Tree trimming - National Safety Council

National Safety Council
Data Sheet 244 Rev. February 2006
Tree trimming
rimming branches and tree limbs growing near, or in possible contact with,
overhead power or communications lines
is a potential source of trouble and can
cause service interruptions. Broken branches and limbs can fall across lines and break
wires or act as conductors between wires
when wet. Broken branches or the wind
can force wires together, causing shorts or
burnouts (Figure 1). This data sheet discusses the hazards surrounding tree-trimming operations and ways to avoid injury.
2. Tree trimmers commonly suffer minor
injuries, such as cuts and bruises from contact with tree limbs and machinery. Major
hazards include:
• Falls from trees
• Contact with energized limbs
• Falling trees and falling limbs
• Improper climbing and working methods
• High-speed moving parts on power equipment (e.g., stump grinders, chipper)
• Units and power saws
• High noise levels from power machinery
• Working in aerial baskets
T
Trimming programs
3. Regular tree-trimming programs can prevent the occurrence or recurrence of haz- Figure 1. A tree trimmer is preparing to remove an
ardous conditions. It may be necessary to overlapping branch near high-powered service lines.
trim trees before they reach wires to assure
safe clearances or to remove broken, dead removal operations (Figure 2). Employers
and overhanging limbs. Sometimes an should document that employees have satisfactorily completed the training program
entire area will need to be cleared.
4. Employers must train and instruct before performing the job assignment.
employees in the hazards involved in their 5. A safe tree-trimming program should
job assignments. Training should include include:
techniques for proper handling of all equip- • Safety rules that are observed
ment used in tree work, maintenance and • Selection of qualified, well-trained workers
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National Safety Council
Data Sheet 244 Rev. February 2006
• Selection, use and maintenance of proper tools and equipment
• Adequate first aid equipment and trained
staff to administer it
• An accident prevention program and
appropriate accident recordkeeping
6. A typical, supervised tree-trimming crew
should have at least two climbers and a
combination truck driver and brushman to
promote safe operation where heavy trimming and topping are necessary. There are
line workers or troubleshooters who do spot
trimming for specific emergency problems
involving wires or public hazards; these spot
trimmers should have an experienced
helper who can join the team in an emergency or under adverse conditions. For seasonal tree crews, some small utility and
transportation companies and some munici- Figure 2. A supervisor is instructing a tree-trimming
palities recruit employees from various crew during a group training course.
departments, but this is not recommended
because these employees usually have lim- At least one qualified assistant should be
ited experience and may not have adequate selected. No crew should work without
tree-trimming equipment available.
supervision.
9. Before each job, supervisors should
brief all workers on the tasks to be perRole of supervisor
7. Supervisors must be familiar with the formed and any hazards of the work;
skills and operations needed to perform a inspect all tools, equipment and protective
tree-trimming job safely. They should fol- gear; and replace defective or worn tools.
The defects should be noted on tags
low five general rules:
• Verify that employees are physically and before returning the tools to the shop or
tool room for replacement.
mentally fit for trimming operations.
• Never use workers who are under the 10. Supervisors should be consulted when
influence of alcohol and/or controlled considering tools and equipment for purchase. Changing a tool or material can enable
substances.
the crew to work more efficiently and safely.
• Never allow horseplay on the job.
• Have a qualified assistant who can
assume control of the crew when needed. Standard equipment
• Always have one person on the ground 11. Types of equipment vary—the equipwhen tree work is being done.
ment used should meet all current ANSI
and OSHA standards (ANSI Z133-1-2000).
8. Supervisors should evaluate skills, experience and medical histories of workers and Work positioning saddles
then try to match each worker to the job. 12. Workers should use tree-trimming sad-
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Data Sheet 244 Rev. February 2006
dle belts and a safety strap during climbing
operations (Figure 3).
13. Tree-trimmer saddles used for climbing
operations shall meet the same design criteria as outlined in OSHA subpart M for the
manufacturing of full-body harnesses. Each
climber should have at least one handline.
The lines should be a synthetic material,
minimum 1⁄2-inch width and a tensile
strength over 5,000 lbs.
Pole pruners
14. Pruners should have handles that have
adequate strength and a minimum of moisture absorption.
Note: Compounding handles located midway
Figure 3. This tree trimmer’s saddle belt is made of
along the handle are not recommended because
nylon-reinforced fabric with the climbing rope tied
they tend to catch on limbs and branches.
into a steel harness strap and the fixtures snapped
into rings of the belt. The wires have been de-ener-
15. Ladders of metal or other electrically
conductive material should not be used.
Wooden ladders that conform to ANSI
standard ANSI A14.1-2000 are recommended. Straight ladder or extension ladder side rails should be provided with slipresistant devices such as spikes, slipresistant feet or similar attachments. Some
ladders have their top rung made of fabric
so it will conform to the shape of a tree.
Saws
16. A saw should have a fiber or leather
guard with a snap, so it can be held by a
ring on a worker’s belt during work or while
changing position on a tree.
Personal protective equipment
17. Proper clothing is important in accident
prevention: workers should not wear loose,
floppy clothing, ragged gloves or worn-out
shoes. Safe clothing for regular tree-trimming crews should consist of high-top
leather shoes with composition soles and
heels, a long-sleeved sweatshirt or close-
gized. (Photo courtesy Asplundh Tree Expert Co.)
fitting jacket, a cap and soft, leather gauntlet gloves.
18. For spot trimming or short-term trimming operations, workers can wear rubber
boots in place of composition-soled shoes.
If overalls or regular work trousers are
worn, the cuff area of the pant legs should
be wrapped around the ankles and tied, a
minimum of a long-sleeved shirt, a hard hat
and quality work gloves should be worn.
19. Tree-trimming workers always should
wear personal protective equipment while
trimming trees. Approved hard hats and
eye protection (ANSI Z87.1) should be
worn by workers engaged in tree-trimming
operations.
PRACTICES AND PROCEDURES
Climbing
20. Before climbing or applying weight to any
tree, workers should inspect tree limbs for
structural weakness. Climbing workers
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Data Sheet 244 Rev. February 2006
should not trust a dead branch to support their
weight. Dead branches should be broken off
as workers ascend. Hands and feet should be
placed on separate limbs, if possible.
21. The location of all electrical conductors
in relation to work procedures should be
noted. The workers should climb on the
side of the tree that is away from electrical
conductors, if possible.
22. When working above the ground,
workers should be tied in with an approved
climbing rope and saddle belt. The climbing
rope should always be used even when the
work is being performed from a ladder or
scaffold. A lanyard for fall protection should
be used whenever possible.
23. In some metropolitan areas where trees
are close to or overhang a street, trucks with
a telescoping tower, hydraulic lifting devices
(aerial sky baskets) or telescoping ladders are
used to reach the main supporting limbs.
Trimming can be performed directly from this
equipment or the equipment can be used to
hoist workers into the work area of a tree.
24. Outrigger stabilizers on high-lift trucks
should be fixed on the ground to decrease
overbalance and rollover potential before
operating any lift device. A steel snap meeting OSHA fall arrest standards may be used.
Aerial lift truck units should be operated only
by qualified personnel according to the manufacturer’s operation instruction manual.
Repairs to the elevating mechanism or its
controls should be made only by authorized
representatives of the manufacturer.
Note: Hydraulic aerial basket devices should be
insulated if they are to be used for line clearing.
Wooden aerial ladders shall not be considered
insulated devices, and they should never be positioned over live conductors.
25. When using hydraulic lifting devices,
operators should not depend on the boom
and associated equipment for insulation.
Operators should be warned not to raise
and project booms over live conductors.
(Insulated devices are available that can be
used safely over live conductors.)
26. For unusual jobs, when it is necessary
to get near or between live conductors, the
utility company should be notified to cover
the wire with rubber protection (insulating
line hose), relocate or de-energize the circuit temporarily until the job is completed.
27. Workers sometimes use extension ladders to climb into trees, or trim trees directly from ladders. The side rails of these
extension ladders should rest on an adequate surface, and the ladder should be tied
to the tree or supported by another worker.
28. When climbing tall trees where the first
branches are high and it is difficult or unsafe
to use an extension ladder, workers should
use climbing ropes. A tree-trimming saddle
belt can be used (Figures 3, 4a and 4b).
29. Climbers should be cautioned to select
a wide crotch, strong enough to carry their
weight, before they throw climbing ropes
into a tree. Ropes should be high enough
within the tree so they will come to a safe
stopping place if another crotch, further up,
is used as a safety line support.
Use of ropes
30. Workers should be trained to tie the
various rope knots and hitches.
31. Ropes should be maintained as follows:
Keep ropes coiled when not in use.
• Carry ropes on the shoulder from one
tree to another. This method will keep a
rope free of kinks, dirt and sharp grit that
can cut the fiber.
• To open a kink, hold the rope loosely.
(Pulling a kink out of a rope damages the
fibers.)
• Store ropes away from all cutting edges
and sharp tools.
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National Safety Council
Data Sheet 244 Rev. February 2006
Figure 4a and 4b. Workers should respect their safety lines and be instructed not to use them for lowering equipment or limbs.
Figure 4b. This is a three-step procedure for tying a
tautline hitch knot.
• Before ropes are used, visually inspect
them along their entire length and twist
the lay open at intervals for spot-checking.
• Do not use climbing ropes to lower limbs
or other parts of trees.
• Do not repair climbing and safety ropes
by splicing.
• Rope ends should be secured to prevent
unraveling.
Safe handling of tools
Figure 4a. These three types of bowline knots can
be used for many situations during a tree-trimming
operation.
• Keep corrosive chemicals, gas, and oils
away from the ropes.
• When running ropes through crotches, over
limbs or against bark, move them slowly
to prevent damage from friction bums.
• For protection against the weather,
cover ropes with a waterproof tarpaulin
or place in a ventilated storage box.
• Wet ropes should not be dried rapidly
near a fire or other intense heat; they
should be hung up, off the floor or
ground, and air-dried.
• Install ventilated storage boxes or fixtures for holding coils of rope on trucks.
• Do not leave ropes on floors where they
may be cut or damaged by sharp tools
(Figure 5).
32. A climbing worker should not carry
saws, pruners and other tools and equipment; tools should be raised or lowered by
handlines. The handline should be attached
at the end of the tool (not in the center) so
the tool will not slip free, fall or become
caught in branches. Canvas buckets are
recommended for small tools.
33. To raise or lower a pole pruner, tie
ropes below cutting jaws and not to or
through the jaws. If a pole is caught in a
tree, and the rope is tied to or through the
jaws, the rope can be cut and the pruner
will drop, injuring workers below.
Note: A worker should carry a pruner with the jaw
forward and in advance of any worker walking
alongside.
34. The following list offers other tips for
handling tools:
• To prevent a saw from falling, fit it with a
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Data Sheet 244 Rev. February 2006
and guide the rotating mechanism at work.
36. The following procedures should be
used when operating power stump
grinders:
• The tightness of grinder teeth lock bolts
is critical; spot-check it before operations
each day.
• Noise levels should be checked by noise
meters. When they are over 85 decibels,
operators should wear hearing protection during operation.
• Operators and workers should wear personal protective equipment (full face
Figure 5. This typical tree-trimming truck has sepashield, goggles, hard hat, gloves and
rate storage compartments for ropes, ladders and
high-top shoes) in the immediate area to
sharp tools. These separate compartments leave the
prevent injuries from flying chips, rocks,
entire truck body free for brush and limbs.
dirt and other high-velocity debris.
strap or tie rope and secure it to the • To provide operators with as much direct
protection as possible from flying debris
worker’s belt.
yet not restrict their vision, enclosures or
• Remove all tools from a tree when the
guards shall be installed on the stump
worker or crew has finished for the day.
grinders.
• Do not use axes and hatchets in trees
because they might fall and injure work- • During grinding operations, side tilt of
grinder units must be kept within limits
ers or cut the supporting lifeline.
that will assure an adequate supply of oil
• Keep sheaths or guards on tools when
from the pan to lubricate the engine.
they are in trucks, racks or tool boxes.
• Hang pull-pruners and pull-saws secure- • Grinder shutdown switches must be
located within immediate reach of the
ly in the vertical position to prevent disoperator when he or she is in position at
lodging.
the grinder controls during operation.
• Do not hang pole pruners or pole saws
on utility wires or cables or leave in the • Put the towing truck gear shift lever in
neutral before a grinder is started. This
tree overnight.
will prevent damage to the truck trans• Hang pull-saws so the sharp edge is
mission from the severe vibration and
away from workers.
rocking motions of the grinder unit during operations.
Power stump grinders
35. A stump grinder is a gasoline-powered
mechanical device with rotating teeth that Power chain saws and generators
shred tree stumps to below-ground levels. 37. The following list includes important
The grinder unit is permanently mounted rules for the operation of power chain
on wheels and is towed and secured in its saws:
operating position by a truck or other auto- • Supervisors should ascertain that any
motive equipment. The controls for the
employee permitted to operate a
grinder are mounted on the side of the unit.
portable power chain saw is qualified to
From this location, an operator can observe
do so (Figure 6).
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National Safety Council
Data Sheet 244 Rev. February 2006
saws from the baskets of hydraulic aerial devices.
Note: Small pneumatically, hydraulically or gasoline-powered saws can be used aloft from
approved aerial baskets.
Figure 6. A trimmer demonstrates the proper way
to grip this power chain saw.
• No one except an operator should be
allowed within a radius of 6 feet of a
one-person power chain saw when it is
in operation, except when it is used aloft
in an aerial basket.
• Small power chain saws, equipped with
approved safety cutting chains and
weighing not more than 10 lbs., may be
used above the shoulder level, provided
that the following precautions are
observed:
a. Saws are suspended from a rope,
crotched above the cutting area,
while the operator on the ground
removes the lower limbs of standing
trees.
b. To assure the operator’s safe footing
while de-limbing a felled tree, the
severed branches must be removed
from the operator’s path as work progresses. Approved, small, gasolineor electric-powered chain saws can
be used aloft in trees or from an aerial ladder if the saw is supported by a
crotched rope independent of the
climber’s rope.
• Do not use electrically powered chain
• When using power chain saws, operators should make certain that they have
secure footing.
• Shut off engines or motors when moving a
power chain saw from one location to
another, except when trees are close
together and the approach is unobstructed.
• When starting gasoline-powered chain
saws with pull cords, hold the saw firmly on the ground or on some solid object.
This prohibits starting a chain saw with a
pull cord by holding it in an elevated position. Gasoline-powered chain saws with
electric starters may be started in an elevated position provided that they are
held firmly in both hands.
Warning: Starting any chain saw by bracing it against any part of the body or
drop-starting is prohibited.
Note: Because the cutting chain of power chain
saws can run when an engine is started, operators
should make sure the immediate area is clear of all
personnel and objects before starting an engine.
• Do not start engines or motors of power
chain saws until the saw is in the immediate work area, except when a warm-up
period is required. If warm-up is required,
do not leave the saw unattended when
the power has been turned on.
• Carry two-person chain saws with the
blade indexed to the vertical or bucking
position.
• When carrying one-person saws a long
distance to the scene of an operation,
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Data Sheet 244 Rev. February 2006
•
•
•
•
cover chains suitably; when carrying
saws a short distance, covers are not
required.
Do not insert cutting chains in guide rail
grooves while motors are running.
All saws operated by two persons
should have the transmission horns or
tail shock guards held against the material being cut before the cuts are started
and during all cutting operations. Directdrive chain saws and one-person gearchain saws should be at full operating
speed before a cut is started.
Cool hot saws for two or three minutes
before refueling. Place a hot saw on a
log, stump or on bare ground rather than
on dry litter or slash.
Refuel in an area free from flammable
materials. Maintain metal-to-metal contact between the gasoline can and the
gas tank while refueling a saw.
Note: Prohibit smoking while a tank is being filled,
and keep approved fire-fighting equipment available in accordance with safety standards.
tool and generator when not in use.
• Inspect electric saws carefully before
use. They should be turned in for thorough inspection after every 60 running
hours. Generators, including ground rod
and cord, should be returned for inspection after every 120 running hours.
• Chain saw operators should wear
approved eye protection.
• Noise levels should be checked by noise
meters. When they are over 85 decibels,
operators should wear hearing protectors.
Power loaders
38. A power loader is a truck-mounted,
hydraulically powered boom and clamshell
device, designed to pick up and load brush
and small logs (Figure 7). Some units are
combination power loaders and haulers with
controls mounted over the truck cab and
truck beds designed to carry tree trimmings.
Many loaders of this type also can dump
loads. Other power loaders are single-purpose vehicles with the loader boom, operator’s seat and loader controls mounted on
the truck chassis instead of over the cab.
• Move saws at least 10 feet upwind from
the spot of refueling before starting a
motor.
• Equip gasoline-powered saws with mufflers to prevent escape of burning carbon particles from the exhaust.
• Ground portable generators and
portable, electrically powered tools as
follows:
a. Connect the generator frame to a
driven ground rod or other suitable
ground.
b. Connect the noncurrent-carrying
parts of the tool and generator frame
with the ground wire of the threeconductor cord through an approved
Figure 7. Workers prepare to unload trimmings from
connector.
• Handle portable, electrically powered tools, a power loader into a truck.
cords and generators with care. Store the (Photo courtesy Denver Forestry Section.)
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Figure 9. A chipper and hauler truck are used at a
trimming operation.
(Photo courtesy Denver Forestry Section.)
Whenever brush extends more than 4
feet beyond the end of the truck bed,
red flags or other legally required warning devices should be placed on the
ends of the brush.
Note: Workers should never be allowed to ride on
Figure 8. An operator prepares to swing about to
top of a load of brush.
unload trimmings. Note: The outriggers have been
properly set prior to loading.
Chippers
(Photo courtesy Denver Forestry Section.)
40. Chippers are mechanical devices with
openings where brush and branches are
fed into rotating knife blades. This machine
chips up the material and blows it into a
metal-enclosed or canvas-covered truck
(Figure 9). This method eliminates the hazards of bulky loads and brush burning. The
following are important safety considerations when working with chippers:
• When attaching a chipper to the hitch at
the rear of a truck, install safety chains,
coupling the chipper to the truck. Enough
slack should be left in the chains to allow
the truck to turn at sharp angles. These
chains should not drag and trail on the
pavement because they could catch on
obstructions and upset the equipment.
Red flags or other legally required warning devices are recommended at the rear
of a chipper. State or provincial laws and
codes should be reviewed and followed
to prevent violations and penalties.
39. The following are important issues
when using power loaders:
• Rollover potential exists with power
loaders; safety precautions should be
taken.
• Keep power loaders at least 10 feet from
all electrical conductors unless the local
power company has been notified.
• As soon as brush is removed from a
tree, it should be hauled away at once or
cut up and piled neatly away from traffic.
• When brush is piled on a truck, it should
be tied tightly to the truck bed by a rope
lattice, tarpaulin or binding. This will prevent the brush from blocking visibility,
scraping against cars in traffic, striking
pedestrians or blowing off and falling
onto streets during transport.
• The width of a load must conform to
local or state ordinances and codes.
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Figure 10. A properly hitched coupling (with locking
key) is ready for operation.
(Photo courtesy Denver Forestry Section.)
• Check the hitching device and coupling
safety chains regularly, especially on
long hauls from job to job, to prevent
them from becoming too loose or separating (Figure 10).
• When parking trucks with attached chippers, give particular attention to the location of the equipment chute opening and
surrounding work. First consider the traffic pattern—keep the equipment from
projecting or blocking the flow of vehicles. When parking along a curb, pull the
equipment far enough beyond the street
intersection to prevent blind spots in any
direction for regular traffic.
• Whenever a chipper is being operated,
protect the work area by cones or barricades. This will protect the workers from
interference from traffic and spectators.
• If a chipper is truck-mounted, with the
chute opening on the side, it should be
parked along the curb with the chute
feed facing the curb. Workers then can
stand on the parkways, out of the traffic
flow and feed the chute.
Note: Workers should never attempt to make
repairs or adjustments to a chipping unit while it is
in motion. They should shut off the ignition switch,
remove the key and disengage the clutch. On some
models, it might be necessary to install additional
lockout devices, using a padlock.
• Whenever this equipment is left alone,
such as during lunch periods, lock out all
starting controls and remove the ignition
key. If the chipper is left parked, unattended, and uncoupled from the chipper
truck, properly chock the chipper unit
wheels to prevent it from rolling away.
• Whenever cutting blades on a chipping
unit are changed or adjusted. Properly
tighten the lock bolts on the blades to prevent separation of the blades during operation. A follow-up inspection of all lock-bolt
work is recommended before chipping
units are restarted. On Allen-head lock
bolts, use only well-conditioned, properly
sized Allen wrenches to assure adequate
tightening of bolts, without slipping and
consequent hand injuries. Replace lock
bolts with stripping heads immediately. To
protect fingers, hands, and arms from
injury during work on chipper blades and
lock bolts, place a portable blade guard
over the cutting edge. Never engage the
clutch on shut down chipper units to act
as a brake on the blade drum while removing, installing or tightening lock bolts.
Instead, use a manual locking device at
access points provided on the chipper.
• Make daily checks on the tightness of
the locking bolts that hold the cutter
blades before starting a unit; then run a
test for a few minutes.
• Operators should wear loose-fitting
gloves and eye protection, such as safety goggles or face shields, while feeding
a unit. Workers located close to the
operation also should wear hand and eye
protection.
• Workers should not attempt to feed
small, short pieces of brush into a chute
by hand. Instead they should use a
longer piece of brush as a pusher. If a
large branch becomes wedged in a
chute, the chipper should be stopped
and the wedged piece removed by hand.
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Note: Before removing any wedged pieces, another worker should stand by the controls while the
piece is being removed to avoid inadvertent starts.
The removed piece should be cut smaller by hand
before returning it to the chipper.
• Instruct workers never to throw sweepings or other foreign materials, such as
stones or nails, into a chipper. These
materials can be thrown back into the
face of an operator or damage the cutting blades, causing them to break.
• Do not allow anyone in a truck or in front
of an exhaust chute while a unit is running. A blast of wooden chips could blow
out of the exhaust chute and into the
bystander’s face, causing serious injury.
OTHER CONSIDERATIONS
Electric lines
41. Never directly or indirectly touch any
communication wires and cables. Consider
them energized with potentially fatal voltage. Workers should observe the recommended minimum working distances from
energized conductors (Table I).
42. There may be laws or ordinances pertaining to the clear space work area.
Professional line-clearing contractors are
more likely to be able to work safely with
tools immediately adjacent to energized
conductors. When securing themselves,
they should make certain they will not
swing or fall into the danger zone.
43. Before climbing, entering or working
around any tree, the worker and supervisor
should make close inspection to determine
whether an electrical conductor passes
through the tree or within reaching distance of the worker. Assign only a qualified
line-clearance tree worker or a qualified
line-clearance tree trainee to the work if it
is found that an electrical hazard exists.
Place a trainee under direct supervision of
qualified personnel.
44. Use pole saws and pruners with dry
wooden poles and no metal parts to make
cuts. Make cuts at the point farthest from
conductors.
45. If a limb overhangs a wire and can be
reached easily from a ladder, tower truck or
Table I: Minimum working distances from energized conductors for line-clearance
tree trimmers and trainees
Voltage Range
(phase to phase)(kV)
2.1
15.1
35.1
46.1
72.6
138.0
161.0
230.0
345.0
500.0
700.0
to
to
to
to
to
to
to
to
to
to
to
15.0
35.0
46.0
72.5
121.0
145.0
169.0
242.0
363.0
552.0
765.0
Minimum Working
Distance
2
2
2
3
3
3
3
5
7
11
15
ft
ft
ft
ft
ft
ft
ft
ft
ft
ft
ft
0
4
6
0
4
6
8
0
0
0
0
in.
in.
in.
in.
in.
in.
in.
in.
in.
in.
in.
(0.6 m)
(0.7 m)
(0.75 m)
(0.9 m)
(1.0 m)
(1.05 m)
(1.1 m)
(1.5 m)
(2.1 m)
(3.35 m)
(4.55 m)
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47. An approved first aid kit, adequately
stocked and maintained, should be available to workers at all tree-trimming operations. All workers should be instructed in
how to use first aid materials. All workers
should be instructed in how to identify and
prevent exposures and problems relating
to common poisonous plants such as poison ivy, poison oak and poison sumac.
48. All workers should know how to perform cardiopulmonary resuscitation and
should undergo frequent refresher courses. When the victim is located in a densely
foliated tree that might hinder immediate
access, the treetop method of resuscitation should be applied immediately.
Treetop resuscitation is the same as the
line worker’s pole-top method (Figure 11).
During this time, openings can be made in
the tree by cutting portions or pulling apart
branches with ropes. The victim should be
lowered through these cleared spaces to
the ground, and cardiopulmonary resuscitation should be administered immediately.
Where there are no tree obstructions, the
victim should be lowered directly to the
ground on a blanket, and CPR should be
applied immediately (Figure 12).
49. Tree-trimming personnel should be
familiar with techniques of rescue from
aerial and live-line wires.
Figure 11. This pole-top procedure for mouth-to-
Figure 12. One man applies resuscitation while
mouth resuscitation can be used for a treetop res-
another assists with external cardiac massage.
the tree itself, a supervisor should have a
qualified lineman cover the wire with flexible, insulated, protective equipment, if the
voltage permits. If the wire is between
spans or towers, the local utility company
should be asked either to move the line or
de-energize it. It is possible to safely
remove overhangs between poles with
electric lines energized.
46. Only qualified workers should handle
fallen or broken wires. Dangerous areas
should be roped off or barricaded, the public utility company should be notified and a
watchman should be stationed to keep the
public away until a line crew arrives.
First aid
cue as well.
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National Safety Council
Data Sheet 244 Rev. February 2006
Felling trees
50. Felling trees requires precise planning
and an exact understanding by each crew
member of procedures to be followed
throughout a felling operation. Planning factors should include the following:
• Tree height
• Wood soundness
• Lean direction
• Ground slope
• Tree species
• Treetop weight
• Wind direction
• Dead limbs or stubs that may break off
and fall during operations
• Proximity to other trees, structures and
wires
• Vehicular or pedestrian access problems
• Positioning of equipment and workers
during an operation
• Type and number of specially qualified
workers needed
• Mechanized and other special equipment needed
• Required personal protective equipment
51. When felling trees over 10 inches in
diameter, a notch and backcut should be
used. The depth of penetration of the
notch should be about one-third the diameter of the tree. The backcut should be
made higher than the point or apex of the
notch to prevent kickback.
52. If a tree is to be felled near overhead
wires, the limbs should be stripped high
enough to allow it to fall without striking
and breaking the wires.
53. No one should work in a tree that
might be struck by another tree being
felled. Workers felling trees must give
ample audible warning signals. They must
keep away from the base as the tree
begins to fall, to avoid unexpected rolls.
They also should stand to one side, preferably behind another tree when felling lean-
ing trees, to avoid dangerous kickbacks.
Once the job of felling a tree has begun, it
should be completed before workers leave
for the day.
54. Large trees can fall sideways, and they
should be side-guyed in both directions to
prevent accidents and property damage.
55. For head-guying, two ropes should be
used—one for pulling and the other as an
emergency line. The head-guy should be
pulled tight before sawing begins in case
the treetop breaks. (The treetop will break
before the tree starts to fall.) As sawing
proceeds, the head-guy and emergency
head-guy may require tightening to keep
them taut. The emergency head-guy
should be kept taut so the fall of the tree
can be controlled should the head-guy fail.
If the truck used by the crew has a winchline, that can be used instead of one rope.
Removal of limbs
56. Removal of large lateral limbs usually
requires roping to prevent damage to the
tree or other property, and to prevent injury
to employees or the public. Limbs that
must be lowered, raised or swung to the
side are roped using the same method. A
heavy limb requires three ropes: butt rope,
top rope and guide rope (Figure 13).
57. The butt rope is passed through a
crotch above the limb to be removed, and
one end is secured to the limb near the
point where the saw cut is to be made. The
other end of the rope is tied to a tree, pole
or other firm support to hold the limb until
it is ready to be lowered.
58. The top rope is passed through a different crotch, whenever possible above
the limb to be removed, and one end is
secured near the outer end of the limb. The
other end of the rope is tied to a tree or
pole until the limb is ready to be lowered.
Where a truck is available, the rope can run
through a snatch block at the base of a tree
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Data Sheet 244 Rev. February 2006
of the top and butt ropes.
62. If no limb or other tree is available for
crotching, the butt rope should be wrapped
around a lower stub or passed through a
snatch block and lashed to the trunk at a
point below the cut.
Note: Under no condition should partially sawed
limbs be allowed to remain in the tree overnight or
after workers leave a worksite—even if the job is
not completed.
Brush removal
63. Members of a crew who handle brush
should be warned to watch the ends of the
brush to avoid striking another worker on
the head or in the face when the brush is
pulled from the tree by pruners. Workers
who handle brush should wear safety hats
and goggles or other suitable eye protection. They should avoid working under
trees that are being trimmed.
Figure 13. This is an example of the proper methodology for using a guide rope, top rope and butt rope
Brush disposal
to remove and lower large lateral limbs.
64. Brush should be disposed of in accordance with waste disposal regulations.
Often, local ordinances will govern the
burning of brush.
• If the brush is to be burned near the job
areas, pile it in a place away from wires,
cables, fences, poles or buildings. Fire
protection equipment should be provided.
Extinguish or guard fires before a crew
leaves for any reason, such as lunch,
breaks, or at the end of the workday.
• Unload brush at a safe distance and
away from fires. The burning area should
be large enough for several piles to be
burned at the same time, with enough
room for unloading at burned-out spots.
• Never back up a truck to a fire for unloading. If the brush on the truck should
catch fire, it might ignite the gasoline
tank or other flammable materials.
and be tied to the frame of the truck for
raising or lowering operations.
59. The guide rope is fastened near the
end of the limb to aid in pulling it around
and guiding it past other limbs or obstructions during the lowering process.
60. With the ropes secured in place, a preliminary saw cut should be made at least 2 feet
from the trunk. When the cut is deep enough
to permit the worker on the ground to pull on
the rope and break the limb, the worker in the
tree should move to a safe position where the
limb being removed cannot kick back and
strike. This position should never be under the
point where the ropes are crotched.
61. Workers on the ground should use a
guide rope to swing the limb to the desired
position, and then lower the limb by means
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Data Sheet 244 Rev. February 2006
Fire hazards
65. Workers should be alert for the following fire hazards and take the recommended
precautions while working around treetrimming equipment:
• Never park in high weeds or grass
because the exhaust pipe could ignite
them and cause a fire.
• Clean chips from the motor, especially
around the exhaust manifold, to prevent
fires.
• Never leave chips in a truck over a weekend because they can dry out and
become a fire hazard.
• Never dump chips into street gutters or
on private property. Children may set fire
to them.
• Dispose of collected wood chips in a
local dump, or give them to property
owners or farmers for cattle bedding.
Public safety
66. Before tree-trimming or removal operations begin, pedestrians and drivers
should be warned with red flags and danger signs set up on sidewalks and on the
street in the vicinity of where the work is to
be done. Block off hazardous areas with
barricades or ropes.
67. When traffic is congested, station a
worker with a red flag to direct those who
must step into the street to go around the
site of an operation. If necessary, call local
authorities to close traffic lanes during
operations. Provide warning lights in
obscure places or in dark areas.
68. Limbs and other brush should be
thrown or lowered by rope away from the
street side and off the sidewalk if possible.
Otherwise, have one worker remove the
brush from the sidewalk as soon as possible. Keep tools and equipment off sidewalks and streets. Keep ropes coiled to
prevent tripping hazards. Workers should
use hand lines to raise or lower tools and
materials and make sure the public is clear
of the area before they do so.
Environmental problems
69. Poisonous plants will adversely affect
many persons on contact. In areas where
poison ivy, poison sumac and poison oak
are growing, workers should be able to recognize each and take special care to avoid
contact with them. They also should avoid
the smoke generated from burning such
plants. The smoke carries oil from the
plant, and contact with the skin may result
in a skin eruption or dermatitis. At the first
sign of irritation, workers should report to
their supervisor and obtain immediate
medical attention.
70. Some workers are allergic to the fine
dust or fuzzy substances given off from the
underside of the sycamore leaf. Such workers should wear dust respirators when
trimming trees during the summer months.
(To avoid this hazard, sycamores should be
trimmed during the winter.)
71. Workers should be cautious when
working in or around honey locust and
black locust trees because some have
thorns that can cause cuts and scratches
and initiate secondary infections.
72. Immediately upon approach of an electrical storm, workers should be ordered
down from trees. They should seek shelter
in the following manner:
• If possible, workers should sit in an automobile or truck. These vehicles should
not be parked in an open space on top of
a relatively bare hill where it is the highest object in the immediate vicinity.
• Workers should keep away from wires,
especially wire fences.
• Workers should avoid taking shelter
under a tree.
73. Except in emergency circumstances,
trees should not be climbed or worked
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Data Sheet 244 Rev. February 2006
during wet or icy weather. It is extremely
difficult to get a good foot or hand hold on
slippery bark, and knots in climbing ropes
are likely to slip if a rope is wet or frozen.
Acknowledgment
This data sheet was prepared by the Public
Utilities Division of the National Safety
Council, 1121 Spring Lake Drive, Itasca, IL
60143.
Sources of information
American National Standards Institute, 1819 L
Street, 6th Floor, Washington, DC 20036. Practice for
Occupational and Educational Eye and Face
Protection, ANSI Z87.1.
Safety Requirements for Portable Wood Ladders,
ANSI A14.1-2000.
Safety Requirements for Tree Care Operations—
Pruning, Trimming, Repairing, Maintaining, and
Removing Trees, and for Cutting Brush, ANSI Z133
.1—1988.
Copyright ©2007 National Safety Council.
All rights reserved.
Although the information and recommendations contained in this publication have been compiled from
sources believed to be reliable, the National Safety
Council makes no guarantee as to, and assumes no
responsibility for, the correctness, sufficiency or
completeness of such information or recommendations. Other or additional safety measures may be
required under particular circumstances.
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