Joyce says report raises many questions on $2b plan but consultants say it's a winner.
Consultants have produced a glowing business case for a $2 billion-plus inner Auckland rail tunnel, without which they warn worsening traffic will turn development away from the city centre.
But Transport Minister Steven Joyce says a report from a $5 million study commissioned by KiwiRail and the former Auckland Regional Transport Authority raises many questions to be worked through before the Government can consider contributing to such a costly endeavour.
Despite the funding uncertainty, the consultants believe the investment will be repaid more than three times over, in "transformational" economic benefits.
Although they estimate a relatively modest return of $1.10c in transport and normal wider economic benefits for each dollar spent on the project - the same as for the proposed $1.65 billion Puhoi to Wellsford highway - they have added a productivity premium to predict an overall gain of $3.50c.
Auckland Mayor Len Brown said yesterday in issuing the consultants' report that they had provided a compelling case for the tunnel, to more than double the capacity of the region's rail network and put most of the central business district within a 500m walk of Britomart or three new underground stations.
"The potential for urban regeneration and additional growth that can be derived from investment in this infrastructure makes it transformative not only for Auckland but for our nation," he said.
"It is the most critical element in Auckland's transformation into a globally competitive urban centre and in becoming the world's most liveable city."
The project, which would involve drilling a tunnel from the western end of Britomart towards two junctions with the western railway line at Mt Eden, was Mr Brown's top transport priority during his mayoral campaign, followed by rail links to the airport and Albany.
But Mr Joyce last night described the inclusion of transformational benefits to calculate a return of $3.50c for each dollar invested as "webs [wider economic benefits] on steroids" and said it was the first time he had seen such an approach in a business case.
He said an estimated $1.99 billion cost for the tunnel did not include $340 million for extra tracks and trains needed to run through it, making a total of $2.3 billion.
"It would be the biggest thing that would suck up all the money in Auckland for quite some time."
But the consultants - from the three firms of Aecom, Parsons Brinckenhoff and Beca - say the potential for urban regeneration means KiwiRail and the new Auckland Transport agency should proceed immediately to gain a designation over the route.
They say that without the project, Britomart will be almost at capacity within three years, leaving virtually no room for extra services after the arrival of electric trains.
Auckland Council member Christine Fletcher, a former mayor and National Party minister who is co-leader of the centre-right Citizens and Ratepayers team, said the tunnel was one part of the mayor's vision which had support across the political spectrum of councillors.
"If there was one driver for amalgamation for Auckland that the Government has delivered on, it was the key issue of transport and they have long said ... that when Auckland has a consensus on this, we'll work with them.
"Well, the consensus is here."
