Sunday, June 15, 2008

ISA HK/China --- Comparison between ANSI and HSE for Arboricultural Practices

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Dear Station Members,

Historically, tree climbing & chainsaw operation in our territory were educated by the British, Australian & lately, US systems. With several systems in place, it has become necessary to study between them, so that myths can be clarified with regard to common belief in our territory whether one system is superior in ways to the others, since it appeared that our Civil Servants were trained in the British system by tradition whereas the public were trained by something else.

In this aspect, ISA HK/China has spent a considerable amount of time to research into the British system & US system, since it is these two systems that our territory frequently refers to & their information is accessible to this Station.

In the US system, the national standard to govern arboricultural work is ANSI z133.1 (2006). This ANSI gives requirements for safety, electrical hazards, vehicles & equipment, power hand tools including chainsaws, hand tools & ladder use, & work procedures including tree climbing, pruning, & rigging. This one set of standards governs all major operations for tree work in the USA & ISA practices would mostly refer to this ANSI for guidelines besides observing local regulations.

In the UK system, it appeared to be the Health & Safety Executive (HSE) which is governing the standards & practices for tree work. HSE has a subsidiary called Arboriculture & Forestry Advisory Group (AFAG) which produced guidelines specifically relating to arboriculture & forestry. HSE & AFAG would provide nearly all the information required in practising arboriculture in Britain.

Upon our studies, it appeared that both ANSI & HSE place similar emphasis on safety & practices in many ways. However, there were also major differences as noted by this station as follows:

Notable Differences between ANSI z133.1 (2006) & HSE Guidelines for Arboricultural Practices

Topic ANSI z133.1 HSE

1. PPE

Helmet, Eye Protection & Safety Boots mandatory All recommended but not mandatory
(See AFAG 401 Tree climbing Operation)

2. Tree Climbing

a. Work positioning System

A climber must be secured at all times on a tree.
Tie-in point should be well above work area.
Do not climb more than 250mm above anchor
point. Slack must not exceed 500mm (see
AFAG 401)

b. Climbing Ropes

Minimum diameter not less than 11mm. Minimum diameter of 10mm (see AFAG 401)

c. Ladder Use

Arborist shall not work from or leave the ladder
until tied-in or otherwise secured. Normally used as a means of access into crown
of tree. Once climber is secured by
ropes/strop & hardness, ladder should be
removed (see AFAG 401)

3. Chainsaws

a. PPE

Helmets, Eye Protection, hearing Aid, Safety Boots
& Chaps while on ground are mandatory. All recommended but not mandatory (see
HSE INDG 317 Chainsaws at Work)

b. age

To comply with local, state or federal regulations. Should not be operated by anyone under
minimum school leaving age or near the age
of 16 years (see HSE INDG 317)

c. Use of chainsaws in tree work

Units shall be operated or maintained only by
authorized & qualified personnel in accordance
with company policies & federal, state or local
laws. A worker should have received appropriate
training & obtained a relevant certificate of
competence or national competence award,
unless they are undergoing such training & are
adequately supervised. (see HSE INDG 317)

d. Refresher training

No specific requirement. Occasional users --- every 2 - 3 years
Full time users --- every 5 years
(see HSE INDG 317)

e. Chainsaw guide bar

Manufacturer’s operating & safety instructions
shall be followed unless modified by this
standard. Choose a chainsaw with the shortest possible
guide bar suitable for the work. (see HSE INDG

f. working from ladders

Prohibited Should only be done by an Arborist trained in &
equipped for tree climbing. (see HSE INDG 317)

g. Chain brake

When a chainsaw is being carried more than two
steps, the chain brake shall be engaged or the
engine shut off. Apply chain brake when walking on site, or if the
saw is not being used for short intervals
(more than 15 secs.) (see AFAG 301)

h. Felling

The crew leader shall determine the number of
workers necessary for tree removal. Felling is a one-person operation. (see AFAG

i. Cuts

Notches shall be used on all trees & trunks
greater than 5 inches (12.7cm) DBH. Always make a sink cut. (see AFAG 302)

j. Chainsaw position to body

Chain saws should be operated away from the
vicinity of legs & feet. Keep the saw close to the body & support the
weight of the saw on the tree or right thigh. (see
AFAG 303)

k. One handed use of chainsaw

The arborist or other workers shall hold the saw
firmly with both hands, keeping the thumb &
fingers wrapped around the handle. Should be restricted to circumstances where one
hand is required to maintain a stable position &
the saw is used at extended reach with the other
hand. (see AFAG 308)

l. Felling size

No specific requirements Require LANTRA Awards if cutting material
under 200mm diameter. Require NPTC Cert. of
Competence if cutting material over 200mm.
(see AFAG 805)

Besides the above major differences listed above, this Station has found that both ANSI & HSE are using very similar principles & practices for tree work & safety. Both are excellent standards to conduct proper arboricultural procedures in our territory. Further studies would be necessary to pick the best practices among them to perhaps merge to suit our local condition, weather & sites.

TCHK ( will conduct its 2nd Chainsaw Operation (On Ground) on Sunday 29.6.08 to the public. This module will follow ANSI z133.1 (2006) for safety & practices. Anyone interested please contact TCHK for booking at their convenience.

best regards,

Sammy Au
Station Manager

The ISA Mission - Through research, technology, and education, promote the professional practice of arboriculture and foster a greater public awareness of the benefits of trees. (

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