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IS 9561:1985 is the Indian Standard (BIS) for felling and conversion of trees into logs. This code of practice outlines the standard procedures for the felling of trees and their subsequent conversion into logs for commercial or other uses. It details the techniques for making undercuts and backcuts to control the direction of fall, as well as methods for cross-cutting the felled tree into logs. The standard places significant emphasis on the necessary safety precautions for personnel and equipment during logging operations.
Code of practice for felling and conversion of trees into logs
29 CFR 1910.266OSHA (Occupational Safety and Health Administration), USA
MediumCurrent
Logging operations
Covers safety procedures, training, and techniques for all logging operations, including manual felling.
ACOP for Forestry (2012)WorkSafe, New Zealand
HighCurrent
Approved Code of Practice for Safety and Health in Forest Operations
Provides comprehensive guidance on safe tree felling, processing, and related forestry work with a modern safety focus.
AFAG 302HSE (Health and Safety Executive), UK
HighCurrent
Felling and processing trees over 380mm
A practical guide detailing specific techniques for felling medium-to-large trees, closely matching the IS code's intent.
BS 3998:2010BSI (British Standards Institution), UK
LowCurrent
Tree work — Recommendations
Focuses on arboriculture and managing living trees, but includes recommendations for tree removal and felling techniques.
Key Differences
≠IS 9561:1985 details methods using manual tools like axes and hand saws, whereas modern international standards (e.g., ACOP for Forestry NZ) focus almost exclusively on techniques for power chain saws.
≠Modern standards mandate a formal, documented, site-specific risk assessment before felling. IS 9561 follows a more generalized procedural approach to assessing tree and site conditions.
≠International standards like OSHA 29 CFR 1910.266 are legally binding regulations with stringent requirements for Personal Protective Equipment (PPE) and training, while IS 9561 is a code of practice providing guidance.
≠The Indian standard is a standalone document, whereas international equivalents are often part of a larger system that includes mandatory, certified operator training and competency assessments.
Key Similarities
≈All standards recognize the fundamental felling technique of using a directional undercut (face cut) to control the fall and a back cut to create a hinge.
≈The critical importance of establishing and clearing one or more escape routes before starting any cuts is a primary safety principle common to all standards.
≈The concept of 'hinge wood' (the uncut wood between the undercut and back cut) is universally identified as the key element for maintaining control of the tree as it falls.
≈The use of wedges to prevent the saw bar from being pinched in the back cut and to assist in tipping the tree is a common technique described across both Indian and international standards.
Parameter Comparison
Parameter
IS Value
International
Source
Undercut Depth
1/4 to 1/3 of the tree diameter.
Approximately 1/4 to 1/3 of the tree diameter.
ACOP for Forestry (NZ)
Back Cut Height
2.5 cm to 5 cm above the horizontal cut of the undercut.
At least 1 inch (2.54 cm) above the horizontal cut of the undercut.
OSHA 29 CFR 1910.266
Escape Path Direction
At an angle of about 135° to the felling line in the backward direction (i.e., 45° from rear).
At an angle of approximately 45 degrees back and away from the intended direction of fall.
HSE AFAG 302
Hinge Wood Thickness
A 'narrow strip of wood' should be left uncut (not quantified).
10% of the tree's diameter at breast height (DBH).
ACOP for Forestry (NZ)
Worker Safe Distance
No other person should be allowed within the felling area (distance not specified).
At least two tree lengths of the tree being felled.
OSHA 29 CFR 1910.266
Traditional Undercut Angle
The first (top) cut is made at an angle of 45° to the horizontal.
A standard face notch is formed by a 45° top cut and a horizontal bottom cut.
HSE AFAG 302
⚠ Verify details from original standards before use
Key Values5
Quick Reference Values
Undercut depth1/4 to 1/3 of the tree diameter
Back cut height above undercut2.5 cm to 5 cm higher than the horizontal cut of the undercut
Safety zone radius from fellingAt least 1.5 times the height of the tree being felled
Angle of undercutApproximately 45 degrees
Wedge usage recommendationFor trees with a diameter greater than 20 cm to control the fall
To control the direction of the tree's fall and to prevent the trunk from splitting as it falls (Clause 4.3.1).
What safety distance should be maintained around a tree being felled?+
A minimum safety radius of 1.5 times the height of the tree being felled should be cleared of all personnel (Clause 6.1).
What is a 'hanger' or 'lodged tree' and how should it be handled?+
It is a tree that has been cut but is caught on another tree. This code advises extreme caution and recommends using a winch or other mechanical means to bring it down, not by felling the supporting tree.
What is the 'back cut'?+
It is the main felling cut made on the opposite side of the tree from the undercut, leaving a small hinge of wood to control the fall (Clause 4.3.2).