First attempt at bridge swinging


Sunday 15 August 1999 - In the afternoon Walter called me and we went climbing under the Van Brienenoordbridge. One of the quays under the first pylon is made from large granite blocks and in many places the mortar has eroded. This leaves a variety of holds for hands and feet, ranging from large jugs to small finger holes. You meet the whole variety when traversing from one side to the other. There is even an overhanging section where you pass under a small footbridge. Lots of fun.

Then we decided to experiment with the "Kiene-swing" (german name) or with "Bridge swinging" (english name). We attached a sling to the handrail of the footbridge, clipped a carabiner into the sling and attached a climbing rope to the carabiner. Then I fastened the other end to my climbing harness and jumped off the quay.

The total length of the rope+sling was only 6-7 meters and if you jumped hard you made a nice wide arc with your ass close to the water. It was big fun (for big children) but we didn't like the scraping sound of the sling along the concrete edge of the bridge. We found a small drainpipe (rainpipe?) leading through the floor of the bridge. We lowered the sling and carabiner through it, attached the rope and continued our game. Now the sling didn't scrape anymore and we were more relaxed. We exchanged turns at the swing and tried to adjust the rope for minumum distance between your ass and the water.
Then while it was my turn I suddenly heard a big splash and found myself lying on the quay with 3/4 of my body in the river. I'll never forget Walter's worried look as he came running towards me asking if I was OK. I still had no notion of what had happened, I didn't feel hurt but was totally surprised and disoriented.

Cold and dripping I tried to find out what had happened. We found out that the sling had broken, while normally it should hold 3000kg. Upon further inspection we discovered a tiny sharp edge at the bottom of the rainpipe. If you didn't know it was there you wouldn't notice it. But it had cut through the sling very effectively. Also the physics had worked perfectly. The sling had broken when the rope was hanging vertically during the swing and the maximum vertical force was being exerted on the anchor. That's why I plunged directly under the anchor, at the edge of the water.

In hindsight I'm very glad we first used a laboratory setup before doing a real 20m swing. Then our mistake would have been lethal. Now I only had a 10cm long thin bruise on my back and another on my right elbow. And I have killed my special 2m40 sling, this really hurts because I was very attached to it (no pun intended, I always use it for my slackrope exercises).

 

Technical tips how to do better next time

Thanks to: Brian Davis, Tony Brocklebank, Nigel Robertson, Urs Vollmer, GŁnter Gersdorf, Steve Bennett, Hoyt McKagen, Nikola Dentschev

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© 1999 Petr Kazil - 21 December 1999