Unison trials helicopter saw technology in Rotorua to keep power lines safe and reliable

Unison Networks (Unison) successfully trialled innovative heli-saw technology in Rotorua last month to improve the safety and reliability of its electricity network. The heli-saw, a large saw suspended beneath a helicopter, can quickly trim large areas of trees, especially in places that are hard for ground crews to reach.

For the trial, Unison partnered with Manawa Energy (now part of Contact) to use the heli-saw on a large forestry block at Tumunui in Rotorua, where Manawa also needed vegetation trimmed away from their critical overhead power lines connecting Manawa’s Wheao and Flaxy power scheme. The collaboration delivered cost savings for both electricity companies and greater efficiency for the property owner. The results were significant. In just three hours, the heli-saw trimmed almost one kilometre of large radiata pine trees near Unison’s power lines. This work would normally take Unison Contracting’s arborists about three weeks to complete by hand, mainly due to the extent of growth in the forestry block and the challenging terrain.

While property owners are responsible for keeping their trees clear of power lines, some sites require specialist equipment and expertise, which is why Unison invests in solutions like the heli-saw. By using this technology, Unison can manage the risk to its power lines from trees, making its electricity network safer, more secure, and more resilient for local homes and businesses. It also reduces safety risks for staff by not having arborists up trees for extended periods of time.

Trees and other vegetation are a major challenge for electricity networks across New Zealand. About 20 percent of power outages on Unison’s network happen because trees or branches touch power lines. Recent strong winds showed how serious this can be, with fallen trees causing outages for hundreds of customers. Restoring power quickly and safely is always Unison’s top priority.

The heli-saw technology is already being used in forestry and farming areas around the country, where big trees need to be trimmed away from power lines. All work follows strict safety procedures, including turning off power lines and working closely with landowners.

Other utility companies, including major firms like KiwiRail and Transpower, have already achieved positive outcomes using heli-saws.

Unison General Manager Networks and Operations, Gagan Chadha said Unison is committed to using smart solutions to manage vegetation and maintain a safe, secure, and resilient electricity network.

“This trial shows our commitment to finding innovative ways to improve safety and reliability of the power supply and to proactively manage risks to our electricity network. If property owners have trees that are difficult to manage near power lines, they can contact their local arborist or Unison for guidance to make sure the job is done safely,” Mr Chadha said.

After the Rotorua trial, Unison plans to use the heli-saw in other areas of its electricity network, including Taupō and Hawke’s Bay. Alongside heli-saws, Unison is also using satellite imagery to make vegetation management safer and more efficient for everyone connected to its network.