A zip line is a cable that is attached to towers or trees in such a way to allow a person to ride along it using the force of gravity. A trolly tracks along the cable allowing riders to reach some very fast speeds depending on the angle of descent.
The example above is from “Adventure Park at Five Oaks” located in the Great Smoky Mountains area. Here you see an example of a redundant system. These very popular Pigeon Forge zip lines entertain thousands of visitors annually.
The zip line rider is secured in a harness that is attached to the trolley. In this example the rider would be attached at two separate points on the harness and then to each trolley independently providing the zip-liner added security.
Some zip lines have brakes built right in but in this example the course was designed in such a way that “gravity braking” helps slow riders as they approach the end. This is done during construction by allowing the lines to sag in such a way to slow the rider’s momentum as they approach the next tower. The rider can also slow themselves down some by using their trailing hand and pressing their palm lightly against the cable with their gloved hand as you can see below.
This article was meant to give the reader just a general idea of what a zip line is. In this case it’s commercial use as a tourist attraction. If you look around online you’ll find the materials used, the construction of and even uses for zip lines can vary widely.