Auckland mayoral hopeful John Tamihere has proposed beefing up the city's Harbour Bridge to 18 lanes - but incumbent Phil Goff says it would bankrupt the city.
"A new 10-vehicle lane harbour crossing, which will carry cars, rail, pedestrians and cyclists, can be completed within six years on the existing bridge piers, replacing the existing bridge," Tamihere said on Friday, claiming its construction will have "minimal disruption to traffic".
"My team have looked at overseas structures and costs and it is very doable," he added, without providing an estimate of the cost.
He did compare it to a bridge 'superstructure' replacement in the US, which reportedly cost NZ$160 million. The original structure was "functionally obsolete", and was completely replaced by the new one.
Tamihere's proposal involves replacing the existing Harbour Bridge with an entirely new two-level structure with the same appearance as the original.
There are currently no rail services on the North Shore.
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"Superstructure replacement will bring forward by decades rail connectivity and improved road provision to the North Shore, at a significantly reduced cost than other options," Tamihere said. "It will be a priority."
Goff called it "total fantasy stuff and fundamentally dishonest to promise" in a tweet.
"Either he intends to bankrupt the city, burden ratepayers with massive extra rates or he is making it up because he know he is never going to deliver it.
"Widening the motorway at either end to match the new lanes would see massive demolition of buildings and destruction of homes and neighbourhoods. This will cost further billions of dollars that Auckland doesn’t have and the Government won't pay for."
Goff estimated it would cost more than $10 billion to build.
The Ohio bridge, on the outskirts of Madison, carries about 10,000 cars a day. The Auckland Harbour Bridge is in downtown Auckland, and carries about 170,000.
Tamihere also vowed to complete the Whangaparāoa Peninsula's Penlink highway, which isn't scheduled for construction for almost another decade.
"I will personally guarantee and commit to the Penlink Highway because it is the right thing to do," Tamihere said.
"Ratepayers and motorists on the North Shore need certainty, not hollow promises and backside covering."
Tamihere has emerged as Goff's main rival in the October vote. Both are former Labour Party MPs.