MIS303 Tree Dismantling 2nd ed.

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This book is one in a series of Minimum Industry Standards produced by Arboriculture Australia Ltd and the New Zealand Arboricultural Association in consultation with the national arboriculture community in both countries. These industry peer-reviewed documents provide a ‘body of knowledge’ which is shared by practitioners and can be used as the basis for training, dissemination of skills and professional development. 

This standard covers the basics of tree dismantling, including rigging techniques, the use of a chainsaw in trees, and some fundamental concepts of rigging forces and rigging system design. 

Information on equipment inspection, site setup, pre-start checks, tree inspection, rope use, knot tying, the operation of chainsaws, tree felling and tree access is contained within the appropriate MISs for those work tasks.

Contents

1: Preparing for tree removal

• Introduction to tree rigging and dismantling

Arriving on site

• Scope of works

Preparing to remove trees – site setup

Tree removal strategies

Tree inspection for dismantling

• Hazard control measures for tree dismantling

Basic rigging concepts

• Parts of an aerial rigging system

Selecting and inspecting rigging equipment

• Rigging equipment: general concepts and terminology 

• Rigging equipment inspection checklist

Aerial rigging systems

• Common components of a rigging system

• Selecting anchor points in trees – tree strength and structural integrity

• Fixed rope anchor points – attaching a rope

• Running bowline

• Round turn with 2 half-hitches

• Main attachment knot plus half-hitch

• Clove hitch with two half-hitches

• Cow’s hitch with better half

• Timber hitch

• Karabiner

• Karabiner and sling

• Shackle or similar connector

• Other fixed-rope attachments

• Moving rope anchor points

• Natural crotch

• Block, rigging block, impact block

• Pulleys

• Rigging rings

• Moving rope anchor point attachment components

• Sling, tape sling, tube tape sling

• Loopie sling

• Whoopie sling

• Dead-eye sling

• Other anchor points and attachment options

• Rope brakes

• Trunk wraps

• Wraps in tree

• PortaWrap or similar floating friction brake

• Bollard, drum or similar

Rigging equipment configuration and proper use

• Example of misconfigured rigging equipment

Designing a rigging system 

• Rigging system design considerations

• Estimating weight of sections

• Tree species density table

Introduction to forces in rigging

• Different loads on components in rigging system

2: Dismantling trees 

• Performing works

Communication during tree work

• Call-and-response protocol

• Hand and whistle signals for use on tree sites

Using a chainsaw in trees 

Cut sequences and techniques – branches

Straight back cut 

• Step cut – undercut made first – top cut inside

• Step cut – undercut made first – top cut outside

• Step cut – top cut made first

• Step cut – lateral cuts

• Scarf and back cut – downward

• Scarf and back cut – upward

• Box cut

Cut sequences and techniques – tree heads and timber

• Falling the head out of a tree

• Falling sections of timber

• Falling sections of timber – landing sections flat

• Cutting techniques where trunk diameter is greater than bar length

• Blocking down: step cuts on timber

Falling techniques for tree dismantling – use of wedges and taglines 

Rigging operations 

Rigging attachment point: cut and behaviour 

• Rigging upright sections

• Rigging lateral sections or branches

Rope control during rigging operations 

Rope control: rope brakes and friction management 

• Installing rope brakes 

• Using rope brakes: adding tension 

• Rope control during rigging operations – general principles 

• Tips for using rope brakes 

Returning rigging components 

Specific rigging techniques 

Natural crotch rigging 

Applying friction at the point of cut 

• Techniques for applying friction at the point of cut 

• Branch removal – wraps method 1 

• Branch removal – wraps method 2 

• Artificial rope brake at point of cut 

• Snatching – wraps at point of cut 

Snatching 

Minimising peak force in negative rigging 

• Estimating peak loads in negative rigging 

• Mass damping 

Bracing a rigging point 

Floating anchors: highlines and multiple point floating anchors

Speed line or zip line 

Running anchor rigging 

• Running anchor rigging example 

Lifting systems 

Guying a tree 

3: Completing tree removal 

• Biosecurity and transmission of pathogens 

Completion of works 

Appendix A: Rigging system diagrams 

Positive rigging systems 

• Simple anchor | friction at base of tree 

• Butt tying 

• Tip tying 

• Use of a tagline 76

• Use of multiple anchor points 

• Cradle rigging 

• Lifting 

• Friction applied at anchor point/s in tree 

• Use of multiple rigging ropes – shared load or load transfer 11

• Floating anchor 1: single floating anchor 12

• Running anchor 1 183

• Running anchor 2: speed line 184

• Floating anchor 2: high line 185

Negative rigging systems 

• Snatching 

• Snatching – friction at point of cut 

• Negative rigging – redirects 

• Friction at the point of cut 1: negative branch rigging 

• Friction at the point of cut 2: transferring loads 

• Running anchor 3: negative rigging 

• Vertical speed line 

Appendix B: Working the angles 

Introduction to forces 

• Working in newtons 

• Force, lever arm and bending moment 

• Lever arm 

• Force vectors at anchor points 

• Deflection forces