New testing technique

[davespencer]

A local consulting arborist in our area has come up with the idea to test the structural stability of trees. As far as I have heard, he sets a line in the tree and uses a come-along to pull the tree sideways. I suppose if the tree does not fail up to a predetermined potential max wind load then it gets a stamp of approval.

Is it just me or does this sound wacky?
How do you explain the dammage if the tree does not meet specs?

This is the same guy that convinced a homeowner their tree could be saved after 5 companies told them it needed to be cut down; by installing seventeen cobras!!!

Dave

 

[Colin]

It sounds like that guy eats stupid biscuits for breakfast.

 

[Mark Chisholm]

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[Mangoes]

Dave

Where was this project done? Out your way or downtown? Care to mention who (via pm). My previous employer was conservative about removals on occasion and he's from your neck of the woods, just wondering if his fingerprints are on that job.

 

[joe]

It's a german technique I believe was developed by a German engineer by the name of Lothar Wessolly. A device called an elastometer is used to help determine the stress at the root flair when a load is applied to the tree as described by you. It was discussed at the old hangout-the I.S.A. webboard.

Joe

 

[Tom Dunlap]

Erk Brudi has worked with a professor of "Statics" to make a system that does just that. When I visited Erk a few years ago I was his climber on a test. There was a 350 year old linden tree on a farm at the base of the Alps. The county or state was going to assume historical care of the tree. Before they did, they wanted to know how stable the tree was. The testing system consisted of two tools that measured the deflection of a beam by a measured load. In this case, the trunk was the beam. I climbed into the tree and set the anchor for the pull. The other end was attached to a tractor. A low load was applied. Something in the neighborhood of 200#. Far below the load that would pull to failure. Erk would take the load angles and put the data into the computer. The meters measured the movement. By working out the physics and knowing the stiffness of the trunk the readings could be used to measure the stability.

This system was engineered and it's been compared to tree failures from known winds.

Erk told me that I was the first American to see the testing system.

The guys system may have some merit if he understood the physics of the test. I can remember just enough of my high school and college physics to see what's going on. There is some similarities to the load on a speedline stuff from the "good ol' ISA threads."