Auckland's underground railway threatens to cost more than $3.3 billion if construction has to wait until 2020 for government funding, the Super City's transport organisation indicated yesterday.
A likely rise of up to $100 million on a price of $2.86 billion for each year for which a construction start is delayed beyond 2015 was seized on by the Green Party in Parliament.
Transport Minister Gerry Brownlee, under questioning by Greens transport spokeswoman Julie Anne Genter, denied a commitment to pay for half of the project from 2020 represented a delay. He said it would be "plain irresponsible" to complete the six-year project by 2021 for expected benefits of just 40c to 90c for every dollar spent on it.
But an Auckland Transport spokesman confirmed an estimated $2.86 billion cost of the project assumed trains would be running through its twin tunnels by 2021, and that the bill would rise by up to $100 million each year after that.
"If the delay was five years, then it will be $500 million," he said.
Mr Brownlee said although the likely financial pay-off before 2012 looked "incredibly poor", the Government had told Auckland Transport it was prepared to move earlier if various conditions could be met.
Those conditions are that annual rail patronage is on track to hit 20 million passenger trips well before 2020 and that employment in downtown Auckland grows by 25 per cent.