More than 1.9 million trips have been made on a new toll road north of Auckland since it opened in February, but almost 28,000 people have not paid to do so.
The $365 million, 7.5km northern gateway route is an extension of State Highway 1 from Orewa to Puhoi. It opened during the Auckland anniversary weekend in January.
The Transport Agency says more than the number of trips in its first half year of operation is 8% higher than forecast.
Some 94% of users have paid, but more than $200,000 in unpaid tolls are still owing.
Other problems faced by the agency include the toll collection system and self-service kiosks.