The Greens are pledging to pull the plug on Auckland's proposed East West link if they form part of the next Government.
It's an arterial road linking State Highway One at Sylvia Park to State Highway 20, and is estimated to cost $1.8 billion.
Infrastructure New Zealand says at $327 million per kilometre the motorway will end up being the world's most expensive road.
Green Party leader James Shaw says there are better ways to spend the money.
"The most efficient way of moving freight around is on rail. It moves faster, greater volumes, and keeps trucks off the road which frees up the road for other users," he says.
Mr Shaw says it won't happen if his party forms part of the next Government.
"We would reprioritise investment in transport towards the modes that move the greatest number of people and freight around at the least cost," he says.
"Image if we spent those billions of dollars on building light rail through to the airport and the sheer numbers of people that would get to move around."
National leader Bill English claims the road is vital to easing Auckland's traffic congestion.
A board of enquiry is considering public feedback and will release a decision on the project's fate in November.