Prime Minister Jacinda Ardern has officially opened Transmission Gully in a ribbon cutting ceremony on site this morning.
In a speech to the waiting crowd she said it was no secret that a road connecting Wellington to the lower North Island through Transmission Gully has been talked about for many decades.
She said it was first mentioned in the Evening Post newspaper in 1919.
Admitting it was not without its challenges, Ardern said Transmission Gully is " a testament to what can be achieved in spite of a rough start and in spite of a one-in-100-year pandemic."
The road could withstand a one-in-2500-year earthquake, Ardern said.
"This is modern infrastructure that is future proofing, that is the gold standard we must pursue in these shaky isles."
Transport Minister Michael Wood also spoke, saying he is the fifth transport minister to be involved with Transmission Gully project as it is known today.
Wood said it was music to his ears to hear the toots from vehicles driving past the ceremony this morning.
"Today is primarily a day of celebration and acknowledging a very significant achievement."
He said Transmission Gully will also be one of the country's safest roads.
"Everyone should be able to get to where they need to, whether, driving walking, or cycling, safety."
Waka Kotahi board chairman Sir Brian Roche said it was a magnificent occasion.
He said Transmission Gully has been a long time coming for everyone and the last few months in particular have been demanding.
"The engineering of this project was always going to be a challenge, but it's fair to say it has been a challenge in many other respects as well."
Roche said it was an amazing piece on infrastructure that will deliver for generations to come.
"Yes, there is still more to be done to fully complete this project, we remain fully focused on ensuring that happens in a timely and cost-effective fashion."
Wellington Gateway Partnership chairman Brian Harrison said the project team has overcome complex challenges during the build.
"We have encountered and absorbed earthquakes, extreme weather events and Covid-19's ongoing disruption to our complex local, national and global supply chains - to get to this day. It is a true testament to the skill and dedication of the some 8,000 individuals who have worked on this project."
More than 12 million hours of work have gone into the construction project.
Harrison said the workforce has come from local communities and regions across the length of New Zealand as well as international expertise.
Ngāti Toa Rangatira chairman Callum Katene said Ngāti Toa travelled the road this morning performing karakia.
The iwi has also given the road the name Te Ara Nui o Te Rangihaeata – meaning the great path of Te Rangihaeata.
The event marks a long awaited milestone for the new $1.25 billion motorway out of Wellington that has been bogged down with delays, construction defects and budget blowouts.
Waka Kotahi NZ Transport Agency has instructed the contractor to open the road by the end of March. The road will open to traffic tomorrow.
It means the four-lane road will be open in time for the Easter break, school holidays, and the return of tourists to New Zealand.
Ardern said Transmission Gully will transform the Wellington region, making it quicker and safer for people and goods to travel through the lower North Island.
"This road represents the largest Government investment in New Zealand's infrastructure in a generation.
"It is an example of modern infrastructure that features the highest safety measures, treads lightly through the environment and is future-proofed for generations to come."
The road will make journeys up to 15 minutes shorter for about 25,000 vehicles a day.
It will improve productivity with people spending less time in cars and more time at work and with family, Ardern said.
The Transmission Gully link roads, connecting the Porirua suburbs of Whitby and Waitangirua to the new motorway, were blessed in a ceremony yesterday.
The 27 kilometre motorway will open two years later than it was orginially expected to.
After a "huge amount of work" on the project over the summer, Waka Kotahi has said it's now confident the road has reached a stage where it is safe for public use.
Its current cost of $1.25 billion will almost certainly balloon even further when negotiations over the fallout from last year's Covid-19 Delta outbreak have concluded.
Transmission Gully is being built through a public-private partnership (PPP), the Wellington Gateway Partnership (WGP), with CPB Contractors and HEB Construction subcontracted to carry out the design and construction.
Infrastructure Minister Grant Robertson said the delay in getting the road open was because of National's "botched" PPP.
"We have cleaned up their mess so commuters going in and out of Wellington will finally be able to use the alternative route."
Robertson said the Government has asked the Infrastructure Commission Te Waihanga to revise New Zealand's PPP guidance to make sure any future partnerships don't encounter the same issues.
Te Waihanga has already undertaken the first part of a review into Transmission Gully which found serious flaws at the planning stage of the project, undermining the successful completion of the motorway.
A further review of the project will be undertaken now construction has been completed.
"Wellingtonians deserve proper answers as to why this road took so long to be completed", Robertson said.
Transport Minister Michael Wood said Transmission Gully is one of the most significant and complex new roading projects ever undertaken in New Zealand - but he undertsood the frustration over how long the road has taken.
"This is an important piece of infrastructure it will be a a huge benefit to the Wellington region but everyone feels a bit of frustration over how long this has taken," he told MIke Hosking.
He added the road was held up by a number of factors, including the Covid-19 pandemic and severe weather events.
"Any reasonable person would expect would create some delays...There were particular factors related to PPP as well."
The road is built over very challenging terrain and required "innovative environmental and construction techniques".
"What was a series of steep valleys, criss-crossed with streams, and flanked by inaccessible hills, is now a state-of-the-art motorway that crosses gullies, passes over waterways and winds through pristine native bush. Around two and a half million native trees and plants were planted as part of the project."
Transmission Gully has been built to the highest safety specifications and will provide a much safer route for road users, Wood said.
Lives will be saved and many serious injuries prevented, he said.
Firefighters responded shortly before 9am on Friday.