Road safety risks prompt Ruapehu tree assessment and maintenance project

A specialised digger with grapple was used to ensure the controlled felling of trees and branches and minimise the impact on surrounding areas.

Dead, dying and leaning trees along Ōhakune Mountain Road have been cut down or pruned due to road safety concerns.

The Ruapehu District Council said an unprecedented comprehensive inspection and maintenance project had been successfully carried out after potential risks to road users were identified.

Infrastructure executive manager Vini Dutra said the project was a collaborative effort among stakeholder organisations and experts to ensure the safety of the road.

“The inspection, conducted by a team consisting of representatives from GHD, Ruapehu Alpine Lifts, the Department of Conservation, Uenuku Charitable Trust and Ngāti Rangi, identified 19 trees across 13 sites that required further investigation,” Dutra said.

“A senior ecologist from Singers Ecological conducted a thorough visual inspection of each tree to assess their health, epiphytic species and potential bat or cavity-nesting bird habitats. The assessment confirmed the need for cutting down 15 trees, pruning or topping three trees, and allowing one tree to fall naturally. Additionally, recommendations were made regarding the relocation of epiphytic plants to ensure their continued growth.”

To minimise environmental impact, inspections were conducted in the areas where the cut trees would fall or where fallen remains were to be removed. This was done to identify any significant tree species that might be affected by the project. The ecological assessment helped determine appropriate courses of action while considering the preservation of the surrounding ecosystem.

“During the inspection process, no bat roosting cavities were identified, and it was advised that the works should take place between late April and early June to avoid disturbing bird roosting during the season,” Dutra said.

During the operation, there was strict adherence to established protocols including environmental regulations and the cleaning of vehicles and equipment, he said.

As the road runs adjacent to Tongariro National Park, no material could be removed from the mountain. Instead, all cut trunks and mulched branches were disposed of in existing disturbed areas and forest margins located next to the road.

Over time, the materials will decompose, contributing to the duff layer on the road shoulders and under the forest canopy. They will serve as a valuable food source for native insects and birds.

All vehicles and equipment were cleaned to prevent the introduction of unwanted plant pests into the Tongariro National Park.

Dutra said the hazardous tree removal was carried out using a specialised digger with grapple saw to ensure controlled felling of trees and branches, minimising the impact on surrounding areas.

“This is the first time that the felling of trees as preventative maintenance has been undertaken and it is anticipated that it will be several years before works of a similar nature is required,” he said.