Bungee Article [Archive] - BLiNC Magazine

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January 3rd, 2008, 02:42 PM

JANUARY 2, 2008
Burning Bridges
Bungee enthusiasts are not jumping for joy

BY MARY SLAUGHTER

Though the term "hucking" probably won't be in any dictionary, it's a necessary addition to the lexicon of anyone who has been bungee jumping. The thing that makes bungee jumping worthy of this unusual term is the fact that jumpers stand poised on the edges of bridges, cranes or helicopter doorways and huck themselves into space. The ensuing freefall is a time for pondering life as the ground rushes up before a nylon-wrapped elastic cord snatches the jumper from death and back into the air.

In Idaho, there are plenty of bridges to huck oneself from. The Perrine in Twin Falls (487 ft), Glenn's Ferry Bridge one hour from Boise (160 ft.), Beaver Dick's Bridge 15 minutes from Boise (90 ft.), Lawyer's Canyon Bridge near Cottonwood (147 ft.), Hansen Bridge between Perrine Bridge and Shoshone Falls (370 ft.) and Bitch Creek Bridge on the Idaho side of the Tetons (144 ft.). The crazy part is: Who initially thought it would be a good idea to attach themselves to the underside of a bridge with a rubber band? Over the Edge Bungee, Inc. was one of the first.

OK, so it wasn't quite a rubber band. As Eric Lyman, founder of Over the Edge, explained, finding the right materials for jumping was about measuring the relationship between stress and strain.

"Stress is the force of the load you apply in pounds, and strain is the length the material stretches under that load," wrote Lyman via e-mail. "Using physics equations anyone may calculate the force that a body generates when it falls a known distance (momentum). Because I knew the stress/strain relationship for rubber strands of bungee cord, I could calculate [how much that] force would stretch the bungee cord."

Years later, Lyman was pleased to find that his original design for bungee cords exceeded accepted safety standards for load-bearing materials in other sports like rock climbing and even in Lyman's sport of bungee jumping. The safety factor of bungee cords is determined by how much stronger the cord needs to be than the amount of force applied to it. Lyman's cords had a safety factor of 13, versus the standard of 10. The bungee cord's durability, as Lyman explained, was developed so that it was good for 1,000 jumps.

"Knowledge of the principles [of momentum, stress and strain] applied together gave me great confidence to design and jump on a bungee cord that decelerated smoothly, was 13 times stronger than needed and would do it over and over again," wrote Lyman.

Safely leaping from a bridge isn't only about the cord. Leapers must also wear a seat and shoulder harness when body jumping or a seat harness and ankle cuffs if going head first. Anyone who plans to jump should wear proper equipment to prevent injuries, which can happen if the setup isn't precise. Improperly applied harnesses or cuffs can cause broken ankles and jumping wrong can "slap" the jumper, causing neck and spine injuries. But doing it right can lead to serious adrenaline rushes and fun.

Lyman is quick to clarify the statistical risks of engaging in any extreme sport. "Depending on which study you check, skydiving has a risk of death that is one in 1,500, BASE jumping one in 1,000. Hot air ballooning, motorboat racing, rock climbing, mountaineering, white water rafting, scuba diving and even skiing are all much more dangerous than bungee jumping, based on a day spent in each activity," wrote Lyman. "Bungee jumping has had only about 15 deaths worldwide, and most of those were in the early experimental years. Bungee jumping is very scary and very safe, near the best of both worlds.

"We have minimized injury by continually improving methods," wrote Lyman. "I have had minor cuts and scrapes that mostly occurred during retrieval in the early days. Others get slapped because they jump wrong. We have never had any serious injuries."

Once the recoil (bouncing) ceases, a jumper is left to dangle from the bridge until the jump crew, consisting of a crew chief, jumpmaster and rope crew, can retrieve him or her. Reclaiming the dangler is a fairly simple process of lowering a climbing rope down the bungee cord, which the jumper then attaches to his/her harness. The team pulls the individual back to the top using a basic pulley system.

The bridge plays a big role in how a bungee jump turns out. Although higher bridges allow for a longer cord and more freefall, bridge height is not a huge factor since the thrill is in the combination of freefall, ground rush and recoil. Naturally, jumpers also get a thrill from the view on the way down.

"The jump is always a kick, but if one jumps too many times at one place, the rush does diminish slightly," wrote Lyman. "The inspirational view is one of the best parts about seeking out a new bridge, and sometimes a simple change in scenery revives the original thrill even if the dimensions remain the same."

A bridge can be used for jumping if it's within reasonable driving distance, has clearance for swinging jumpers and has strong anchoring points for attaching cords. Every jumper is attached to the bridge through multiple carabiners and the cord is anchored at separate, independent anchoring points for redundancy at major beams in the bridge. The beams are designed to bear the weight of two loaded semitrailers.

"A major beam in a bridge does not even blink at the load of a bungee jumper," wrote Lyman.

Of course, without the bridge, bungee jumpers are limited to flying out of helicopters and cranes, and in the past, bungee jumpers have come under fire from the Idaho Transportation Department. Bungee jumping from bridges is legal, but the ITD complains that bungee jumpers damage handrails, block pedestrian traffic and distract drivers. The recent closure of the Perrine Bridge to bungee jumpers has angered Lyman and his crew, and they are once again battling bridge closures. Lyman has fought to remove signs from bridges that state: "No jumping from bridge. No loitering on bridge." Police have been unable to resist harassing jumpers, questioning the legality of what they are doing. Lyman responded to the Perrine closure in a letter to newspapers after the signs were posted on Nov. 2.

"Bungee jumpers are becoming more common and pose no more of a distraction to motorists than BASE jumpers or pretty girls," wrote Lyman. "Ironically, the greatest distraction has always been the police themselves who investigate these non-crimes with their lights blaring."

Nathan Jerke, the public information specialist for the Twin Falls branch of ITD, confirmed that signs had been posted.

"Our primary goal is to prevent any additional distraction," he said. "A pretty girl walking on a walkway that is there for people to walk across is a little different from someone standing there with a harness on getting ready to jump."

BASE jumping is still permitted on the bridge (BASE stands for building, antenna, span, earth). According to Jerke, BASE jumpers also stand there getting ready to jump, but the amount of time spent on the bridge is considerably less and, therefore, less distracting.

"For bungee jumping they take time to set up a platform. It's more of an extended event. It blocks the walkway, and they are attaching equipment to the bridge. It has caused damage to the hand railings," said Jerke. "Someone can come along with a parachute on their back and jump off. It takes two or three seconds."

Lyman insists that bungee jumpers never cause damage, never block walkways and if drivers slow down to watch, well, who wouldn't? Bungee jumpers may be ill-fated in the bridge battle since Twin Falls has decided BASE jumping is an economic boon for the town and had their first BASE-jumping-celebratory-festival last summer.

"The city of Twin Falls has hung their hat on BASE jumping," said Jerke.