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skiclimb
Dec 28, 2010, 2:43 AM
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A buddy of mine is a window-cleaner in business for himself. Apparently OSHA requires a second backup rope for all repelling. On a second ANCHOR no less. Apparently so does the top industry standardization organization.
Ok from my point of view a second line is unnecesary but I will admit it is SAFER. No harm in that. (except unecesary cluster and encumbrance)
My main issue is this.
The BACKUP ANCHOR. I see no way for a backup anchor to EVER add to safety infact it has the distinct possibility of reducing anchor effectiveness due to splitting limited anchor points.
The rule I learned is that two anchors are ALWAYS weaker and less safe than the best possible single anchor. This just seems like holy writ to me.
I see no way around this rule. (well one due to human error).
Am I missing anything or are OSHA and others just plain dead wrong here?
(This post was edited by skiclimb on Dec 28, 2010, 2:44 AM)
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spikeddem
Dec 28, 2010, 2:57 AM
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You can probably repel people better whipping two ropes around rather than just one, so I suppose I agree with them.
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jt512
Dec 28, 2010, 3:01 AM
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skiclimb wrote: The BACKUP ANCHOR. I see no way for a backup anchor to EVER add to safety infact it has the distinct possibility of reducing anchor effectiveness due to splitting limited anchor points. The rule I learned is that two anchors are ALWAYS weaker and less safe than the best possible single anchor. This just seems like holy writ to me.
There's a rule about two anchors? Who would even think of that?
Jay
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skiclimb
Dec 28, 2010, 4:03 AM
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jt512 wrote: skiclimb wrote: The BACKUP ANCHOR. I see no way for a backup anchor to EVER add to safety infact it has the distinct possibility of reducing anchor effectiveness due to splitting limited anchor points. The rule I learned is that two anchors are ALWAYS weaker and less safe than the best possible single anchor. This just seems like holy writ to me. There's a rule about two anchors? Who would even think of that? Jay
Long ago crevasse rescue mentor. Refuting an old edition of Freedom of the Hills.
(This post was edited by skiclimb on Dec 28, 2010, 4:05 AM)
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wiki
Dec 28, 2010, 4:16 AM
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Your main line goes on one anchor (often a single bolt or sling around structure. This must be rated to 12kN (possibly 8 or 10kN n the US). Your backup line goes on another. You can attach both ropes to both anchors if you wish or depending on local legislation - equalised as if it is a climbing anchor.
Just as you wouldn't trust one bolt with your life at the top of a sport route, you don't have both ropes off a single bolt at the top of a building. Bolts have been known to fall out especially in 40 year old concrete.
How on earth is 2 anchors weaker anyway?
You have a second line because rope access guidelines weren't made for window cleaners. They were designed for access on oil rigs etc...
Often you are playing with hot and sharp things on the ropes. I have a work-mate who cut almost all the way through his main line with an angle grinder once...
OSHA isn't stupid in this case and neither are the people who have been doing this for years.
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moose_droppings
Dec 28, 2010, 4:20 AM
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skiclimb wrote: A buddy of mine is a window-cleaner in business for himself. Apparently OSHA requires a second backup rope for all repelling. On a second ANCHOR no less. Apparently so does the top industry standardization organization. Ok from my point of view a second line is unnecesary but I will admit it is SAFER. No harm in that. (except unecesary cluster and encumbrance) My main issue is this. The BACKUP ANCHOR. I see no way for a backup anchor to EVER add to safety infact it has the distinct possibility of reducing anchor effectiveness due to splitting limited anchor points. The rule I learned is that two anchors are ALWAYS weaker and less safe than the best possible single anchor. This just seems like holy writ to me. I see no way around this rule. (well one due to human error). Am I missing anything or are OSHA and others just plain dead wrong here?
The problem is your mixing common sense with OSHA.
The two are oxymorons.
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epoch
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Dec 28, 2010, 4:23 AM
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OSHA does things the way they do because people have died. So, they changed things to better allow rope access work in a safer manner. In industrial rope access work two is better than one. Redundancy plays a big role in safety.
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skiclimb
Dec 28, 2010, 4:59 AM
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wiki wrote: How on earth is 2 anchors weaker anyway?
2 anchors are always weaker then one anchor using all points of both anchors. (assuming you set it up correctly)
To epoch
I certainly can understand redundancy and safety. I have no argument with two lines being safer. It may not be realistically needed for a window cleaning repel in many cases but it is safer.
But two anchors is not safer in any realistic way I can see. I am however very seriously asking if someone can explain why. I am quite capable of having overlooked something and am trying to learn what it might be.
(This post was edited by skiclimb on Dec 28, 2010, 5:07 AM)
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USnavy
Dec 28, 2010, 6:04 AM
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skiclimb wrote: A buddy of mine is a window-cleaner in business for himself. Apparently OSHA requires a second backup rope for all repelling. On a second ANCHOR no less. Apparently so does the top industry standardization organization. Ok from my point of view a second line is unnecesary but I will admit it is SAFER. No harm in that. (except unecesary cluster and encumbrance) My main issue is this. The BACKUP ANCHOR. I see no way for a backup anchor to EVER add to safety infact it has the distinct possibility of reducing anchor effectiveness due to splitting limited anchor points. The rule I learned is that two anchors are ALWAYS weaker and less safe than the best possible single anchor. This just seems like holy writ to me. I see no way around this rule. (well one due to human error). Am I missing anything or are OSHA and others just plain dead wrong here?
A two rope system is pretty much the industry standard (or so was back when I was working in the industry). Generally you have a working line with say a Petzl ID'L attached (assuming your rappelling) and a second safety line with a Petzl ASAP attached to that.
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TarHeelEMT
Dec 28, 2010, 6:05 AM
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They require this for rescue as well. In fact, not only do we have to have a backup belay rope, but the belay itself has to be backed up by not one, but two prussiks.
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charlie.elverson
Dec 28, 2010, 6:06 AM
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I haven't looked at the stuff in a while, but if I remember right, OSHA does not require redundant anchor points. They require a safety factor of 2 and the rated strength of the point to be 22 kn. That is what constitutes an anchor. So, the secondary line being attached to a second anchor makes sense because then the anchor points are redundant. However, there's nothing prohibiting attaching both lines to a single redundant anchor point, like a belay anchor master point (I think).
Is there anyone here who has looked at the guidelines more recently? I think this is more or less correct, but it's a bit fuzzy.
(This post was edited by charlie.elverson on Dec 28, 2010, 6:09 AM)
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bill413
Dec 28, 2010, 1:56 PM
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skiclimb wrote: A buddy of mine is a window-cleaner in business for himself. Apparently OSHA requires a second backup rope for all repelling. On a second ANCHOR no less. Apparently so does the top industry standardization organization. Ok from my point of view a second line is unnecesary but I will admit it is SAFER. No harm in that. (except unecesary cluster and encumbrance) My main issue is this. The BACKUP ANCHOR. I see no way for a backup anchor to EVER add to safety infact it has the distinct possibility of reducing anchor effectiveness due to splitting limited anchor points. The rule I learned is that two anchors are ALWAYS weaker and less safe than the best possible single anchor. This just seems like holy writ to me. I see no way around this rule. (well one due to human error). Am I missing anything or are OSHA and others just plain dead wrong here?
I have rappelled off of buildings where what appeared to be a solid structure turned out not to be. The use of multiple anchor points (whether brought to a single master point or kept separate) seems to me to be quite reasonable.
And, back to the question - how are two anchors weaker than a single one? If they are both loaded, the load is split between them, resulting in a system that can hold more than a single anchor. If they are not both loaded, you still have the original strength of the loaded anchor. The only way I see for multiple anchors to be weaker is if they are both loaded, and the "master point" angle between them is such that you've multiplied the loading.
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skiclimb
Dec 28, 2010, 3:55 PM
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perhaps it is the definition of "anchor" that is the problem. I think of an anchor as the complete system that incorporates one or more points and includes the rope /webbing/attachments for the belay or repel rope itself.
Multiple points incorporated into a SINGLE anchor is of course good. Two seperate anchor systems utilizing different points BAD. all points should be incorporated into a single anchor system for the most strength possible.
Perhaps this IS what OSHA is saying when it says multiple anchors. Perhaps it means what I call multiple points. Can anyone clarify?
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bill413
Dec 28, 2010, 4:59 PM
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skiclimb wrote: Two seperate anchor systems utilizing different points BAD.
Again, why?
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tower_climber
Dec 28, 2010, 5:51 PM
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bill413 wrote: skiclimb wrote: Two seperate anchor systems utilizing different points BAD. Again, why?
I think he's saying that if you have points to build two separate anchors with multiple points, then building them all into a single anchor would be safer than splitting them into two anchors. For instance, 4 points in one anchor would be safer than two points in two anchors. Am I interpreting this correctly?
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skiclimb
Dec 28, 2010, 5:56 PM
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tower_climber wrote: bill413 wrote: skiclimb wrote: Two seperate anchor systems utilizing different points BAD. Again, why? I think he's saying that if you have points to build two separate anchors with multiple points, then building them all into a single anchor would be safer than splitting them into two anchors. For instance, 4 points in one anchor would be safer than two points in two anchors. Am I interpreting this correctly?
Roger.
Now it may not really matter if both anchors are overkill bombproof but basically incorporating all points in one anchor is generally desirable for simple repel situations.
(This post was edited by skiclimb on Dec 28, 2010, 5:58 PM)
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bill413
Dec 28, 2010, 7:18 PM
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skiclimb wrote: tower_climber wrote: bill413 wrote: skiclimb wrote: Two seperate anchor systems utilizing different points BAD. Again, why? I think he's saying that if you have points to build two separate anchors with multiple points, then building them all into a single anchor would be safer than splitting them into two anchors. For instance, 4 points in one anchor would be safer than two points in two anchors. Am I interpreting this correctly? Roger. Now it may not really matter if both anchors are overkill bombproof but basically incorporating all points in one anchor is generally desirable for simple repel situations.
Ah. OK.
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rrrADAM
Dec 28, 2010, 8:42 PM
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More individual anchors equals better than less, always.
Example:
Window washer is suspended by two anchors, phaving a 3rd and or 4th anchor for people to tie into is best, as it only takes one anchor to fail on the window washing platform, now all of the weight, will dynamically load the single anchor left. What would you rather be anchored to in this case? The window washer? The anchor that failed? Or an idependant anchor just for people? Window washer could plumet to the ground, yet you'd still be hanging there.
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wiki
Dec 28, 2010, 8:55 PM
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skiclimb wrote: perhaps it is the definition of "anchor" that is the problem. I think of an anchor as the complete system that incorporates one or more points and includes the rope /webbing/attachments for the belay or repel rope itself. Multiple points incorporated into a SINGLE anchor is of course good. Two seperate anchor systems utilizing different points BAD. all points should be incorporated into a single anchor system for the most strength possible. Perhaps this IS what OSHA is saying when it says multiple anchors. Perhaps it means what I call multiple points. Can anyone clarify?
When OSHA says an anchor, it means 1 single point. For example a bolt or a sling around a suitable structure.
If you are using an absolutely bomber piece of structure i.e a lift-house, you can anchor both ropes off it. You should use a different sling and carabiner for each rope (or in most cases you wil just tie the rope around). This counters user-error and gear failure.
Its hard to explain but as some one who moved into rope acces after being a climber for years, it makes sense when you actually use the systems.
In the picture, the one on the left is how we anchor in NZ, the one on the right is the more common international standard. The black circles are a single bolt (could also be a sling around a structure.)
Hmmm not sure how to embed it...
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anchors.JPG
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patto
Dec 29, 2010, 8:51 AM
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Having two anchors and two ropes creates a redundant SYSTEM. A redundant system can be superior to a system with merely redundant strength.
Redundant systems mean you don't get a systemic failure leading to failure.
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rockcastle
Jan 3, 2011, 3:28 AM
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When I was a bridge inspector at a previous job, we set up our rapelling anchors with a loop of webbing cinched around a bridge component with one carabiner, another loop with a another carabiner, and a rope with a figure eight knot through both carabiners. We only used one rope, though. My employer told me at the time, which was 10 years ago, that this method was approved by OSHA.
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j_ung
Jan 3, 2011, 1:55 PM
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I have no idea what rule you're talking about, but regardless... attempting to apply commonplace rock climbing practices to industrial rigging is a recipe for insanity. It's best to think of them as two completely different animals.
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ClimbSoHigh
Jan 3, 2011, 6:20 PM
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I'll take a stab at this. What I think is confusing you with you "Rule" about linking anchors is that the climbers anchoring situation differs from the window cleaners. Climbers need to keep things simple and quick. Often complete safety is traded for speed, which is why 3 good pieces equalized, or 2 1/2" bolts is generally accepted as safe enough for a belay anchor, but obviously you would be marginally safer with 3 bolts, or 20 for that matter. As climbing is an activity, not a job, people can decide for themselves what they are comfortable with. We atempt to make things redundant as much as we can, but we all know that some things are not redundant when climbing, (like the rope when on rappel).
Since window cleaning is a job, and speed is not a safety consideration, why not use two ropes, on 2 overly bomber anchor points (2" bolts or structural steel) I do not see why it confuses you that 2 COMPLETELY independant rappel systems is safer than 2 that share a master point, where if the master point fails, there is no back up.
I guess to sumarize, in rock climbing, gear is less available and speed can translate to safety. In window cleaning, you can bring as much gear as needed, and speed of set up is not a safety concern nor is retrieving gear. Lastly, OSHA has to set rules for work safety that will help keep the dumbest of the dumbest safe. Add that to workers comp laws, and there is a clear motivation to make the cleaning rig as safe as possible, which is also why they generally use steal carabiners, which you will never find on a climbers harness. When you think about all the competant climbers getting killed on rappel, it makes sense that OSHA would adopt stricter requirements than the climbing norm.
Interesting enough, OSHA only steps in for rapelling jobs like window cleaners where speed is not a safety concern. Some jobs, just like rock climbing, deem speed to be a safety factor, and in the following case speed trumps almost all safety.
What do you guys think of the redundancy for this OSHA approved workplace procedure?
http://www.youtube.com/watch?v=s_n3Dln4Y74
Enjoy!
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