As the taxi van neared the Waterview Tunnel, its speed continued to fluctuate between slower and higher speeds.
Motorways units located the van on SH20 near the Mount Albert area.
The 40-year-old male driver was taken into custody and allegedly returned a breath-alcohol result more than six times the legal limit of 250mcg, for drivers 20 and over.
“It’s deeply concerning to us that a professional driver has been transporting passengers while allegedly under the influence of alcohol,” Russell said.
“I shudder to think what might have happened had this man not been stopped.”
Russell praised the actions of the initial caller.
“The person that reported this to us should be commended for seeing something and doing something about it, calling police.
“I understand the caller also got behind the van and put hazard lights on to try and warn other motorists, and we acknowledge their assistance.”
The driver has been summonsed to court on a charge of being a transport service driver with breath alcohol over 400mcg per litre.