Matt Coldicutt and Rose Hansen and their newborn Tom. Matt Coldicutt and Rose Hansen and their newborn Tom.

Home was a quarter of a rugby field above the earth, past the strip lights and the electronic signs and the pre-cast concrete rings, as the wheels turned on Matt Coldicutt and Rose Hansen's 2003 Nissan Primera stationwagon.

The Mt Albert couple were eating ice creams and celebrating the opening of New Zealand's longest road tunnel, one they don't actually use that much, but one which will always have a place in the story of their lives.

They got a box of boysenberry Trumpets from Pak’n Save, Coldicutt says of that first trip through the newly opened Waterview Tunnel.

"Then we just drove through the tunnel as many times as it took to eat the two Trumpets each. We went through two or three times."

They need little excuse to indulge in their favourite ice cream, the 31-year-old says.

But the couple do have an affection for that tunnel they hardly use.

They’re putting the building blocks of life together in their doer-upper first home - bought in 2013 before stricter deposit rules were imposed - above it.

Waterview Tunnel buildings flanked by housing, Hendon Avenue. Waterview Tunnel buildings flanked by housing, Hendon Avenue.

The renovations roll on, the kōwhai and the Abyssinian banana palms – grown from next door's cuttings – are thriving, and four wee sweethearts have come into their lives, Rhode Island Red chooks Janis and Bessie, kelpie/wirehaired-pointer cross Poppy and, most recently, six-week-old son Tom.

There's a pride in the connection you have with an inanimate part of modern city life, when you know it runs right below you.

Especially when your twin brother only lives above the side of the tunnel across the street, Coldicutt boasts.

"We're on the apex, the high point of the tunnel," Coldicutt says proudly of the couple's Hendon Ave home.

"If you toot when you go past [southbound section] 54, you’ll know you're under us."

This is life above the tunnel that opened a year ago on Monday, quickening journeys and changing lives; the tunnel that took five years and the labour of 11,000 people to turn into reality.

There's life below, too, and not just that of the fleeting occupants of 63,000 vehicles passing through the twin tunnels each day.

Former Prime Minister Bill English opens the Waterview connection tunnel. The Waterview Connection was commissioned, designed and built by an international partnership called the Well Connected Alliance, comprising the NZ Transport Agency, Fletcher Construction, McConnell Dowell, Parsons Brinkerhoff, Beca, Tonkin & Taylor and Japanese construction company Obayashi Corporation. Former Prime Minister Bill English opens the Waterview connection tunnel. The Waterview Connection was commissioned, designed and built by an international partnership called the Well Connected Alliance, comprising the NZ Transport Agency, Fletcher Construction, McConnell Dowell, Parsons Brinkerhoff, Beca, Tonkin & Taylor and Japanese construction company Obayashi Corporation.

Nudging the 80km/h speed limit it takes 2m 10s – you'll be singing the last chorus of The Beach Boys' I Get Around before you're back above ground – to connect from Auckland's Southwestern Motorway to its Northwestern Motorway, or vice versa.

It takes a hell of a lot longer to keep this $1.4 billion king of transport infrastructure running, and safely, so you can catch that plane, tuck your little one in at the end of the day or, if the mood takes you, eat a box of Trumpets and toot as you pass section 54.