The expressway that has been proposed - that would allow state highway traffic to bypass Levin, solving its congestion challenges, could cost taxpayers more than $1 billion.
The New Zealand Transport agency has narrowed the potential routes for the Ōtaki to north of Levin expressway down to three options south of Levin which can connect to any of three route options north of Horowhenua.
Emma Speight, the Agency's director of regional relationships for the lower North Island, has told “Stuff” that the cheapest combination could cost $690m and the most expensive had $1.06b price tag.
She says "As you move into more challenging construction environments the costs absolutely go up.
The most expensive route involves building 12 bridges, while the others will require nine.
Since 2013, there have been 11 deaths and 43 serious injuries along the sections of SH1 and SH57, which the new expressway will replace as the main route through the area.
The Labour-led Government has not been willing to commit, at this stage, to completing the highway that was green-lit when National was in power.