Another major state infrastructure project's budget has ballooned with a crucial rail line set to triple in cost to $17 billion.
But Queensland's opposition says the government is "cooking the books" by unprecedentedly factoring in maintenance costs into the budget blackhole.
The Cross River Rail project is a 10.2km tunnel connecting Brisbane's north and south, initially forecast to cost $5.4 billion.
It was slated to be completed by 2025 and running passenger trains by 2026.
However, the Liberal National Party government has revealed the total cost has blown out to $17 billion with the project expected to be delayed until 2029.
This includes the cost of building the tunnel and maintaining it doubling to more than $10.5 billion.
The government has accused its predecessors of hiding an extra $5 billion to fund integration works to connect the tunnel with the existing rail network, a new signalling system and temporary rail replacement buses.
The blowout also includes $1.5 billion due to the project running late and contractor claims which the government is negotiating.
"These are all essential costs that Labor chose to hide from Queenslanders," Transport Minister Brent Mickelberg told reporters on Wednesday.
The Brisbane project is one of several infrastructure blowouts the LNP has unearthed since it defeated Labor in the October 26 state election, including an extra $500 million required for Roma Street train station to provide links to Brisbane Arena for the 2032 Olympics.
Other states have faced major cost increases on infrastructure projects, with Melbourne's Suburban Rail Loop nearly doubling from $50 billion in 2018 to $96 billion in 2024.
Sydney Metro was overly optimistic, with the operational city and southwest line priced at $12 billion before rising to $21.6 billion.
The under-construction west line is also set to double from its $13 billion forecast while the planned line to Western Sydney International Airport is estimated to cost at least $11 billion.
Other interstate projects with ballooning costs include the delayed delivery of two new Spirit of Tasmania ferries, with the project price rising to around $1 billion.
Costs for the Queensland rail project have been disputed by the state opposition with the government accused of inflating the price by including maintenance projections and replacement buses.
"The Crisafulli regime has completely cooked the books in a world-first, very creative accounting measure," shadow treasurer Shannon Fentiman said.
But Mr Mickelberg rubbished the opposition's criticism, arguing Queenslanders deserved to know the true total price tag.
"It's just another example of Labor trying to use smoke and mirrors to hide the true state of affairs when it comes to big projects," he said.
