The Christchurch City Council is backing the idea of an extra lane on the city's northern motorway.
It voted in support of the third lane along with other local authorities at a meeting yesterday.
The lane would be for southbound traffic from Tram Rd to Q-E-2 Drive, and the council said it would be for buses and cars with more than one person.
A separate cycle lane was also part of the proposal.
The Transport Agency will consider the proposal in June.