While I was at TCI I watched a demonstration that was done at the tree where a limb was lowered with port-a-wrap tied to an opposing tree. It was not discussed that when you lower wood in this manner you have to decrease your load greatly. I have read accident reports where this style of rigging was done and the tree was broken and the climber died. I think that when anyone does demonstrations they should discus the types and kinds forces a load can place on a tree. Proper training needs to be stressed.It is extremely important that you learn all that you can about the forces that a tree will take in all of the rigging methods that are used. I know that time was short and they needed to show alot of different ways to do things but not informing people about life threating situations involved with the different methods is irresponsiable.
Side loading trees when rigging
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Back to engineering and physics. What kind of trees were they? How heavy was the load and how was it rigged in? How high was it rigged in the trees. You are asking for structural integrity of trees or green wood. Hard or soft wood? With so little to go on at best it would be a guess. What was the diameter of the second tree at the TIP and were the roots sound? Even if you know all this it is still a guess but an educated one that is better than just trying it on no information.
Back to engineering and physics. What kind of trees were they? How heavy was the load and how was it rigged in? How high was it rigged in the trees. You are asking for structural integrity of trees or green wood. Hard or soft wood? With so little to go on at best it would be a guess. What was the diameter of the second tree at the TIP and were the roots sound? Even if you know all this it is still a guess but an educated one that is better than just trying it on no information.
At tear off was the hitch under the support anchor? (Swing) Was line pre/ self tightened? (Impact force) Was there a pulley on Upper Support Anchor? (2x loadforce on support) Then, up to 2x that if line is draped over limb to retrievable and remotely retrieve pulley, for total of almost 4x load force impact on Upper Support Anchor. Were the lines on Support pair-allel or open to wider angle (less load on Support). Was the line allowed to run (through metal/heat disapating devices only)? (So that not all of loadforce was applied to support, hitch and braking) Load shared by other upper supports?
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Tom Dunlap
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I was part of that demo. All three of us emphasized that the demo that we did was part of a "Theater of the mind". We demonstrated some basic techniques that solve problems.
At the beginning of the demo we suggested the everyone do more homework before taking on new skills. The Art and Science of Practical Rigging is the best place to start.
In an earlier demo Mahl covered rigging false crotches. In that presentation he talked about the loading of anchor points.
When Mahk, Robert and I put our heads together we decided to show many techniques and encourage people to do their homework. When we only have fifty minutes, we can't go into too much depth on any subject.
We were very careful to cut only small limbs so that we never overloaded any of our rigging.
This all speaks to the fact that our profession, in the US, is just starting to provide good quality educational opportunities for field workers. Like any education, the students need to go to school and make sure they have instructors that know all of what they're supposed to teach.
I spent time with a friend from the UK looking over the training requirements that they have in place. In order to do a variety of arbo tasks, workers must go through standardized training and be certified. While Paolo and I were talking I told him that the "Wild West" attitude of the US will prevent this training and certifying to be accepted in the US for many years. Everytime a new rule comes into being from the government, there is incredible resistance from the workers. Sometimes Americans think that they can do as they please and any regulations infringe on some "right". Too bad, the program that the UK has in place seems like a good plan to keep arbos alive and healthy.
Off the soapbox and off to work!
Tom
At the beginning of the demo we suggested the everyone do more homework before taking on new skills. The Art and Science of Practical Rigging is the best place to start.
In an earlier demo Mahl covered rigging false crotches. In that presentation he talked about the loading of anchor points.
When Mahk, Robert and I put our heads together we decided to show many techniques and encourage people to do their homework. When we only have fifty minutes, we can't go into too much depth on any subject.
We were very careful to cut only small limbs so that we never overloaded any of our rigging.
This all speaks to the fact that our profession, in the US, is just starting to provide good quality educational opportunities for field workers. Like any education, the students need to go to school and make sure they have instructors that know all of what they're supposed to teach.
I spent time with a friend from the UK looking over the training requirements that they have in place. In order to do a variety of arbo tasks, workers must go through standardized training and be certified. While Paolo and I were talking I told him that the "Wild West" attitude of the US will prevent this training and certifying to be accepted in the US for many years. Everytime a new rule comes into being from the government, there is incredible resistance from the workers. Sometimes Americans think that they can do as they please and any regulations infringe on some "right". Too bad, the program that the UK has in place seems like a good plan to keep arbos alive and healthy.
Off the soapbox and off to work!
Tom
r/ctree;
You picked a contoversial discussion topic.
Don't be discouraged from bringing it up.
If you believe the loading from the type of rigging is more risky than what would be considered safer and more conventional, your argument should be supported with the accident report data along with what you know about this type of rigging. Not every1 knows what you are talking about nor how well they can take your word about the issue.
Excuses will never replace what could and should be discussed about rigging. Doing homework, figuring the equations which help lead to the rules of thumb we use daily, is most important. I see the seminars as providing a lead to what needs to be learned. I don't think seminars are ment to replace in depth training. If 1 cannot build on the material from the seminars, the seminars are not providing adequate leads. IMO there is a valid complaint if forces due to rope and block angles were not at least mentioned.
For those who want to know more about rigging, and forces in rigging, The Art and Science of Practical Rigging videos will be the best tree rigging resource. The work book is also good.
Joe
You picked a contoversial discussion topic.
Don't be discouraged from bringing it up.
If you believe the loading from the type of rigging is more risky than what would be considered safer and more conventional, your argument should be supported with the accident report data along with what you know about this type of rigging. Not every1 knows what you are talking about nor how well they can take your word about the issue.
Excuses will never replace what could and should be discussed about rigging. Doing homework, figuring the equations which help lead to the rules of thumb we use daily, is most important. I see the seminars as providing a lead to what needs to be learned. I don't think seminars are ment to replace in depth training. If 1 cannot build on the material from the seminars, the seminars are not providing adequate leads. IMO there is a valid complaint if forces due to rope and block angles were not at least mentioned.
For those who want to know more about rigging, and forces in rigging, The Art and Science of Practical Rigging videos will be the best tree rigging resource. The work book is also good.
Joe
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I can't comment on the TCI seminar because I didn't see the whole thing. I had noticed they had set up a mini speed line at one point though. It is a lot to do and explain in a short time.
I do agree with r/c that any time you are side loading a tree, it needs to be supported, usually with a guy rope or two. Setting up a speedline without a guy, should be a rarely used and considered a high risk technique for only the strongest trees and low, low rigging point.
It reminds me of a cambium saver, most guys try using one for the trees health and find out it's a heck of a lot easier to climb on one. That's how the guy rope worked it's way into my bag of tricks, I did it for safty a few times and found out how much better the speedline works with the tree guyed.
I would no more consider a speedline without a guy, than I would a climb without a saddle.
I do agree with r/c that any time you are side loading a tree, it needs to be supported, usually with a guy rope or two. Setting up a speedline without a guy, should be a rarely used and considered a high risk technique for only the strongest trees and low, low rigging point.
It reminds me of a cambium saver, most guys try using one for the trees health and find out it's a heck of a lot easier to climb on one. That's how the guy rope worked it's way into my bag of tricks, I did it for safty a few times and found out how much better the speedline works with the tree guyed.
I would no more consider a speedline without a guy, than I would a climb without a saddle.
Mahk
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r/c
Your point is well-taken. The possible danger of side loading a tree to the point of failure is a definite concern when using a speed line. This possibility was mentioned in the talk, but should perhaps have had more emphasis. I remember saying something like:
'If you wanted to fell this tree, then you might set things up in exactly this fashion. Put a rope high in the tree, anchor it to a distant point and apply some force/load to the rope. When using a speed line you have to be very careful not to dump loads into the speed line and not to overload the speedline with too big a piece.'
Next time we should add more warnings and demonstrate catching a top with a lowering line and then transferring the load to the speedline.
There is a lot to cover and some things will always be omitted, but issues of safety should be sparkiling clear. I appreciate constructive comments. Thanks.
Mahk
Your point is well-taken. The possible danger of side loading a tree to the point of failure is a definite concern when using a speed line. This possibility was mentioned in the talk, but should perhaps have had more emphasis. I remember saying something like:
'If you wanted to fell this tree, then you might set things up in exactly this fashion. Put a rope high in the tree, anchor it to a distant point and apply some force/load to the rope. When using a speed line you have to be very careful not to dump loads into the speed line and not to overload the speedline with too big a piece.'
Next time we should add more warnings and demonstrate catching a top with a lowering line and then transferring the load to the speedline.
There is a lot to cover and some things will always be omitted, but issues of safety should be sparkiling clear. I appreciate constructive comments. Thanks.
Mahk
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Kneejerk Bombas
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I noticed in that TCI set up the speedline itself was routed through a pulley, on the high end, then down to the base of the tree.
Why was this done?
I wonder if the speedline was routed through the pulley, then back to an anchor point behind the tree, if this would be as good or better, than tieing it to the tree and tieing a guy rope.
Why was this done?
I wonder if the speedline was routed through the pulley, then back to an anchor point behind the tree, if this would be as good or better, than tieing it to the tree and tieing a guy rope.
Tom Dunlap
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Since Robert set up the rig, I can't address his reasons.
I think that the rope must have gone directly to the base of the tree since we didn't have any other option on the back side. That only changes the angle of the rope at the top redirect.
You're right I believe. This would put a deflection load as well as a compression load. A back guy or even a vertical guy would probably be a better option.
You do have to admit though, considering what we put on the system, the limbs were so small that we were still within a good margin.
Thanks for the feedback. This helps us make better presentations next time.
Tom
I think that the rope must have gone directly to the base of the tree since we didn't have any other option on the back side. That only changes the angle of the rope at the top redirect.
You're right I believe. This would put a deflection load as well as a compression load. A back guy or even a vertical guy would probably be a better option.
You do have to admit though, considering what we put on the system, the limbs were so small that we were still within a good margin.
Thanks for the feedback. This helps us make better presentations next time.
Tom
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Actually Tom, the tree at the show was guyed. It was tied to the ceiling girder. That probably wouldn't work as well on the job though.
Tom Dunlap
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Unless we can guy to a nearby cloud or Sky Hook
Tom
Tom
John Paul Sanborn
Above average climber
As long as you regularly admonish people to start low and slow (light n' slight??) when trying new rigging methods, you should be ok.
"learn how the different parts of the system react to the loads before you start putting big wood on. Remember (from the earlier session) that many techniques can multiply force to the anchor points."
"learn how the different parts of the system react to the loads before you start putting big wood on. Remember (from the earlier session) that many techniques can multiply force to the anchor points."
I talked to mark at the show about this peticular problem. I not saying that what you did was wrong. You guys did a wonderful job on your demos. What I saw hit home with me because I know that a climber died because he did noy know. The only way to educate is to study trees and the forces applied to them when rigging and teach other what has been learned. I have a question for you guys. Do you think that a 450 lb top can break a 13" tree four feet off the ground if the load line it anchored on a seperate tree trunk 25 ft away? I know the answer but what do you guys think. I want give out all that I know about this subject yet so maybe the disscussion can continue.
Stumper
One Man Band
The fact that you posted these details implies that it did indeed happen. I can't imagine that happening on sound wood of most species without a high fall factor or some horrendous leverage factors. I look forward to hearing the details.
Tom Dunlap
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With enough drop, that 450# piece could put quite a load on the trunk. Combine that with some trunk defects and you have a failure.
What are the details?
Tom
What are the details?
Tom
load factor
After a few days of rain I can see this load being dropped a few feet and the roots fail to hold and the whole tree comes up to greet you. If your lucky it will hang up on a lower limb and not knock you out of the tree. I was lucky and climbed down and cut the rope. You learn to pick on bigger trees and don't drop the tops, ease them out. Can you say EASE it out. You would not believe what the energy level is of the top after it goes six feet then tightens up.
After a few days of rain I can see this load being dropped a few feet and the roots fail to hold and the whole tree comes up to greet you. If your lucky it will hang up on a lower limb and not knock you out of the tree. I was lucky and climbed down and cut the rope. You learn to pick on bigger trees and don't drop the tops, ease them out. Can you say EASE it out. You would not believe what the energy level is of the top after it goes six feet then tightens up.
Loading a rig in a upsidedown "U" like that in a Skinny, flexable "boinging" trees, one to the other at the tops can pull the 2 together, especially when impact loaded, very esay to get tossed!
If memory serves me right the piece fell close to nine feet. Which ended up putting over 85000 lbs of persure on the tree trunk. The tree was resisto graphed into swiss cheese but no flaws were found. The main reason That I wanted to post this was to inform others that good wood can break if you load it to much. You need to calculate you loads and use sound rigging practices and not experiment on the job before you have been properly trained in the climbing and rigging practices that you use. Alot of people say time is money but how much time is your life worth?
How did the distance the piece fell get measured that 9 feet was the total distance of fall? Did the top that was rigged come from a different tree or was the top from the tree which broke?
What was used to conclude there was 85,000 lbs of pressure which caused the tree to break?
I can't see using a resistograph for this specific circumstance to detect flaws in the wood after a break like the 1 being described. Was it resistographed before it was rigged?
Joe
Tom Dunlap
Addicted to ArboristSite
If you estimated an 85k load I'll bet that there was probably a higher load. At some point, any tree will fail. Even the most structurally sound and defect free trunk can only take a certain load.
Take smaller pieces.
Tom
Take smaller pieces.
Tom
