Cultural and environmental concerns have forced a rethink of plans for a bypass at Mt Messenger on State Highway 3 in Taranaki.
The Transport Agency (NZTA) has released a new set of options for the $80-$90 million bypass that forms part of a $135m upgrade of State Highway 3 from Mt Messenger to Awakino.
The transport sector and public heavily favoured an Option 3 in the original bypass proposal that crossed Ngāti Tama land and an area of bush that kōkako are being released into.
The new plans, most of which still cross iwi land, all propose the building of tunnels and bridges or flyovers designed to "tread lightly on the land" and lessen the impact on the environment.
Option A - the closest to the old Option 3 - is 5.4km and runs west of the existing highway. Options B1 and B2 are 5.2km and also run west of the existing highway.
Option C is a totally new route running east of the existing road and it is considered the least ecologically damaging option.
Option D is a 4.2km route that shadows the existing highway.
NZTA highways manager Ross I'Anson said it had listened to Ngāti Tama, local authorities and members of the public who had raised concerns about ecological damage.
"We have guys walking through there with local iwi looking at every native bird spices or insect species and plant life, so we're very much aware we've got to do the right thing."
Mr I'Anson said the agency's prime goal was still to deliver a viable bypass.
"Our view hasn't changed in terms of getting the best option possible and that would be the most efficient, the most resilient route.
"The one factor for us is what is going to be achievable and what's affordable so we haven't moved completely away from those three (original) options."
Mr I'Anson conceded the new designs could make the project more expensive.
'Big impact on the ecology'
The landscape and waterways in the Whitecliffs and Mt Messenger area are considered spiritually and culturally significant to Ngāti Tama.
Collectively known as Parininihi, they were returned to Ngāti Tama in its 2003 Treaty settlement. The iwi it has been active in protecting what is considered the largest continuous piece of lowland coastal forest in the North Island.
Iwi member Conrad O'Carroll, Tiaki Te Mauri O Parininihi Trust's kōkako project manager, said he was still concerned about the threat to the forest.
"I still don't like Option A. I've always been pretty clear about that because that's about where the coastal forest goes into inland forest. That's where the forest kind of changes.
"It's quite an important area and with a road going in there it will have a big impact on the ecology."
Mr O'Carroll favoured the new route Option C. "If they avoid the wetland that would have the least effect on the ecology and potentially you could improve the ecological values in there by going that way."
However he appreciated that NZTA had listened to the trust's concerns and included bridges, flyovers and tunnels in all of the designs, which would lessen their environmental impact.
'Do it once and do it right'
Road Transport Association area manager Tom Cloke said the new, more ecologically-friendly route was not a viable option.
"We certainly wouldn't support Option C in any way at all. It's probably the longest option and we believe it has the most vulnerability going forward over the years coming."
Mr Cloke said the association's approach was still "do it once and do it right" and it would support Option A, which was closest to the early Option 3.
"It's straight, it allow you to maintain your speed, it has good passing lanes in it. It would be there for a really long time and maintenance would be down so it's a really good option."
NZTA is holding public consultation meetings in New Plymouth, Urenui and Mokau this week and to announce a preferred option for the bypass in August and begin construction in mid-2018.