Opponents of the Basin Flyover are cracking the champagne now it's finally not going ahead.

The NZTA has announced it won't appeal a High Court decision to back the project being scuppered, effectively ending any chance of it happening.

Wellington City Councillor Iona Pannett said she's over the moon.

However, she still wants answers for why the Transport Agency took the case in the High Court in the first place.

She said it needs to be asked why a million dollars of taxpayer money was wasted on legal action.

"The other question we need to ask is why $1 million dollars has been wasted on the legal action around this. This is tax payer money."