About 20,000 people went through the Waterview tunnel today, among them a 10-week-old baby and a former prison officer who had also in the 1950s scattered the remains of one of the men killed during construction of the Auckland Harbour Bridge.
The tunnel will open to traffic around the first weekend of July, but the New Zealand Transport Authority is not giving the exact date or time for safety reasons and to avoid queues of motorists.
It completes the 48km western motorway ring route - a second motorway route through Auckland - and includes a giant motorway interchange at Great North Road to connect the Southwestern and Northwestern motorways.
I'm very interested in how it is going to go and excited about the fact it will make it easier to get to Auckland Airport
Prime Minister Bill English was joined by Transport Minister Simon Bridges and Finance Minister Steven Joyce to cut the ribbon on the $1.4 billion tunnel project, saying it was part of massive pipeline of investment to support a strong economy and population growth.
English said the Waterview tunnel project was 60 years in the making and a big day for New Zealand.
"There are a lot more projects in the pipeline and this gives us real confidence that we have got the infrastructure capacity to do the investment that is needed to support growth in New Zealand."
Bridges said the twin tunnels, which completes the 48km western ring route, marked a pivotal milestone not just for Auckland but New Zealand's highway network.
After speeches and the ribbon cutting, it was the turn of about 20,000 Aucklanders to enter the underground tunnel at the Mt Roskill end, for a chilly walk on a 2.5km or 3.5km circuit.
The first member of the public to enter the northbound tunnel was student Azwhayn McLean, who used the speed of his wheelchair to make history.
"I'm pretty excited. I thought other people would beat me in. I've been interested is seeing how it has unfolded and how it is going to go.
"It's an exciting development of what is happening in Auckland at the moment,
I'm very interested in how it is going to go and excited about the fact it will make it easier to get to Auckland Airport," said the 26-year-old, who lives in Ponsonby.
John Harris, an 82-year-old retired prison officer and bus driver, was unsure if the tunnel would do much to stop the city's traffic jams, but was looking forward to driving through it.
Harris did not walk over the harbour bridge before it opened in May 1959, but met the widow of an English worker who drowned during the construction period. He was a member of the Northcote Birkenhead Yacht Club and took the worker's ashes to be sprinkled around the piles of the bridge.
No-one was killed during five years of construction on the Waterview tunnel, but a 33-year-old project worker called Dennis died of cancer. A gantry was named after him and painted yellow in honour of the Cancer Society.
Tomorrow night, a cocktail party will be held inside the tunnel to raise funds for the Cancer Society.
Azaria Webster would have been among the youngest people to go through the tunnel at 10 weeks old. She was wrapped up warm in the arms of her grandfather, Leith Carter, of nearby New Windsor.
"I've watched it along the way. It's interesting to see the end product and it's what I would expect but when it comes to congestion I'm not convinced it will help," Carter said.
Brett Gliddon, NZTA's Auckland and Northland highway manager, said the tunnel had involved a lot of people, a lot of effort and a lot of time to deliver a great result.
"This is definitely a career highlight," said Gliddon about the twin, 2.4km tunnels, twice the length of the Auckland Harbour Bridge and the longest road tunnel in New Zealand.
He said it had been a big and complex project, involving the tenth largest boring machine in the world at the time, called Alice.
"It wasn't simple. We turned Alice around in a very tight, confined space. It was one of the first times in the world someone has done that with a machine like that," Gliddon said.
Auckland Mayor Phil Goff welcomed the tunnel project, but expressed concern about a $4b gap in the $24b joint Government and council infrastructure spend in the city over the next 10 years. With rapid population growth, he said the gap was $7b.
"While we applaud this tunnel, it's great we have connected the network up, it will take pressure off local roads ... but in peak-hour congestion this road will become congested just like every other.
"We need to think beyond this project now and that means a public transport system that large cities always rely on to get less congestion on the roads," Goff said.