Some local residents are worried about the noise coming from traffic using Auckland's newly opened Waterview Tunnel.
The $1.4 billion tunnel opened to the public early this morning after months of delays.
Waterview resident and local community board member Margi Watson said while the tunnel itself was great, vehicles driving in and out of it were very noisy.
"There's still engine braking by trucks permitted on those ramps, which is incredibly noisy, the surface is supposed to reduce the noise.
"What will be really telling will be what that noise will be like in the future when Auckland's traffic patterns settle down and how much of that motorway noise, because the ramps are so high, are going to drift over those communities."
Ms Watson said some residents had already been discussing the noise issue.
But other motorists couldn't get enough of the newly opened Waterview Tunnel and were turning around and driving back through it again, the Transport Agency said.
The first vehicle travelled through the tunnel at 12.47am today.
CCTV footage showed the first cars entering the northbound tunnel, travelling from Owairaka to Waterview, accompanied by three New Zealand Police vehicles.
The Transport Agency had refused to say exactly when the tunnel would be opening to avoid long queues as motorists tried to see the new tunnel first-hand.
It said motorists should avoid rushing to drive through the tunnel in the first few days after opening to help ease congestion.
Brett Gliddon from the agency said some motorists could not get enough of it.
He said there was a "bit of sightseeing going on" with motorists going through the tunnel one way and then turning around and coming back the other.
Traffic was starting to build but everything was working as normal, Mr Gliddon said.
And most motorists were following rules and not changing lanes inside the tunnel, he said.
Transport Minister Simon Bridges said the tunnel was the most significant change in Auckland's transport system since the opening of the Harbour Bridge in 1959.
The tunnel, between Point Chevalier and Mount Roskill, was due to be completed in April but that was pushed back after a sprinkler system was found to be faulty.
Open days this month attracted tens of thousands of walkers and cyclists.