The Lines Company (TLC), based in Te Kūiti, has just undertaken the first successful trial of its heli-saw, a new piece of specialised tree-trimming equipment that could transform New Zealand’s electricity sector. But how does it work?
Is it a bird? Is it a plane? No, it’s a...heli-saw! The tool is a saw hanging from a helicopter and would be used to keep trees off power lines.
The heli-saw, owned by Lakeview Helicopters, was trialled by TLC in a forestry block in Kuratau near Taupō last month.
In a little over an hour, the heli-saw successfully trimmed 950m of radiata pine along a corridor housing a 33kV network line.
The tree clippings were left at the base of the trees, leaving two blocks of trees - 9 and 14 years old -undamaged.
TLC vegetation manager Jason Gaukrodger said the trial was “sensational”, saving the company many weeks of work and thousands of dollars.
It proved the heli-saw technology had incredible potential, Gaukrodger said.
“I had high expectations, but this blew me out of the water in terms of how efficient it was. It was much faster than I anticipated, and the pilots had incredible control,” he said.
“This technology has the potential to be transformational for electricity distribution companies like ours, as well as for the forestry sector.”
TLC chief executive Mike Fox said for customers the potential benefits could be huge.
TLC services 24,000 connections across some of New Zealand’s most challenging geographical terrain.
About 10 per cent of its network – or 150,000ha – is covered in forestry blocks, some poorly maintained.
The company had 269km of power lines running through forestry blocks as well as 106km of line through Department of Conservation (DoC) land.
It was an ongoing battle to keep trees clear of power lines, making the network vulnerable to storms and weather events.
“Cyclone Gabrielle is a good example of what can happen. Across our network, we sustained around $1.65 million in damage just from that one event, and the vast majority of that cost was from trees falling into lines,” Fox said.
“In a normal year, we’d invest around $1.6 million in vegetation management, but in the future we will need to invest more because of increasingly volatile weather patterns and the increase in commercial forestry.
“Over the next 10 years, we’ve budgeted a further $200,000 to $600,000 per annum to keep trees away from power lines and in some cases, reroute some lines away from trees completely.
“Those costs are huge, and at TLC we don’t have a big customer base to spread them across. The financial impact is significant, costing each customer on average $60 to $90 per year.”
TLC said they would continue to trial the heli-saw technology this month, on a plantation forest south of Piopio in the King Country.
As part of this, a 2.6km corridor would be trimmed.
Gaukrodger said the forestry sector was invited to see the heli-saw in action at Kuratau and left impressed.
“This technology helps both TLC and forestry owners manage the risk from trees and does so cost-effectively, especially in steep or hard-to-access terrain.
“The other option is felling the trees completely, but removing edge trees opens up forestry blocks to wind. We can send arborists in to trim trees, but we are literally looking at weeks and weeks of work. With this technology, weather permitting, we’re talking hours.”
Gaukrodger said safety was TLC’s primary concern when it came to the heli-saw, but they were approved by the Civil Aviation Authority for under H125 B3E and AS350 B2 helicopters.
“We began looking at this technology a few years ago, so have had time to think about every facet of safety. We’ve put a huge amount of time into health and safety documentation and into developing a helicopter guide for use on our network.”
Gaukrodger was optimistic the upcoming trial in the King Country would be successful.
“This is a tool desperately needed by our industry and none of us want it to fail. It has the potential to transform the way we manage vegetation and that’s important for TLC because across our network, more and more land is now going into commercial forest.
“It also allows us to reduce safety risk because we’re not having arborists up trees for extended periods of time, sometimes in challenging terrain.”
Heli-saws had the potential to help distribution companies better manage faults, he said.
“If a tree brings a line down and if weather permits, we could trim the whole corridor, doing the job once and doing it properly. We have to get ahead of the game and used appropriately, this could be a game-changer for us and the wider sector.”