Starts off as a joke, but it’ll end in tears. You look like the wreck of the Hesperus. Pride comes before a fall. You’ve ruined Christmas.

These pearls of wisdom should be familiar to anyone born in the ’50s, the Old Testament for families, when parenting skills simply required love and the frequent hosing down of a child’s expectations.

It didn’t work but didn’t do me any harm, either.

The most poignant of them all was when Mum would lament “we can never have nice things”, usually after we’d set fire to some heirloom in the backyard. She was right. When we were clearing up the family home, it struck me that our parent’s things had worn out along with them.

Now, of course, we can always have nice things, whether we’ve got the money for them or not. As individuals we expect it, and as a community we demand it from our governments. Under the cover of the COVID pandemic, our state and federal governments have gone on an unprecedented borrowing binge. Even South Australia’s former Liberal treasurer Rob Lucas, a renowned tight-arse, piled debt on at an eye-watering rate.

And yet we keep wanting things we can’t afford.

The Big Three are the $9.9 billion earmarked for the “hard bit” of the North-South Corridor on South Road, the $2.05 billion for a new Women’s and Children’s Hospital and the $593 million bill for a state-owned “world’s largest hydrogen plant” promised for Whyalla.

SA can’t afford any of these projects and certainly can’t afford all three. At least one of them, preferably two, has to go.

In June, incoming Labor Treasurer Stephen Mullighan’s first budget projected SA’s total government sector debt would reach an alarming $33.8 billion by 2024-25, the end of the budget’s four-year “forward estimates”.

He revealed that soon after being sworn in, he’d asked Treasury boffins a debt question.

What would our debt figure be if SA continued the current level of spending on big projects, otherwise known as “capital investment”? The answer was a shock – $65 billion by 2035.

He said this would be “catastrophic” and meant we’ll have to pull our borrowing heads in after the completion of the Big Three. Good luck with that. Something tells me SA will easily hit the “catastrophic” target unless our governments demonstrate a policy courage that’s been missing for the last 30 odd years.

On Wednesday, I called Tom Koutsantonis, former Treasurer and now Transport and Infrastructure Minister responsible for the $9.9 billion South Road monster.

Before the state budget, he hit the big red pause button on the former Marshall Government’s complicated shandy of tunnels, overpasses and lowered motorways for the 10.5-kilometre Torrens to Darlington stretch of South Road.

This took a few hundred million dollars off the books for the 2022-23 financial year, making the budget papers look slightly less sick. He’s asked his department to conduct a review of the Marshall Government’s plans and that is now overdue.

It seems the department’s advice is unambiguous – Adelaide can’t afford not to complete a project it can’t afford

So, had he considered simply killing the project stone dead?

“I have put that question to the department,” he said. “What would happen if we don’t do it?

“They say we’re the last capital city in Australia, on the mainland, to run a grid network to move traffic without a non-stop motorway that sits on top of the grid.”

He said not completing the corridor will start to have “real world impacts” on an overloaded traffic grid and a public transport network that’s already a “scheduling mess”.

The South Road choke was now seeing big movements of cars “rat-running” down Marion, Unley and Goodwood Roads, and added congestion on east-west roads such as Daws and Richmond roads and Sir Donald Bradman Drive. He said the city’s public transport routes, including the O’Bahn and Seaford line, were also “close to capacity”.

Does it have to be expensive tunnels, then?

“I’ve seen the modelling,” he said. “I don’t think an elevated motorway is cheaper. Weighing it all up, I think tunnels are going to be the solution. And I don’t think we can afford not to do it.”

Why not a toll road, built and operated by a private consortium?

“It would be a career-limiting move,” Koutsantonis replied.

Because the corridor completion is being jointly funded with the Commonwealth, he argues that if the project didn’t go ahead SA would lose roughly $5 billion – the federal cash earmarked for South Road couldn’t simply be switched to an alternative project.

This argument points to a serious flaw in the Commonwealth funding model, because it means state governments grab money for projects that the federal government decides are important. It often results in a skewing of buckets of cash to roads instead of smarter, long-term solutions, like passenger rail.

It seems the department’s advice is unambiguous – Adelaide can’t afford not to complete a project it can’t afford.

It also seems the Minister is going to junk the “final” Liberal plan and go for longer twin tunnels. He fully expects the final cost will blow-out beyond the $9.9 billion estimate. No kidding.

In July, InDaily reported that Infrastructure SA, created by the Marshall Government to provide independent oversight of major projects, had waved an amber flag on the South Road upgrade.

Its so-called “gate 2” assessment, delivered last October, gave the project an amber rating, meaning there were “major issues and/or risks identified with appropriate mitigation measures provided”.

If SA’s transport bureaucrats think a “non-stop motorway that sits on top of the grid” is going to fix Adelaide’s traffic mess, they need to pause and smell the two-stroke. Non-stop motorways in other capital cities do stop – often – and generate more traffic, not less.

Premier Peter Malinauskas has nailed his government’s green credentials to the promised Whyalla hydrogen plant. That just leaves the $2.05 billion new Women’s and Children’s Hospital in the frame, for those sad and lonely individuals worried about debt.

The existing children’s hospital might be a bit long in the tooth, but it works perfectly fine, doesn’t it?

Tom Koutsantonis is part of the team reviewing this project too. The father of two young daughters likes the idea of a new hospital.

“We can have nice things,” he said.

Yes, Minister. But eventually, someone’s going to have to pay for them.

Matthew Abraham’s political column is published on Fridays.

Matthew can be found on Twitter as @kevcorduroy. It’s a long story.