ANSI Z-133

I need to point out that the comments in this article represent my opinion, not the official interpretation of the ASC Z133 Committee.

Due to be published early this year, Z133 has gone through some rather significant revisions of late. The purpose of this article is to make you aware of the more significant changes, as well as the reasons they were made. I will separate those reasons into three broad categories: 

• The Struggle for Recognition and Acceptance 
• Embracing New Techniques and Equipment 
• Raising the Bar for Safety

The Struggle 

The arborist profession continues to suffer from an identity crisis that manifests itself in many ways. The example most relevant to this conversation is that regulatory agencies such as OSHA, insurance companies and even contract managers fail to realize that we’re a “grown-up” industry whose leaders are well aware of the problems we face and responsible enough to do something about them. Instead, these groups persist in trying to make us fit into boxes created for other groups.

The new Z133 helps us assert our identity. Thus, for the first time, it defines arboriculture as “the art, science, technology and business of utility, commercial and municipal tree care,” and arborist as, “an individual engaged in the profession of arboriculture.”

The Standard recognizes that as professionals, we have to exercise discretion in some situations. Thus it says, “This Standard may require situational modifications in response to personnel emergencies and is not intended to limit the options available to emergency responders.” It also recognizes that we all must take personal responsibility for safety when it says, “Each employee shall comply with the appropriate federal or state occupational safety and health standards and all rules, regulations and orders that are applicable to his/her own actions and conduct.”

As a matter of fact, the arborist profession has developed enough of a name for itself that it is deserving of its own type of rope, henceforth referred to in Z133 as arborist climbing line. Identified by the manufacturer as suitable for tree climbing, arborist climbing lines are half-inch diameter, made of synthetic fiber, with a minimum nominal breaking strength of 5,400 pounds and a maximum working elongation below 7 percent.

That having been said, the revised Standard acknowledges that, “In arboricultural operations not subject to regulations that supersede Z133.1, a line of less than one-half-inch diameter may be used, provided the employer can demonstrate it does not create a safety hazard for the arborist.” In other words, Z133 recognizes that innovation has brought us new, proven techniques that force some of us to look outside the box.

New techniques and equipment

The Z133 Standard was last published seven years ago. We are not exactly a high-tech industry, where today’s PC is tomorrow’s doorstop, but for us change has occurred relatively quickly since the “Z” was last brought up to date.

The revision is current with today’s philosophies and mindsets. In one part it says, “Communications shall be established between the arborists aloft and the arborists and other workers on the ground before cutting and dropping limbs. The command ‘stand clear’ from aloft, and response ‘all clear’ from the ground are terms that may be used for this purpose.”

The Standard recognizes that poor communication has been the downfall of many an arborist, and it is giving credence to the so-called “command and response” system that has only recently come to the forefront. The concept pops up again in the tree removal section, where the Standard admonishes the saw operator and the rest of the crew to communicate.

The Standard recognizes the various labor/equipment/life-saving gadgets introduced to the industry in the past 10 years. It begins by defining, in alphabetical order, the ascender, positive-locking carabiner and Prusik loop. It validates the Blake’s hitch and split tail for use in climbing.

It recognizes both the full-body harness/fall-arrest lanyard and the body belt and lanyard as suitable fall protection in a bucket truck, choosing to emphasize that it is less important which you choose, but that “fall protection shall be worn when working aloft.”

The Standard introduces the concept of being “secured,” describing the arborist who is safeguarded from unintended movement by a climbing system that is attached to the arborist and connected to a tree or other stable support. Examples of being secured include but are not limited to: being tied in, using a work-positioning lanyard, being on belay, or using a Prusik loop or ascenders while ascending.

There are some significant changes in the area of connections for climbers. Carabiners used in securing the arborist climbing line and/or the work-positioning lanyard to the arborist climbing saddle shall be of the self-closing positive-locking type, with a minimum tensile strength of 5,000 pounds. Rope snaps used in climbing now must be the self-closing, locking type (as opposed to simply self-closing) with a minimum tensile strength of 5,000 pounds.

Do you know the difference between a conventional, a Humboldt and an open-face notch? Can you think of an example of where one would be preferable over the other two? The Standard provides a full description, illustrations and even specifications for making the back cut: “With a conventional notch or Humboldt notch (between 45 and 70 degrees), the back cut shall be 1 to 2 inches above the apex of the notch to provide an adequate platform to prevent kickback of the tree or trunk. With an open-face notch (greater than 70 degrees), the back cut should be at the same level as the apex of the notch.”

Some of you are yawning right now, because these cuts are as old as the crosscut saw. Still, the inclusion of all three in most arborists’ mental toolboxes is a relatively recent event.

Finally, there are a number of new informative annexes. Annex C lists general safety procedures that apply to all tree work for the control of hazardous energy. Annex E is a green log weight chart, providing weight-per-cubic-foot values for almost 60 species of tree. Annex F covers the impact of OSHA and ANSI standards upon municipal forestry departments. It lists the states under federal OSHA enforcement, states with OSHA-approved state plans, and states with unapproved plans, and also highlights which states have safety laws applicable to state and local government employees. In addition, it lists the states where violation of a standard is considered negligence; states where violation of a standard is considered evidence of negligence; and states that are undecided on the issue.

Raising the bar for safety 

The arborist profession has made great strides in safety, but we need to press forward diligently. In a typical year, 25 people lose their lives in this profession while many others sustain injuries. Through this Standard, we can communicate and encourage the best practices and raise the bar for safety. I am sure that the thought present in the minds of the ASC Z133 Committee members in this cycle of revision was no different from that of members during previous revisions: “We have to do even better.”

Many of the changes in the new Z133 bring greater specificity to its requirements. This will help everyone, including the folks at OSHA, to better understand how the committee intended the Standard to be applied.   Here are some of the new “Shall” requirements: 

• Clothing and footwear appropriate to the known job hazards shall be approved by the employer and worn by the employee.
• Chain-saw-resistant leg protection shall be worn while operating a chain saw during ground operations.
• Training shall be provided in emergency response procedures appropriate and applicable to the work to be performed.
• Line clearance shall not be performed during adverse weather conditions such as thunderstorms, high winds, and snow and ice storms.
• Qualified line-clearance arborists and qualified line-clearance arborist trainees performing line clearance in the aftermath of a storm or under similar conditions shall be trained in the special hazards associated with this type of work.
• Line-clearance operations shall be suspended when storm work or emergency conditions develop involving energized electrical conductors. Electrical system owners/operators shall be notified immediately.
• Arborists, workers and mechanics shall not, under any circumstances, reach into the infeed hopper when the cutter disc or rotary drum or feed rollers are moving.

Arborists operating cranes should take particular note of the brand-new section on cranes, reproduced in full below. The part in italics was the only requirement conveyed in the 1994 revision of Z133:

“Riding the load line of a crane while it is under load tension shall be prohibited, except for circumstances outlined [below].  “A qualified arborist may be hoisted into position utilizing the crane, provided that he/she is tied in with an arborist climbing line and arborist saddle meeting the requirements of this Standard and secured to a designated anchor point on the boom or line.

The following procedures shall be followed when an arborist is to be lifted by a crane:  “The person specifically responsible for the work shall only authorize the use of a crane when he/she has determined that it is the safest and most practical way to perform the work or gain access to the tree. Such authorization should be made in writing and be retained at the job site.  “The crane operator shall be familiar with the potential hazards and operational techniques encountered in tree work. 

“The arborist climbing line shall be secured to the crane in such a way that it does not interfere with the function of any damage-prevention or warning device on the crane, and so that no part of the crane compromises the climbing line or any other component of the climbing system.  “The crane operator and the person responsible for the work to be performed shall meet prior to the work to review procedures to be followed. If the work involves a signal person and/or arborist being lifted in addition to the person responsible for the work, they shall participate in the review.

“Communication between the crane operator and the arborist being lifted shall be maintained either directly or through the appointed signal person.

“The crane shall be supported on a firm surface and maintained in a level position. The crane operator shall use blocking or other means if necessary so that the support medium does not exceed its load-bearing capabilities. When provided, outriggers shall be extended and properly set. Lifting of arborists shall not be permitted when the crane is supported solely on its tires.

“The crane operator shall test the adequacy of footing prior to any lifting. A green log weight chart should be available to the crew.

“The lifting and supporting shall be made under controlled conditions and under the direction of the arborist or an appointed signal person.

“The crane operator shall remain at the controls when the arborist is attached to the crane.

“The crane boom and load line shall be moved in a slow, controlled, cautious manner with no sudden movements when the arborist is attached. The lifting or lowering speed shall not exceed 100 feet per minute. The crane shall be operated so that lowering is power-controlled.

“The crane carrier shall not travel at any time while the arborist is attached.

“The arborist shall be detached from the crane any time it is under load tension. EXCEPTION: The person specifically responsible for the work shall only allow the arborist to remain attached to the crane while it is under load when it is determined that all reasonably possible alternative methods are inaccessible and attachment to the subject tree would create a greater safety risk due to its hazardous condition. Possible alternative methods include, but are not limited to: 

• securing to the tree and detaching from the crane before it comes under load;
• use of a second crane;
• use of an aerial lift device;
• use of an adjacent tree."

Another recurring theme in the new Z133 is the replacement of “Should” requirements with “Shall, with exceptions” requirements, such as in the statement immediately above. This removes all vagueness when you apply the requirement. Here are a few more examples:

"Chain saws weighing more than 15 pounds (6.8 kilograms service weight) shall be supported by a separate line or tool lanyard when used in trees, except when work is performed in an aerial device. EXCEPTION: This requirement does not apply during topping and removal operations where no supporting limb will be available." 

"Chain saws shall be held with the thumbs and fingers of both hands encircling the handles during operation. EXCEPTION: The employer demonstrates that a greater hazard is posed by keeping both hands on the chain saw in that particular situation. This exception should not apply to lightweight chain saws (under 15 pounds) when used in a tree."

"Arborists shall use a second point of attachment (work-positioning lanyard or double-crotched rope) when operating chain saws in a tree, unless the employer demonstrates that a greater hazard is posed by using a second point of attachment while operating chain saws in that particular situation."

"Equipment used to secure an arborist in the tree or from the bucket shall not be used for anything other than its intended purpose. EXCEPTION: The arborist climbing line may be used to raise and lower tools.”

"Arborists shall be tied-in or secured while ascending the tree and remain tied-in or secured until the work is completed and they have returned to the ground.

• "EXCEPTIONS: While ascending a ladder to gain access to a tree, however, arborists shall not work from or leave the ladder until they are tied-in or secured. "

• "While ascending a tree where the density of branches growing from the stem prevents the arborist from crotching the arborist climbing line or work-positioning lanyard through the branches, then and only then, is the three-point climbing technique acceptable."

"When a pull line is being used, workers not involved in removing a tree or trunk shall be clear by a minimum of one tree length, unless it is necessary to have a team of employees involved in the removal operation."

"Workers not directly involved in manual land-clearing operations shall be at least two tree lengths away from the tree or trunk being dropped.  EXCEPTION: The presence of site restrictions, such as waterways or cliffs. Other arborists and workers shall be beyond the trees’ striking range and as close to twice the height as practicable."

Statistically, the big three killers in arboriculture are electrocutions, falls and struck-by’s. Recognizing that our woes come primarily from these accident categories and a few others, the Standard’s writers beefed up the corresponding sections of the Standard. But first, recognizing that accidents of all kinds are caused when there is a lack of awareness of hazards at the work site, the committee has included job briefing language in Z133. The Standard defines a job briefing as “the communication of, at a minimum, the hazards associated with the job, work procedures involved, special precautions, electrical hazards, job assignments and personal protective equipment. It shall be performed by the qualified arborist in charge before the start of each job. The briefing shall be communicated to all affected workers.”  If you are working alone, you need not conduct a job briefing. The committee wouldn’t want your clientele to think you are hearing voices. Here is a synopsis of the new language to help arborists avoid the “big three” hazards:

"Electrical shock may occur during a ground fault simply by standing near the grounding object with one’s feet apart. With step potential, a person could be at risk of injury during an electrical fault simply by standing near the grounding point or points."
"Manual pole pruners, pole saws, and other similar tools with poles made of metal or other conductive material shall not be used in line-clearance operations or in other operations where electrical hazards exist. Tools shall be equipped with wooden or nonmetallic poles and the actuating cord shall be made of non-conducting material."
"A visual hazard assessment including the root collar shall be performed prior to climbing, entering or performing any work in the tree."
"If ascenders are used, the arborist must be tied-in to the ascender with an arborist climbing line, climbing hitch, and arborist saddle."
"Arborists shall have a minimum of two means of being secured available while working aloft, for example, an arborist climbing line or a work-positioning lanyard."
"When it is necessary to shorten or remove branches before dropping the tree, the arborist shall attempt to determine if the tree can withstand the strain of the lowering procedures. If not, other means of removing the tree should be considered."
"Before beginning any tree-removal operation, the chain saw operator and/or crew leader shall carefully consider loose limbs, chunks, or other overhead material; and size and terrain characteristics or limitations of the work area."
"Workers shall be positioned and their duties organized so the actions of one worker will not create a hazard for any other worker."
"Workers returning to the work area shall not enter until the chain saw operator has acknowledged that it is safe to do so."
"Crew leaders shall determine if one or more employees are necessary for tree removal operations.”
"Clear obstructions at the base of the tree or trunk and along the escape path. The chain saw operator shall use this path for egress once the cut has been completed."
"Once the back cut has been completed, the chain saw operator shall immediately move a safe distance away from the tree or trunk on the planned escape route."

What I have covered is by no means every last change in the new Z133 Standard. I urge you to obtain a copy of the new Standard when it comes out, put it to good use in your operation, and let your ASC Z133 Committee members know how they can enhance the next revision of the “Z.”  The ANSI Z133 Standard is available through Tree Care Industry Association. To order standards, please click here.

The International Society of Arboriculture is the Secretariat for Z133. To address a question or concern about the ANSI Z133 Standard to the ASC Z133 Committee Secretary, please click here.

Figure 1- A conventional notch is a directional felling cut into the side of a tree facing the intended direction of fall consisting of a horizontal face cut and an angle cut above it, creating a notch of roughly 45 degrees.

Figure 2 – A Humboldt notch is a directional felling cut into the side of a tree facing the intended direction of fall consisting of a horizontal face cut and an angled cut below it, creating a notch roughly 45 degrees. A Humboldt cut is usually reserved for larger trees on steep slopes.

Figure 3 – An open-face notch is a directional felling cut into the side of the tree facing the intended direction of fall consisting of two cuts creating a notch greater than 70 degrees.

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