Designers of Auckland's $2 billion Waterview motorway tunnels project are trying to solve congestion and safety problems at a three-tiered interchange between two state highways.
Among 12 options under consideration are shifting Great North Rd to the west through Waterview, and then sending it over the new motorway interchange en route to Pt Chevalier, instead of under it.
The Transport Agency said these were only preliminary ideas, with no formal standing.
But they had to be refined into a short-list before decisions could be made on whether to deviate from an earlier proposal presented to a Government-appointed board of inquiry.
The agency's northern highways manager, Tommy Parker, acknowledged that moving Great North Rd westward through the Waterview straight, to allow traffic to emerge from a motorway tunnel on the eastern side, would have "huge implications".
Asked about the idea, he said: "We are nowhere near that - it is just blue-sky thinking."
But Mr Parker confirmed that the agency had asked project contractors to consider variations to the interchange proposal approved by the board of inquiry, to minimise conflicting traffic movements.
Northwest Community Association convenor Bill McKay welcomed the agency's efforts to improve traffic flow, saying it would reduce pollution.
"The last thing we want is a lot of bumper to bumper traffic with all the fumes and so on."