Taxpayers footed a hefty bill as the New Zealand Transport Agency spent millions on the controversial Basin Reserve flyover proposal before it was rejected by a Board of Inquiry.
Figures released to Radio New Zealand show the government agency spent nearly $11 million from 2012 until the proposal was declined earlier this year.
They show it spent $10.9 million on the planned $90 million overbridge in Wellington, including $3.4 million on Resource Management Act submissions and $2.3 million on legal fees.
The NZTA's state highway manager, Rod James, said other projects that have gone to a Board of Inquiry have faced similar expenses - and that means the cost is justified.
"It certainly is a lot money. It's not out of context with other similar processes, I would say. This kind of democratic process is an expensive undertaking."
The costs also included $2.8 million spent on staff attending the Board of Inquiry and NZTA used 35 experts to press its case.
Mr James said the fact the hearing went twice as long as scheduled did not help. "The hearing was 12 weeks longer than it was originally scheduled for. You can imagine all the people that were required to be at the hearing for an additional 12 weeks, so that certainly adds up in terms of additional costs."
In its final decision released earlier this month, the Board of Inquiry said NZTA failed to adequately consider alternative options, and its mitigation measures against adverse cultural and heritage effects were not good enough.
Wellington City Councillor Iona Pannett has always been against the flyover, saying NZTA has spent a ridiculous amount of money on a flawed idea.
"It's an enormous amount of money - and it does just highlight that when you're in an urban environment, costs do go up because you need to look at all the mitigation. It certainly would've been better if they spent that money up-front to find a better solution."
Wellington Central MP Grant Robertson said $10.9 million of taxpayers' money has gone to waste.
"NZTA didn't get those things right that the Board of Inquiry have highlighted. Obviously money will always be spent on a project like this - but, ultimately, all you need to do is listen to what the Board of Inquiry said to realise that money has definitely been wasted here."
But Transport Minister Gerry Brownlee said that is simply not true. "Every effort was made and I think the expenditure shows that. I don't agree with anyone who says it was a waste of money. Good process should not be stalled to save costs."
Mr Brownlee said more money would now have to be spent to find a solution. "It's back to the drawing board and probably a lot more money spent trying to get a solution."
NZTA would not say whether it would appeal the Board of Inquiry's decision, and has until Friday to make one.