The Big Read: Where are Northland's bridges?

Three of the 10 bridges promised by the National Party two years ago shouldn't or can't be built and there are no firm plans for three others, NZ Transport Agency documents show.

NZTA's experts have found there is no economic or safety reasons to build those three of the bridges and environmental reasons outweigh any benefits.

But Transport Minister Simon Bridges reaffirmed his 2015 "10 Bridges" commitment to Northland and promised the bridges would be built - with one exception.

The exception is the bridge which isn't a bridge - the Darby and Joan ramp north of Dargaville in the Waipoua Forest which protects the root structures of two giant kauri it passes over.

"We hadn't really thought about those conservation issues sufficiently but I think we would struggle to get consent," said Bridges.

The promise to turn 10 one-way bridges in Northland into double-lane bridges was made during the 2015 byelection which saw NZ First's Winston Peters take the seat from National.

National lost the byelection but said it would stand by its promise to build bridges which had not been priority projects on NZTA's list of roading projects.

Labour leader Jacinda Ardern was asked at a meeting with school children in Kaeo today what had happened to the promise.

"I'll ask Simon Bridges about the bridges," she replied.

NZTA documents show Bridges was told in 2016 four of the bridges would be underway by 2018 - with work on two of those now expected to begin this year.

The documents project the cost of the four bridges about to start around $60 million - well up on the original cost estimates for all 10 bridges of $32m-$69m.

But the NZTA briefing said two one-way bridges on State Highway 12 should not be built.

On each of the other one-way bridges on SH12, Bridges was told: "Not recommended for replacement as there are no maintenance issues with the bridge.

"There are no customer delays due to very low traffic volumes on this section of SH12 and there is no accident history. Environmental impact of replacement outweighs benefit."

It also said a third on the same highway - the Darby and Joan Bridge - "would require removal of the trees which are situated in the heart of the Waipoua Forest".

NZTA said three of the other promised bridges - including one on SH1 north of Okaihau - needed business cases to be developed.

Bridges said the two SH12 bridges would still be built as part of developing infrastructure in Northland to meet economic and tourism needs.

Bridges said some work would also be done with the Darby and Joan Bridge but "it may not be a double-lane bridge given the conservation issues".

Asked who came up with the list of 10 bridges, he said: "The government."

Bridges said: "People will have their political fun with them but no one is going to regret building them when they're done."

He said those looking for instant results needed to realise large infrastructure projects needed significant work before the earthmoving began. "This has always been a six-year pledge."

This election's candidate for National in Northland is Matt King - former police officer, former Honda motorbike salesman, business owner and farmer - said voters appeared to have expected results by now.

"It's on the tip of everyone's tongue," King said. He's been told the consents will be granted any day and that will allow construction to start at Matakohe, Taipa and Kaeo.

"I tell everyone but they just don't believe me. I'm in a rock and a hard place. Unofficially, I know what's going on. If I had a magic wand I'd say, 'Just put the press release out now'."

Peters has made a mockery of National's pledge over the bridges since they were announced.

Told of NZTA's recommendations, he asked: "What background work did they do when they made the announcement? It's cavalier in the extreme."

Of the bridges where work is soon to begin, there has been a symbolic "sod turning" ceremony at Matakohe which is due to receive resource consent. NZTA is building two bridges and straightening out the road with work expected to begin next month and end in 2019.

Construction of the bridge on SH10 at Taipa was also expected to start later this year.

Kaeo was the place where the "10 bridges" announcement was made and NZTA's system design manager Brett Gliddon said construction would get underway next year "subject to consents and property purchase".

The Weekend Herald tracked down farmer Bill Kerr as the land owner NZTA is negotiating with and found he's got the government over a barrel.

Kerr has farmed the land north of the Kaeo bridge for 27 years, including the paddocks the new bridge need to cross.

He's perfectly willing to sell - but told NZTA there's a wee job he'd like done first.

When NZTA came calling, Kerr wanted to talk about a drain he wanted under the road a few kilometres north of the bridge. The road there is mangroves one side (high tide laps against the road) and paddocks on the other.

When the paddocks flood, the water can't drain out under the road.

For three years he'd wanted NZTA to do something. For three years he'd watched fields flood.

Then Bridges named Kaeo's bridge as one of his 10 bridges.

"I hold the trump card," Kerr said. "Of course it's going ahead. You've got to have a new bridge. We're going forward, not backward.

"We're going to build a bridge and get the f***ing traffic over it."

So, sure, he'll sell the land - but not yet. "They're still working on the drain. You're f***ing with an Irishman here."

Once the drain was done, he would sell the land.

Kerr said he wouldn't be voting for the government though. "I'm voting for Winston Peters. I have ever since that Bolger."

• Information about the Matakohe project will be available Saturday October 7 from 11am-3pm at the Matakohe War Memorial Hall.