Accident Investigation: Sharing Lessons from a Tragic Experience

This article is being published in a joint effort between TCIA and BDG Trees, LLC, to openly share the investigative findings of a fatal accident that occurred in August 2019 in New Orleans, Louisiana. It is our shared belief that by openly communicating throughout the industry the lessons learned and corrective actions taken, we can raise awareness and ultimately prevent other arborists and line-clearance tree trimmers from suffering a similar fate.

Accident description

A four-person manual crew, or climbing crew, was removing a multi-lead chinaberry tree. Based on investigative findings, while maintaining OSHA minimum-approach distances, the crew leader was in the tree using climbing spikes, standing on the side of the tree with his back toward the power lines. Multiple gaff marks on the trunk indicate the crew leader was moving around on the same area of the tree trunk, possibly repositioning. His left climbing spike “kicked out,” causing him to lose balance and control of an insulated, fiberglass pole pruner he had just unhooked from an adjacent overhead tree branch.

The findings show the crew leader was holding the pruner pole near the butt end of the lower section when his left climbing spike kicked out. He was tied in with two safety straps wrapped around the tree and connected to his climbing saddle. This further indicates he had stopped working and was repositioning. When his climbing spike kicked out, his body swung pendulum-like into the tree trunk as the pruner pole he was holding fell backward over his head, contacting a 7.2 kV, single-phase primary. The momentum caused by the combination of the crew leader’s body motion and the weight of the pruner pole falling back over his head created enough force to cause the primary wire to slide up the hard, slick surface of the pruner pole into the crew leader’s right shoulder, making a direct contact. The crew leader received a fatal electrical shock.

Key findings

The crew leader had unhooked his climbing line and snapped it to the D-ring on the right side of his saddle. This was a key piece of evidence, in addition to the multiple gaff marks and attachment with the two safety straps around the tree, all of which indicate the crew leader was repositioning.

BDG investigators believe that, based on the remaining portion of the tree, the victim was either repositioning to cut the final limb growing off the main leader just below him, or was preparing to move down to re-tie in and continue piecing down the remaining portion of the leader he was standing on.

There were no eyewitnesses to the actual event; however, two employees witnessed him dropping the pruner pole after the initial electric contact had been made. Investigators believe he had reached over and grabbed the pole pruner to reposition it to another limb or move it to a lower position in the tree as he was piecing the tree down. His hands would have been gripping the pruner pole at a point close to the butt end of the pole, leaving most of the pruner length and weight above his head and outstretched arms. When his spike kicked out, he never let go of the pruner pole as it was falling backward over his head into the power line.

Investigative conclusion

Placing the pruner pole high up on a tree limb above and to the side of his work position combined with the spike “kicking out” caused the crew leader to lose control of the pruner pole. The combination of motion and momentum created by the employee’s body weight swinging toward the tree trunk as his spike kicked out and the weight of the pole pruner falling resulted in the power line being struck with enough force to cause the wire to slide up the pole, making direct contact with the crew-leader’s shoulder and resulting in the electrocution.

Investigators believe the fact there were no burn marks on the crew-leader’s hands indicates they were near the butt end of the pruner pole and thus separated from contact with the power line when the conductor contacted his shoulder.

Lessons learned

If the crew leader hadn’t placed the pole pruner so far above his head and grabbed it near the butt end, he might not have lost control of the pruner after his spike kicked out. Placing the pruner on a lower limb where better control could have been maintained, or lowering it completely to the ground, could have prevented the electrical contact.

Preventive measures

Hand tools that are not being used during the tree-trimming or tree-removal operation should be secured by attachment to a handline or the saddle or lowered to the ground. A hand tool such as this pole pruner should not be hung so high in a tree that grabbing it could compromise control and balance of the pole pruner due to its length or weight.

Mario Herrera is safety supervisor with BDG Trees, LLC, in Houston, Texas.

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