Into the wild weather with innovative machines

Facing difficult ground conditions and dire weather, the team at Marais Laying has successfully laid optic fibre cable along the highway between Haast and Lake Hawea, thanks to some clever machinery.

The mountains of the South Island’s west coast offer some of the most stunning scenery along with the wildest conditions in the country, but this rugged beauty is matched by dramatic weather.

In this landscape of hard rocks and freezing rain, a hardy team from Marais Laying has installed a fibre duct, running 119 kilometres along SH6, from Haast to Lake Hawea.

This project is extremely important for the tourism in the area, along with the residents, as it provides a second communications route. The vulnerability of a single fibre route was highlighted after the Kaikoura earthquake damaged the cable resulting in communications blackouts, something the authorities are keen to prevent happening again.

This was never going to be a simple project. The geography alone posed numerous challenges. On top of that, a timeframe of just 18 months and the requirement from the client for as a low environmental footprint meant several innovative solutions were needed to complete the project safely and on time.

To get it right, the team spent significant time planning the project. Their efficient and effective solution involved non-traditional machinery and methods, and a few unusual safety protocols.

Three teams of eight worked on the project, with the workers based in either Haast or Wanaka ­– at either end of the long and narrow job site. They were prepared for high rainfall, freezing temperatures, rockfalls and slips, and the lack of mobile coverage that comes with such a rugged and remote site. They also got to enjoy breath-taking scenery and some very clever new equipment.

Adrien Merceron, national manager of Marais Laying, says; “This was a challenging project. The site was very remote, the ground conditions extremely rocky, the comms were virtually non-existent, and the weather could be wild. But by using innovative machinery, we could deliver this project quickly and efficiently.”

Rather than using a traditional excavator fitted with a rock breaker to dig a trench alongside the highway, Marais Laying deployed a ST2 wheel trencher. This tool cuts a smooth narrow trench through the hardest rock, and faster and more efficient than traditional trench excavation.

On this project, it sawed a 280mm wide, one-metre-deep trench through the rock, laying the fibre cable and a tracing wire as it went. The ST2 made short work of laying the cable in the berm – its cutting blade can be offset from the machine and operated by remote control, allowing it to trench in more difficult terrain.

In places, there was no room in the berm and the cable had to be laid in the road instead. For this, Marais Laying imported a Tesmec trencher, the TRS885. This chainsaw trencher is designed specifically for fibre-optic projects and can excavate up to 800mm deep, laying cable as it goes.

“The TRS885 performed extremely well in what was very difficult ground conditions,” says Adrien.

In addition, a TRS300 was also put to work on site. This rocksaw trencher is a more compact model that can excavate to 650mm deep, more than enough for this project.

Once the cable was laid, it was covered with a layer of basecourse using a special chute on the back of a tipper truck to allow the narrow trench to be filled without spilling aggregate.

Compacting the basecourse with a traditional foot rammer was not an option, so Marais Laying imported a special vibrating wheel compactor from Europe to do this job.

The first of its kind in the country, the compaction wheel is mounted on a skid steer and travels along the narrow trench, compacting the basecourse evenly and to Transport Agency specifications, before it was covered in asphalt.

Together, these tools substantially reduced the impact on the site and allowed the project to move at a faster pace. However, there’s only so much machinery can do on a challenging site when weather is a major factor.

Work began on site in September 2020 at a time in Spring when torrential rain is not uncommon, which exacerbates the risk of rockfalls and slips. From the start, the teams had to be on high alert for natural hazards. Compounding this was the lack of cellphone coverage. Teams could only get reception in the first couple of kilometres at either end of the site.

The solution to this was old-fashioned two-way radio, but even this has its limitations in mountainous areas, so each team also had a satellite phone.

Because of the risk of rockfalls or slips cutting them off from the towns at either end of the site, or their base in the middle, the teams also had emergency survival kits with them, giving them the ability to camp on site for up to three days if needed.

The machinery too had ‘emergency survival kits’ with a complete set of spare parts on site.

“Because of the remoteness of our location, it could take four to five hours to get a replacement part if we had a breakdown, but by having spare parts on site, we didn’t waste time getting machines repaired and back to work,” says Adrien.

“We had to be very innovative to overcome a number of challenges on this project. Our specialised machinery performed very well in these very difficult conditions, as did the team, and we were able to get the result the client wanted, on time and on budget.”

Now completed, the project is stage one in a two-stage project to deliver broadband and mobile services for the West Coast as well as provide resilience of the telecommunications network in the event of natural disasters.

Stage two will see another 120 kilometres of cable laid from Milford to Te Anau.


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