The previous two articles in this series covered tree-worker incidents within the U.S. Bureau of Labor Statistics’ event category, “Contact with an Object,” involving either struck-by or caught-in events. These are two of the four horsemen of the arboricultural apocalypse, if you’ll pardon the Biblical reference. This article will cover the event category “Falls, Slips and Trips.” The next and last segment will focus on “Electrical Contact.” Combined, these four horsemen account for more than 80% of fatal and nonfatal incidents involving tree workers.
Falls are a constant threat to the aerial arborist. Falls account for about one-third of our fatal incidents and nearly half of the severe, nonfatal ones. About two-thirds of the fatal and nonfatal fall incidents involve climbers.
Falls involving climbers
There are two ways climbers fall. They either fall from the tree or fall with the tree. Let’s start with falling from the tree; there are two common reasons for this fall – repositioning without being secured and anchor failure.
Everyone knows climbing without fall protection is not allowed; from the moment you leave the ground to the moment you return to earth, you must be attached. Unfortunately, climbers still too often un-clip for “just a second” to isolate a climbing line, and that is the “second” when they lose their balance and fall. The irony is that what often knocks them off balance is the rope snap or carabiner on the lanyard or climbing line that was tossed over the overhead limb striking them in the face.
Example:
A climber was ascending on a moveable rope system, the old body-thrust technique using a Blake’s hitch. As he worked his way up over limbs, he noticed his line was not isolated but had a limb between the working and standing parts. He stood on a limb, untied the hitch and threw his snap over the limb above him. As he reached out to catch the snap, he slipped and fell 35 feet to the ground. EMS was summoned, and the worker died two days later due to the injuries.
Anchor failures can be attributed to a number of causes, from cutting the branch serving as the anchor to the anchor failing under the dynamic loading by the climber.
Example:
A climber was 55 feet up in a pine beginning the process of dismantling the tree. He used an upright limb as the tie-in for his orange climbing line and tied off a white tag line on a lower limb. The ground worker tended the white line, which was run through a lowering device. The climber had the ground worker hold the line while he cut the limb. The climber did not realize he was cutting the upright limb that was his tie-in point instead. The climber was pulled to the ground by the cut limb, landing on the concrete driveway with the limb, which weighed approximately 200 pounds, falling across this chest. The climber was dead when EMS arrived.
We also have had the tie-in point fail under the dynamic loading of the climber ascending. Since we are selecting our anchor from the ground, climbers must be able to see the anchor point and assess whether it can support the climber’s weight.
Example:
The climber had his climbing line set approximately 70 feet from the ground and over a limb approximately 3 inches in diameter. The climber and the ground worker both pulled on the line before the climber began ascending. The climber was about 30 feet up the line when the branch snapped, causing the climber to fall. The climber landed on his feet before falling backward. He fractured his ankle from the fall.
The Z133 safety standard notes under section 8.1.11 that a climber shall (if suitable) subject the anchor point to a load approximately twice the weight of the climber before ascending. This approach is problematic for climbers. First, consider that you are subjecting the anchor to a potentially failing stress before using it – not standard procedure in most industries; you don’t try to break something before using it. Second, subjecting the anchor to twice the climber’s weight requires two people, the climber and a second worker of similar weight, to hang from the line – pulling while standing on the ground is not the same force. Unfortunately, we have had incidents where climbers have depended on this test for an assurance that the anchor can support the load.
The incidents described thus far involved climbers falling from the tree. There are nearly an equal number of incidents where the climber falls with a failing tree. These usually involve the climber either cutting the top out of the tree and letting it freefall to the ground, or rigging a large limb out of the tree with the shift in load causing the entire tree to fail.
Example:
A climber was topping out a spruce tree. When the climber cut the top 12 feet out of the tree, the ground worker had the rigging line wrapped tightly around the trunk of an adjacent tree so that the top came to a stop. The trunk swayed, and then the entire tree uprooted and fell. The still-attached climber landed with the tree on the concrete pavement. He was dead when EMS arrived.
The crew must inspect the tree before climbing and rigging. Equally important is the ability to identify defects and plan the operation accordingly. The reports for incidents where the climber fell with the tree sometimes note that the crew thought the tree was sound.
These are two of the most common situations where climbers fall, but they are not the only ones. Among many others, we have climbers fall when they cut their only means of being secured with a chain saw. We had a climber cutting branches at about 75 feet up when he cut through the one attachment he was using at the time. He died from the fall. We also have nonfatal injuries when a climber on a descent ran out of line. These often occur within 15 feet of the ground and only result in a sprained ankle and a bruised ego!
Falls involving aerial-lift operators
Aerial-lift falls account for about one-third of our fatal falls and a sixth of our severe, nonfatal falls. They are also similar to climber falls in that they are either falls from the lift or falling with the failing lift. The incidents involving an aerial-lift operator falling from the bucket almost all have one factor in common – the operators were not wearing any fall protection. Why they tumbled out of the bucket, however, was due to a multitude of causes, from overreaching while cutting a branch to having the boom struck by a falling tree or branch. Fall protection shall be worn by the operator whenever aloft, and its absence is a common theme to incidents.
Example:
The aerial-lift operator was dismantling a tree. He had just cut the top out, without using a pull line, when it spun and fell on the boom. The impact ejected the operator, who fell, along with the chain saw, to the ground. The operator landed face down and died of blunt trauma to the head and neck.
The single agent responsible for aerial-lift falls is not wearing fall protection. Wearing fall protection, like wearing seat belts, is a simple but effective safety rule. However, car seat belts differ from much of our fall protection in that car systems are designed to keep you in the seat, whereas our fall-arrest systems are not designed to keep you in the bucket. Think of a seat belt that would allow you to tumble out of the car, but you are still attached to the car as it rolls over – maybe not the best approach. We have had operators fall out of the bucket who were injured by striking the boom or the tree.
The single agent responsible for aerial-lift falls is not wearing fall protection. Wearing fall protection, like wearing seat belts, is a simple but effective safety rule. However, car seat belts differ from much of our fall protection in that car systems are designed to keep you in the seat, whereas our fall-arrest systems are not designed to keep you in the bucket. Think of a seat belt that would allow you to tumble out of the car, but you are still attached to the car as it rolls over – maybe not the best approach. We have had operators fall out of the bucket who were injured by striking the boom or the tree.
We do have fall (travel)-restraint systems that work like seat belts in that they are designed to keep you in the bucket. These are not the old body belt and a single short lanyard, but a system with two short lanyards to limit travel and keep the operator in the bucket at all times. One interesting finding is that, if the boom fails, the operator has a better chance of survival if he or she is still in the bucket when it hits the ground, as opposed to falling alongside the failing boom.
We also have operators falling with a failed boom. These failures often can be attributed to overloading the boom – using it as a crane when it’s not designed for this use – or operating an old lift that has missed a lot of inspections or maintenance. I often have tree workers ask which brand of lift has the most failures, but the make does not appear to be a factor. A common factor is that the boom is more than 20 years old and on at least its third owner.
We also have a few falls every year when the boom and the truck flip, either because the outriggers were not used or pads were not in place. Most newer booms will not operate unless the outriggers are in place, and this has saved lives. I am sure a few readers can recall feeling the bucket sway when fully extended, only to look down and see the outriggers still up. The requirement for pads is not mandatory, but we have had overturned vehicles from the outriggers sinking into soft ground.
Ladder falls
About a sixth of our severe, nonfatal falls occur while standing on or leaving a ladder. There are a few fatalities doing this as well. The most common incident is from a climber stepping off the ladder and onto a branch before being secured. We also have a few when the ladder pulls away from the tree as the climber’s weight shifts or a bent branch pushes out. This leaves the climber with the hesitating moment when the ladder is perfectly balanced and the slightest movement causes it to settle back on the tree or fall away. It’s a pretty scary moment – avoid it by staying secured.
Avoiding falls
How can we reduce the possibility of a fall, regardless of its source? Here are some of the key considerations along with the corresponding Z133 paragraphs in parentheses for reference.
Climber falls
• A climber must be tied in and use a second means of being secured (lanyard or second climbing line) when operating a chain saw in a tree unless the employer demonstrates a greater hazard is posed by the use of a second means of being secured in this specific instance (6.3.6).
• A climber has a climbing line and another means of being secured on his or her person at all times while aloft (8.1.3).
• A climber shall be secured at all times while ascending a tree and tied in once the work begins and remain tied in until returned to the ground (8.1.6).
• A stopper knot shall be tied in the end of the climbing line to prevent it from pulling through the hitch (8.1.13).
• The tree must be inspected before rigging to determine whether it can withstand the forces and strains of the operation (8.5.1).
Aerial-device falls
• Never use a boom as a crane or hoist unless it was designed by the manufacturer for this purpose (5.2.3).
• Always use outriggers and place them on a pad (5.2.5).
• Never overload the rated lift capacity of a device (5.2.8).
• Always wear fall protection whenever aloft (5.2.7).
Ladder falls
• Do not work from or leave the ladder to enter the tree until you are tied in or secured (8.1.7).
About this series
This is the third in a four-part series of articles looking at causes of the majority of incidents in the tree care profession. Part 1, “Avoiding Struckbys,” ran in the April 2019 issue of TCI Magazine. Part 2, “Caught-in or Compressed-by,” ran in May.
Dr. John Ball, CTSP, is professor of forestry at South Dakota State University and a Board Certified Master Arborist. This article is based on his presentation on the same subject at TCI EXPO in Charlotte, North Carolina, last fall. To listen to an audio recording of that presentation, go to this page in the digital version of this issue online, under the Publications tab, and click here.
