Zipline Designer

The starting point of the Wild Zipline Safari is a dizzying 7 meters (23 feet) off the ground. As I stood on the platform, my guide clipped my harness to a trolley. This device contains two or more pulleys—grooved wheels that a cable or rope can pass through. The pulleys dangle from cables stretching between observation decks placed across the park. I took a deep breath and stepped into the air.

The downward force of gravity sent me zooming over the park’s pastures and watering holes. The entire time, I used my muscles to balance in a sitting position. To slow down and come to a stop, I placed a gloved hand on the cable above me to create friction—a slowing force created when two objects rub against one another.

After my exhausting but exhilarating ride, I spoke with engineer Larry Gerstner, who designed the center’s zipline course and several others in Ohio. He explained how he builds these thrilling rides.

At the Wilds, we arranged the course’s 12 towers so visitors could see as many different exotic species as possible. I first evaluated the area’s topography, or physical features. I surveyed the location of trees and measured the ground’s elevation. This helped me determine the length of each zipline and the location and height of each platform.

I had to make sure that the heaviest of riders wouldn’t accidentally bump into the ground below or anything in their path—such as an animal. I actually measured the tallest giraffe, which stands 5.5 m (18 ft), to make sure riders would be able to clear its height. We also built a fence around the base of each tower so any person needing to leave the ride—for example, if he or she became ill—could do so safely without having a dangerous encounter with the park’s wildlife.

If a cable is less taut, riders will start their adventure at a steeper angle to the ground. That causes them to go faster. At the end of the line, they’ll actually be going uphill, which helps slow them down. Other factors like wind and a person’s position while riding can affect speed. A person who pulls his or her legs and arms into a cannonball shape is more aerodynamic—having a shape that allows air to flow easily around an object—than a person hanging loosely in the air.

After we build a zipline, members of the building crew take many test runs in different wind conditions. We adjust the end elevation until we find the ride’s “sweet spot”—a top speed of about 64 kilometers (40 miles) per hour that’s both exciting and safe for a rider.

At the Wilds, we built some of the platforms on constructed towers and others around tree trunks. We also left room aroundthe platforms for the trees to grow. We frequently consult with tree specialists called arborists to determine tree health and remove unhealthy ones in the zipline’s path.

It’s great to see people complete their first zipline course. I love seeing how excited they are about what they’ve accomplished.