The Cave/Cliff Unit participated in a joint exercise at Cummins Falls State Park with the Tennessee State Parks and the Jackson County Rescue Squad. The exercise focused on recreating a single rope high-line failure that occurred during the evacuation of a patient by Park Rangers and the local rescue squad in the summer of 2015. 20 plus rescuers spent the day meticulously recreating the rigging, anchoring, angles and dynamics involved in the original failure in an attempt to repeat the failure and determine the ultimate cause. Taking a scientific approach, CHCRS deployed dynamometers to determine the maximum forces created during the failure. After hours of preparation, a litter was loaded with 470 pounds of test dummies and rope, then deployed. The line was tensioned to approximately 170 degrees with a force of over 7 kilonewtons (approximately 1,575 pounds) before the failure occurred. While 7kn of force is well within the working range of the rope, it was determined that poor rigging at the lower end station allowed the rope to be severed by a sharp edge.
In conclusion, the failure demonstration was successful in educating everyone on the importance of understanding and practicing the fundamentals of high-lines, rigging, rope protection and multiplying forces with angles. The goal of CHCRS participation was to help the responding agencies understand the dynamics behind the failure and to prevent a repeat of this event.
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