Te Ara Nui o Te Rangihaeata – Transmission Gully

Riparian PlantingBiodiversityRoading and TransitNative Planting

Jun 11

Written By Kauri Park

Te Ara Nui o Te Rangihaeata - Transmission Gully motorway is a 27km long, four lane stretch of motorway north of Wellington and part of the State Highway 1 route. The motorway which opened in March 2022, provides a safe, modern, and reliable route to and from Wellington.

Ecosystem – Planting for sustainability

Achieving good long-term environmental outcomes was a big part of the Transmission Gully project and Kauri Park’s planting of 2.5 million plants played a significant role in the results.

Once the project is finally completed it will have enriched more than 27 kilometres of streams with riparian planting, providing shade and a better habitat for native fish, eels, birds, and insects. More than two million native trees and plants have been planted on the valleys and slopes surrounding the motorway, including seedlings of long-living tree giants like tōtara, matai and rimu. This will create one of the most significant lowland native bush areas in the Wellington region and reduce erosion and sediment entering streams and ultimately Te Awarua-o-Porirua Harbour.

With the increased habitat, it’s expected that iconic songbirds like tui and bellbirds will successfully nest in the new bush and rarer species like native falcon or kārearea will migrate from the Tararua, Rimutaka and Akatarawa Ranges and kākā to and from the likes of Kāpiti Island.

Ecovitalism – Only the tough survive

The size of the project and the inhospitable terrain made Transmission Gully one of Kauri Park’s most challenging projects. The poor soils, rock and wind tunnel environment made it more important than ever to ecosource plants that would survive these conditions which we did with the help of local interest groups who collected a portion of seeds. By growing these seeds in our nursery under conditions that mimic their final destination, we produced resilient plants that will lead to the long-term success of the project.

Having our own fleet of delivery vehicles meant that we could provide the flexibility that this project demanded in both timing and location. Even then, access to the planting sites was near impossible and some of the 2.5 million plants planted had to be transported by helicopter to drop zones before being carefully manoeuvred down the steep terrain.

Given the difficulties with access, Kauri Park’s mission to create self-sustaining plants will come into its own as the areas surrounding Transmission Gully flourish and get to canopy.