They promised authorities they would not cross the Auckland Harbour Bridge without permission but on Sunday protesters on foot and bikes surged through a police cordon and onto the motorway.
Thousands of people burst through police cordons to get on to the bridge on Sunday morning, campaigning for walking and cycling access to the bridge.
The illegal protest has disappointed police and the New Zealand Transport Authority (NZTA).
"Everyone is entitled to a peaceful protest but at the point where they break the law, as soon as they cross onto the motorway, that's not on and the answer is no," says Wayne McDonald, NZTA regional director.
McDonald says organisers of the Get Across campaign did not stick to their agreement.
He says they had promised not to go on the bridge during the protest when the NZTA explained it was unsafe to be there.
Protesters were moved onto lanes three and four to avoid a swaying motion on the clip ons.
"We were forced into closing the bridge to make sure no one was injured," McDonald says.
"We wanted to avoid people trying to move from the clip on onto the truss section over gaps in the road deck which are dangerous for anyone not in a vehicle, especially small children."
The northbound lanes of the bridge were closed for over an hour after protesters broke through barriers. Outnumbered police were powerless to stop people getting onto the bridge in a demonstration calling for better pedestrian and cyclist facilities.
The Transport Agency has rejected calls for cycling and walking access on the bridge and has refused to let protesters walk across because of safety concerns.
ONE News reporter Melissa Stokes says hundreds of people walked across the bridge in a peaceful protest.
She says there were lots of families with young children and people told her it shows the appetite of Aucklanders for a cycleway on the bridge.
Traffic in the areas leading to the bridge came to a standstill but motorists travelling from the North Shore to Auckland City were still able to use it.
The organiser of the Get Across campaign says he was was caught by surprise when people started storming their way onto the bridge. Bevan Woodward says he had insisted protesters should obey police if permission was not granted for them to cross.
The Transport Agency says the protest won't speed up the provision of non-car access. McDonald says the agency has plans, but they are 30 years away. He says the size of the demonstration came as no surprise.
McDonald says the agency understands what the protesters want,
but it can't be done just yet. He says the bridge will remain a
motorway until a tunnel across the Waitemata Harbour is complete.