Kokanee Mountain Zip Line near Nelson, British Columbia, offers six lines that weave down a steep valley surrounded by high alpine peaks to the north and a large lake to the south. The geography provides stunning views, but also interesting weather patterns, according to co-owner and GM Jay Manton, who runs the operation alongside his brother, Todd.
Kokanee experiences katabatic, or downslope, winds, which flow down the valley from a large mountain glacier. As a result, late afternoon gusts pick up almost daily, bringing a consistent 15-20 mph tailwind to zip-line riders around 4 or 5 p.m.
“Our longest line is located directly down the valley, and riders can gain excessive speed if the right gust catches them,” says Manton.
Though an engineer by trade, Manton says wind was only a minor consideration during Kokanee’s design and build phase. The revelation that high winds would be an issue happened after the zip lines were already operational. “We had not realized the extreme weather fluctuations we would be dealing with daily in our valley,” he says.
Kokanee is not alone. As with any operation in the outdoors, it takes time to learn your area and understand what it can throw at you. Still, it’s easier to design things right at the beginning versus trying to retrofit after you’re operating.
“It’s important to think about your specific course and the conditions that occur there,” says Lori Pingle, co-owner of Get a Grip Adventures in Columbus, Ohio. “The course should be designed and tested considering the wind conditions at that site. The wind considerations are also going to vary based on the course construction—a course in the trees will be affected differently than a course out in the open, or a course utilizing man-made structures.”
Design/Build
According to Aerial Designs owner Valdo Lallemond, understanding prevailing winds during initial site analysis is the first and most important step. “We try to understand, what are the main winds? We try to understand the seasonal changes, and we try to understand the force of the winds,” says Lallemond.
There’s a lot to consider when planning a course around wind. For example, headwinds, tailwinds, and crosswinds—in any combination—can have varying effects on speed and braking over the length of a single zip line.
“Wind can affect whether or not a guest makes it to the other side of the zip, or could cause them to zip faster than normal,” says Pingle. “These conditions can change throughout a day, throughout a season, and over the course of the year.”
Lallemond says Aerial Designs strives to understand the geographic factors that make winds stronger. The topography of a mountain or a canyon, for example, creates interaction between cool and warm air flowing upslope or downslope, resulting in consistent mountain-plains wind.
In certain cases, “builders may allow for seasonal adjustments in the tension of the lines, just as they would in cases of extreme swings in heat and cold,” he says. “Lines sag more when they’re hot, and they’re tighter when it’s cold. On any particular zip line, it’s the extremes that are the focus of attention, whether that means temperature, length, pitch, or wind exposure.”
“Once we have that understanding,” adds Lallemond, “we take into account what kind of zip lines we are building.” And once a course is designed, they adapt to the variables through the design and operation of the braking system.
“If you have a very long or very fast zip line, you have to do a lot of braking,” Lallemond notes. “In those cases, we often use a ZipStop, but after the ZipStop, we put a second system, such as an ABS, that allows us to do even more braking, and to pull people in if they don’t make it to the arrival platform.”
Trees are also a major consideration in a wind-prone environment, says Scott D. Baker, Registered Consulting Arborist and Board Certified Master Arborist with Tree Solutions Inc.
“All trees are able to move around substantially when loaded by wind forces,” says Baker. “Every different forest ecosystem will have different species, and all of them will have specific characteristics.”
In the design and building phase, Baker looks at the support trees closely, testing, if necessary, for decay using acoustic tomography and micro-resistance drilling. “We can also test for stability and fracture safety,” he says. “We look at any tree within range of the course elements and if conditions of concern are present, those trees would receive a close inspection.”
Each course should have its own wind parameters provided by the manufacturer—and sometimes refined by subsequent vendors, says Pingle.
Still, as Kokanee discovered, sometimes the precise impacts of wind aren’t measurable until a course is put into use. Therefore, “It’s not uncommon for builders to test elements and converse with clients on a regular basis over the course of a year or two post-build to learn the parameters,” says Lallemond.
Operational Impacts
In response to its unanticipated afternoon downdrafts, Kokanee had to tweak operations variables for guest safety and comfort. “We set our brake system out further to give the participant more time to slow down,” says Manton. “We also decreased our weight limits to mitigate any issues.”
Kokanee also learned to employ a classic cannonball at times to move folks along. “During the day the wind is moving up the valley, which can cause our smallest participants to come into landing areas extremely slow or, in rare instances, not make the end of the line. We’ll use the classic cannonball position to try and get those participants to the end.” On the flip side, using the starfish position to slow guests down has had limited success.
Lallamond says that some operators will even add weight to people on a headwind day. “You want to avoid a backpack or something dangling,” he says, “but it’s typically put on the person, like a weight vest or belt, as long as it doesn’t cause discomfort or pain. Or, you do tandem zipping, where an adult goes with a kid, for combined weight.”
One solution for lines that run too fast or too slow in wind is to change the curve of the zip line, adds Lallamond, often done by the operators per manufacturer’s recommendations, and mostly accomplished using Quicklinks.
Aside from the obvious safety precautions, guest comfort—both mental and physical—is a huge consideration on gusty days.
“Not only can wind affect the speed which people travel on the zip lines, it can also make platforms shake or move and can create a noisy environment,” says Pingle. “I have seen guests get motion sick from being on platforms in trees that were swaying, even though the course was operating within the established wind parameters.”
Guides at Kokanee are trained to inform guests about wind factors, and discuss the higher speeds and greater forces on the guest when the brake engages. “Being honest with guests about what they are going to experience has been the best way to accommodate for guests’ comfort,” Manton says.
In fact, Kokanee’s training course for guides evolved along with the park’s operational wind considerations, so guides can recognize unsafe conditions specific to the enironment they operate in. “During operations, your guides are your best source of information for conditions on the course, and must be willing to change procedures to accommodate for a safer course for all involved,” says Manton. That inlcudes delaying or canceling tours if the winds are blowing too fast.
Don’t Blow It Off
There are a variety of potential wind impacts for park designers and operators, and various ways to mediate or counter them. Adding weight, changing stance, thoroughly training guides, and understanding the prevailing winds within your area prior to finalizing your park design are all key.
“It’s easier to design the line slower or faster at the beginning than try and retro-fit the lines after you are operating,” reminds Manton. “This means getting data from local resources (i.e., airports) and from the valley you intend to operate in (i.e., anemometers, weather stations, etc.).” This data will help determine the most efficient way to manage the guests’ speed.
Manton won’t make the same mistake twice. He says Kokanee staff is working on opening another operation a few hours away, and wind has become a major topic of discussion. “Prior to finalizing any lines, we need to understand the prevailing wind, and any lines that are running with the prevailing winds, we decrease the grade of the line.”
In the end, we can’t control Mother Nature, we can only work with her.
