Peter Dunne proposes multi-billion-dollar Wellington tunnels

The war over Wellington's Ohariu electorate has begun with a multi-billion-dollar idea from incumbent United Future MP Peter Dunne.

He's proposing to replace a steep section of State Highway 1 with a pair of tunnels twice the length of Auckland's new Waterview Connection.

A slip in the Ngauranga Gorge last week caused headaches for Wellington commuters. But for Mr Dunne, it was an opportunity.

"The gorge has been a failure in recent weeks with slips and other hazards and bad weather, and I don't think we can have our main access way put at threat," he said.

Slip at Ngauranga Gorge blocks SH1 access into Wellington

His solution is to build a tunnel under the gorge, bypassing it altogether - at a length of more than 4km.

Mr Dunne's idea is inspired by Auckland's new Waterview Tunnels which are 2.4km long, cost $1.4 billion to build and have just opened after four years of construction.

The Wellington equivalent is likely to be expensive, but Mr Dunne admits he doesn't "have a costing figure" for his proposal.

The timing of this plan isn't a coincidence. An election is looming, and he's facing a challenge from Labour's Greg O'Connor.

"There's much better things that these billions of dollars can be spent on than just an expensive election promise.

"No one has asked for a tunnel any more than anyone has asked for a wall."