Green Party transport spokeswoman Julie Anne Genter said the flyover was a waste of public money.
"The Basin Reserve flyover plan is incredibly expensive, opposed by Wellingtonians and will have a negative impact on the heritage value of the Basin Reserve,'' she said.
The flyover was a solution looking for a problem as NZTA data showed traffic volumes on Buckle Street and Patterson Street were declining.
"The vast majority of people coming into Wellington take public transport, cycle or walk. Great investment in light rail and buses, as well as cycle lanes could significantly reduce traffic flows in this area further."
But Wellington Airport chief executive Steve Sanderson said he supported the flyover decision.
Passenger numbers were forecast to double from five to 10 million by 2030 and a connecting road from the Airport to Wellington central was critical.
"Travel times in Wellington already have significant variations due to congestion with the trip between the Airport and CBD taking between 13 and 45 minutes. We are supportive of the process and initiatives to promote public transport that make it easier and safer for everyone to travel," he said.