Engineering Recommendation G96 Issue 1 2014 Use of Mechanical

PRODUCED BY THE OPERATIONS DIRECTORATE OF ENERGY NETWORKS ASSOCIATION

www.energynetworks.org

Engineering Recommendation G96

Issue 1 2014

Use of Mechanical Harvesters in Vegetation

Management

© 2014 Energy Networks Association

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ENA Engineering Recommendation G96 Issue 1 2014

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CONTENTS Page 1 INTRODUCTION

1.1 Purpose ................................................................................................................. 2 1.2 Limitations ............................................................................................................ 2 1.3 Background .......................................................................................................... 2 1.4 Scope .................................................................................................................... 4 1.5 Definitions .............................................................................................................. 5

2 LEGISLATION AND GUIDANCE NOTES .................................................................... 9

3 ADVANCE WORK PLANNING ...................................................................................... 9 4 JUSTIFICATION PROCESS ......................................................................................... 9

5 RISK ASSESSMENT PROCESS ................................................................................ 12

5.1 Overview of Red Zone Harvesting Hazards ......................................................... 13 5.2 Preliminary Risk Assessment Principles .............................................................. 13 5.3 Site Specific Risk Assessment Principles ............................................................ 14 5.4 Risk to Operators ................................................................................................. 16

6 SAFE METHODS OF WORK 6.1 Work Planning Principles ..................................................................................... 16 6.2 Site Factors to be considered .............................................................................. 18 6.3 Control Measures to be considered ..................................................................... 20 6.4 Method of Working .............................................................................................. 21 6.5 Electrical Protection and Documentation ............................................................. 30 6.6 Competencies...................................................................................................... 30 6.7 Emergency Procedures ....................................................................................... 30 6.8 Review and Audit ................................................................................................. 32

7 FUTURE REVIEW AND DEVELOPMENT PROCESS ................................................ 33

APPENDICES

Appendix I - Competencies for Key Roles in Red Zone Harvesting Appendix II - Model Preliminary Risk Assessment for Red Zone Harvesting Appendix III - Risk to Operator Flowchart Appendix IV - Machinery Types Appendix V - Model Method Statement Appendix VI - Model Pre Start Checklist

ENA Engineering Recommendation G96 Issue 1 2014 Page 2

1 INTRODUCTION

1.1 Purpose

The purpose of this Engineering Recommendation is to give guidance to Network Operators when mechanised tree felling operations are carried out within the Red Zone of live overhead power lines.

1.2 Limitations

Third Parties working independently of Network Operators must not use the methods described in this document, but instead should follow the guidance in FISA (Forestry Industry Safety Accord) 804 (Electricity at Work: Forestry).

Whilst accepting that in most cases mechanised tree felling with an appropriate harvester is preferable to manually felling, it should be acknowledged that live line felling is the exception, with the majority of work being undertaken with the lines made safe. Felling within the Red Zone of live overhead power lines should only be undertaken when it is unreasonable "in all circumstances" for a line to be made dead. A robust and thorough justification process as detailed in Section 4 should ensure that this is the case.

1.3 Background

It is estimated that in the UK there is around 5,000km of overhead network that is either adjacent to or passes through commercial forestry plantations. This equates to a potential additional volume of around 200,000 tonnes available to be harvested from the Red Zone annually. Forecasts show that the volume of timber available is likely to steadily increase over the next 20 years.

Two other factors are likely to increase the volume of timber to be felled in the Red Zone. Firstly, there is a legacy of a great deal of timber that has been left standing in the Red Zone. This is due mainly to the difficulties involved with making the network dead combined with additional costs of disruption to felling production plans resulting in the felling not being viable. In the event that timber markets improve then this remaining standing timber may become viable, adding to harvesting volumes. In any case this remaining timber will have to be removed at some time in the future to remove the hazard to the network of over mature, standing timber.

Secondly, Engineering Technical Report ETR 132 (Improved Network Performance Under Abnormal Weather Conditions By Use of a Risk Based Approach to Vegetation Management Near Electric Overhead Lines), places an additional requirement on Network Operators to ensure that a significant amount of the overhead network is made resilient to vegetation related faults over a twenty five year period. Although there are many possible ways of achieving resilience, it will inevitably lead to a large number of trees being removed in the Red Zone.

Current guidance on harvesting adjacent to overhead power lines is largely based on FISA 804. This guidance allows felling in the Amber Zone of a live line with suitable controls, but does not allow any felling within the Red Zone of a live line. This requirement results either in the line being made dead, to allow the third party to safely harvest the timber using conventional techniques, or the Network Operator carrying out the work with the line live in accordance with ENA Engineering Recommendations. Prior to the publication of this document the only guidance available is given in ENA Engineering Recommendation G55, Safe Tree Working in Proximity to Overhead Electric Lines. This guidance relates almost entirely to manual techniques and gives little or no advice on suitable controls for mechanised techniques which could offer less exposure to risk.

In the event that a line cannot be made dead, then the Network Operator may be forced to dismantle the trees, or carry out manual felling with suitable control measures in line with ER G55. Both of these options present significant hazards to operatives, including:


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Working at height to dismantle trees or attach ropes for felling

Large amount of chainsaw work

Falling or hung up timber

A review of incidents occurring on vegetation management work related to overhead power lines over the last 5 years shows that chainsaw usage and related activities account for nearly all of the incidents. Mechanical harvesting work does not feature in any incidents that involve injury, and there were very few electrical incidents. It is fair to say however that there have been several instances of third party work that have resulted in inadvertent contact with Circuit Conductors (either a falling tree, extraction works or direct contact by machine).

It is not possible to draw concrete conclusions from this review because the volume of work completed by chain saw has been much greater than by harvesters over this period. The initial indications are that the overall risks of felling or dismantling large volumes of trees using chain saws are much greater than felling them using harvesters, even when work in proximity to live lines is considered.

As part of the work of the Working Group producing this document, a limited amount of mechanised felling has been carried out within the Red Zone of live lines under the control and guidance of Network Operators. This work has been done where a full justification has been made and suitable control measures have been agreed and implemented. In these circumstances it is generally agreed that with the line live there is less risk to individuals by carrying out felling using mechanised means than there is by doing it manually. It is also appreciated that if the use of harvesters next to live lines is to be developed then most of the equipment currently used in the UK, although extremely sophisticated, does not satisfactorily address the issue of controlling the direction the tree falls, particularly with weight-biased edge trees next to the line. It therefore either cannot be used safely or must be used with additional controls in place as detailed in this document.

This Engineering Recommendation aims to consider the risks associated with live Red Zone harvesting and establish the limitations attached to this task. It will then identify the suitability of various available machinery combinations and identify areas of development that may be beneficial. It will also move on to establishing suitable control methods and harvesting techniques to allow the work to be carried out safely.

In summary, this Engineering Recommendation will propose that where it is justified to remove trees within the Red Zone of a live line, and there are a significant number of trees, then provided that a full hierarchy of suitable control measures are in place then felling with an appropriate mechanical harvester will provide a safer alternative than that presented by the use of manual methods.


1.4 Scope

This document aims to give guidance on work using mechanical harvesting methods within the Red Zone of live overhead power lines that is either instigated by the Network Operator (for enhanced network security for example) or by a Third Party (usually commercial harvesting). In either case these recommendations shall only be used where the work is managed by the Network Operator. In this respect the Network Operator will assume the role of Forestry Work Manager as defined in the FISA booklet “Guidance and Managing Health and Safety in Forestry”. The Network Operator then accepts responsibility for the following tasks in respect of the work:

Use information provided by the Landowner to prepare a risk assessment

Select competent staff or contractors who have made adequate provision for health and safety

Make the machine and system choice

Specify the health and safety measures for staff or contractors working on the site and others who may be affected by the work activity

Liaise with the Landowner

Monitor health, safety and network security using a Network Operator Site Supervisor who will be permanently on the site during work

It is recognised that when the Network Operator accepts the role of Forestry Work Manager there will be instances where the work is happening concurrently with other work activities. In these cases provision must be made to ensure that the safety and contractual responsibilities of all parties are clear throughout the operations. Thorough consultation at the planning stage between the Network Operator and the Landowner is essential. This document does not seek to detail the variety of responsibilities that may need to be allocated nor does it seek to give guidance on the collaborative process required to achieve this.

If the Network Operator cannot competently deal with the responsibilities involved in taking on the role of Forestry Works Manager then they should not proceed.

This document will also give guidance on the following:

Providing a suitable justification process for carrying out mechanised felling adjacent to live lines in accordance with Regulation 14 of the Electricity at Work Regulations

The most suitable types of equipment to be used

Risk assessment processes

Suitable control measures and their limitations

Emergency procedures

Competencies required for key roles

Trials that have taken place as a result of compiling this Engineering Recommendation have identified methods that increase control over the felling direction. Works that take place as a result of this document will also identify techniques and equipment that will further improve control. Further development work by Network Operators should continue to take place to ensure that the best available techniques are being used.

It is important to note that this Engineering Recommendation gives guidance on tree felling with specific regard to the electrical hazard associated with tree felling operations and does not seek to advise on managing the non-electrical hazards.


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1.5 Definitions

Defined terms are in bold text throughout the document. For the purposes of this

ER the following definitions will apply:

Amber Zone The area from the Red Zone up to a distance of one further tree length

from overhead Circuit Conductors (see Figure 1).

Circuit Conductor An electrical conductor arranged to be electrically connected to a

network.

Forestry Work Manager

As defined in the FISA publication “Guidance and Managing Health

and Safety in Forestry”, the person who commissions work on a

forestry site and is responsible for selecting the right contractor for the

job, specifying the measures for the contractor to do the work safely

and making sure those measures are followed during the work.

Landowner As defined in the FISA publication “Guidance and Managing Health

and Safety in Forestry”, the person in control of the land on which the

forestry work takes place. (This can be a forestry management

company or land agent working on behalf of a public or private owner).

Operator The harvester operator that has been authorised in writing by the

Network Operator as being suitably experienced and competent to

carry out Red Zone harvesting and also to be competent in the use of

the particular machine chosen for a particular work site. The Operator

must have a detailed knowledge of emergency procedures and have a

proven means of communication with the Control Engineer.

Network Operator The organisation that operates and/or owns a distribution network and

is responsible for keeping vegetation clear of overhead lines. A

Network Operator might also be referred to as a Distribution

Network Operator (DNO) or Transmission Systems Operator (TSO).

Red Zone The area adjacent to the line containing all trees within falling distance

of the Vicinity Zone of any Circuit Conductor and all trees which

could cause damage to any support structure (see Figure 1).

In normal circumstances and for ease of measurement the extent of

the Red Zone is measured on the ground from a point on the ground

vertically below the outer Circuit Conductor to the centre of the tree

(this results in a larger Red Zone than shown in Figure 1). Only when

specifically dealt with in the risk assessment and agreed by the

Forestry Work Manager or Landowner and the Network Operator

can a more specific assessment of tree falling distance to the Vicinity

Zone of any Circuit Conductor be made. It is important to note that

this takes full account of variations in line height, cross arm widths,

steep slopes, valleys and variations in tree heights. The extent of the

Red Zone could therefore vary greatly along the length of the line. It is

essential where this more precise definition is used that the

measurements are taken using accurate methods and suitably trained

personnel (see Figures 2 and 3).


Site Supervisor A supervisor who is provided by the Network Operator who has been

authorised in writing and has overall responsibility for site safety in

respect to the electrical, site and tree related hazards presented by the

operation. As specialist knowledge is required it would be appropriate

if this role is contracted out. The Site Supervisor must have a suitable

level of knowledge of the capabilities of the machine and Operator

and also of the characteristics, size and species of the trees to be

worked on. The Site Supervisor should be able to demonstrate a

thorough understanding of the issues covered in the FISA booklet

“Guidance and Managing Health and Safety in Forestry”. The Site

Supervisor must be in a position of safety and be able to observe the

felling operations and be capable of stopping work immediately where

necessary. The Site Supervisor must be in immediate contact with

the Operator and have a proven means of communication with the

Control Engineer. (Note that where further knowledge is needed to

fulfil the role of Site Supervisor fully then a Senior Authorised Person

can be used to assist on site)

Vicinity Zone The zone around an exposed live Circuit Conductor which, if

maintained, will ensure that the danger of burn or electric shock is

prevented. The distances, which depend on Voltage, are shown in

Table 1.

Table 1 Vicinity Zone Distances

System Voltage Vicinity Zone

Up to and including 1 kV 1m


Up to and including 33 kV 2.5m


Up to and including 132 kV 3.5m




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One tree length

Vicinity

Zone

RED ZONE AMBER ZONE

One tree length

Figure 1 – Red/Amber Zones

Vicinity

Zone

AMBER ZONE

AMBER ZONE

One tree

length

One tree length

RED ZONE

RED ZONE

One tree length

One tree length

Figure 2 Red and Amber Zones on a side slope


AMBER ZONE

TREES

RED ZONE

TREES

Plan Elevation

Side Elevation

Figure 3 Example of how the Red Zone can vary along the length of an

overhead power line (when accurately measured by trained personnel)


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2 LEGISLATION AND GUIDANCE NOTES

This section is not intended to provide references to all the legislation and guidance that would provide a comprehensive guide to Health and Safety or the management of Electricity Networks. It is assumed that companies using this guidance already have a comprehensive Health, Safety and Environment management system in place dealing with all other risks. The documents referred to below are only those which have a specific bearing upon the issue of vegetation management work in proximity to live overhead electric lines.

1. ENA Engineering Recommendation G55 - Safe Tree Working in Proximity to Overhead Electric Lines.

2. ENA Engineering Technical Report ETR 132 - Improved Network Performance Under Abnormal Weather Conditions By Use of a Risk Based Approach to Vegetation Management Near Electric Overhead Lines

3. ENA Engineering Technical Report 136 – Vegetation Management Near Electricity Equipment – Principles of Good Practice

4. The Electricity Safety, Quality and Continuity Regulations 2002, as amended 2006 and 2009.

5. The Electricity at Work Regulations 1989

6. ENA SHE Standard 008 - Notes of Guidance on the Principles of High Voltage

Overhead Line Live Working 7. The Management of Health and Safety at Work Regulations 1999 8. Forest Industry Safety Accord (FISA) booklet – Guidance and Managing Health and

Safety in Forestry 9. Forest Industry Safety Accord (FISA) Safety Guide 804: Electricity at work: Forestry 10. HSE Guidance Note GS6 (Fourth edition) - Avoiding danger from overhead power

lines

3 ADVANCE WORK PLANNING

It is recognised that a considerable amount of Red Zone harvesting can be avoided with thorough, long term planning. This can be as long as five years ahead of planned felling or planned outages. Where the felling is required by third parties or by a Network Operator there should be a two way process with Network Operators communicating long term outage plans for strategic circuits to major stakeholders. Stakeholders should also provide detailed information on constraints and long term felling plans.

4 JUSTIFICATION PROCESS

It is always preferable from the point of view of safety that any tree felling work in the Red Zone is carried out with the line made safe in accordance with the Network Operator’s Distribution Safety Rules and this document. As the background to this document describes, there are significant risks involved in felling or dismantling trees using traditional chainsaw methods, whether working near to a live line or not. It is therefore accepted that mechanical harvesting can eliminate or as a minimum reduce the non-electrical risks. Where it is possible to undertake part of any tree felling operation by using a suitably configured mechanical tree harvester then this should be the preferred option, providing that site conditions allow its safe use and the procedures detailed in this document are complied with in full. The use of mechanical harvesting methods, or any other method, within the Red Zone with the line live can only be permitted when the duties imposed by Regulation 14 of the


Electricity at Work Regulations 1989, are fully met; this is because Red Zone harvesting involves working adjacent to a live line and would be regarded as being live work. It is important to note that Red Zone Harvesting is not considered to be “Live Line Work” as defined in the ENA document SHEC 009 (Notes of Guidance on the Principles of High Voltage Overhead Line Live Working) as this refers to work on the network. This means that Regulation 14’s three conditions need to be satisfied i.e.:

(a) it is unreasonable in all the circumstances for the line to be dead; and (b) it is reasonable in all the circumstances for the work to be carried out while the line is

live: and, (c) suitable precautions are taken to prevent injury.

Condition (a) A written justification must be produced in every case when deciding whether it is unreasonable for an overhead power line to be made dead. A flowchart which assists in making this decision is shown in Figure 4.

Work Activity

No

Regulation 14(a)

“Unreasonable in all the circumstances

for it to be Dead”

Are there significant implications

for working isolated?

Is there any justification for utilising

Live Red Zone techniques?

Regulation 14(b)

“Reasonable in all the circumstances

to be at work near it while it is Live”

Is there a safe working procedure that

effectively deals with the hazard and

Risks of Live Red Zone working?

Regulation 14(c)

“Suitable precautions taken to prevent

injury”

•Trained staff

•Use of suitable tools and equipment

•Inspection and testing of tools and

equipment

•Supervision

•Audit

Refer to Section 4 – Justification Process

Yes

Is there a recognised documented and

Approved Live Red Zone working

procedure?

Refer to Section 6.3 – Controls to be

considered

Yes

No

No

No

WORK

DEAD

Yes

Can the Live Red Zone working be limited

to allow the bulk of the work activity to be

carried out Dead?

Are there unforeseen events or difficulties with the Live Red Zone techniques or equipment?

Review justification before restarting work.

If in doubt, continue the work DEAD.

Yes

LIMITED LIVE RED

ZONE WORKING

ALL WORK CARRIED OUT

WITH CIRCUIT LIVE

Yes

Figure 4 – Regulation 14 Decision Flowchart


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Factors to be considered when making the decision include:

Supplies to more than 15 customers will be affected by making the line dead.

Supplies to any customer(s) will be affected for longer than 8 hours by making the line dead.

Any of the affected customer(s) affected by making the line dead have had 3 or more interruptions within the previous 12 months.

Any of the affected customer(s) rely on supply for essential medical or disabled access equipment.

Interruption to supplies will result in unacceptable interruption to commercial, industrial or agricultural operations, or public services.

Interruption to supplies will have a significant adverse impact on public safety e.g. loss of traffic signals, fire alarm systems etc.

Isolation of a circuit will result in unacceptable reduction to system security.

Supply voltage cannot be maintained within statutory limits with alternative feeds.

Costs and risks, including environmental risks, associated with all stages in the use of standby generation, connection, running, refuelling, paralleling, interruptions and security.

Hazards arising from switching and applying local earthing.

Where any of the above factors are identified then specific details must be given in the live line justification document. Note - The above guidance is based upon ENA SHEC009 Notes of Guidance on the Principles of High Voltage Overhead Line Live Working. Condition (b) When it is unreasonable to make a line dead then any work should still be carried out at a safe distance from any live conductor, if it is at all reasonable to do so. This will be the case for any person whose work is not directly involved in felling, e.g. the Site Supervisor as it would usually not be reasonable for them to be working where there is any danger from the live Circuit Conductors. Planning of the work should therefore be undertaken to ensure that this is the case. People directly involved with the tree felling work in the Red Zone, whether harvester operators, supervisors or chainsaw operators, will be required to work where the risk of electrical injury may arise. This work must therefore be subject to a suitable and sufficient site specific risk assessment carried out by people who are competent to carry out such assessments. The live working activity should proceed only if this risk assessment indicates that it is reasonable to do so and that the risks can be adequately controlled using suitable precautions to prevent injury, as required by condition (c). The decision should not be taken lightly, bearing in mind that the electric shock or burn risks associated with working live can result in fatality or serious injury. Condition (c) If conditions (a) and (b) are met final authorisation for the work can only be given once the Network Operator is satisfied that all the necessary site specific precautions are in place to prevent injury. As the precautions rely, to a degree, on the site conditions at the time of the


intended work, final authorisation can only be given on site and for that specific period of time. The selection of a safe system of work should be the outcome of a thorough risk assessment process and requires detailed planning before the work starts. Precautions should include:

the use of people who are properly trained and competent;

the provision of adequate information and instruction to the people carrying out the work including the risks involved, the safe methods of work to be followed, and the emergency procedures to be followed in the event of mishaps;

the use of suitable machinery and equipment and protective clothing

the use of accompanying persons if their presence contributes significantly to ensuring that safe systems of work can be, and are, followed;

the disabling of auto-recloser functions for the duration of the work;

plans to cater for changes in circumstances, such as communications failure and deteriorating weather conditions; and

effective control and supervision of the work area.

5 RISK ASSESSMENT PROCESS If the management of the risks involved in Red Zone harvesting is to be successful then it must be a collaborative activity. This is particularly true of the processes for carrying out both the preliminary and site specific risk assessments. To ensure that these assessments are both suitable and sufficient they should involve, as necessary, the Landowner, the Network Operator, the original Forestry Work Manager (for any adjacent works not covered by this document), the Site Supervisor and Operators. All parties should have input into the risk assessment processes rather than it being the responsibility of a single person. Such a collaborative approach will help to ensure that all the substantial risks are identified and that there is a thorough understanding amongst those undertaking and managing the work of the risks and the precautions that are required if the work is to be completed safely. It is the Network Operator’s responsibility to ensure that a suitable Preliminary Risk Assessment has been carried out and is in place before engaging any mechanical harvesting work in the Red Zone. A model Preliminary Risk Assessment to assist in this process is included in Appendix II. Although this document only deals with hazards associated with the electrical risk the Network Operator may choose to incorporate this in to other Preliminary Risk Assessments that may cover all other aspects of the work. The Preliminary Risk Assessment shall be available to all staff and stakeholders and will be used along with a detailed site survey to ensure that the correct decisions are made concerning machinery selection and work methods to be used. It is also the Network Operator’s responsibility to ensure that a suitable and sufficient Site Specific Risk Assessment is then completed and agreed between all parties before works commence. Again this may be incorporated in to other risk assessments that cover the electrical hazards.


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5.1 Overview of Red Zone Harvesting Hazards The hazards associated with Red Zone harvesting can be considered as being either primary or secondary hazards. Primary hazards are those that could lead to contact with a power line and secondary hazards are those that could result in injury following an electrical contact. Clearly the risk assessment process must result in suitable machinery and methods being chosen with sufficient control measures in place to either eliminate the risks associated with primary hazards or reduce them to an extremely low level. In other words the likelihood of an electrical contact must be extremely low; if this cannot be demonstrated then Red Zone harvesting must not take place regardless of any live line justification process. Despite the possibility of an electrical contact being extremely low the secondary hazards must be fully considered with suitable controls in place where necessary. A summary of the main hazards is shown in Table 2:

Primary Hazards (could result in an electrical contact)

Secondary Hazards (could result in injury following an electrical contact)

Lean and weight distribution of tree Failure of network protection to operate

Size of tree Failure of communications to the control engineer

Ground conditions Touch potential (touching the ground and machine simultaneously)

Wind conditions Step potential (potential difference on the ground)

Health and condition of tree (and surrounding trees)

Tyre pyrolysis (explosion caused by decomposition in the absence of oxygen within the tyre material at elevated temperatures (heating caused by electrical discharge))

Harvester suitability High energy release at the point of vegetation contact at higher voltages

Harvester proximity to the line

Operator error (or lack of competence)

Machinery malfunction

Table 2 Summary of Primary and Secondary Hazards

5.2 Preliminary Risk Assessment Principles The Preliminary Risk Assessment will identify common hazards associated with the electrical hazard on all Red Zone harvesting sites. A range of suitable controls will then be identified that can then be incorporated in to any method statement used for the work. A model document is included for reference in Appendix II. The Preliminary Risk Assessment must include reference to the following (this list is an example and not exhaustive):

Electrical apparatus/ Overhead lines: - Assessment of the Network and risk in the event of an incident


- Required Documents (Permits /Limitation/Isolations) - Auto-reclose facility in place. - Specific Network Operator’s instructions.

Felling head: - Control of tree - Processing ability

Base unit: - Stability - Fault path to ground - Tyre pyrolysis

Tree felling procedures/operations: - Operators’ Training/Competence - Reference to Barrier trees - Control measures in place

Ground / terrain: - Identify road crossings - Ground conditions, roughness and slope - Goalposts in place

Wind speed / direction: - Pre-planning to include weather forecast - Wind speed/direction thresholds for additional control measures - Wind speed/direction thresholds when harvesting should be stopped - Methods of measuring and monitoring wind conditions

Public: - Signs/barriers/banksmen in place - Visibility throughout the planned working hours

Emergency Procedures 5.3 Site Specific Risk Assessment Principles A Site Specific Risk Assessment must also be carried out in addition to the Preliminary Risk Assessment. It is essential that the Site Specific Risk Assessment is reviewed throughout operations and at the start of each day. This allows control measures to be altered if necessary as a result of any unexpected changes in circumstances such as the weather, machinery performance, terrain or variations in crop size. If suitable control measures cannot be applied then the works must be suspended until a safe solution can be found, or circumstances return to those manageable under existing controls. The Site Specific Risk Assessment must include all principles contained in the Preliminary Risk Assessment section (5.2) and also include the following (this list is by way of example and not exhaustive):

Justification for working with the line live

Access and egress to site including continuous monitoring for any alteration/changes to the site

Electrical Risks: evaluation of any relevant electrical risks specific to the site. In particular is the voltage to be worked on acceptable to the Network Operator?


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Work methodology

Harvesting head and base including capability and capacities

Means of marking any appropriate zones or barrier trees

Safe position of Site Supervisor

Hazardous trees

Crop size and species and any variations

Ground conditions and terrain variation

Position that timber produce is to be left to enable safe extraction

Acceptable weather limits. (For example, felling should not take place if wind conditions are such that control over felling direction might be lost)

Continual assessment of Public Safety and Public exclusion (as appropriate)

Emergency procedures specific to the site including emergency contact numbers

Location and phone number of nearest A&E hospital.

Designated meeting place (useful in remote areas to guide the emergency services to the worksite)

Nearest access point

Type of access (public road/light vehicles, four wheel drive)

Suitable helicopter landing area

Contact details for all relevant parties, particularly: - Site Supervisor - Operator - Control Engineer - Forestry Works Manager(s)

It is essential that satisfactory control measures are in place for all identified hazards before works start. All staff involved in the works should be suitably briefed in the contents of the Site Specific Risk Assessment to be able to understand the risks and the control measures. It is suggested that a formal sign-off should be carried out following this briefing. In the event that any member of the working party identifies concerns that are not adequately addressed then work should not continue unless suitable control measures can be agreed and implemented.

Any visitors to site or any additions to the working party must also be fully briefed on the Site Specific Risk Assessment.


5.4 Risk to Operators

In the event of an incident it is likely that the Operator will be most at risk. It is therefore essential that sufficient control measures are implemented such that it would require multiple control measures to fail before the Operator is exposed to significant risk. An example of an analysis of possible failure scenarios is shown in Appendix III. No attempt has been made to assign likelihoods to each event but it can be seen that with sufficient controls in place the possibility of the Operator being placed in a position of danger is extremely low.

Each Network Operator should ensure that they undertake a similar analysis and they are satisfied that the likelihood of the Operator suffering injury is extremely unlikely.

6 SAFE METHODS OF WORK

6.1 Work Planning Principles It is essential that sufficient time and resource is allowed to suitably plan any Red Zone harvesting. The comments in Section 3 must also be noted in that forward planning and early two way communication between third parties and Network Operators will avoid the need for Red Zone harvesting in many instances. For all works involving the use of mechanical harvesting methods within the Red Zone of live overhead power lines then the Network Operator will take on the role of the Forestry Works Manager. This document does not give guidance on the collaborative process required to ensure that site safety and commercial responsibilities are understood and agreed before works start. Although outwith the scope of this document, it is expected that works will generally be carried out in accordance with the ENA Engineering Technical Report 136 (Vegetation Management Near Electricity Equipment – Principles of Good Practice). Although outwith the scope of this document, any relevant Estates and Wayleaves issues must be considered at the planning stage. It is especially important that any plans for new planting adjacent to overhead power lines are considered at an early stage to avoid unnecessary risk during harvesting operations in the future. Consideration should be given at this point to securing a wider wayleave where appropriate. Irrespective of who is initiating the work, it is essential that all key parties are notified at an early stage and made aware of the proposed method of work. Where it is established that Red Zone harvesting is to be carried out then the Network Operator is responsible for the planning which should take place in line with the guidance illustrated in Figure 5 on the following page: It is recommended that a pre-start checklist similar to that in Appendix VI is used to ensure that all steps have been taken. This checklist should be started at an early stage in the process and then revisited immediately prior to works starting to ensure that all control measures are in place.

Figure 5 – Work planning guidance (see overleaf)


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Programme any allowable third party Amber Zone or preparatory works

Decide method (barrier or clearfell) and resources to be used

Establish and document that it is unreasonable to carry out the work dead

Programme any required shutdowns

Establish the scope of works

Establish and mark the extent of the Red Zone

Assess network condition and rectify defects as necessary

Establish extraction methods and routes

Agree contractual issues and handover details with landowner or original Forestry Works Manager

Partially complete pre-start checklist and risk assessments. Pass copy to landowner if required

Determine electrical hazard control measures

If relevant, agree and mark extent of any barrier to be used. Mark any hazardous trees that are not to

be felled due to their fragile nature or are outwith the capability of the harvester

Ensure all controls are in place prior to starting. Final walkover by Site Supervisor and Operator to identify any additional hazardous trees that are not to be felled or any manual preparatory work.

Complete site specific risk assessment.

Contact landowner and carry out a full site survey to establish constraints

Establish the scope of any Amber Zone or shutdown works

Confirm that it is reasonable to carry out the works with the line live

Ensure that the Site Supervisor, Operator and any other working parties are authorised, competent, briefed and have signed onto the appropriate site specific documentation.

Complete pre-start checklist.

Review weather forecast at an early stage to allow postponement of works where necessary


6.2 Site factors to be considered

Determining the suitability of a tree felling site for Red Zone harvesting will not always be a straightforward process. It is up to each Network Operator to ensure that all relevant variable factors have been considered before either deciding not to use mechanisation or going ahead or developing a suitable method statement.

The choice of suitable machinery and method of felling must be considered during any site surveys, taking into account the following (this list is not exhaustive):

Height of trees

Diameter of trees

Volume of trees

Species of trees (Characteristics)

Variability of the crop

Health of the crop

Stability of the trees

Presence of any dead or hazardous trees

Spacing of the trees

Evidence of recent thinning operations

Ground conditions including soil type and depth

Exposure of site to wind

Slope

Environmental constraints

Voltage of line (and Vicinity Zone)

Height profile of line (taking account of sag and sway)

Condition of the network

Distance of base of nearest trees to the line

Accessibility of the crop (for example has the Amber Zone been felled)

Availability of suitable, safe position for the Site Supervisor

Manual preparatory work that may be required such as brashing (removal of lower branches), pruning of any branches in the Vicinity Zone or debuttressing (removing buttresses to improve ability to make felling cuts)

Presence of fences, roads, paths and buildings

Access routes for any machinery

Third party access

There is clearly a great deal of experience and considered judgement needed here. It is unlikely that a single person will have all the skills necessary to suitably assess all of these factors. So it is recommended that the site survey is compiled by the Site Supervisor (or Forestry expert employed by or contracted to the Network Operator) with contributions from a combination of personnel, including the Network Operator Engineer, the Landowner (or representative) and the Harvesting Contractor (preferably the Operator),

When considering the voltage of the line adjacent to any Red Zone harvesting it is important to note that in the event of an inadvertent contact with Circuit Conductors then the energy that could potentially be released is proportional to the square of the voltage (Figure 6).


Page 19

Figure 6 Energy Multiplication Derived From Network Voltage

Where there are also multiple control measure failures and given certain conditions then it may be possible that there is a risk to site staff from the release of this energy in the form of fire or explosion. This risk is significantly increased at voltages of 275kV and 400kV.

There are clearly several factors that can affect the likelihood of such an energy release including:

The quality of electrical contact between any tree and conductor

The resistance of the tree which may be dependent on moisture content and timber characteristics

The distance between any conductor contact and the ground

The nature of the fault path to earth which could be through the tree, through the harvester or a combination of both. Factors that affect this include whether or not the harvester head is touching the ground, whether the harvester is mounted on rubber tyres or metal tracks and the resistivity of the ground or soil type

The protection settings on the circuit

The length of time that the tree has been in contact with a conductor (the tree will dry out and carbonise as the impedance reduces)

Weather conditions

There are also factors that will have a significant effect on the severity of any outcome of such an energy release, such as the distance of Site Supervisor or Operator to any point of contact and the degree of protection offered by the harvester cab.

0

200

400

600

800

1000

1200

1400

11kV 33kV 66kV 132kV 275kV 400kV

Proportion of potential energy released compared to 11kv (ie 11kV=1)


It is the responsibility of the Network Operator to assess the likelihood and severity of all identified risks as part of their decision making process: if it is considered that the risk is significant then Red Zone harvesting should not proceed.

6.3 Control Measures to be Considered

Having surveyed the site, the Network Operator must ensure that suitable control measures can be implemented before deciding to continue with Red Zone harvesting. The primary consideration must be to have robust and sufficient control measures to ensure that it is extremely unlikely that a tree held by the harvester could contact or come close to a live line. To achieve this a far greater degree of control is needed than in normal harvesting operations. With this in mind there are certain control measures that will be mandatory in order that Red Zone Harvesting can be carried out in accordance with this Engineering Recommendation.

These are:

Works must be personally supervised at all times by a Site Supervisor.

There must be an immediate method of communication between the Site Supervisor and Operator. This should be an “open mic.” and headphones type system or better allowing continuous hands free communication. The only exception to this is for barrier felling where a less immediate and continuous form of communication may be appropriate, in this instance a walkie talkie system would be appropriate.

The Control Engineer must be aware of the work taking place and must have a reasonable understanding of Red Zone harvesting practices and procedures in general and a thorough understanding of communication and emergency procedures.

There must be a tried and tested method of communication between the Site Supervisor and the Control Engineer.

Trees that have been identified during site surveys as being unsuitable for Red Zone harvesting must be marked clearly by an agreed method.

Wind speed and direction thresholds are established at levels where additional controls are needed and where Red Zone Harvesting must be suspended.

Weather forecast should be checked before arranging machinery to be sent to site and again the day before and the morning of works commencing

Wind speed and direction is monitored and recorded on a regular basis to be determined by the Network Operator.

Any auto reclose facility on the network must be disabled during the works.

There must be no possibility of a machine being positioned such that it could breach the Vicinity Zone, this should be ensured by measuring the full reach of the machine and then physically identifying a line that the machine must not cross.

There must be a position of safety available to the Site Supervisor with particular reference to the chain shot hazard and any risk presented by broken Circuit Conductors or electrical discharge.

The Operator must be authorised in writing by the Network Operator.

The Operator must be capable of contacting the Control Engineer.

Of the many other control measures available, it is strongly recommended that the following are considered:


Page 21

Back up systems of communication between the Site Supervisor and the Control Engineer are available (such as multiple network mobile phones, or satellite phones)

Suitable maximum daily working times are in place

Suitable regular breaks are scheduled during the day for the Site Supervisor and Operator

Dielectric footwear and insulated rubber gloves are available to the Operator in the event that an emergency exit from the cab is necessary before it has been confirmed that the line has been isolated and earthed

Simulated emergencies have been practiced on site with actual communication tests with the Control Engineer

6.4 Method of Work

6.4.1 General Before a Network Operator embarks on any mechanised felling within the Red Zone of a live line then they must have a well considered and approved method statement or work procedure in line with this Engineering Recommendation. Where requested this method statement should be made available to the Landowner for information and comment. A model method statement is presented in Appendix V; note that this is an example of an appropriate method statement and indicates where variations could be made by individual Network Operators. In addition any techniques and machinery used must have been suitably trialled in a non-live environment and be approved by the Network Operator. Having carried out the planning steps in Section 6.1 and considered all the site factors in Section 6.2, the chosen method of work (either barrier felling or clearfell as discussed in section 6.4.2) must be fully detailed, recorded and agreed between the Site Supervisor and the Operator before works commence. It is recommended that the method of working is recorded on a document such as the Pre-Start Checklist (an example is shown in Appendix VI). Any deviations from the agreed method must be discussed between the Operator and Site Supervisor and be recorded before the work method is altered. The Pre-Start Checklist will not be completed until immediately before works start. However, much of the information such as location, method of working, machinery choice, control measures and contact details will be established at an early stage. At this point a partially completed Checklist should be offered to the Landowner for their information. At least two weeks prior to the start date is suggested allowing sufficient time for any relevant feedback to be given incorporated in to the work planning process. Methods of work must be established solely on the basis of minimising the risks of working adjacent to a live line and not on the basis of cost, speed or any timber production considerations. As Red Zone harvesting is a closely supervised task requiring the full concentration of the Operator and Site Supervisor it is important that as much associated work as possible is done either before the supervised operation or left until afterwards.


6.4.2 Choice of Method

In general there are three distinctly different approaches to Red Zone harvesting:

Barrier felling (Figure 7) relies on standing edge trees acting as a physical barrier in the event of a harvester losing control of the tree. The emphasis here is on ensuring that a sufficiently robust barrier is in place and is much less dependent on the capability of the harvester. This method will obviously result in the barrier trees having to be removed by another method at a later stage; this must be done within a reasonable timescale to avoid any unnecessary risk of damage to the network from falling trees.

Clear felling (Figures 8 and 9) is used where the harvester used is capable of clearing trees adjacent to a live line (including the edge trees). With clear felling the emphasis is more on choosing a harvester that is capable of providing enough directional control and ensuring that the trees have been assessed as being within the capabilities of the harvester and Operator.

Mechanised topping could be an approach where Red Zone trees can be cut at height. This may be to avoid any possibility of breaching the Vicinity Zone as the top would not be within falling distance; it could be used to reduce the size of the tree to be felled or to overcome difficulties presented by the base of the tree, such as a sweeping stem presenting weight bias problems. This approach particularly relies on having manufacturer’s or other competent body’s written confirmation of machine suitability for the task.

6.4.2.1 Barrier felling

The basic principle of this method is to fell trees with a harvester using standing edge trees as a physical barrier in the event that a harvester were to lose control of a tree (Figure 7).


Page 23

Figure 7 – Barrier Felling Diagram

This method of tree removal can only be used where there are sufficient control measures in place which can be maintained to avoid an electrical incident.


Prior to any Red Zone harvesting, an assessment will be made of the standing crop to determine if there is potential to use the outer edge trees as a barrier and, if so, to determine the extent of this barrier. Factors to consider include:

No part of any Barrier Zone tree can be within the Vicinity Zone, some pruning may be necessary to ensure this in advance.

Stability of the crop.

Presence of any gaps in the upper canopy of edge trees as a result of windblow, dead trees, wide spacing or poor growth.

Species and health of trees in terms of branch and stem strength.

Previous thinning or pruning regimes. In addition to examining the edge trees the crop should be inspected further back for clear areas of windblow or suppressed trees. This would present a potential hazard for any distant trees that fall in the wrong direction and are allowed to gather momentum. If a satisfactory barrier can be established then this must be clearly defined by marking the trees to be left for manual removal. This barrier must consist of a number of rows and in a non uniform crop will be a line of variable width. The type of harvester and head to be used must also be suitable, taking the importance of control and the size of the crop into account. Individual trees which are identified as being unsuitable for the head and base unit should not be felled using this method and must be clearly marked or removed by other methods in advance. With works in progress it must be ensured that:

The trees furthest from the line are taken first to avoid opening up holes adjacent to the barrier zone.

The harvester and head should be orientated to give maximum leverage away from the line.

Trees must be felled away from the line.

Trees must not be felled into other standing trees in order to avoid a ‘domino effect’ towards the line.

If, in the process of harvesting, it is considered that the barrier zone is not adequate then works must be suspended and the barrier zone re-assessed or works abandoned.

6.4.2.2 Clearfell

This method shall only be used where it can be shown that the head and base unit are capable of providing the principle control measure of ensuring the correct direction of fall of the tree. It is particularly important to consider that, unlike barrier felling, the edge trees will be felled; these are generally more heavily branched on the outside and leaning slightly outwards, in other words they are weight biased towards the line. This in effect means that this method will only be suitable for a limited range of specialist harvesters using specific techniques or for smaller trees. If machinery has been modified in any way to improve directional felling control, then this modification must either be approved by the manufacturer or other competent body. The Network Operator must ensure that sufficient trials have been carried out enabling a suitable risk assessment to be completed and that sufficient controls have been identified


Page 25

and are in place to reduce any risk to an acceptable level. An example of this would be where the addition of a hook welded to the boom of an excavator base would give additional control ensuring that a tree cannot fall back where the boom is being used to apply a force to the tree (this arrangement is shown in Figures 7 and 8). Although termed “clearfell” there may well be a number of trees that, as a result of the site survey detailed in Section 6.2, are considered to be unsuitable for mechanised felling. These will either be removed by other methods in advance, or while the harvester waits, or clearly marked to be left for removal as soon as possible afterwards. 6.4.2.3 Mechanised Topping Mechanised topping of trees presents some additional hazards, namely the increased possibility of loss of control of the head, machine roll-over and the greater range of chain-shot (where a chainsaw head is being used). In addition (unless specifically sought by an operator) it is unlikely that the head and base unit combination have been approved by manufacturers or other competent bodies to work above ground level. In particular, conventional harvester heads that are suspended from an A-frame do not offer sufficient control for topping to be carried out safely. If this method is used it is the responsibility of the Network Operator to ensure that there is manufacturer’s or other competent body’s written confirmation of machine suitability for the task. The Network Operator must also ensure that a comprehensive risk assessment has been carried out and that they consider sufficient and suitable controls are in place to reduce risk to an acceptable level. It is recommended that this method should only be used where the Network Operator has a procedure incorporating the following control measures (in addition to those in Section 6.3):

A heavy, tracked base unit with a short boom should be used

The Operator must have proven experience of using the head

Do not top trees in strong winds

The base unit should be placed as close to possible to the tree to avoid over

stretching

Tops only to be a maximum of 75% of the full capability of the head and base

Top to be assessed as within the capability of the head and base unit

Topping only to be done when there is a reasonably clear stem to avoid unseen,

thick branches preventing a clean cut

Once cut the top is not to be rotated down but lifted slightly, slewed round slightly and

then lowered vertically to the ground, this should avoid unbalanced forces leading to

machine roll-over.

Topping only to be done when the machine is reasonably level and on stable ground

Exclusion zones are enhanced due to the higher risk of chain-shot travelling further

distances (where applicable)

On site these control measures must be discussed and agreed by both the Site Supervisor and the Operator prior to each individual tree being topped.


6.4.3 Harvester Head and Base Unit The choice of head and base unit will be governed by a wide variety of factors including terrain, ground conditions and size of the trees to be felled. As all heads and base units have limiting factors to a greater or lesser extent with respect to the control of direction of the tree, it follows that there will be situations where site factors are such that no mechanised option is suitable to remove trees with the network live. A full discussion of currently available options is included in Appendix IV. As the main consideration in machinery choice is to select a machine that allows the risks of working adjacent to a live line to be minimised, it is important that this choice is not constrained by what is easily available or cheaper in terms of machines or contractors. 6.4.4 Preparatory Work Any necessary preparatory work should be completed before Red Zone harvesting begins. Examples where work may be required are:

Felling of non-Red Zone trees to allow access, for example where the Amber Zone

trees have not yet been removed

Brashing (removal of lower branches of trees). This is likely to be essential for trees

with substantial lower branches and would be carried out with chainsaw or pole

pruner. This ensures that the Operator has good visibility and the head can grip and

fully cut through the stem correctly

Debuttressing where necessary (see Section 6.4.8)

Manual removal of trees identified as being unsuitable to be removed by the

harvester with the line live. Although these can be left at the end, it may be

necessary to remove them to allow access to the remaining trees

Preparation of brash mat roads for the harvester to travel on where brash already

exists

6.4.5 Sequence of Tree Removal There are two aspects to this. Firstly establish the direction of progress along the length of the line, i.e. left to right or right to left, this will depend mostly on access, terrain and choice of base unit. Secondly and more importantly it must be established if the trees furthest from the line or those closest are to be felled first. It will usually be preferable to start with the trees furthest away and work towards the line as this provides the maximum protection for the line and a clear area for line-side trees to be felled in to. This method will normally be available as it is likely that the Amber Zone will have been felled in advance. Where ground conditions or standing trees allow this then working from the line outwards should only be allowed where the harvester can be positioned safely and there is room to fell the trees away from the line without risk of hang-up or strain on the machine. 6.4.6 Direction of Felling The direction of felling the trees should be established to minimise the possibility of contact with the Circuit Conductors in the event of loss of control of the tree. Ideally this would


Page 27

normally be at an angle of 90° away from the line. This may vary given the presence of other conductors or constraints on the position of the harvester. In most cases it will be perfectly acceptable to fell anywhere between 45° and 90° away from the line, depending on the weight bias of the trees. If for any reason the felling direction is intended to be any less than 45° away from the line (to avoid other infrastructure or environmental constraints for example) then this should only be done if risk assessed with adequate control measures justified and documented. Otherwise these trees should be removed by manual methods or with the line isolated and earthed for a short duration. 6.4.7 Position of the Harvester In most cases the harvester will be best placed further away from the line than the tree to be felled as shown in Figures 8 and 9. This may not be possible or desirable in certain circumstances, mostly dependent on ground conditions. This is particularly the case where the gradient would place the harvester in a position that would compromise directional control. It is also the case that certain combinations of head and base unit offer the greatest directional control when pushing the tree away from them, as with feller bunchers or fixed heads. Where there is a need for the harvester to be placed between the line and the tree, and where ground conditions allow, then this should only be done when the risks have been considered and can be suitably controlled. The main hazard is the proximity of the harvester to the line, either with respect to direct contact (or arcing) or the likelihood of a broken conductor coming in to contact with the harvester. To mitigate against direct contact or arcing, the harvester must be positioned far enough away from Circuit Conductors such that there is no possibility of any part of the machine or head breaching the Vicinity Zone, regardless of the intended method of operation. Generally this will be done by measuring the maximum extent of reach of the harvester and, taking the conductor height in to consideration identifying a line on the ground that cannot be crossed by any part of the machine, as shown in Figures 8 and 9. The position of this line and the method of marking must be recorded on the site specific risk assessment. It will be acceptable to use features such as a fence or a line of trees or stumps. The possibility of the harvester being struck by a falling conductor when working within the last line of trees must be considered particularly when working on the inside of a non-section angle pole.


Minimum 45

Minimum distance

to be marked on

ground

Direction of fall

Figure 8: Clearfell method of harvesting (showing optional hook) (not to scale)


Page 29

Minimum distance to be identified

Force applied

here by boom

Level of felling cut

X

Optional hook to

prevent tree

falling back

Figure 9 Side elevation showing clearfell method of felling (showing optional hook) 6.4.8 Double Cutting or Debuttressing Where tree diameters are approaching the limits of the head, particularly where buttress roots are present, then there is a possibility that the Operator, having committed to a single felling cut, fails to cut completely through the stem. This is potentially a dangerous situation as the harvester may not be able to fell the tree and will have to re-position the head leaving the tree liable to fall uncontrolled. Alternatively, if the tree is felled there may be a holding force from the uncut timber that could twist the tree, increasing the risk of it falling in the wrong direction. If this is likely and the tree is assessed as being suitable for mechanised felling, then it will be acceptable to either remove the buttresses by chainsaw to improve the ability to make felling cuts or carry out a double cut where a first cut is made in the front of the tree (in the intended direction of fall) and a second cut is made to fell the tree. The first cut must not be more than one third the diameter of the tree; this will ensure that the tree remains stable whilst the head is being re-positioned for the second cut. Where the debuttressing option is chosen then it must be noted that the tree is then in a weakened state until felled. The suitability of the trees and wind conditions must be assessed prior to debuttressing and they must be left in this condition for as little time as possible with none being left overnight.


6.5 Electrical Protection and Documentation Where auto-reclose protection schemes exist and company policy requires it, auto-reclose features on controlling switchgear will be rendered inoperative. The issue of a safety document such as a Limitation of Access will be dependent on the site conditions and the Network Operator. 6.6 Competencies The Network Operator must ensure that all staff involved in harvesting operations in the Red Zone are experienced and competent for both tree work (specific to type of machinery used) and for work in proximity to the electrical network. Competence in harvesting operations should be demonstrated through training (including refresher training), assessment and qualification under the nationally recognised Forest Machine Operator Certification Scheme and be subject to verification by the Network Operator. Where a suitable national qualification does not exist for a specific type of machine then the Network Operator must be satisfied that the Operator is suitably competent. The Network Operator must also ensure that the Operator is suitable in terms of their ability to work under constant supervision and to apply control measures not normally associated with normal production driven harvesting operations. If a machine has to be changed during the planned operation, then competencies must be checked to ensure they apply to the new machine. If the machine has not been used in the past, but it is adequate for the felling planned, then trees outside of the Red Zone can be felled until the Operator is familiar with its controls, has the appropriate FMOC competency and the Network Operator has assessed and authorised them for the use of that machine. For network electrical competence the Network Operator will ensure that training, assessment and authorisation awarded to the staff engaged meet the individual Network Operator’s requirements. A Site Supervisor provided by the Network Operator must be on-site during all Red Zone Harvesting operations. Control engineers must have a reasonable understanding of Red Zone harvesting practices and procedures in general and a thorough understanding of communication and emergency procedures. It is recommended that site visits are used to familiarise control engineers. An example of minimum competencies required can be found in Appendix I. 6.7 Emergency Procedures Each Network Operator must have a suitable documented emergency procedure to cover electrical emergency as a result of Red Zone harvesting. The procedures must state what constitutes an electrical emergency and must define how robust communications between both the Site Supervisor and Operator and the Control Engineer will be provided and maintained. The emergency procedures must be known and understood by all staff on site and the Control Engineer.


Page 31

It is recommended that Emergency Procedures are practiced by simulation on a regular basis. This should normally be at the start of each job or at least once per month if work is continuous. Procedures should be amended to reflect any identified issues as necessary. (Note that jumping from the harvester itself should not be practiced unless ground conditions at the landing point offer no real chance of injury.) Where a tree or any equipment makes contact with a live line or where a fallen Circuit Conductor is on the ground or on or near any machinery then the following actions are necessary: 6.7.1 Emergency Procedures for the Operator

Release the tree from the harvester head (if safe to do so).

Stop work.

Switch off machine.

Stay in the cab in all circumstances except where there is danger to life e.g. fire.

Talk to Site Supervisor immediately and confirm that he is communicating with the Control Engineer, if he is not capable of making contact then contact the Control Engineer.

Put on dielectric footwear and insulated gloves (where this is specified in the emergency procedures).

Only start the machine and attempt to drive clear of the line if instructed to do so by the Control Engineer (this will only be where the Site Supervisor has advised a course of action that the Control Engineer agrees with).

Ensure no-one approaches the harvester, Circuit Conductors, towers or trees.

Only exit the cab of the machine when instructed by the Site Supervisor (after confirmation with the Control Engineer that the line has been made safe).

In the event of fire then use the engine or cab fire extinguishers as necessary.

If there is a risk to life by staying in the cab then exit the cab and jump to the ground as far as possible from the machine ensuring that there is no contact with the machine and the ground at the same time.

Get away from the machine, shuffle or jump from one foot to the other ensuring feet are not spread over an area that could introduce a step potential. (Note that if dielectric footwear is worn then the risk of step potential is reduced so walk swiftly away from the machine).

Do not return to the machine until it is safe to do so and it has been confirmed that the line has been made safe.

6.7.2 Emergency Procedures for Site Supervisor

Remain at a safe distance (at least 15m) from any electrical apparatus, tree, machinery, fences, gates, metal or conductive equipment.

Talk to the Operator to confirm the nature of the emergency, remind him to release the tree, switch the machine off, stay in the cab and put on dielectric footwear and insulated gloves (where this is specified in the emergency procedures).

Keep any other site staff at a similar safe distance.

Contact the Control Engineer.

Arrange for Control Engineer to contact emergency services if necessary.

Only instruct the Operator to exit the cab after it is confirmed that the line has been made safe. The only exception to this is where there is risk to the Operator’s life in which case instruct him to jump as far as possible from the machine ensuring that there is no contact with the machine and the ground at the same time.

Administer First Aid where necessary and only if safe to do so.


6.7.3 Emergency Procedures for Any Other Site Staff

Remain at a safe distance (at least 15m) from any electrical apparatus, any tree in contact with electrical apparatus, machinery, fences, gates, metal or conductive equipment.

Ensure that all others remain at a safe distance. 6.8 Review and Audit Both field audits and management system audits are necessary to ensure that Mechanical Harvesting Techniques are compliant with company procedures. The purpose of audits is to confirm through gathering of evidence that work is being carried out safely on site and to ensure that it is being managed and monitored effectively. They also present opportunities for improvements. Audits should be scheduled on the basis of the risks involved in the activity to be audited. The results of previous audits and events such as accident reports, near miss reports and hazard reports should be used to adjust frequency. Field audits should be conducted on a regular basis so that each team is audited during a set period. Management system audits need to be planned as part of a risk based audit programme; typically they would initially be carried out annually and then adjusted based on the factors mentioned above. Field audits can be either programmed or unannounced; some of the audits carried out should be by external auditors. The results of all field audits should be documented and fed back to staff on site at the end of the site visit to allow any findings to be clarified. There must be a formal method of recording any non-compliances, observations and corrective actions arising from audits. Non-compliances and observations must be fed back to the management responsible for the area being audited. Responsibility for carrying out corrective actions with deadlines must be clearly assigned to appropriate individual managers who have the authority to implement them. The system should prompt for completion of corrective actions to ensure closure. Learning points should be fed into company Health and Safety communication systems. As individual Red Zone harvesting jobs will be of a reasonably significant size it is appropriate that each job is thoroughly reviewed on completion. This review must include both the Site Supervisor and Operator. Any significant learning points that arise must be included as amendments in either the Network Operator’s method statements or preliminary risk assessments, The reporting of near misses should be encouraged as a positive action so that lessons can be learnt from them before more serious incidents occur.


Page 33

7. FUTURE REVIEW AND DEVELOPMENT PROCESS 7.1 General ENA Engineering Recommendations are reviewed periodically following changes in technology, legislation, regulation and best practice to see if they require revising. 7.2 Specific Factors affecting Mechanical Harvesters The range of machinery available for forestry work is changing rapidly. The biggest single factor is probably the degree of control that future machines may have over the felling direction of trees. Future changes in technology, especially harvesting machinery, may enable much greater control to be exercised when felling trees. If significant improvements in technology and the degree of control are made, ENA will undertake to review this document in order that they are safely incorporated into vegetation management.

ENA Engineering Recommendation G96

Issue 1 2014 Appendix I Page 34

Appendix I – Competencies for Key Roles in RZH

Role / Operation

Minimum competency

Awarding body

Units

Pre

RZ

harve

sting

Site surveyor (combined electrical and RZ harvesting knowledge required)

NPTC UA / (NO)

UA5 (Utility Arboriculture Surveyor), or equivalent as agreed with Network Operator Authorised in writing by the Network Operator to carry out Red Zone surveying.

Harve

sting o

pe

ration

in R

Z

Operator of Harvesting / Extraction Plant in RZ

NPTC UA / (NO)

UA1 (Basic electrical awareness), or evidence of suitable electrical hazard awareness and emergency training by the Network Operator.

NPTC FM

FM01 (FM Base Machines) specific to machine being used

FM2.1 (FM Grapple Felling Operation) FM2.2 (FM Grapple Processing Operation), FM3.2 (Forwarder) as appropriate

NO

Authorised in writing by the Network Operator to carry out live harvesting work on a specific site within a specific time frame only. The only exception to this will be where the staff or contractors are committed to this task and carry that authorisation as part of their full time duties. Minimum competencies must be fulfilled before authorisation is issued

Must be familiar with details of any safety documentation and know how to contact Control.

RZ Harvesting Site

Supervisor

NPTC UA UA1 (Basic electrical awareness)

NO

Harvesting experience and knowledge of the operation of the machine being used. Knowledge of risk zones specific to machine Evidence of training incorporating the requirements of the FISA booklet “Guidance and Managing Health and Safety in Forestry”. Authorised in writing by the Network Operator to supervise Red Zone harvesting. Will hold any relevant safety document and must be authorised in writing by the Network Operator to accept that type of document. Will know how to contact Control will have practised this and will ensure all others are aware of how to contact Control.

SAP Issuing Any safety

documentation for RZH (where

relevant)

NO

SAP authorisation scope includes voltage and system concerned. Check justification. Ensure network arrangements are suitable for work to be carried out. Ensure operators are suitable authorised. Issue safety document where relevant to Operator or Site Supervisor and ensure contact and emergency details are available and understood.

All other operatives working on RZH site

NPTC UA / (NO)

UA1 (Basic electrical awareness), and / or evidence of suitable electrical hazard awareness and emergency training as required by the Network Operator. Must be aware of contents of any safety document and know how to contact control.

All operatives to hold emergency first aid at work certificates with specific training for the remote environment


Issue 1 2014 Appendix II Page 35

Appendix – II – Model Preliminary Risk Assessment for the use of Harvesters for tree works in the Red Zone of Live Overhead Power Lines IMPORTANT - Please note this Risk Assessment deals only with the specific additional risks that result from the use of a Harvester for tree works in the Red Zone of Live Lines, it does not deal with routine risks from Harvesters or other aspects of forestry working.

The Hazard Who

could be harmed?

Level of risk

before control

measures

Selection of control measures available to reduce risk Monitoring

responsibility

New level of risk after

control measures

1. Contact with Circuit Conductors or damage to electrical apparatus during access and egress.

All staff on worksite

Medium Prior planning of access and egress routes

Signage and goalposts in place where necessary

Adherence to GS6

Application of FISA guides

Height/reach of machine to be limited mechanically or electronically as per Network Operator’s requirements.

Site Supervisor to be used with proven means of immediate communication.

Not entering risk zones, using recognised means of contact with machine operators i.e. radio and mobile phone. If a mobile phone is used then ensure there is a good signal prior to the start and throughout the course of the works.

Site Supervisor

and Operator

Low

2. Direct contact of machine with Circuit Conductors and apparatus during tree felling operations.

Operators High The harvester must be positioned at all times to ensure that in the event of hydraulic failure or Operator error there is no possibility that any part of the machine could breach the Vicinity Zone. This must be assessed in advance, taking in to account the terrain, line height and maximum reach of the machine. This exclusion zone should be marked on the ground so that it is visible to the Site Supervisor and Operator, for example paint, tape, high stumps, trees or existing boundaries such as fences may be appropriate. Any operations requiring the machine to be positioned closer can only be done under the supervision of an SAP.

Site Supervisor

and Operator

Medium



The Hazard Who

could be harmed?

Level of risk

before control

measures


responsibility


control measures

If the height or reach of the machine has been limited mechanically or electronically then an exclusion zone may not be required provided that with limiters in place there is no possibility of any part of the machine breaching the Vicinity Zone.

Survey the site to ensure that where there are any steep slopes that any potential slide or overturning of the harvester is avoided by manual felling.

Operator trained (including emergency procedures) and authorised by Network Operator.

Site Supervisor to be used with proven means of immediate communication with the Operator.

Where protection schemes permit and company policy requires it, auto-reclose features on controlling switchgear are rendered inoperative.

Operator has proven communication with the Control Engineer and Site Supervisor.

Satisfactory live line justification carried out.

Correct machine identified.

Agreed method of working including orientation of machine.

3. Tree felled directly on to live conductors through operator error.


High Operator trained (including emergency procedures) and authorised by the Network Operator.

Operator has proven communication with the Control Engineer and Site Supervisor.

Work follows an agreed felling plan devised between the Site Supervisor and Operator. Any deviation from this plan should be agreed between all parties.

Site Supervisor

and Operator

Low



The Hazard Who

could be harmed?

Level of risk

before control

measures


responsibility


control measures

Smaller trees furthest from the line will be worked on first to establish machine and Operator’s capabilities. The Site Supervisor will constantly monitor tree felling and will stop work at an early stage if there is any doubt that trees can be felled in a controlled manner.


The Control Engineer is aware of the works and is prepared to isolate the network remotely and immediately in an emergency.

Where it is clear that control of the tree is being lost then the Operator should, where possible, take evasive action to avoid the tree hitting the line. The Operator should use other controls such as slewing away from the line and running the tree through the head. If it is clear that the tree is going to contact conductors then the tree should be released from the head to avoid indirect contact with the conductors.

4. Incident caused by fatigue or lack of concentration


High Agreed duration and frequency of breaks and maximum daily Red Zone harvesting time must be determined by the Network Operator.

Work must be suspended if any phone calls are received or made by either the Site Supervisor or the Operator. Similarly if either is distracted for any reason. The Operator shall not listen to music or the radio.

Site Supervisor

and Operator

Low

5. Loss of control of tree due to machinery capabilities or mechanical failure.


High Choice of harvester base unit and felling head to be adequate and agreed in advance with the Network Operator taking in to account the terrain, ground conditions, size of trees and likely weather conditions.

All trees will be assessed in advance by the Site Supervisor and Operator. Any trees that are either too large or have a substantial weight bias towards the line and could not easily be felled in a controlled manner will be marked and not felled by the harvester with the line live.

Site Supervisor

and Operator

Low



The Hazard Who

could be harmed?

Level of risk

before control

measures


responsibility


control measures

Base unit and head are to be fully serviced and inspected for wear and tear and damage on a daily basis prior to working with particular reference to the condition of hydraulic hoses.

Ensure that all windows are clean, offering maximum visibility. Ensure the Operator has sun glasses in the event of low sun.

A new or nearly new chain (where relevant) should be used. In the event of a chain breakage during felling then the tree should remain secured until a suitable plan of action is agreed between the Site Supervisor and Operator.

Sufficient spares such as chains and bars must be available.

Where it is clear that control of the tree is being lost then the Operator should, where possible, take evasive action to avoid the tree hitting the line. The Operator should use other controls such as slewing away from the line and running the tree through the head. If it is clear that the tree is going to contact the line then the tree should be released from the head to avoid indirect contact with the line.

6. Loss of control of tree due to weather conditions or other site factors.


High Wind speed and direction is likely to have the greatest adverse effect on felling direction.

Advance planning must include a review of the forecast wind speed and direction. This review should take place at an early stage to allow steps to be taken to avoid any pressures to proceed with work, such as machinery being transported to site. The forecast should also be checked on the day of works before going to site to avoid similar pressures.

Ground wind speed and direction is to be monitored frequently (for example with a windsock and a hand held anemometer).

The Network Operator should establish two wind speed and direction thresholds. The first [for example 12mph or Beaufort force 4] would indicate when felling can only continue if steps are taken to ensure there are adequate controls to cope with a moderate wind (for example it may be acceptable to fell

Network Operator, Site

Supervisor and Operator

Low



The Hazard Who

could be harmed?

Level of risk

before control

measures


responsibility


control measures

trees that present a lesser hazard such as smaller trees or trees that are on the edge of (but within) the Red Zone with a significant barrier of trees between them and the line).

The second, greater, threshold [for example 19mph or Beaufort force 5] would indicate when Red Zone felling must be suspended. Work must not then restart for at least an hour and where there is clear evidence that the wind speed has reduced to acceptable levels.

The wind speed nearer the top of the tree cannot be accurately measured but will have the greatest influence on felling direction. Ground wind speed might bear no relation to wind strength at the top of the tree particularly if there is shelter provided by other trees at a lower level. In addition gusting wind will also present problems. Both gusting and tree top wind speed must be frequently assessed by the Site Supervisor and Operator. This will be done by observing tree tops (and windsock if used) and the Operator assessing the effect of the wind during felling. Regardless of ground wind speed, works must be suspended if there is gusting or tree top wind speed towards the line that would have a significant detrimental effect on the ability of the harvester to control the trees.

Work must be suspended if weather conditions such as rain, snow or lightning make operations unsafe or fog or lack of daylight significantly reduces visibility for the Site Supervisor or Operator.

Survey site in advance for any damaged or partially windblown trees that may break or fall towards the line if dislodged by a felled tree. Any such trees must be marked and dealt with manually. Both the Site Supervisor and Operator must continue to assess the trees as works progress.

Survey site in advance for terrain hazards such as steep slopes, gullies, drainage ditches and watercourses. Where there is any risk of instability of the machine that may result in a slide towards the line or loss of control of a tree then the trees must be marked and felled manually.



The Hazard Who

could be harmed?

Level of risk

before control

measures


responsibility


control measures

Where it is clear that control of the tree is being lost then the Operator should, where possible, take evasive action to avoid the tree hitting the line. The Operator should use other controls such as slewing away from the line and running the tree through the head. If it is clear that the tree is going to contact conductors then the tree should be released from the head to avoid indirect contact with the conductors.

7. Tree knocked on to conductors due to contact with felled tree.


High Crop assessed prior to works for dead trees and branches and stability of root plates. Tree species to be taken in to account.

Advance survey and assessment must be carried out for the suitability and stability of any Barrier Trees.

In the event of an emergency and loss of control of the tree the Operator will release the tree from the head at the earliest opportunity.

Site Supervisor

and Operator

Low

8. Contact with conductors by a top breaking out

All site staff

Medium Operator is trained and authorised.

Site Supervisor monitors work to ensure that trees are felled smoothly, avoiding any sudden or aggressive movements.

Site Supervisor continually monitors the trees for excessive movement as they are being felled

Site Supervisor

and Operator

Low

9. Tree or branches being forced too close to conductors by the harvester whilst grabbing the tree or removing branches

All site staff

Medium All trees must be out of the Vicinity Zone prior to work starting.

Site Supervisor to monitor works to ensure that the trees are grasped by the harvester in a controlled manner, avoiding any shaking of the tree. If the Vicinity Zone is breached or there appears to be a possibility of it being breached then work must be suspended.

Site Supervisor

and Operator

Low

10. Public entering the risk zones of felling and extraction operations

Public,

all staff

Medium Operator, banksmen and Site Supervisor to ensure work stops as soon as any unauthorised individual approaches risk zone.

Site Supervisor

and Operator

Low



The Hazard Who

could be harmed?

Level of risk

before control

measures


responsibility


control measures

Use of signage, barriers and banksmen where necessary.

Near-by householders warned of works and possible disruption.

11. Direct or indirect contact with fallen live conductors

Public,

all staff

Medium Advance survey to establish any containment measures required for the avoidance of any damage or falling conductors, on other spans out with the working zone.

Advance survey to identify significant wire fences and necessary control measures.

Operator, banksmen and Site Supervisor to ensure work stops as soon as any unauthorised individual approaches areas where conductors might fall and near any previously identified wire fences


Site Supervisor

and Operator

Low

12. Failure of communication methods

All site staff and public

Medium All communications systems to be checked immediately prior to works starting for both correct operation and sufficient battery capacity.

A second, independent means of communication must be available on site and checked.

Emergency numbers must be stored in all phones for quick use in an emergency.

Work must be suspended if any phone calls must be received or made by either the Site Supervisor or the Operator. Similarly if either is distracted for any reason.

Site Supervisor

and Operator

Low

13. Explosion of tyres (pyrolysis) from fault current heating up tyres


Medium Several factors affect the likelihood of pyrolysis occurring such as the voltage of the network, the fault path to ground (including the impedance of the tree and machine) and the time taken for network protection to operate or be isolated. The Network Operator must carry out a risk assessment of the likelihood of tyre pyrolysis in the event of failure of several other control measures. This risk

Network Operator

Low



The Hazard Who

could be harmed?

Level of risk

before control

measures


responsibility


control measures

assessment may affect the choice of drive mechanism for the harvester base unit (wheel or track based).

14. Electrocution in the event of emergency exit from the machine cab

Harvester Operator

High The Operator must be authorised by the Network Operator and this authorisation process must include a proven, detailed knowledge of the emergency procedures.

The use of dielectric footwear and insulated gloves should be considered by the Network Operator for use by the Operator in an emergency.

The harvester must have an automatic CO2 engine fire extinguisher and a CO2 manual fire extinguisher in the cab. In the event of a fire in the cab the Operator must make all attempts to extinguish the fire before deciding to exit the cab.

In no circumstances should the Operator exit the cab and be in contact with the ground and the cab at the same time. This should be reinforced to the Operator by the Supervisor immediately before exiting.

Site Supervisor

and Operator

Low

15. Third party approaching a “live“ machine


Medium In the event of an emergency all staff on site must be made aware and be instructed to stay at least 15m away from the machine, any conductor or tree in contact with any conductor. Immediate arrangements must be made to ensure that all members of the public are also kept at least 15m away.

In the event of an incident no person can be allowed to approach the cab of the machine for any reason until it has been confirmed that the line has been isolated and earthed.

Site staff Low


Appendix III Issue 1 2014

Page 43

APPENDIX III – Risk to Operator Flowchart Note that this is an illustration of possible risks to the operator. No attempt has been made to assign likelihoods to each event but it can be seen that with sufficient controls in place the possibility of the Operator being placed in a position of danger is extremely low.

Tree felled to ground in

correct directionSafe

No

Yes1

Operator releases tree

from harvester head

Operator stops work

and site supervisor

contacts control

No

YesSafe

2 3

Tree falls past

conductor (no contact)

No

Yes

Safe

4

Tree makes brushing

contact with conductor

and falls to ground

(conductor intact)

Operator stops work

and site supervisor

contacts control

No

Yes

Safe

5 6

Tree hangs up in a

position leaning

towards conductors

Operator stops work

and site supervisor

contacts control

No

Yes7 8

5All agree a method of

getting tree safely to

groundSafe

9

Safe

Network is made safe in

accordance with

Operational Safety Rules

(earths applied)

Tree remains on line or

breaks conductorSafe

Electrical protection

operates

Circuit locks out (auto

reclose previously

disabled)

Site supervisor

contacts control via

satellite phone

Operator releases tree or

moves clear following

instructions from controlOperator Safe

Site supervisor

contacts control via

satellite phone

Control room switches

out network and confirms

to site supervisor

Operator remains in

cab and contacts

control

Machine catches fire or

is unsafe

Operator puts on

dielectric wellingtons

and insulated gloves

Operator successfully jumps

clear avoiding simultaneous

contact with machine and

ground or any step

potentials

Operator successfully jumps

clear avoiding simultaneous

contact with machine and

ground or any step

potentials

Safe

No

No

Yes

No

Yes

Yes

No

No

No

No

Yes

Yes Yes

Yes

No Yes

Yes

No

No

No

Unsafe

Unsafe

Unsafe

Yes

Yes

No

Dielectric wellingtons and

insulated gloves provide

sufficient electrical

protection

No

SafeYes

10

11

12

13

16

17 18 19

20 21

23

24

Safe

Yes

25

Control contacts site

supervisor and gives

advice

15

26

Control confirms that

line has tripped (still to

be treated as live)

14

Operator remains in cab

awaiting further

instructions

22


Issue 1 2014 Appendix IV

Page 44

APPENDIX IV – Machinery Types

Machinery Choice Equipment for the mechanised felling of trees has been developed both in the US and Europe over the last 20 or so years. Most of the equipment has primarily been developed for the harvesting of softwood (conifers) as these form the bulk of the commercial timber crop and tend to be more consistent in shape and structure and therefore easier to manage mechanically. In general the American approach has been to build machines which fell trees for subsequent de-limbing and cutting to length away from the stump (whole tree harvesting), whereas in Europe the approach is to fell and process trees in-situ with a single machine (known as shortwood or cut to length harvesting). Equipment developed for whole tree harvesting is theoretically likely to be better suited to controlled felling in the proximity of overhead electrical equipment than that designed for shortwood working, however both are capable of safe operation and shortwood equipment is much more widely available in the UK. Equipment can be considered in terms of the base (power) unit and the felling head or mechanism as detailed below.

Base Units

The primary classes of base unit may be considered to be:

1. Purpose built tracked harvester base units 2. Purpose built wheeled harvester base units 3. 360 degree tracked excavator conversions 4. Purpose built tracked (reach-to-tree) feller buncher base units 5. Purpose built wheeled (drive-to-tree) feller buncher base units

Key Features Tracked harvester base units are similar in appearance to a zero-tail swing 360 degree excavator with a wide and long tracked undercarriage, long reach crane and small fully guarded operator cab. The unit may be self-levelling with the undercarriage able to tilt back and forward to compensate for slopes and keep the centre of rotation vertical. Wheeled harvesters are invariably articulated, the smallest machines having four equal wheels. The majority of machines however have six or eight wheels and may be fitted with band tracks to improve flotation/traction. A long reach crane is generally fitted to the forward section of the machine in front of the operators cab, with the engine, pumps etc. in the rearward section. Some larger machines may be fitted with swivelling cabs which move with the crane and/or self-levelling capability. Tracked excavator conversions are fully guarded 360 degree excavators to which a variety of heads may be fitted. There is a considerable size range with machines from 7.5t through to 30t plus fitted with different heads. Head fitting may be direct to the original machine quick-hitch or to a nose-cone replacing the dipper ram and bucket linkage.


Appendix IV Issue 1 2014

Page 45

Tracked feller bunchers (“reach to tree” feller bunchers) are amongst the biggest and heaviest machines used in the forest. The basic design is as for a tracked harvester base unit, but fitted with a shorter reach and heavier duty crane to handle the additional loads imposed by a feller-buncher head. Wheeled feller bunchers (“drive to tree” feller bunchers) resemble a wheeled loading shovel, with an articulated four wheeled base unit and a mounting unit on the loader arms to which a feller buncher head or tree shears may be attached. All machines must have protective structures (Operator Protective Structures etc.) designed for forest use. Terrain capability In the UK harvesters are generally operated on a bed of branches (brash mat) derived from the material stripped from previously harvested trees. This allows them to traverse very soft ground without damage or sinking, however the cut timber from the harvested trees used to create the mat is inevitably deposited on the edge of the working strip. Feller bunchers cut and move whole trees either by reaching across and depositing them in the chosen location or by picking the tree up and travelling with it carried in the head. As they do not remove the branches from the stem they cannot produce a brash mat to support themselves. Wheeled harvesters fitted with band tracks and tracked harvesters both running on brash mats can cope best with soft ground. Excavator conversions are not quite as capable on steep slopes or soft ground. Tracked feller bunchers should have far greater terrain capability than their “drive to tree” wheeled equivalents. Direction of working Tracked harvesters have the facility to rotate on their base unit and to rotate the felling head. As a result they can to some extent operate from within the block, reaching towards the edge trees felling back into the block. Wheeled harvesters have the same capacity to reach towards the tree from inside the block and position the harvesting head on the outside of the tree, felling in a 270 degree arc, but generally have a less powerful crane than tracked base units. Excavator conversions may function in the same way as a tracked harvester or a “reach-to-tree” feller buncher depending on the head with which they are equipped. Power and reach are likely to be intermediate between the two. “Drive to tree” feller bunchers can only cut and lay down trees immediately in front of them, due to the configuration of the head and loader arms, and must therefore be operated at an angle to the overhead line to minimise the risk of trees falling towards the line. “Reach to tree” feller bunchers grasp and fell trees in line with the crane which can be rotated around the centre of the machine as with a 360 degree excavator. As a result they can be driven parallel to the line along the edge of the block and fell trees away from the line.


Issue 1 2014 Appendix IV

Page 46

Heads / felling attachments

Felling attachments can be broken down into 3 broad types with a couple of variations within the main categories:

1. Harvester heads a. Conventional (dangle) heads b. Fixed/rotating harvester heads

2. Feller buncher heads

a. Hot saw feller buncher heads b. Intermittent feller buncher heads

i. Circular saw based ii. Chainsaw based

3. Tree shears

Conventional Harvester Heads Harvester heads are normally suspended from a brake link and rotator on the end of a long reach crane (controlled rotation about the vertical axis and braked movement in two horizontal axes). The unit consists of a spine suspended within a wish bone or A frame which allows the spine to tilt forward through 90 degrees or more, a series of curved hydraulically operated knives mounted at right angles to the spine, and a series of drive rollers or tracks with a hinged hydraulically driven chainsaw mounted in the base of the unit. In operation the head is positioned against the tree trunk, with the rollers against the stem and the knives around the trunk, the stem is severed by the chainsaw and the spine pivoted within the wishbone to help the tree over/allow the head to follow the falling tree. The stem is then drawn through the knives by the rollers and the limbs stripped off with the chainsaw used to sever the stem at pre-determined intervals to create logs to whatever specification is required. Although the crane and head combination allows considerable reach, there is limited directional felling capability. This lack of control of felling direction is a limiting factor when dealing with trees immediately adjacent to power lines. Subject to trials then modifications to the head or boom or the use of an over-sized head and machine may improve the degree of control of felling direction. Heads with a maximum felling diameter of 80cm in a single cut are widely available for use with larger base units. Fixed Harvester Heads Fixed/rotating harvester heads carry out the same functions as conventional ‘dangle’ harvester heads, but are mounted on a heavier duty crane and rotate about two horizontal axes under hydraulic control. The unit can therefore be operated in a similar fashion to a feller buncher to grasp and pick up smaller stems with the delimbing knives and will de-limb and cut to length like a conventional harvester head. It cannot be rotated about the vertical axis to position the head on either side of the tree to allow the saw to cut in from whichever direction the operator chooses. A 70cm felling diameter fixed head is available.


Appendix IV Issue 1 2014

Page 47

Feller Buncher Heads Feller buncher heads consist of a cutting mechanism at the base of a heavy rigid spine fitted with horizontal gripping arms. They are generally mounted on a linkage on the end of a heavy duty boom or loader arms, which allows controlled movement in one or two horizontal axes. Hot saw feller buncher heads use a continuously rotating circular saw head to sever the stem of the tree. Intermittent heads use either a hydraulically driven circular saw head or chainsaw mounted in the base of the head. With a fixed saw the head configuration does not permit the stem to be securely gripped until the cutting process has begun (this limits its suitability for trees immediately adjacent that may have fragile branches or head). However once gripped and severed the tree can be lifted and manoeuvred at will. Pivoting circular or chainsaw cutters can be deployed once the stem has been gripped; this improves the control of trees that are liable to snap or shed branches. The heads cannot generally be rotated about their vertical axis and can therefore only cut away from the boom/base unit. Typical felling capacity of feller buncher heads is 55cm, though models with 72cm or more capacity are manufactured. Tree Shears Tree shears are basically very similar to feller buncher heads, but use low speed hydraulic knives to sever the stem of a tree. The unit configuration is such that the stem is encircled and partially gripped prior to cutting and firmly gripped as the stem is severed. The cut stem can then be lifted and manoeuvred as with the feller buncher head. Tree shears up to 50cm diameter capacity are available in the UK.


Issue 1 2014 Appendix V Model Method Statement Page 48

APPENDIX V Red Zone Harvesting Model Method Statement

Note that this Appendix illustrates an example of a possible method statement or procedure that

would be suitable to allow Network Operators to undertake Red Zone harvesting work. Where

specific controls are noted, but the option exists for alternative controls, then this has been

illustrated with comments in square brackets.

1 INTRODUCTION

1.1 This method statement sets out how staff and contractors working on behalf of the Network

Operator carry out mechanised tree harvesting within the Red Zone of a live overhead power line.

1.2 It is important to note that this method statement gives guidance on tree felling with specific regard

to the electrical hazard and does not seek to advise on managing the non-electrical hazards. Other

hazards should be dealt with in accordance with other Network Operator procedures and Forestry

Industry Safety Accord (FISA) guidelines.

2 CONTENTS

1 Introduction

2 Contents

3 Justification Process

4 Work Planning and Site Survey

5 Risk Assessment and Control Measures

6 Electrical Control Measures

7 Machinery Choice and Work Method

8 Competencies

9 Emergency Procedures

Appendix 1 Beaufort Scale

3 JUSTIFICATION PROCESS

3.1 It is preferable to carry out Red Zone tree felling works with the line isolated and earthed. Where

the shutdown option presents significant hazards then live work can be considered, using either

manual tree cutting techniques in accordance with ENA Engineering Recommendation G55 as

detailed in [Network Operator procedure name] or by using mechanised methods as described in this

document. If the work is to be carried out with the line live then this must be justified in accordance

with Regulation 14 of the Electricity at Work Regulations 1989. In considering the hazards associated

with a shutdown the following should be considered:

Number of customers

Customer interruption history

Duration of outage

Security of the network

Costs and risks (including environmental) associated with providing generation

Switching operations

3.2 Once a justification has been made to carry out the works with the line live then it must be decided

if manual or mechanised techniques are to be used, or whether no safe technique can be specified.


Appendix V Model Method Statement Issue 1 2014 Page 49

This decision should be based on the degree of risk associated with each method and in general

mechanical methods are preferable as the hazards associated with working at height adjacent to

electricity, chainsaws and being struck by falling trees are removed. However there will be situations

where the volume and complexity of the work would not merit the risks associated with bringing

heavy machinery on to site. In this case the main factors to considered are:

Access issues

Ground conditions

Number of trees

Size of trees

3.3 More detail on determining the suitability of mechanised harvesting is provided in section 4

(Work Planning and Site Survey).

3.4.1 3.4 If works are to proceed using a harvester adjacent to a live line then as with conventional

methods the justification process must be recorded on [Network Operator live line

justification document]. This must include details of both the justification to work with the

line live and the decision to use mechanised methods over manual methods.

4 WORK PLANNING AND SITE SURVEY

4.1 Work Planning

4.1.1 Where it is established that Red Zone harvesting may be required to be carried out then planning

and establishing suitability should take place in line with the guidance Figure 1 overleaf:

Figure 1 – Work planning guidance (see overleaf)



Programme any allowable third party Amber Zone or preparatory works

Decide method (barrier or clearfell) and resources to be used

Establish and document that it is unreasonable to carry out the work dead

Programme any required shutdowns

Establish and mark the extent of the Red Zone

Assess network condition and rectify defects as necessary

Establish extraction methods and routes

Agree contractual issues and handover details with landowner or original Forestry Works Manager

Partially complete pre-start checklist and risk assessments. Pass copy to landowner if required

Determine electrical hazard control measures

If relevant, agree and mark extent of any barrier to be used. Mark any hazardous trees that are not to be felled

due to their fragile nature or are outwith the capability of the harvester

Ensure all controls are in place prior to starting. Final walkover by Site Supervisor and Operator to identify

any additional hazardous trees that are not to be felled, or any manual preparatory work. Complete site specific

risk assessment.

Contact landowner and carry out a full site survey to establish constraints

Establish the scope of any Amber Zone or shutdown works

Confirm that it is reasonable to carry out the works with the line live

Ensure that the Site Supervisor, Operator and any other working parties are authorised, competent, briefed and

have signed onto the appropriate site specific documentation

Complete pre-start checklist.

Review weather forecast at an early stage to allow postponement of works where necessary



4.2 Site Survey

4.2.1 A site survey must be carried out to determine the suitability of a site for Red Zone harvesting.

The findings of this survey should be recorded on the Red Zone harvesting site survey record

[Network Operator document reference]; this should also act as a check to ensure that all relevant

factors are considered.

4.2.2 The Site Supervisor and the Operator are responsible for deciding the suitability of a site for Red

Zone harvesting and developing a suitable method statement when close enough to implementation

date. It is recommended that the site survey is contributed to by a combination of personnel,

including the Network Operator Engineer, Site Supervisor (or Forestry expert employed by or

contracted to the Network Operator), the Landowner (or representative) and the Harvesting

Contractor (preferably the Operator),

4.2.3 To choose suitable machinery type and appropriate method of felling the following must be

considered during any site surveys (this list is not exhaustive)

Height of trees

Diameter of trees

Volume of trees

Species of trees (characteristics)

Variability of the crop

Health of the crop

Stability of the trees

Presence of any dead, or hazardous trees

Spacing of the trees

Evidence of recent thinning operations

Ground conditions including soil type and depth

Exposure of site to wind

Slope

Environmental constraints relevant to the harvesting operation

Voltage of line (and Vicinity Zone)

Height profile of line (taking account of sag and sway)

Condition of the network

Distance of base of nearest trees to the line

Accessibility of the crop (for example has the Amber Zone been felled)

Availability of suitable and safe position for the Site Supervisor

Presence of fences, roads, paths and buildings

Access routes for any machinery

Third party access

4.2.4 Any trees that are identified as being unsuitable for mechanised felling with the line live

must be clearly marked with paint, visible from all sides.

5 RISK ASSESSMENT AND CONTROL MEASURES

5.1 Risk Assessment

5.1.1 Red Zone Harvesting will only be used where the trees have been assessed in accordance with

Section 4; any trees not to be felled mechanically must be clearly marked. Before works start, the Site



Supervisor and Operator will assess the trees and mark up any additional trees that they do not

consider suitable for felling.

5.1.2 Works will only commence after both the Site Supervisor and the machine Operator are satisfied

that sufficient control measures are in place and can be maintained to avoid electrical incident and

other health and safety concerns. After works commence this decision making will be continued on a

tree by tree basis.

5.1.3 In order that the risk assessment process remains dynamic then the works will start with those

trees that present a lesser risk and the performance of the machine and Operator continually

monitored, taking in to account the weight bias, ground conditions, slope and wind. Any trees that

have not been previously marked and appear to be approaching the capabilities of the machine will be

left, marked and manually felled or dismantled.

5.1.4 An assessment of the network including support structures must be made to determine the

consequences of conductors being broken in terms of risk to the rest of the network and the general

public; works will not continue until these risks can be reduced to an acceptable level. This

assessment will be recorded on the [Network Operator site specific risk assessment document].

5.1.5 A Preliminary Risk Assessment for Red Zone Harvesting has been prepared and is detailed in

[Network Operator document reference]. This covers generic hazards for live Red Zone Harvesting.

5.1.6 A site specific risk assessment shall be carried out each day on site. Everyone on site shall be

party to the production of this Risk Assessment and shall sign on to it. The work party for Red Zone

felling will only be made up of those directly involved with the activity such as the Site Supervisor,

Operator, Chainsaw Operator and any banksmen. Any other personnel engaged in other work must

remain outside any exclusion zones and be covered by a separate risk assessment. All hazards not

contained in the site specific risk assessment should be identified and noted along with appropriate

control measures. It should include the following (this list is an example and not exhaustive):

Access and egress to site where appropriate

Electrical Risks: evaluation of any relevant electrical risks specific to the site

Work method; Machine/head type to be used

Means of marking any appropriate zones, barrier trees or trees identified as unsuitable for

harvester felling

Ground conditions and terrain variation

Weather conditions including wind speed and direction and forecast

Public safety and public exclusion (as appropriate)

Emergency procedures specific to this site

Location of nearest A&E hospital

5.1.7 It is essential that satisfactory control measures are in place for all identified hazards before

works start.

5.1.8 The risk assessment will be discussed with any other adjacent work parties affected by this

work, who should then sign on to the risk assessment.

5.1.9 A [Network Operator dynamic or review risk assessment document reference] allows for

continual assessment and any new hazards and controls will be noted in this section along with

appropriate control measures. If any new person arrives on the site then works will stop. If they are

directly involved in the works they will be informed of all risks and control measures and asked to

sign on to the risk assessment to confirm his/her understanding. If they are not directly involved in the

works then they will be informed of the hazards and directed to a safe place outside any exclusion

zones and/or away from the site. Works can then restart.



5.2 Control Measures

5.2.1 Having surveyed the site, and carried out the risk assessment it must be ensured that suitable

control measures can be implemented before deciding to continue with live Red Zone harvesting. The

primary consideration must be to have robust and sufficient control measures to ensure that it is

extremely unlikely that a tree held by the harvester could contact or come close to a live power line.

To achieve this a far greater degree of control is needed than in normal harvesting operations. With

this in mind there are certain control measures that will be mandatory in order that Red Zone

Harvesting can be carried out. These are:

Any trees that are judged by either the Site Supervisor or Operator to be unsuitable for Red

Zone felling must be clearly marked by an agreed and understood method that is visible from

all approaches.

Exclusion zones must be in place as detailed at the end of this section.

Works must be supervised at all times by a Site Supervisor.

There must be “open mic.” hands free communication [or similar and as stated in Network

Operator procedure] between the Site Supervisor and Operator, this will be by way of radio

headsets. An exception to this may be in the case of barrier felling where a lesser degree of

supervision may be appropriate. In this instance a two way “walkie talkie” system may be

appropriate to be used when necessary.

The Control Engineer must be aware of the works taking place.

There must be a tried and tested method of communication primarily between the Site

Supervisor and the Control Engineer but secondly between the Operator and the Control

Engineer. A back up system must be available such as PMR handsets, or satellite phones.

Any auto-reclose facility on the network must be disabled during the works.

There must be a position of safety available to the Site Supervisor with particular reference to

the chain shot hazard, falling objects and any risk presented by broken conductors or

electrical discharge.

The Site Supervisor and Operator must be authorised as detailed in section 8.

On any one day works must start with less hazardous trees (smaller trees and further from the

line); this allows the Operator and machine to “warm up” and to confirm to the Site

Supervisor that the harvester and controls are operating as they should.

Wind speed and direction is monitored by regularly observing the tops of trees and the effect

reported by the Operator on trees being felled [in addition other methods as stated in the

Network Operator procedures and Preliminary Risk Assessment such as the use of a wind

sock and/or anemometer can be used] . With any wind speed [or strength] of [wind speed or

Beaufort scale as stated in the Network Operator Preliminary Risk Assessment] or above in

any direction towards the line then action must be taken in line with the Preliminary Risk

Assessment [Network Operator document reference]. The Beaufort scale is shown in

Appendix 1 [or similar and as stated in Network Operator procedures].

Suitable regular breaks are scheduled during the day for the Site Supervisor and Operator, as

a minimum these must be at least a full five minutes every hour [or as stated in Network

Operator procedures].

There will be a maximum of 8 hours Red Zone harvesting time per day and both the Site

Supervisor and Operator must be fit to carry out their tasks adequately[or similar, and as

stated in Network Operator procedures].

Timings of work breaks along with any details of any checks such as wind speed will be

recorded on [Network Operator log sheet document].

Dielectric footwear and class 2 insulated rubber gloves and leather over gloves are available

to the Operator [if stated in Network Operator procedures] to be used in the event of an

emergency exit from the cab.

Simulated emergencies have been practiced on site with actual communication with the

Control Engineer. (Any jump down from the harvester itself should not be practiced unless

ground conditions at the landing point offer no real chance of injury).



[Note other mandatory controls may be added as necessary by the Network Operator]

5.2.2 Other control measures to be considered will depend on the hazards identified during the site

survey and risk assessment process. Many of these are detailed in the [Network Operator preliminary

risk assessment document reference].

5.2.3 Where possible trees should be felled and left in a safe position to be processed at a later time

without supervision. This has the benefit of allowing the Site Supervisor and Operator to remain

focussed on the critical task of ensuring trees are felled in the right direction rather than being side-

tracked by the secondary task of processing trees. Reducing the actual time spent Red Zone harvesting

also allows work to be planned more effectively in relation to wind forecasts and also minimises the

amount of time the network is set at abnormal protection settings.

5.2.4 Felling over several days may leave certain trees exposed with a greater risk of being blown on

to the line. This will also be the case for any trees left as unsuitable for harvesting live. A thorough

assessment of this exposure and the weather forecast must be made in time to allow trees to either be

felled manually or to postpone some felling until the following day.

5.3 PPE Requirements

5.3.1 All site staff including the Operator when outside the cab must wear the following PPE as a

minimum [or as stated in the Network Operator procedure and supported by risk assessment]:

Safety helmet (to EN397)

Safety glasses (to EN166 349F)

Hi visibility clothing (to EN471:2003)

Gloves suitable for handling tasks envisaged

Protective boots with good grip and ankle support (to BSEN ISO20345:2004

5.3.2 In addition the Operator must have dielectric footwear and class 2 insulated gloves and leather

over gloves available [if required by the Network Operator procedure] in the event of an emergency

as detailed in section 9. Before work on every site the Operator and Site Supervisor must visually

inspect this PPE. In particular the gloves should be sealed, squeezed and inflated to identify any

punctures and also inspected for any signs of yellow showing through on the outside of the gloves. If

there are any punctures or signs of yellow then the gloves must be discarded. They must also be in

electrical test date, they must be re-tested at least every twelve months or immediately after being

used in an emergency.

5.4 Exclusion Zones

5.4.1 Arrangements for all exclusion zones must be detailed on the stage 2 risk assessment.

5.4.2 At all times the harvester must be positioned to ensure that there is no possibility that any part of

the machine could breach the Vicinity Zone. This must be assessed in advance taking in to account

the terrain, line height and maximum reach of the machine. This exclusion zone should be marked on

the ground so that it is visible to the Site Supervisor and Operator, for example paint, tape, high

stumps, trees or boundaries such as fences or walls may be appropriate.

5.4.3 The Site Supervisor must stand in a position of safety taking in to account chain shot, terrain,

falling trees and conductor damage. Generally they will be at the rear of the machine, not in line with

the bar and chain when cutting, at least two tree lengths away and not under any conductors. This

must be discussed and agreed with the Operator in advance. As they are in constant communication

the Site Supervisor will stop the Operator if they find themselves in a potentially unsafe position.



5.4.4 They must also be able to see the harvester, the tree being worked on and the conductors. They

will monitor operations as they proceed, paying attention to tree and machine clearance from

conductors, damaged or hung up trees and weather conditions and alert the Operator if a conductor is

contacted or there is immediate risk of contact. The Operator must be aware of where the Site

Supervisor is at all times. If the Operator cannot easily see the Site Supervisor or considers that they

are in an unsafe position, then the Operator must stop work and inform the Site Supervisor to correct

the situation.

5.4.5 Any other site staff, adjacent working parties or members of the public must be either at least

two tree lengths or outwith the machine/head manufacturer’s exclusion zone, whichever is the greater.

If the likelihood of members of the public being present has been identified then suitable signage and

barriers must be in place with banksmen being used where necessary.

6 ELECTRICAL CONTROL MEASURES

6.1 Where available and appropriate as agreed with the Control Engineer the auto-reclose facility on

the network must be disabled during the works. This means that in the event of a line trip the line will

not be re-energised unless agreed with the Control Engineer. Generally when the auto-reclose is

disabled the instantaneous protection will be enabled; if instantaneous protection is not available then

works will only proceed following a risk assessment and agreement with the Control Engineer.

6.2 The Site Supervisor will be the point of contact with the Control Engineer and must be capable of

immediately calling the Control Engineer at any time. As a back up the Operator must also be capable

of calling the Control Engineer.

6.3 Fully charged satellite phones or mobile PMR sets must be available to both the Site Supervisor

and Operator to be used either in the event of an emergency or where there is a poor mobile signal.

6.4 Personnel must be trained in their use. Even where there is a strong mobile signal this may be lost

in the event of an interruption to power supplies.

6.5 Both methods of communication shall be tested at the start of each day.

6.6 The Site Supervisor will contact the Control Engineer by [Network Operator specific method and

procedure] before works start and after they have stopped each day.

6.7 The Site Supervisor and Operator must be in “open mic.” communication with each other at all

times by way of radio head sets [or similar, and as stated in Network Operator procedure]. If this

system fails or either party is distracted by a telephone call for example then works will stop

immediately. A back up system must also be in place.

6.8 In the event of an emergency the Site Supervisor will contact the Control Engineer immediately

by [Network Operator specific method and procedure]. If this method is unsuccessful then the

[Network Operator specific back up procedure] must be used.

6.9 If the line trips for any reason then the Control Engineer will contact the Site Supervisor (or

Operator if unavailable). Tree cutting work will be suspended until the circuit has been re-energised

or the fault location is confirmed as being outside the work zone.

6.10 On completion of work at the end of each day the Site Supervisor will contact the Control

Engineer and confirm that works are complete and that the harvester is clear of the line.



6.11 As a precaution the Operator will be issued with dielectric footwear and class 2 insulated gloves

and leather over gloves [if required by the Network Operator procedure]. These are to be kept in the

cab and only worn if he has to exit the cab in an emergency where there is a risk of a potential

difference between the cab and the ground or a step potential away from the machine (see Emergency

Procedures Section 9).

7 MACHINERY CHOICE AND WORK METHOD

7.1 It is essential that the work methods and machinery types to be used have been properly selected,

are suitable for the task and have been trialled and accepted by [the Network Operator]. Only two

methods have been suitably trialled and accepted [or as detailed by Network Operator]; these are

barrier felling and fixed head harvester and are detailed below.

7.2 Any other felling method or machinery combination not covered in this procedure must not

be used adjacent to a live line until it has been thoroughly trialed and this document has been

updated and approved.

7.3 Barrier Felling

7.3.1 The basic principle of barrier felling is to fell trees with a harvester using standing edge trees as

a physical barrier in the event that a harvester were to lose control of a tree.

7.3.2 The resultant barrier trees cannot be felled using this work instruction and will either

require a shut down, or manual felling or dismantling in accordance with G55 and [Network

Operator document reference]. The only exception to this will be where a different approved

harvester/head combination is used with an appropriate method in line with this work

instruction.

7.3.3 The site survey (section 4) will be carried out with additional emphasis on the suitability of the

standing crop to determine if there is potential to use the outer edge trees as a barrier, and if so then to

determine the extent of this barrier. Factors to consider will be:

Stability of the crop

Presence of any gaps in the upper canopy of edge trees as a result of windblow, dead trees, wide

spacing or poor growth

Species and health of trees in terms of branch and stem strength

Previous thinning or pruning regimes

7.3.4 In addition to examining the edge trees the crop should be inspected further back for clear areas

of windblow or suppressed trees. This would present a potential hazard for any distant trees that fall in

the wrong direction to gather momentum.

7.3.5 If a satisfactory barrier can be established then this must be clearly defined by marking the trees

to be left for manual removal or future shutdown. This barrier may be a number of rows and in a non

uniform crop will be a line of variable width.

7.3.6 The type of harvester and head to be used must also be agreed as being acceptable, taking the

importance of control and the size of the crop into account.



7.3.7 With works in progress then it must be ensured that:

The trees furthest from the line are taken first to avoid opening up holes adjacent to the barrier

zone.

The harvester and head should be orientated to give maximum leverage away from the line.

Trees must be felled away from the line.

Trees must not be felled into other standing trees in order to avoid a ‘domino effect’ towards the

line.

Trees or timber will stacked at least 10m from any conductors allowing safe future extraction. If

extraction of timber is carried out at the same time as harvesting then risk zones must be adhered

to and felling operations suspended when travel underneath the line is needed.

Individual trees which are encountered as works progress that are beyond the capability of the

machine/head combination, but have not previously been identified, must be left to be dealt with

manually or under a shutdown.

Where works take place over more than one day then particular attention must be paid to weather

conditions (particularly wind speed and direction), ground conditions and any deterioration in the

barrier zone; findings and controls must be recorded on the [Network Operator site risk assessment

document reference].

7.4 Fixed Head felling

7.4.1 Only the Logmax 7000XT fixed head on a tracked base [or other head and base unit that has

been trialled by the Network Operator and approved as being suitable] can be used with the

technique described here. The 7000 fixed head is unique in that it has a powered rotator unit that can

control the direction and rate of fall of the tree. This differs from a traditional dangle type grapple

head that exerts little control over the direction and rate of fall after the tree has started falling.

7.4.2 In general the harvester will travel parallel to the line on a brash mat of cut branches. It will

travel far enough away from the line to avoid any possibility of the harvester head breaching the

Vicinity Zone.

7.4.3 Where the ground conditions dictate then it may be more appropriate to have the machine facing

the line. This can only be allowed if there is no physical possibility of the head breaching the Vicinity

Zone.

7.4.4 Trees will generally be felled away from the line at an angle of at least 45°. The trees furthest

from the line will be cleared first to ensure that trees are always being felled in to a cleared area. As

felling progresses the angle of felling will be monitored to ensure that it remains at least 45° from the

line. There may be occasions due to terrain and the need to maintain the safe distance of the harvester

from the power line that it would be safer to fell trees at an angle of less than 45°. If this is the case

then works should only continue where the control measures are detailed on the [Network Operator

site risk assessment document reference].

7.4.5 Once cut the Logmax 7,000 fixed head [or other Network Operator approved head] is capable

of lifting the tree and then the base unit can slew it or move around site with it still in the vertical

position. However this should be kept to a minimum and the tree rotated to the ground as soon as

possible to minimise any unnecessary forces on the tree and base unit from any gusts of wind.

7.4.6 If the trees must be processed as works progress then they must be de-branched ensuring that the

stem of the tree has no possibility of breaching the Vicinity Zone, this will be monitored by the Site

Supervisor. Timber will be stacked at least 10m from any conductors allowing safe future extraction.

If extraction of timber is carried out at the same time as harvesting then risk zones must be adhered to

and felling operations suspended when travel underneath the line is needed.



7.4.7 If, in the process of harvesting the ground or weather conditions deteriorate (particularly wind),

or it is considered that the harvester and Operator are not demonstrating adequate control, then works

must be suspended. In these circumstances the Control Engineer should be contacted to establish if

the circuit needs to be re-set for normal working.

7.4.8 Any trees marked as unsuitable to be felled live must not be felled using this method.

7.4.9 Daily planning must take account of trees that might be left temporarily at the end of the day,

particularly if high winds are forecast. Any trees liable to be windblown on to the network should

either be removed or works suspended early in the day to avoid leaving them vulnerable.

7.4.10 Works will generally be carried out as shown in Figure 2:

Minimum 45

Direction of fall

Minimum distance to avoid

breach of Vicinity Zone

Figure 2: Fixed Head Method of Harvesting



7.5 Topping Trees with a Fixed Head.

7.5.1 In certain circumstances it may be beneficial to cut trees at height. For example where there is a

sweep towards the line at the base of the trunk or where there are very large branches lower down the

tree. The fixed head offers an opportunity to do this but this technique presents some additional

hazards, namely the increased possibility of machine roll-over and the greater range of chain-shot.

7.5.2 This method can only be used where the following control measures are in place:

Only the Logmax 7,000XT fixed head [or other head that has been trialled by the Network

Operator and approved as being suitable] can be used for this technique

Tops can only be a maximum of 75% of the diameter and weight capability of the head and

base

Both the Site Supervisor and Operator must have assessed each tree, agreed that it is

acceptable to top and agreed the height at which it is to be cut.

The base unit should be placed as close to possible to the tree to avoid over stretching

The height of the topping cut must not be at the maximum reach of the head and there must be

sufficient additional reach to allow the top to be lifted off the cut

Topping is only to be done where there is a reasonably clear stem to avoid unseen, thick

branches preventing a clean cut

Once cut the top is not to be rotated down but lifted slightly, slewed round slightly and then

lowered vertically to the ground, this should avoid unbalanced forces leading to machine roll-

over

Topping is only to be done when the machine is reasonably level and on stable ground

Exclusion zones must be enhanced due to the higher risk of chain-shot travelling further

distances (where applicable)

8 COMPETENCIES

8.1 Operator

8.1.1 The Operator is likely to be a contractor and will hold a [Network Operator Operational

Authorisation reference]. This authorisation will only be issued by [Operational Training] following a

successful assessment by an [Operational Trainer]. This assessment will be made up of an on-site

practical assessment and the sitting of a formal written question paper [Network Operator document

reference]. This authorisation will also be subject to an additional site specific authorisation as

detailed in paragraph 8.1.3.

8.1.2 The Operator will hold the NPTC Forestry Machine Operator Certificates appropriate to the

machinery being used.

8.1.3 The Operator will be briefed on relevant sections of FISA 804, techniques to be used, specific

control measures in place, site specific hazards and emergency procedures in the event of an electrical

incident or near miss. The Operator’s understanding of the above will be tested and recorded on the

[Network Operator pre start checklist document]. In addition to the operational authorisation the

Operator will be authorised for the specific site and only for the duration of the agreed works [or as

stated in Network Operator procedures].

8.1.4 Works will not start until the [Network Operator pre start checklist document] has been

completed and signed off.



8.2 Site Supervisor

8.2.1 The Site Supervisor will hold a [Network Operator Operational Authorisation reference]. This

authorisation will only be issued by [Operational Training] following a successful assessment by an

[Operational Trainer]. This assessment will be made up of an on-site practical assessment (where

evidence of knowledge of harvesting techniques and machine limitations must be demonstrated) and

the sitting of a formal written question paper [Network Operator document reference].

8.3 All Site Staff

8.3.1 All personnel on site must have First Aid Training in line with Health and Safety (First Aid)

Regulations.

8.3.2 Competencies for other non-mechanised harvesting activities are detailed in [Network Operator

document reference].

9 EMERGENCY PROCEDURES

9.1 There are several scenarios that could require emergency action including:

The Operator loses control of a tree (for example due to wind, Operator error or mechanical

failure) and it rests against another tree, not in contact with any conductors. He will stop work

and await instruction from the Site Supervisor.

The Operator loses control of a tree and it contacts and remains in contact with a live

conductor.

The Operator loses control of a tree and it contacts and breaks a live conductor.

The Operator loses control of a tree; it contacts a live conductor and falls clear with the

conductor remaining intact.

The Operator is unaware that a tree has contacted a live conductor.

The Operator loses control of a tree and it contacts a pole or tower.

Due to the exposure of edge trees, a tree that is not being worked on is either blown partially

over or fully on to a conductor.

9.2. Where it is clear that control of the tree is being lost then the Operator should, where possible,

take evasive action to avoid the tree hitting the line. He should use other controls such as slewing

away from the line and running the tree through the head. If it is clear that the tree is going to contact

conductors then the tree should be released from the head to prevent indirect contact with the

conductors.

9.3 In all of the above emergency scenarios the immediate action will be similar; release the tree from

the harvester head if possible, immediate contact between the Operator and Site Supervisor, stop

work, contact the Control Engineer and secure the area. Thereafter the appropriate course of action

will be decided jointly by the Operator, Site Supervisor and the Control Engineer.

9.4 Emergency procedures should be rehearsed prior to each Red Zone harvesting job. As a minimum

this should include a simulated emergency call to the Control Engineer and an emergency exit from

the harvester cab. The jump itself should not be practiced unless ground conditions at the landing

point offer no real chance of injury. This should be recorded on the [Network Operator pre start

checklist document].



9.5 Emergency Procedures for Operator (this guidance must be clearly visible in the cab):

Release the tree from the harvester head.

Stop work.

Switch off machine.

Stay in the cab in all circumstances except where there is danger to life e.g. fire.

Talk to Site Supervisor immediately and confirm that he is communicating with the Control

Engineer; if he is not capable of making contact then call the [Network Operator Control

Engineer emergency number].

Put on dielectric footwear, insulated gloves and over gloves [if stated in Network Operator

procedures].

Only start the machine and attempt to drive clear of the line if instructed to do so by the

Control Engineer.

Ensure no-one approaches the harvester, conductors, towers or trees. If seen, draw this to the

attention of the Site Supervisor.

Only exit the cab of the machine when instructed by the Site Supervisor (after confirmation

with the Control Engineer that the line has been made safe).

In the event of fire then use the engine or cab fire extinguishers as necessary.

If there is a risk to life by staying in the cab then exit the cab and jump to the ground away

from the machine and continue to walk swiftly away [or if there are no dielectric gloves and

footwear then “bunny hop” or run ensuring both feet are not touching the ground at the same

time]. It is important to choose the escape route carefully to avoid any falls which could result

in injury from a step potential.

Do not return to the machine until it is safe to do so and it has been confirmed that the line has

been isolated.

9.6 Emergency Procedures for Site Supervisor

Talk to the Operator to confirm the nature of the emergency, remind him to release the tree,

switch the machine off, stay in the cab and put on his dielectric footwear, insulated gloves and

over gloves [if stated in Network Operator procedures].

Remain at a safe distance (at least 15m) from any power line, tree, machinery, fences, gates,

metal or conductive equipment.

Keep any other site staff at a similar safe distance.

Contact the Control Engineer by [Network Operator specific method and procedure].

If the Control Engineer does not call back within one minute then the [Network Operator

specific back up procedure] must be used.

Arrange for Control Engineer to contact emergency services if necessary.

Only instruct the Operator to exit the cab after it is confirmed that the line has been made

safe. The only exception to this is where there is risk to the Operator’s life in which case

instruct him to jump as far as possible from the machine ensuring that there is no contact with

the machine and the ground at the same time.,

Administer First Aid where necessary and only if safe to do so.

9.7 Emergency Procedures for Any Other Site Staff

Remain at a safe distance (at least 15m) from any power line, tree, machinery, fences, gates,

metal or conductive equipment.

Ensure that all others remain at a safe distance.



Appendix 1


Appendix VI Model Pre Start Checklist Issue 1 2014 Page 63

Appendix VI Model Red Zone Harvesting Pre Start Checklist Site name: Location: Grid Ref: Proposed Start Date of Works:

Contact Details Name Contact Number

Network Operator Manager

Site Supervisor

Operator

Landowner Forestry Work Manager

All boxes below are to be checked off before works starts Live working

Line is to remain live

Live line justification [Network Operator live line justification document] has been completed,

briefed and is available on site

Line security and Risk Assessment

Competent person has checked the condition of the line and equipment and it is safe to

proceed

Road crossings, fences, footpaths etc. in proximity to the line which may be affected in the

event of an emergency have been identified and ensure control measures are identified and put in place

Goalposts and signs etc. are in place where necessary

The Control Engineer has been made aware of the operation and has the operator’s contact

details

If auto-reclose facility is present then arrangements must be in place set to one shot to lock-out

Site Conditions (has the following been considered and included in the risk assessment where

relevant?) Constraints information obtained from landowner and incorporated in to risk assessments.

Terrain assessed as being within the machine’s capability

Conditions (poor drainage or wet ground)

Roughness (stumps, boulders etc.)

Slope

Provision made for measuring and monitoring wind strength [for example windsock and/or

anemometer as detailed in the Network Operator method statement]

Weather and visibility acceptable and forecast checked

All trees to be felled are outside the Vicinity Zone

Structures (walls, fences, pipes, cables) identified and control measures in place

Suitable positions of safety are available to allow works to be adequately supervised


Issue 1 2014 Appendix VI Model Pre Start Checklist Page 64

General Work Methods

Site Supervisor and Operator have had a final walk over of site

Operator briefed and understands method statement and risk assessment and is aware of control

measures

Operator will comply with relevant aspects of FISA 603 (Mechanical harvesting)

Operator understands methods of marking and understands which trees are not to be harvested

Operator understands distance from the line that is marked and that the machine cannot cross

First trees to be worked on identified as being of a low hazard nature to allow a suitable “warm up” period

FISA 804 briefed (relevant parts briefed) understanding checked and leaflet signed

Other machine operators on site have been briefed not to cross under the line during Red Zone felling

operations. Details of method and relevant control measures (e.g. fixed head or barrier method):

Details of other Operators working Barrier Zone Method (where applicable)

Tree species

Stability of crop

Presence of gaps or any standing dead trees

Tree health

Evidence of thinning

Tree spacing

Minimum number of rows to be left as a barrier

Barrier Zone clearly marked and operator made aware

Operator satisfied with suitability of barrier

Machinery Type

Base type Head type

Size of machine acceptable for tree size and conditions

Base is mounted on a suitable drive system (metal tracks or tyres) [supported by the Network

Operator Preliminary Risk Assessment]

Age and reliability of machine


Appendix VI Model Pre Start Checklist Issue 1 2014 Page 65

Maintained correctly, service history checked. Hours since last service

On-site inspection of machine and head satisfactory including hydraulic hoses, chain and bar

Sufficient spare chains and bars available

Suitability for terrain

Operator satisfied with suitability of machine

Cab clear and tidy

Training/Competence (Operator and Supervisor)

Authorisation and competence checked, note certification details and other evidence

Supervisor Operator

First Aid qualifications held by Site Supervisor and Operator.

Familiarity with particular machine checked

Supervisor Operator

Awareness of electrical control measures including auto reclose settings

Supervisor Operator

Communications and Emergency Procedures

Open mic. headset communications tested [or similar and as detailed in the Network Operator

method statement], spare batteries available

Mobile phone signal and battery checked as acceptable or satellite phones in place

Secondary back up system available and checked

Primary and secondary communication systems tested between Site Supervisor and Operator

Contact established as acceptable with the Control Engineer

Call waiting facility enabled on all phones

Simulated emergency procedures rehearsed, including contact with the Control Engineer and emergency exit from the harvester cab

Emergency contact numbers entered into all phones

Briefing of emergency procedures in [Network Operator method statement]

Emergency procedures are clearly visible inside the harvester cab

Explain circumstances which would be defined as an emergency (also covered during

authorisation training)

Dielectric footwear, class 2 insulated gloves and leather over gloves have been inspected and

are readily available in the cab of the harvester [if required by the Network Operator method statement]

First Aid kit in each vehicle and carried by the Site Supervisor


Issue 1 2014 Appendix VI Model Pre Start Checklist Page 66

Landowner Communications

Any additional site information has been taken in to account in determining methods and

control measures

Pre Start Checklist (partially completed with basic details including work methods and

machine and head to be used) has been offered for information at an early stage (preferably at least two weeks before works start)

Date offered: Refused or accepted:

Any feedback received from the landowner regarding work methods and control measures has

been considered and incorporated where necessary. Harvester Operator Declaration and Authorisation Machine Operator Declaration I am satisfied with the arrangements made for controlled Red Zone harvesting and understand the emergency procedures. I understand that I am authorised to carry out Red Zone harvesting in

accordance with [Network Operator method statement] on this site only

Name: Signature: Date: Network Operator Authorisation (can be authorised by the Site Supervisor) The above operator has been briefed and understands the arrangements made for controlled Red Zone harvesting and understands the emergency procedures. The operator is authorised to carry out Red Zone harvesting on this site only.

Name: Signature: Date: