Measuring forces and stresses during rigging operations

2008 | Brian Kane, University of Massachusetts

Rigging is one of the most dangerous aspects of arboriculture, and a number of fatalities have occurred during rigging operations.  Rigging causes substantial stress on the rigging gear as well as the tree.  Increasing the inherent danger of rigging is the structurally-deficient condition of many trees that are removed using rigging.  Despite the risks to life and property, there are no robust studies of the forces generated during rigging operations. This study was part of an ongoing research project being conducted by the principal investigator.  Field work during the summer of 2007 provided useful baseline data that raised several important questions.  This funding helped continue this work to address questions developed from previous work.  Trees were removed with conventional rigging techniques (i.e. from Donzelli and Lilly 2001) and forces (at the block and the port-a-wrap), stresses (at breast height and at the rigging point), and dynamic motion of the tree (at breast height) measured.  Tops and pieces exhibited different relationships with mass, which was the best predictor of force at the block and tension in the rope. Other variables (i.e., fall ratio and distance, notch angle, etc.) were less robust predictors and showed counter-intuitive relationships with forces. There were few differences in stress generated when removing tops and pieces, which appeared to be due to greater deflection higher in the trunk when tops were removed.

Year: 2008

Funding Duration: 3-5 years

Grant Program: Hyland Johns

Grant Title: Measuring Forces and Stresses during Rigging Operations

Researcher: Brian Kane

Key words: Rigging operations; rigging gear; climbing; trunk stress, biomechanics

Peer Reviewed Publications:

• Kane, B., S. Brena, and W. Autio.  2009. Forces and stresses associated with tree rigging. Arboriculture & Urban Forestry. 35:68-74. View the Publication >

• Karvanirabori, P. (2009) Analytical Modeling of Tree Vibration Generated During Cutting Process. M.S. Thesis. Dept. of Civil Engineering, Univ. MA Amherst. View the Publication >

General Audience/Trade Publications: none

Presentations: none

For more information on this project, contact the researcher via TREE Fund at treefund@treefund.org.