I wanted to
address the recent Barnum Rigging accident...
I can say a few things..
1. They were mimicking something that we do.--basically a mobile with bodies--some of what you have seen at all souls has had as many as 20 individuals hanging.
2. This is known as "single
point loading"
3. The gear being used to hang that
armature and the bodies was far underrated..and at a single
point should have had a 20,000lb. shackle--not a single 45KN rated caribiner--which is what failed. Basically hanging an elephant with a paperclip.
4. Our single
point systems are designed at 10 to 1 or greater. and as redundant as possible. coming into a swivel is always a crux--because it can't be backed up effectively..but it can be--as we do--be top rated gear that is engineered for 10 to 20 x times the "working load limit" it comes down to paying top dollar for the next
level of gear which will ensure success---ie. outside of an earthquake or a catastrophic force taking something infrastructure down.
5. There are basically 2 type of riggers in the industry--those that rock climb---and those that do not..
The later (unless they are known to be safe and have been known to "Rig Big" [ex. Bill Sapis, Simon Franklyn etc.] and know the mostly simple math behind designing points)
is to be watched very carefully as they do not have real world experience loading systems that are duty enough to absorb
shock loading and other kinetic forces that seems small to our eye--but in the case of that rig--all it took was for all the performers to use their core muscles and raise their legs up--and that extra 400-600 lbs of kinetic forces gave that single steel caribiner it's last ride..
6. several things to consider when rigging bodies:
a.
rating on climbing pieces is maximum load for "1" fall
b. working load is not calculated on climbing gear..but you can count on 1/3 the
rating usually-when in doubt--back it up-redundancy is your best friend
c. designing the rig from the start using sound math and extra care to ensure you are creating the gear package components properly--a chain is as strong as its weakest link. Gear failure IS NOT AN OPTION and it shouldn't be when you have performers risking life and limb on
hand and core strength alone-(as many apparatus cannot have
safety gear ie. silks, corde lisse--things that spin basically)
d. The circus world in particular--the single
point is everywhere due to the use of swivels. Basic Petzl and other branded climbing/arborist swivels are incredible pieces--for one or 2 people at most with moderate to no shocking loading. They need to be be kept clean, inspected and retired if any stick or any
play has occurred or the ears of them are too knurled from use. The next
level of swivel starts at $400 and goes up and up. My big rig swivels are $1200 and live in a padded case.
e. Steel is Real--use it where ever you can--(the piece that broke in the Barnum Accident was steel-although it was outclassed by the weight to load ratio)
f. Material usage and wear are a science..steel breaks down aluminum-rope cuts everything-as well as itself-gear has a life for use with bodies and then it goes to the guy
wire pile for the merchandise tents. Retire human rigging gear frequently and often-we all love the feel of fresh pieces
g. team work and another trusted and respected eyeballs on the systems each night of a show