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BTB 40: HOW STEEP IS STEEP IN NEW ZEALAND?

Contrary to popular belief the New Zealanders did not invent bungee jumping.

– Gary Olsen, factory sales representative, international

Extreme Logging

Simon Keeling and David Kirke from the Oxford University Dangerous Sports Club made the first ever jump using an elastic bungee cord off the Clifton Suspension Bridge in Bristol, England on April 1, 1979. However, the New Zealanders have certainly taken the pursuit to new heights by popularizing the activity despite all the potential risks involved. Bungee jumping, jet boating, mountain climbing, abseiling, skydiving and extreme snowmobiling are classified as ‘extreme’ sports and might involve waiving the life insurance policy of the participant.

Tigercat LS855C carrier with cable assist in steep slope logging application

Tigercat LS855C carrier with cable assist

Cable Assist Logging

Tethered or cable assist logging, now a growing trend in New Zealand, Chile and the Pacific Northwest, is a serious attempt to get the boots off the ground and improve the level of safety, especially on the steep and broken terrain characteristic of these countries. Despite valid concerns by nearly all logging machine manufacturers, most end users are of the opinion that the operator of a purpose-built, leveling track feller buncher or harvester, inside a proper forestry ISO ROPS, FOPS and OPS certified cab that is responsibly secured with one or two wire ropes and anchored at the top of the slope, is much safer than a chainsaw operator or a choker setter in the same terrain. With this in mind, contractors and forestry companies have chosen to implement such systems by purchasing a used bulldozer or excavator weighing around 30 tonnes, then rigging it with either a single 29 mm (11/8 in) wire rope or twin 22 mm (7/8 in) cables to a winch system. The other end connects to a hitch point on say, a Tigercat LS855C carrier fitted with a Tigercat 5195 directional felling saw. The hitch point has a load cell or tension monitor that links to a digital display in the cab so that the operator controlling the whole system by remote control is always aware of the tension on the cable. To avoid tension spikes, the cable must remain under load at all times.

Tigercat H855C carrier with cable assist in steep slope logging application. A chain is attached to the rear of the carrier for added safety.

Tigercat H855C carrier with cable assist

Tigercat Engineers in Field

All logging contractors going down this avenue are critically mindful of the risks involved and are approaching with care. The New Zealand forestry industry, through the auspices of the Forest Industry Engineering Association (FIEA), raised awareness of this logging method as well as other technologies by organizing the HarvestTECH 2015 Steep Slope Conference in Rotorua this past June. Tigercat, in trying to fully understand the application and how its track carriers, felling heads and six-wheel skidders are being used on steep terrain, sent a strong group of thirteen delegates including engineers, factory field representatives and Ken MacDonald, Tigercat’s CEO and owner. The group not only attended and participated at the Steep Slope Conference but also visited numerous Tigercat customer sites not limited to tethered applications. The value and importance of seeing machines in the field and listening to operator feedback remains a top priority with Tigercat’s engineering staff and this two week trip proved invaluable in this regard. Customers were almost overwhelmed by the strong interest that Tigercat has in ensuring it continues to produce machines that meet evolving contractor requirements. Amongst all the disagreement relating to these emerging methods, one point is quite clear. It is the background, training and ability of the operator to assess and mitigate risk on a constant basis that most affects safety in any forest, despite all the cutting edge technology

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