The Transport Agency has told Transmission Gully's contractor, Wellington Gateway Partnership, it must open the Wellington highway within the next two weeks.
It will be the sixth attempt at opening the 27-kilometre road.
The $1.25 billion dollar project has been beset with delays, including because of the Covid-19 pandemic and is almost two years past its original due date.
Wellington's mayor Andy Foster was among local mayors welcoming the announcement, saying that the news, which has come on the heels of international border restrictions lifting, increases the economic confidence for the city.
Earlier, Waka Kotahi cut back red tape for the builder CPB HEB by allowing it to defer completion of 19 safety and quality assurance tests, and dropped some requirements of a further 30 tests.
A final pre-opening safety inspection would still be required.
However, Waka Kotahi Transport Services general manager Brett Gliddon said despite pavement and road-surface tests still among the tests not met, based on expert advice they were confident the road was safe.
"We have not been prepared to compromise on the road's safety, however all of the critical safety assurance tests have now been completed to a standard that gives us confidence the road will be a safe, reliable route for motorists between Wellington and the rest of the North Island."
"Now that we have deferred these quality assurance requirements, we believe there is nothing substantial that can't be finished by the end of March, which would prevent the road from opening. We have told Wellington Gateway Partnership (WGP) that we expect the road to be opened as soon as possible and that responsibility now sits with them."
Under the Public Private Partnership (PPP) WGP is responsible for determining when the road can be opened.
Subsequent to the Covid-19 outbreak in August 2021, Waka Kotahi, WGP, CPB HEB and Ventia have been negotiating an early access arrangement, which would allow motorists to use the road before all of the road opening completion requirements set out in the contract have been met.
As agreement had not been able to be reached, Waka Kotahi has formally directed WGP to allow the public to use the road before the end of March 2022.
Waka Kotahi said it would not be announcing a specific opening time for the road, in order to prevent any queuing which could cause safety and congestion issues.
Mayors thrilled
Porirua Mayor Anita Baker was pulled out of a Zoom meeting this morning to be told the news.
"We finally have a date, it's unbelievable really... two weeks to go."
She has been assured the tests that have been deferred are not to do with the environmental impacts of the road, which was something she had been worried about.
"I wanted to make sure all the silt ponds and the planting and everything was done so they've assured me that will have no impact on our harbour... so I'm satisfied."
Kāpiti Mayor K Gurunathan said while another opening date felt a bit like déjà vu he was confident this time it was the real deal.
"The planning, construction and protracted sign-off process needed to get the road open has tested everyone's patience, especially those of us in Kāpiti.
"We are pleased the agencies involved have managed to balance the need to achieve high standards with getting the road open."
He said the new road was much-needed as the region continued to grow and many people commuted too and from Wellington each day.
"Kāpiti whānau need to know when we are going into Wellington, as many of us do every day, that if things go wrong, we can expect to be able get home safely in a reasonable time. This new road will give us the security we need."
Meanwhile, Foster was looking forward to the economic boon.
"This is especially as it comes on the heels of border restrictions lifting, the economy moving forward and the increasing confidence being felt across our communities.
"People have been waiting for a very long time for this, highly frustrated at seeing the road so close yet so far.
"Today's news brings with it a huge social, environmental and economic benefits for Wellington and ultimately the country in light of the capital city's position in the national supply chain."