*Not my post* This is just a very interesting post on Redundancy from Richard Delaney on his Rope Test Lab page. Redundancy in Vertical Rescue I have been meaning to write something on this for quite a while - so here is a brief intro to my thoughts. For me, this is all about having no single point or person of failure in our systems. It is not about whether an individual component is strong enough - come on, seriously how many pieces of “certified-for-use” equipment have magically failed? Redundancy in the rope systems we use is almost entirely about the possibility of human error or environmental influence. Here I am thinking: incorrectly tied knot, poor inspection failing to recognise dangerously worn equipment, incompatibility between compontents (ie thin rope in descender), carabiner loaded on an edge, tripod tipping over, rockfall hitting rope, lateral movement on edge cutting rope,… and misunderstood creep in practice ending with systems looking nothing like what was originally intended. The biggest frustration for me with discussions about one or two ropes is that it has everything to do with the ability of two (roughly) equally tensioned ropes to deal with a rock-fall or other rope cutting events. Many studies have shown us that Dual Main/shared tension/mirrored/Twin Tension/TTRS/DCTTRS have more than double the survivability of single systems or tensioned main/slack belay/DMDB systems. It is more like 4 times better as we have halved the tension AND we have two ropes for that event to cut. As for hardware like Kootenays, double pulleys, swivels, rigging plates, maillon rapide, rings, etc. The descision to back these up is also not that hard. Again, it is not about strength. Seeing a sling through all the carabiners around a rigging plate is ridiculous - if the plate breaks, it WILL cut/snap the sling. It is all about the human and the potential for misuse. Well, there have been a few known examples of swivels coming undone… As for competition rules and pass/fail criteria set by certifying bodies, that is completely up to them and it is simply a part of defining the rules. I have been very involved with developing SPRAT’s position which is simple: “Failure of a component between an anchorage and a harness shall not result in a free fall or swing fall in excess of the limits described in Section 4.2, unless the introduced component: - Is manufactured as a closed component that cannot be opened without permanent damage. - Has no moving parts. - Is designed to accommodate multiple connections. - Has a minimum strength of either 24kN (5400 lbf), or two times the highest calculated required anchorage system strength within the rope access system.” (SPRAT Certification Requirements, 4.3.5) My advice is, with work and rescue, strive to have systems where the action, or inaction, of any single person cannot result in failure. We need to look after each other as we all make mistakes. Sure, there may be times where no one else is there or we need to use a single rope system - but these should be the exception and we should be completely alert, almost nervous - as if having to drive a car with no seat belt and no brakes.