Collapsed trees with tree support systems?

peder-d

peder-d

Location
Aarhus, Denmark
has anyone any pictures of collapsed trees with tree support systems installed (for example cobra or similar)?

We are very often discussing how it would look like and often debates weather the healthy part of the tree would react to the burden of the failed part.
 
I've heard about literally hundreds of stem failures above steel cabling, especially within storm-damaged areas of the Carolinas and north, but few on cobra. No pictures to offer. Perhaps in this era of electronica, climbers are more likely to break out their phones to document. Looking forward to posts!
 
I've seen hooks pull, cables break and cobra tighten up or rub apart. Probably improperly installed mostly. I've never seen failure above steel and I suspect that's mostly due to not installing high enough. I've heard of stem failure with cable holding the pieces from hitting the target. Cobra is probably the best initially installed but I am really curious to see how 35 year old cobra will compare to steel? I was installing a bit of cobra and went back to through hardware steel and considering going to through cable. I think we are still waiting for an ultimate product but the options we have now aren't horrible.


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Plenty of hardware failure. Eye bolts and jlag snapping, cobra cable failure 2 or three.
Really what I have seen is what is expected.
Cable to low =fracturing at point of attachment and failure above cable.
Good to read you Tobe. Don't be a stranger
 
I've seen a bunch of cable failure, and few tree failure. Have not seen a dynamic system fail yet (but it's rather new in our world). Steel tends to break in the dead end (whether the thimbles are installed properly or not) when using EHS. My experience with common grade is they are breaking at the end of the splice but have seen it break in the center a couple times. I've seen a few j-lags pull but not many (using mostly through bolts).
As for tree failures it's normally above the cable (normally in birch). I have not seen a tree failure cause a cable failure.

Ps. Cobra I believe has a useful life of 8 or 10 years. So really it should not be in service beyond that point.
 
"Ps. Cobra I believe has a useful life of 8 or 10 years. So really it should not be in service beyond that point."

Precisely. Besides their position being outgrown by the host tree, dynamic systems loose elasticity, and as noted, risk girdling if not maintained properly. They're not a place it and forget it system like crotch bracing. It's proving difficult to adjust this mentality among static/steel installers ...and customers too who don't want the ongoing maintenance..

Supplemental support positioned in the outer 2/3rds range between limbs has a leveraging effect on its target. The opposite becomes true as branches outgrow their installation.

Regarding j-lags, a large number of installers avoid them 100%, opting only for through bolting. Makes sense to me. Peace
 
34 years in the biz and I;ve never seen a tree fail above a cable.... though I have seen many cable and hardware failures, mostly due to improper installation, and a few from lightning strikes.. the dynamic systems never got much traction around here... I've only seen a few ever.. can't say that 8-10 life expectancy does much for my opinion of them. I've seen steel cables doing they're job 25 years later.. I put em in high... try to go to 6" diameter wood whenever possible..
 
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There's a brand-new-looking steel cable in an Aesculus for over 40 years (at least, per neighbor). It had the good fortune of a garage being installed over much of its rootzone, so the dreaded "karate chop" failure did not occur from unmanaged end growth.

I've seen/evidence of several failures above cables that were too low for one reason or another; reported in a few. Hundreds is a lot. but worldwide, no doubt, over the years.
I've seen several cobra / type constrictions. High maintenance but can work well.

Through-cabling hardware is specced most of the time here; 80%? Can also work with a cable as a brace rod.
 
Daniel said:
34 years in the biz and I;ve never seen a tree fail above a cable.... though I have seen many cable and hardware failures, mostly due to improper installation, and a few from lightning strikes.. the dynamic systems never got much traction around here... I've only seen a few ever.. can't say that 8-10 life expectancy does much for my opinion of them. I've seen steel cables doing they're job 25 years later.. I put em in high... try to go to 6" diameter wood whenever possible..
Click to expand...

As far as failing above the cables our last ice storm that's where we saw well over half our damage limbs held but tops busted off to release the leverage a little bit. We are still cleaning up mother natures reduction prunes all over the place.

I worked on a 100' hickory. 2 co-dom stems by a patio on a golf course. this tree had been meticulously cared for, regular pruning some reductions etc.
My best guess from memory is main crotch was about 30' up so about 70' of tree above. The tree was in good condition but through a wind storm one half of the tree busted. Not 100% of but lets call it 95%. We had installed a Cobra cable a year or two previous to the storm and it was the only thing that saved there club house.
I didn't in my wildest dreams think that cable would have held the way it did, it stretched to about 3/8" dia. the tension was beyond belief.
That storm put my faith in cobra cables for sure. I have no numbers of weight and I'm sure that it was purely half just lucky but that it held.

I've seen others like that kind of situations lots of poplars, manitoba maples, silver maples, apples, etc. So these aren't prime species in my books but when old Mrs. Smith planted that tree 50 years ago with her husband and child that have both died and it's her memento or it's there only tree in there yard and they like it, cabling becomes an option to help prolong things.

I've only been in it about 10 years but I know you never say never.

As for the 6" wood rule that may work where you are but lots of trees I've done are cabled at tie in height cause that's the tree's height and shape so the cable can be around a wrist size anchor if that's the best option.

A cables job is to help the tree move in unison not letting co-doms leave each other past the point of no return.

The more leverage the less force needed=the less leverage the more force needed.

Cabling, pulling, rigging it's all based around that fundamental rule. (Well 1 of them there are a few more)
 
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peder-d said:
has anyone any pictures of collapsed trees with tree support systems installed (for example cobra or similar)?

We are very often discussing how it would look like and often debates weather the healthy part of the tree would react to the burden of the failed part.
Click to expand...

I have a picture somewhere of a large Callery pear lead that broke during a hurricane here. The cable held it and kept it from hitting the house. I'll try to locate it if it will help Peder?
 
Couple/three opinions in addition to above...J Lags although still spec ed thru ANSI are a dinosaur and should be eliminated completely despite the opinion of that board.

Tree cables, even properly installed can CAUSE rather than mitigate possible co dom failure...both by barn door effect and by improper installation leading to failure leading to whiplash. Sometimes the tree just allows NO beneficial locations to give relevant support and are just better off left alone or go to pruning considerations exclusively.

Like Daniel said...very few elastic cable installations in our area. I think most are installed by those unschooled and fearful to install steel supports. I see the elastic cable as a panacea and with the kind of storms around here...they'd never hold up. I think the above opinions with hundreds of failures above steel cable is a silly exaggeration. But if you sell elastic cables for a living...you have to sell them.

Sometimes insight in areas unthought of previously can be helpful...If a co dom has a fault that leads downward in a J shape away from the trunk... drastically on a big lead co dom...one must be very careful to read this and not proceed with supports. I have seen those type of leaders "slide off" through sheer weight and not even hinge at all...just detach, go butt first straight down...and cause mass havoc when they tip over tearing out any and all previous installed cables.
 
I cut down a big cherry years back that had over 95% decay in the main lead over the house.. this thing was reaching for the light and overgrown, hadn't been touched in years.. REALLY heavy.. had a triangular cable system, cables must have been 15-20+ years old... I was amazed at how well the triangular cables spport... makes sense from what little geometry and engineering I remember...
 
Mark Chisholm said:
I have a picture somewhere of a large Callery pear lead that broke during a hurricane here. The cable held it and kept it from hitting the house. I'll try to locate it if it will help Peder?
Click to expand...

That would be great! :) very interesting.
Thanks.
And have a great Christmas, all of you! House full of guests- have to go for now.
 
KevinS said:
As far as failing above the cables our last ice storm that's where we saw well over half our damage limbs held but tops busted off to release the leverage a little bit. We are still cleaning up mother natures reduction prunes all over the place.

I worked on a 100' hickory. 2 co-dom stems by a patio on a golf course. this tree had been meticulously cared for, regular pruning some reductions etc.
My best guess from memory is main crotch was about 30' up so about 70' of tree above. The tree was in good condition but through a wind storm one half of the tree busted. Not 100% of but lets call it 95%. We had installed a Cobra cable a year or two previous to the storm and it was the only thing that saved there club house.
I didn't in my wildest dreams think that cable would have held the way it did, it stretched to about 3/8" dia. the tension was beyond belief.
That storm put my faith in cobra cables for sure. I have no numbers of weight and I'm sure that it was purely half just lucky but that it held.

I've seen others like that kind of situations lots of poplars, manitoba maples, silver maples, apples, etc. So these aren't prime species in my books but when old Mrs. Smith planted that tree 50 years ago with her husband and child that have both died and it's her memento or it's there only tree in there yard and they like it, cabling becomes an option to help prolong things.

I've only been in it about 10 years but I know you never say never.

As for the 6" wood rule that may work where you are but lots of trees I've done are cabled at tie in height cause that's the tree's height and shape so the cable can be around a wrist size anchor if that's the best option.

A cables job is to help the tree move in unison not letting co-doms leave each other past the point of no return.

The more leverage the less force needed=the less leverage the more force needed.

Cabling, pulling, rigging it's all based around that fundamental rule. (Well 1 of them there are a few more)
Click to expand...


Hey Kevin. Very interesting story. Can you remember the size of the cobra attachment points? And just roughly, how large were the top it held?
Any pictures? :-)
 
We do both dynamic and static cable. We use dynamic with proper end weight reduction pruning. With the idea that at some point the lead being supported will be reduced to the point where very little risk is present. The option of moving the dynamic cable during this process is nice. Static cables are used in circumstances in trees that can't be reduced over time as effectively. We hand splice common grade. I have seen a few ehs break at the preform. We use lag or through bolt depending on the situation.
 
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