14 Dec 2017

Wellington road plan would not withstand earthquake

9:16 pm on 14 December 2017

Earthquake hazards have forced the Transport Agency to go back to the drawing board over a long standing roading project in Wellington.

The route of the new road could go through Takapu Valley.

The planned route through Takapu Valley. Photo: RNZ

The road would have linked Petone with Grenada and provided an alternative to traffic-clogged Ngauranga Gorge.

This route has been talked about for decades and is currently in the design and investigation stage.

Any decision to proceed is still a long way off, until at least resource consent or funding has been approved.

But the agency is worried about the earthquake resilience of the scheme and is also concerned about dangers to steep cuttings from storms.

A special evaluation found the current alignment of the road might not stand up to landslides following a major earthquake, deemed to be magnitude 7.5.

As a result, the project would not reflect the high priority on resilience by local and central government.

In addition, the costs have more than tripled since widely quoted figures of $250 million to $270 million were published two years ago.

NZTA staff said none of the figures can be taken for granted since the scheme is still in its design phase.

But the latest evaluation puts the costs at $955m.

Accounting for estimates of contingency costs from a major disaster, the scheme would cost $1.443 billion.

Put another way, the cost would be $125m per kilometre, just for the earthworks, compared with $38m for Puhoi to Warkworth.

In the meantime, the agency plans further discussions on this road.

"We will now work with the local councils to review the project objectives," the agency's Director of Regional Relationships Emma Speight said.

"Together, we will reconsider the need for an expressway standard, examine some of the discarded options and explore how the project could enhance and promote public transport and cycling.

"The communities affected by the project also need to be part of this conversation. Once we've agreed with councils on the project objectives, we'll talk with the community about the project's next steps and the opportunities they will have to provide input."