A Government-ordered review has found a council business case overstated the potential economic benefits of an Auckland CBD rail link by nearly $3 billion.
Transport Minister Steven Joyce today released a Ministry of Transport-led review of the Auckland Council and Auckland Transport Agency business case for the CBD rail link.
The review found the estimated construction costs for the project - a total of $2.4 billion - are correct, he said.
But he said the transport benefits of the project are estimated at $387 million, rather than the $1.3 billion assessed in an Auckland Council and Auckland Transport Agency business case.
Its assessment of $3.3 billion in wider economic benefits from the project was also "very significantly overstated" and the real figure was "more like $305 million", he said.
"In short, the review says more work needs to be done to determine the full future transport needs of central Auckland before proceeding with a project like the CBD Rail Link," Mr Joyce said.
"However, the review suggests that in the meantime, it makes strategic sense for Auckland Council to move to protect the route, and I agree with that."
The review also said the project would have only a modest impact on traffic volumes.
It found the link was likely to remove up to 1400 cars of the estimated 29,000 cars travelling into the CBD during the morning peak in 2041.
Auckland Mayor Len Brown countered with a claim the project would be transformative for the region.
It was vital to start planning the project now to prevent future cost increases and potential overloading in Auckland's public transport network, he said.
He announced plans to protect the rail link route and to buy property necessary for its construction.
"The need for the tunnel is now urgent.
"Within two years most of the usable train paths in and out of Britomart will be in use, providing virtually no room to add future services at a time when public transport patronage is going through the roof.
"The potential urban redevelopment and additional growth derived from investment in this infrastructure would make the project transformational not just for Auckland, but for New Zealand as a whole."
The rail tunnel would include three stations at key locations to ensure most of the inner city is no further than 500 metres from any station and would mean more and faster services out to west and south Auckland, Mr Brown said.
"The rail tunnel will unlock unused capacity across the whole rail network. It will double the number of trains that can go through Britomart, let Aucklanders and freight more move around the region more easily, and reduce congestion on our roads."
The Government review suggested the Auckland Council undertake several steps to improve the future case for development of the CBD Rail Link, including implementing the city's spatial plan and city centre master plan to quantify where future CBD growth will be, create large scale residential developments along the rail corridors to capitalise on rail upgrade projects and build additional park and ride facilities to increase public transport demand.
The review noted, late in the process, Auckland Council and Auckland Transport provided a new alternative policy case which provided a range of new assumptions and policy considerations to the previous business case, however Mr Joyce said there was insufficient time for officials to assess the new plan.
"It appears to contain some things that are specifically related to the CBD Rail Link, and some things that would improve transport in Auckland, regardless of any decision to build the CBD Rail Link."
"I think the timing of the latest policy proposal underscores the need to go carefully through the spatial plan process and the various transport options; to make sure that together we make the right investments in future Auckland transport projects at the right time.
"In the meantime, we continue to invest $1.6 billion to electrify and modernise Auckland's commuter rail network to provide for the next stage of growth in rail patronage. This Crown investment will help deliver a modern, fast and superior commuter rail experience from 2013/14."