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Improperly cut tree kicked back, striking arborist

Date of incident: June 2015
Notice of incident number: 2015161750050
Employer: Tree service company

Incident summary

Several trees were being felled on a residential building site. The hemlock being felled at the time of the incident was growing out of an old tree stump 4 to 5 feet (about 1.4 metres) above the ground. An arborist cut a step in the side of the old stump to reach the hemlock he was falling. Another worker used an excavator bucket to touch the hemlock to provide directional control as the arborist cut the undercut and backcut. The hemlock began to fall. As it fell, it brushed a nearby tree. The butt of the falling tree came off the stump and kicked backward, striking the arborist. The arborist succumbed to his injuries in hospital.

Investigation conclusions

Cause

  • Improper falling cuts caused loss of control of tree: The arborist placed improper falling cuts into the tree. The dutchman created by the poorly constructed falling cuts caused a loss of directional control of the falling tree, resulting in the tree brushing the nearby tree as it fell. The tree began to fall before the arborist had cleared the immediate area and signalled to the excavator operator. Cutting off the holding wood contributed to the tree falling before the arborist was able to have the excavator operator push the tree and provide directional control. The tree hit a nearby tree and came backward off the stump, striking the arborist.

Underlying factors

  • No antikickback step on stump: Because the backcut was incorrectly placed below the level of the undercut, there was no antikickback step on the stump. Without an antikickback step present, there was nothing to hold the falling tree on the stump when it struck the adjacent tree.
  • Stump conditions affected escape from stump and distance tree travelled: Because the arborist was working on a step he had cut into the old stump, his escape from the stump was slowed. Due to the stump’s height, the tree butt travelled a greater distance than it would have from a shorter stump, and the tree travelled toward the arborist.
  • Moving into safe area delayed: Once he had climbed down from the old stump, the arborist did not move into a safe area as quickly as possible. The arborist was still in the hazard area near the falling tree’s stump when the butt of the tree kicked backward from the stump.
  • No oversight or correction of unsafe falling practices: The arborist’s unsafe falling practices were able to occur in part because neither the general contractor nor the landscaper that contracted him had expertise in falling or tree removal. As a result, the arborist’s falling activities were not adequately overseen to ensure safety. The arborist himself was supervising the falling activities.

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Publication Date: Jul 2017 Asset type: Incident Investigation Report Summary NI number: 2015161750050