If in doubt, take a smaller piece
By Dr. Brian Kane, ISA Certified Arborist Massachusetts Arborists Association Professor University of Massachusetts- Amherst
Rigging is one of the most hazardous tasks a climbing arborist does. It involves working aloft, cutting with a chainsaw, and large pieces of wood moving rapidly—sometimes, very close to the arborist. To avoid injuries and property damage, climbing arborists must estimate the rigging loads and predict the movement of the piece once it’s cut.
Few studies have carefully measured loads in a rigging system; knowing what they are and how they change with different rigging tools is essential to maintain safety. If the loads at different points in a rigging system are known, it helps climbing arborists understand how to manage loads to minimize the likelihood of failure of a component in the rigging system, including the tree itself.
We measured tension in the lead and fall of a rigging line secured at the base of a tree and conducted drop tests with different rigging lines (new and used) and blocks (traditional blocks with a rotating sheave and rigging rings). Presumably, a traditional block would offer less friction than rigging rings. When there’s less friction, the load at the anchor will be greater, increasing its likelihood of failure. But if there’s more friction, then a shorter length of line carries the load, increasing its likelihood of failure.
We didn’t find compelling evidence that traditional blocks or rings were preferable. One reason is that the presumption that traditional blocks offer less friction than rings is based on slowly raising or lowering loads, which are not like the “shock loads” that often occur when rigging. If the sheave of the block can’t rotate quickly enough to keep up with the shock load, the rigging line will slide along the sheave, just as does when sliding over rigging rings. The surest way to reduce the likelihood of failure is to rig smaller pieces.
Thank you, Dr. Kane, for your insightful information. You can see Dr. Kane’s TREE Fund webinar from February 2021, “Loading a Tie-in Point While Climbing” HERE and complete a 20-question quiz online for an opportunity to earn CEU credits. For more information and for the quiz link, visit our Webinar Archives page and scroll down to the listing.
Grant and Scholarship Cycle for Spring 2023 Closing Soon
TREE Fund’s Grant and Scholarship Cycle for the Spring of 2023 is now open. Letters of Inquiry must be received by March 1 and applications submitted by March 15. See details regarding requirements for each grant and scholarship on their individual pages.
Survey to help Canadian TREE Fund
Our friends at the Canadian TREE Fund have teamed up with the University of British Columbia on a survey gathering the opinions of arborists.
A University of British Columbia research project is asking Canadian and American arborists and urban foresters their opinion on research needs in arboriculture and urban forestry and how industry professionals are receiving information. Those who partake in the survey will be entered into a drawing for one of ten gift cards in the amount of $100 CAD each to an arborist supply store. Please consider participating in the anonymous survey by visiting https://ubc.ca1.qualtrics.com/jfe/form/SV_2nTfr0MfT1tIodw. Any comments or questions can be directed to the Primary Contact and Co-Investigator Alexander Martin (firstname.lastname@example.org) or to the Principal Investigator, Dr. Andrew Almas (email@example.com) of the Faculty of Forestry, University of British Columbia
Ride with us at the Tour des Trees this fall
Rider numbers are growing and people are getting excited! Have you always thought about joining us at the Tour des Trees? This is the year to ride!
Join TREE Fund for 380+ miles at this year’s ride from Reno, NV, past Lake Tahoe, and into northern California. Ride dates are September 26 to October 2. This year’s ride is shaping up to be a beautiful, can’t miss event, so add your name to the list today! For more information and to register, visit www.treefund.org/tourdestrees.
We are deeply grateful to the following people and organizations who contributed $2,500 or more to the TREE Fund in January 2023:
Asplundh Tree Expert, LLC
See the full list of lead donors who make our vital tree research and education work possible on our website.
TREE Fund is proud to partner with the Alabama Cooperative Extension System to bring you free education offerings. We are now able to accommodate up to 3,000 participants!
Tuesday, March 21. 1:00pm CST.
*Note updated day and time
Presenter: Dr. Andy Kaufman, University of Hawaii.
Building Urban Tree Resiliency by Mitigating Below Ground Infrastructure Techniques.
SA CEU Credits: BCMA Science: 1; Climber Specialist: 1; ISA Certified Arborist: 1; Municipal Specialist: 1
TREE Fund’s 1-hour webinars are free and offer 1.0 CEU credit for live broadcasts from the International Society of Arboriculture and the Society of American Foresters. Registration and information will become available on our website approximately two weeks before each webinar date.
Missed a webinar? Watch it anytime on our website.
CEU Credit for Recorded Webinar
TREE Fund now offers ISA CEU credits for one recorded webinar: “Loading of a Tie-in Point While Climbing.” If you missed this webinar, you can now watch the recording and earn ISA CEU credits by completing a 20 question quiz with 80% accuracy. Learn more on our website.