The City Rail Link continues to remain out of reach.
A study 18 months in the writing has failed to convince Transport Minister Gerry Brownlee the rail link is an essential component in the race to fix Auckland's existing and impending traffic woes.
The City Centre Future Access Study warns of significant delays and congestion in Auckland within 10 years.
The study claimed private vehicle speeds in the city centre at peak times will more than halve to 7kmh by 2021 and down to 5kmh - walking pace - by 2041.
The report was completed in consultation with central government officials but despite that Mr Brownlee says the tunnel is not viable.
He says the report is too narrowly focused.
It depicts an access crisis for the city centre if public transport is not reshaped and strengthened.
Mayor Len Brown says two-thirds of New Zealand's population growth over the next 30 years will be in Auckland and accommodating that growth would require significant investment to complete the public transport networks.
"We must complete the City Rail Link without delay," he says.
"It is an essential investment for the whole of Auckland because it doubles the capacity of the rail network and improves access to our town centres adjacent to rail.
"The city centre will increasingly be the focus for high productivity jobs and the City Rail Link enables this growth."
The study identified the City Rail Link as "essential" and stated that bus-only investment will provide short-term benefits, although in some cases it would be ‘worse than doing nothing' for private vehicle travel times.
The tunnel has the backing of Auckland Transport chairman Lester Levy.
"The study underlines the importance of the City Rail Link to improving the entire transport network," Mr Levy says.
"It provides a logical and factual basis on which the work already under way can continue."
Mr Brownlee says while useful the report fell some way short of convincing the Government it should provide financial support to any fast-tracking of the proposed City Rail Link.
"The Government is not discounting the potential for enhanced rail services to improve central Auckland congestion in the future, be it along the proposed City Rail Link route or another service.
"But this valiant attempt to make it stack up struggles to make the case."
Mr Brownlee expected a broader review of potential transport solutions for Auckland rather than the narrow case studies released.
"Completion of the western ring route in 2017 will also draw many thousands of traffic movements away from the CBD, yet none of these major transport corridors is explored in detail.
"Also overlooked is that evolving workplace practices and emerging technology will most likely have a considerable impact on peak hour travel over the next 30 years."
He says the study's modelling suggested the City Rail Link was not viable in the next 15 years.
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