western Sydney Airport project updates and interim bus announcement, approx. January 2026). For that family, the daily trip to the terminal now runs on a road, not the railway they were sold.
What the government did
Sydney Metro is Australia's largest transport project under construction and the country's first fully automated, driverless heavy-rail network. Its first stage, Tallawong to Chatswood, opened under the former Coalition government in May 2019. Labor, elected in March 2023 under Premier Chris Minns, inherited two more projects already under construction: Sydney Metro City & Southwest, extending the line under Sydney Harbour and through the CBD to Sydenham and on to Bankstown, and Sydney Metro West, an entirely new line from the CBD to Parramatta via a string of new inner-west and harbourside stations. A third project, Sydney Metro — Western Sydney Airport, links St Marys to the new airport and the planned Bradfield city centre.
Within six weeks of taking office, the Minns Government ordered an independent review of the whole program, announced on 13 April 2023 and led by former federal transport department secretary Mike Mrdak, after early advice showed both under-construction projects running well over their publicly stated costs. Its preliminary findings, folded into the 2023 Budget, put Metro West at $25.32 billion — at least $12 billion (approx.) above the cost implied by its original business case — and City & Southwest at "at least $20.5 billion," roughly $2 billion (approx.) higher than the previous government's most recent projection (NSW Government, "Sydney Metro Review," media release, 13 April 2023). Rather than pause or descope, the government pressed on: it opened City & Southwest's central section, Chatswood to Sydenham, on 19 August 2024, and kept building Metro West and the airport line. In December 2025 a further internal budget review found another $6 billion (approx.) was needed across the program; the government responded by committing an extra $2.4 billion to keep the projects funded (NSW Government, ministerial release on updated Sydney Metro project costs, 5 December 2025).
The strongest case
A driverless, harbour-crossing rapid transit network built at a scale Sydney has not attempted in decades
Put at its best, Sydney Metro is the most significant expansion of Sydney's rail network in generations. The City & Southwest line was designed to relieve the city's sole rail crossing of the harbour, which had operated near capacity for decades, running fully automated, computer-controlled trains as often as every four minutes in peak periods with a theoretical capacity of roughly 40,000 passengers per hour per direction — a turn-up-and-go frequency no timetabled, driver-operated line in Australia offers (Sydney Metro / Transport for NSW, network and service information).
The patronage numbers support the case that Sydney wanted this. More than a million trips were recorded on the new city section in its first four weeks, and by its first anniversary the M1 line was carrying an average of around 210,000 trips a day, including roughly 120,000 (approx.) through the harbour tunnel — trips that used to compete for space on the double-decker suburban network and the Harbour Bridge's road lanes. Transport for NSW recorded more than 17.8 million (approx.) additional ticketed public transport trips across the whole network in the line's first twelve months compared with the year before, evidence commuters switched modes rather than simply relabelling the same trips (Sydney Metro, "Sydney Metro City celebrates its record-breaking first year of passenger services," approx. August 2025).
The city-shaping case is real too. Metro West's business case was assessed by Infrastructure NSW as returning $1.34 in benefits for every dollar spent once wider economic benefits are included — a positive ratio on the government's own published evaluation (Infrastructure NSW, Sydney Metro West Final Business Case Evaluation Summary, July 2020). The Bays West precinct alone is planned to deliver up to 8,500 homes, at least 10 per cent of them affordable or essential-worker housing, on a 95-hectare harbourside site built around the new Bays West Metro station (NSW Government, "Minns Government to deliver thousands of homes near the Bays Metro Station," ministerial release, approx. 2024). For a state with a severe housing shortage and a Western Sydney growing faster than its transport links, a driverless rapid-transit spine built to carry that growth is exactly the kind of long-lived infrastructure a government should build — one Sydney had left dangerously late by the standards of comparable global cities.
The evidence: what the primary record shows about cost
Two things matter for judging this program: what it has delivered, and what it has cost — and the NSW Audit Office's own account of the second is unflattering. Its Capital Projects 2025 report, tabled in Parliament on 18 March 2026, found that more than three-quarters of Transport portfolio projects, including both Metro West and City & Southwest, still carry no published estimated total cost in the state's Infrastructure Statement, listed instead as "n.a." despite repeated ministerial cost announcements made outside the Budget process (NSW Audit Office, Capital Projects 2025, 18 March 2026). The Audit Office recommended that, by 30 June 2027, Sydney Metro begin publishing a cost range in line with a 2022 Premier's Memorandum on infrastructure transparency that has gone largely unheeded for these two projects since it was issued.
What has been disclosed tells a stark story of escalation. City & Southwest's original 2016 business case put its cost at $11.5–12.5 billion (approx.); the Mrdak review found it had reached at least $20.5 billion by April 2023; the December 2025 review put it at $22–23 billion (approx.) (NSW Audit Office, Capital Projects 2025; NSW Government, Sydney Metro Review, 13 April 2023; NSW Government, ministerial release, 5 December 2025). Metro West's 2020 final business case did not disclose a cost estimate at all — the government asked Infrastructure NSW not to publish one while procurement was under way (Infrastructure NSW, Sydney Metro West Final Business Case Evaluation Summary, July 2020) — before the 2023 review put it at $25.32 billion and the 2025 review at $27–29 billion (approx.).
The critique: money outrunning the plan
The clearest problem is transparency, and it is the Audit Office's own finding, not an opposition talking point: two of the state's largest infrastructure projects have run for years — in Metro West's case, since before construction started — without a published cost the public or Parliament could hold the government to. A project that will not say what it costs cannot be shown to have blown a budget, because there is no published number to blow. That gap has let cost growth accumulate through one-off ministerial disclosures rather than against a figure tracked in the Budget Papers as required by the government's own transparency policy.
The government's own December 2025 review, not an outside critic, found specific instances of poor cost discipline inside a program Labor has now controlled for close to three years. It identified $110 million (approx.) redirected out of the Metro West budget toward the Eastern Creek Speedway and never replaced; $500 million (approx.) in tunnelling-package overruns to private contractors that were not disclosed publicly as they accrued; and the effect of building three metro lines at once rather than in sequence, which the review found had the projects competing against each other, and against the rest of the construction industry, for the same tunnelling crews and materials (NSW Government, ministerial release, 5 December 2025). Transport Minister John Graham described the pattern as "the infrastructure equivalent of robbing Peter to pay Paul" — a frank assessment, but one describing decisions and disclosure gaps that occurred on this government's watch, not only ones it inherited.
Some of the blowout genuinely is inherited. The 2016 and 2020 business cases were prepared, and Metro West's deliberately kept undisclosed, under the Coalition government that commissioned both projects; the harbour tunnel had already been bored and major contracts already signed by the time Labor won office in March 2023, narrowing any government's room to descope rather than fund the shortfall. But the further $6 billion identified in December 2025 sits inside a term Labor has now held for more than two years, and the transparency gap the Audit Office found is one the current government has had two Budgets to correct and has not yet fixed.
The critique: the airport mismatch and an untested business case
The mismatch is starkest on the Western Sydney Airport line. Western Sydney International is on schedule to open for its first flights in October 2026 (approx.), but the roughly $11 billion (approx.) metro line built specifically to serve it is now targeted for mid-to-late 2027, with an "elevated" risk of slipping to 2028 flagged in the project's own documents, partly because of a commercial dispute with private delivery partner Parklife Metro, which has lodged claims of up to $2.2 billion (approx.) and could add more than $1 billion (approx.) to the cost. The free interim bus announced in January 2026 is a sensible stopgap, but it concedes that the airport's most transformative piece of connecting infrastructure will not exist when the airport opens. The Sydenham-to-Bankstown conversion, City & Southwest's other unfinished leg, has also slipped into the second half of 2026, with more than 130 days (approx.) of construction lost to industrial action (NSW Government, "South West Metro conversion period to be extended into 2026," ministerial release, approx.).
The financial case has not been retested against the real cost either. Infrastructure NSW's 2020 evaluation put Metro West's benefit-cost ratio at 1.34 including wider economic benefits, or just 1.04 — barely above break-even — on the narrower measure that excludes them. Both ratios were calculated against a cost base the government would not publish, but which the Audit Office's later account implies sat well under half of the $27–29 billion the project is now expected to cost. No re-costed benefit-cost ratio has been published against that current price tag. A project that clears the bar at 1.04 against an undisclosed, since more-than-doubled cost has not been shown to be a good investment at its current price — it has simply never been tested at that price at all.
A project that will not publish what it costs cannot be shown to have kept to a budget it never set.
The risk to the future
A transformational network whose next stages are being funded one review at a time
Sydney Metro's finished sections are already doing what a metro is supposed to do: shifting hundreds of thousands of daily trips onto a fast, frequent, harbour-crossing rail spine and unlocking city-scale housing precincts like Bays West that would not otherwise exist. That achievement is real and, once built, largely permanent — the risk is not that the transformation stalls, but that the way it has been paid for keeps repeating. Two budget reviews in under three years have each found billions more required than the figures the public was previously given, with no published cost baseline for either flagship project against which the next blowout could even be measured. A state Budget that must also fund hospitals, schools and housing cannot keep discovering multi-billion-dollar Metro shortfalls by review rather than by tracking against a public number without eroding the trust it needs to fund the next stage — an extension into the Southwest or north — on its word alone.
The Western Sydney Airport line carries the sharpest version of this risk. Its economic logic rests on connecting the new Aerotropolis and Bradfield city centre to rapid transit from day one; if the airport opens in October 2026 to a car- and bus-dependent catchment and the metro does not arrive until 2027 or later, the growth corridor's early development pattern — car parking, road capacity, low-density logistics estates — risks locking in before the rail-oriented city the project was built to create ever opens. A metro line delivered years after the development it was meant to shape does not get a second chance to shape it.