Construction expert says second Auckland harbour crossing is our 'Big Dig'

An Auckland construction expert says a second harbour crossing is the city's 'Big Dig' and six years to prepare is a realistic timeline given the behind-the-scenes work needed before shovels are put in the ground.

But Auckland's Mayor is far from impressed and wants to work with a faster, cheaper and better plan.

First there was Skypath, then there was the 'Northern Pathway' which was just Skypath with flasher graphics. Then John Tamihere wanted to put 18 lanes over the top.

Now the Government says we must go under the harbour. But all those tunnels are going to take a while.

"This is Auckland's 'Big Dig'," said Professor John Tookey, a construction expert at AUT's School of Future Environments.

Prof Tookey said some of the hardest work will happen before the 'dig' even starts and 2029 for the first shovels in the ground is a realistic timeline.

"Astronomic, it's huge. Lots of moving parts. Lots of consents required, lots of commercial relationships that need to be set up and established, lots of money deals that have to be established, and finalised and put into a position where risks are allocated," he said.

"It's insanely complicated, and absolutely no surprise whatsoever it's going to take six years."

And across the Auckland divide, Devonport knows better than most how much another crossing is needed.

"The tunnel makes sense," one person told Newshub.

"I think I'll be 70 by the time it's finished! Oh and I'll be gone!" another added.

"And we've seen this bridge gets closed what happens," a third added.

Yes we have.

Aucklanders don't need reminding of the great 'Carmaggeddon' of 2020 when a single steel strut damaged by a toppled truck stopped the city in its tracks for days.

But Auckland's Mayor said both major political parties' transport plans won't happen unless they work in partnership with Auckland, and that's not what's happened here.

Wayne Brown said the proposals to start by 2029 are about politics, not transport, and he and Auckland Council are looking forward to working on better, faster, and cheaper plans.

Sunday's announcement also makes an allowance for two of the existing bridge lanes to be given to pedestrians and cyclists, but Bike Auckland wants one lane now.

"That would set us up for the behaviour change and motive, to make sure future plans are a success," said Bike Auckland chair Karen Hormann.

But bike, drive, bus - most Aucklanders agree we need to build a bridge alternative so we can all get over it.