Melbourne’s $15.5 billion Metro Tunnel will finally open to passengers in December but only at a quarter of capacity, allowing limited trains at a reduced number of stations along the cross-city rail line for its first two months.

The precise start date depends on the project receiving a final sign-off from the rail safety regulator. The initial timetable is limited to 30 off-peak services each weekday, and a full timetable will not start until February 1.

The announcement marks a major milestone for a government that has built its reputation on its Big Build projects and the end of a turbulent eight years of construction that at times brought parts of the inner city to a standstill.

The government first committed to delivering the project in 2026 but brought it forward by a year before the state election in 2018.

An internal timeline set for the builders, but not advertised publicly, anticipated completion in September 2024.

The Age revealed in August 2024 that the Allan government had offered the builders additional payments worth up to $888 million if they met milestones that ensured trains could take passengers by the end of 2025.

Premier Jacinta Allan said on Tuesday the state’s investment was “worth every cent”.

During the soft launch, trains will run every 20 minutes between 10am and 3pm on weekdays from Westall and West Footscray stations.

At weekends, they will run every 20 minutes from 10am to 7pm, and extend to East Pakenham every 40 minutes and Sunbury every 60 minutes.

These are in addition to existing Sunbury and Pakenham/Cranbourne timetabled services, which will continue to operate through the City Loop.

The full timetable has not been released, but the government said from February trains would run at least every 10 minutes from 6am to 10pm between Watergardens and Dandenong, with services every three to four minutes in peak hours.

The Metro Tunnel project consists of a nine-kilometre rail tunnel between Kensington and South Yarra, with five new underground stations at Anzac (opposite the Shrine of Remembrance), Town Hall, State Library, Parkville and Arden (in North Melbourne).

The Metro Tunnel links the Sunbury and Cranbourne/Pakenham lines, which will come out of the City Loop and form a new cross-city rail connection.

Victoria has poured $13.48 billion into the project, which had an original budget of $10.9 billion.

As cost overruns piled up during construction, builder CYP agreed to deals in which it contributed close to $2.2 billion, pushing the total cost of the project to about $15.5 billion.

Allan said the gradual increase in services – which The Age first revealed in June – was standard for large rail projects.

“The best way to make sure everything runs well is to open the tunnel and run the services first and then make the big timetable switch,” she said.

Allan said she was confident the project would receive the final sign-off from the National Rail Safety Regulator by December but would not announce a firm opening date until then to avoid a repeat of the embarrassing delay to Sydney’s Metro last year.

“We have looked to the north and learnt the lessons for what happened with the Sydney Metro,” she said.

Public Transport Users Association spokesman Daniel Bowen said the launch timetable could confuse passengers if Transport Victoria and Metro Trains did not communicate the limited operations clearly.

“The fact you’ll be able to take a train to the hospital precinct [at Parkville] is great, but then when it’s time to come home, the trains may have stopped for the day,” he said.

But Bowen said a soft launch also had advantages, including the ability to iron out unexpected bugs in the new tunnel and stations.

“The last thing they would want is a major disruption interrupting a peak hour and delaying thousands of passengers if the new infrastructure had issues,” he said.

Bowen said the February 1 timetable should have trains arriving at least every 10 minutes all day, every day from Sunbury to Dandenong, and that trains should run that frequently across the network with more capacity in the City Loop.

The importance of the announcement to the Labor state government’s identity – and electoral fortunes – was clear from the large contingent of MPs attending the announcement.

Labor made building the tunnel a key election promise, while pledging to ditch the planned East West Link, in its surprise 2014 victory that ended a one-term Coalition government.

The tunnel plan was central to then-premier Daniel Andrews’ image as a leader capable of “getting it done”.

Allan was tied to the Metro Tunnel project from day one as public transport and later transport infrastructure minister, charged with overseeing its delivery until her elevation to premier in September 2023.

“It has been the honour of my life to see this project through from conception to completion because this is something that will improve the lives of Victorians,” Allan said on Tuesday.

“It is the biggest overhaul of our transport system since the 1980s – since the City Loop opened all those years ago – and we are proud that it has been our Labor government and Labor governments before it that have built and upgraded so much of our transport system.”

The government intends to open another signature project, the West Gate Tunnel, by the end of this year.

Doing so will provide Allan with two proof points of Labor’s agenda as she seeks in 2026 to be the first female premier to win a state election in Victoria and secure a historic fourth term for the party.

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