How does zip lining work

Home Science Behind Zip Lining. Design of a Zip Line Every zip line consists of a trolley attached to a steel cable that is typically covered with a vinyl coating. Some of the questions that need to be answered are: How long of a distance will the zip line span? How high should the start and end points be? What is the topography of the ground relative to the zip line cable?

What will the start and end points be attached to and how can they be secured? How much tension should there be to give the zip line an appropriate slope? What will the weight limitations be? I don't want to destroy the topography because it's the very beauty they came to experience. Several cities in the United States have decided against zip-line construction because of environmental and habitat concerns [source: Dailey ].

The first rule of zip line safety is to trust the professionals. The European Ropes Course Association regulates zip lines in Europe, and accredits courses for safety. Some governments Australia and Germany , as well as some U. Now, let's get to the nitty gritty of what we're really all thinking about before we step into nothingness: What the heck is going to happen if the cable breaks?

And keep in mind that pounds kilograms is generally the weight limit for any one zip-line rider depending on the company and particular zip line itself , lest you think that only waifs and sprites are gliding down a line. As Gustafson points out, a cable "doesn't catastrophically fail overnight. These smaller filaments show signs of wear before a line snaps suddenly, and staff members are expected to inspect lines daily for signs of wear.

Some companies will use two smaller cables with two pulleys. Gustafson argues that having two small cables -- not to mention twice the pulleys, the carabiners and other equipment -- increases the risk for both human error and unequal distribution on the ropes. However, you don't have to immediately abandon your zip-line adventure if you're on a course with a double-cable system.

Gustafson recommends you make sure to ask if the cables work together, as opposed to one being a "back-up. Gustafson says to picture it like car tires ; if the tires on the right-hand side have lower pressure than the tires on the left, the wear will be different. It's the same with ropes -- a balanced system makes a safer system.

Now that you've received safety instructions, consider yourself prepared to learn about some zip-line trips that have gone very, very wrong. Of course, you can't tell immediately how safe a zip line tour is.

But here are a few things you can do to help ensure your safety:. While most zip lines in the United States that are regulated by the PRCA or ACCT have standardized ratings and training, it doesn't necessarily mean that flying through the air on a wire many, many feet above the ground doesn't present hazards. One of the first recorded accidents to occur on a zip line was in , when Robert Cadman of Shrewsbury, England, attempted to zip line from the top of St.

Mary's Church in Shrewsbury on a rope fastened to a tree, meters Unfortunately, Cadman's rope broke, and he plunged to his death [source: French ]. The recent popularity of zip lines has also caused more attention to be drawn to zip-line accidents.

In March , Barbara Sue Fojtasek fell more than 30 feet 9. Fojtasek was suspended in the air with an instructor when the primary line broke. A guide apparently failed to correctly set up the safety line, which is in place in case of a primary line malfunction.

Also in , a seventh-grader in Tennessee died from a zip-line accident after staff members at the church retreat he was attending failed to move a ladder that blocked the line [source: Stambaugh].

Although the boy was wearing a helmet, he sustained a fractured skull and vertebrae, as well as brain and other injuries from the high-speed crash into the ladder. This accident, which left the boy in a coma for four days before he eventually died, also points out that zip-line accidents aren't merely mechanical in nature.

Humans run these operations, and people do make errors in judgment or simple mistakes. Both of these more recent accidents speak to a larger problem. While many large-scale operations in the United States are standardized and regulated, many smaller operations -- or operations outside the United States -- are largely self-regulated.

As we said before, beware the zip lines that aren't professionally accredited, and those do-it-yourself zip lines that seem easy enough to attempt. Instead, read on to discover some professional courses that are a safer -- and way more exhilarating -- ride. Now that we know how zip lines work, why they developed, and the safety and accident risks, consider yourself ready for the zip-line trips you can take. These aren't the backyard lines your neighbor Jimmy rigged up; these are some serious hair-raising adventures for both fun and, as we'll see, work.

Costa Rica is an extremely popular destination for zip-line or canopy tours. Soaring above and through the rainforest , the industry has become one of Costa Rica's biggest draws. Sun City, South Africa, boasts the world's longest and fastest zip line. Descending into a canyon, it's meters It supposedly reaches speeds of more than kilometers per hour But is it the scariest? Consider St.

Augustine Alligator Farm in St. Augustine, Fla. When the air resistance reaches a certain point, that is when the object reaches terminal velocity: the maximum speed of travel for that object in those conditions.

Air resistance is always acting against the direction of travel, so you may notice your speed leveling out as you get further down the line. The key difference in the science behind zipline travel for a heavier person compared to a lighter one involves air resistance and terminal velocity.

You may notice that the air resistance equation above says nothing about the mass of the traveling object. The air resistance experienced does not depend on how heavy the object is. Terminal velocity is achieved when the force of the air resistance is equal to the force. This is due to gravity. M is the mass of the object, and g is the acceleration due to gravity, which is essentially a constant on a fixed line.

So as an object gets heavier, its force due to gravity, increases. This means that the object is able to go faster before reaching terminal velocity and leveling out. The science of ziplining is best understood by experience. So get out there and feel the force for yourself. Written By: Michelle Patten. The longest, fastest ziplines within miles This is not a canopy tour!