A beleaguered, multi-million-dollar shade structure in the centre of Darwin is costing taxpayers $100,000 per year to maintain, more than double what was previously estimated.
The 55-metre structure on Cavenagh Street was built almost five years ago as part of a government initiative aimed at reducing scorching temperatures in the CBD, which can top 60 degrees.
But tropical vines that were supposed to stretch over the wooden frame to provide shade have failed to fully grow, leaving large parts of the street below still in the sun.
Last year, a Freedom of Information request by the ABC revealed the shade structure had reduced maximum temperatures by less than one degree, prompting the opposition to liken the heat-mitigation initiative to "an episode of the ABC's Utopia comedy".
Now, in response to questions from the opposition, the government said the cost of pruning, fertilising and irrigating the slow-growing vines would be almost $100,000 this financial year, and the same the following year.
The annual outlay is double what the government estimated in 2021, when it said the cost of monthly maintenance would amount to $50,000 per year.
However, the government said only about $13,000 ended up being spent on maintenance last financial year.
"Currently there are no plans to replace the existing vine," a government spokesperson said in a statement.
"Trials are being undertaken to establish alternative species of vine to coexist with current species."
The government has also provided an update on the total cost of setting up the shade structure almost five years ago.
While the original figure in 2018 was $2.7 million, the government now has now said the structure cost $3.1 million to construct, and a further $215,000 to design.
The Country Liberal Party opposition has long-criticised the project and the government's handling of it.
"Not only has this been a huge waste of taxpayer money from the get go, but the vine itself has been a complete failure," the opposition's Gerard Maley said.