More than 8000 people turned out to take a look at a 7.5km toll road, north of Auckland, before it opens to motorists next year.
The northern gateway toll road is a 7.5km extension of the northern motorway between Orewa and Puhoi.
People were invited to cycle, walk or take a bus tour of tunnels on the route on Sunday.
The new toll road will allow state highway traffic to bypass Orewa, easing traffic congestion in the town.
Motorists will have the option of using the free, alternative route along the existing State Highway One via Orewa and the Hibiscus Coast Highway.