Resealing works on SH12 adopt Kauri Dieback precautions


Waka Kotahi NZ Transport Agency is working hard to help protect the precious Waipoua Forrest in Northland from Kauri Dieback disease.

The Transport Agency’s contractors are working to repair and reseal 11 kms of State Highway 12 through the Waipoua Forest in Northland and are adopting special practices to protect against the spread of the disease.

The Kauri Dieback disease is devastating kauri trees is the Waipoua Forest, which is home to New Zealand’s largest known living kauri tree, Tāne Mahuta. The disease is easily spread through soil being carried on dirty footwear or by animals, equipment and vehicles.

Transport Agency Northland System Manager Jacqui Hori-Hoult says it’s the first time there’s been major work on the road since it was completed in 1996.

Contractors are digging up the road surface to carry out repairs before resealing, as well as rebuilding the roadside drainage system and cutting back vegetation.

“To drive the winding state highway through the forest is like taking a journey back in time to before European settlement and logging transformed the landscape. The forest grows right up to the road’s edge, with the tree canopy overhanging the road and it’s home to many rare native plants including native orchids. It’s a pristine and spectacular environment and we want to do everything we can to preserve it.”

“Because of the Kauri Dieback, the road team has to clean all vehicles and equipment before going into the forest and when they come out. Everything they disturb – whether they are digging up the road surface, trimming vegetation or fixing the roadside drainage - has to be picked up and taken out of the forest to a contaminated waste dump.”

It’s the first time since the discovery of Kauri Dieback that a roading project of this scale has been undertaken.

Kauri Dieback is a disease caused by a microscopic fungus-like organism, called Phytophthora agathidicida (PA) that kills trees of all ages. It lives in the soil and infects kauri roots, damaging the tissues that carry nutrients and water within the tree, effectively starving it to death. There is no known cure.

Waipoua is a former state forest, now managed by local iwi Te Roroa with governance support from DOC, MPI, the Northland Regional Council and local councils, the Transport Agency and roading contractor Fulton Hogan. The work is being carried out under the Waipoua Forest Management Plan which covers the edge of the road and its interface with the forest. The plan manages the effects of the highway on the forest’s biodiversity.

Te Roroa Development Group General Manager Snow Tane says it’s a good team effort.

“Te Roroa is thankful for commitment and support from Waka Kotahi and roading contractor, Fulton Hogan to the work being undertaken in Waipoua including their response to mitigating against Kauri Dieback which is essential to the well-being of the ngahere.”

SH12 forms part of Northland’s Twin Coast Discovery Route.

“The Transport Agency thanks road users, our partners and local communities as we carry out this essential work to maintain the state highway’s safety and resilience,” says Ms Hori-Hoult. 

A road re-sealing crew at work in the Waipoua Forest on SH12

A road re-sealing crew at work in the Waipoua Forest on SH12.

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