Research Programme
Engineering
Review and Development of Safe Working
Issue: 1.0
Balfour Beatty
Date: 1st December 2006Project Report
T345 - Review and Development of
Safe Working Practices in
Electrified Areas – Report No. 2
Prepared for
Rail Safety and
Standards Board
Balfour Beatty Rail Projects Limited Midland House Nelson Street Derby DE1 2SA
WWW.bbrail.com
© Copyright 2007 Rail Safety and Standards Board
This publication may be reproduced free of charge for research, private study or for internal circulation within an organization. This is subject to it being reproduced and referenced accurately and not being used in a misleading context. The material must be acknowledged as the copyright of Rail Safety and Standards Board and the title of the publication specified accordingly. For any other use of the material, please apply to RSSB's Head of Research and Development for permission. Any additional queries can be directed to [email protected]. This publication can be accessed via the RSSB websitewww.rssb.co.uk
EXECUTIVE SUMMARY
The Rail Safety and Standards Board's (RSSB's) Research Programme is responsible for the development and delivery of much of the railway industry’s safety-related research and development. RSSB has awarded a contract to Balfour Beatty Rail Projects under this programme for the Review and Development of Safe Working Practices in Electrified Areas.
The project aims to review the basis on which practices for isolation and earthing during construction, renewals, commissioning, and maintenance have evolved; and make recommendations for revised standards that will lead to greater safety for workers as well as more effective maintenance possessions. It also looks at issues related to working on functioning electrification systems, such as touch voltages and live line indication.
The project is delivered in the form of two separate reports. This report (Report No. 2) addresses the issues of::
how isolation and earthing practices have evolved
incidents where human contact with a live conductor have occurred, including human factor analysis
tasks undertaken in an electrified railway and the risks associated with them; and training in respect of working on electrical equipment.
It also discusses some developments of processes, standards, and equipment, which can lead to enhanced safety and efficiency.
Section 3 of this report highlights the standards applicable to the scope of the study and against which the research was conducted. It also lists other pertinent legislation and documents applicable to rail electrification systems including:
Railway Safety Principles and Guidance Part 2, Section C Guidance on Electric Traction
Systems
BS EN 50122-1 1998 Railway Applications – Fixed Installations, Part 1 – Protective
Provisions Relating to Electrical Safety and Earthing
Network Rail Safety Information Bulletin No IMM/GE/001; August 2004 Traction Return
Circuit Continuity Bonds
BR 12034/16 Railway Electrification 25kV A.C. Design on B.R.
Section 4 of the report sets down the history of the isolation and earthing process and details how it has evolved from pre-World War II to the present day. The review has concluded that the isolation process presented in RT/E/S/29987 is a well proven, methodical way to achieve safe working on or adjacent to 25kV overhead line equipment (OLE). The continuation of the 29987 User Group is seen as key to continuous improvement in the promotion of safe working practices in electrified areas.
The review has identified the problem of over issue of overhead line permits on some major work sites due to bad practice and misinterpretation of the rules. It recommends that enhanced communication of rulebook requirements is undertaken in this area.
The continued use of long earths in the absence of designated earthing points (DEPs) is a cause for concern and we recommend that a national database of DEPs be progressed in Phase 2 of this project. Knowing and understanding where DEPs are not available will allow action plans to be formulated to mitigate this risk in the future.
The review has identified the hazards that exist from 25kV OLE. It is felt that benefit could be gained from producing a publication highlighting these hazards to raise awareness/understanding to Controller of Site Safety (COSSs) and Personal Track Safety (PTS) holders.
The level and content of electrification training on both PTS and COSS courses is a cause for concern and we recommend that Phase 2 of this project reviews both PTS and COSS course content and with the collaboration of Network Rail and Sentinel produces new slides, training plans, and assessment tools.
The project recognises the good work already undertaken on the changes to Standards and processes for AC overhead line nominated persons (NP) and authorised persons (AP).
The review has highlighted non-compliance issues with Module 6 of RT/E/S/29987 in regard to isolation planning, it is however, recognized that this non-compliance is being addressed by the 29987 User Group.
The importance of identifying all recipients of overhead line permits in pre-planning is covered in clause 4.16 of this report.
The over issue of permits to COSSs and machine controllers whose work activity does not require an isolation is another area of concern and needs to be addressed in both training and cascade briefing.
Review of electrical clearances to earth has identified differences in the various publications covering this issue and in particular in the Railway Safety Principles and Guidance Part 2 Section
C. We recommend a detailed review of electrical clearances given in these documents by the
various stakeholders, and that a uniform approach be agreed.
The human factors element of the study set out to achieve the following objectives:
Review existing literature to identify any previous work on electrified areas, to avoid duplication of effort
Review a sample of railway incidents involving electrified equipment to determine why the people involved behaved the way that they did.
Predict the types of human error that could feasibly occur considering the tasks that personnel are required to perform in and around electrified areas.
Previous research has provided a great deal of practical information on why people behave (intentionally or unintentionally) in a way that goes against safety procedures, including recommendations for the reduction of such behaviours in the future.
There is also best practice guidance available on teamwork within the rail industry, which is written in such a way as to make translation into recommendations relatively simple. This guidance can be used to identify ways of reducing the likelihood of teamwork failures in future. Research into communications errors during railway maintenance suggests that the primary cause of such errors is the design and usability of communications procedures.
Research into distance judgement suggests that even experienced crane operators find it very difficult to judge accurately the clearance from overhead lines. In cases where raising part of a vehicle could expose the occupants to the risk of electrocution, the use of distance markers should be considered.
As part of the human factors input to this project, a predictive error analysis was conducted using the task-based risk assessments developed by OLE and DC electrification specialists from Balfour Beatty Rail. The object of this exercise was to predict the types of human error that could occur whilst working in AC or DC electrified areas.
The predictive analysis of human error conducted to supplement the risk assessment of tasks conducted in electrified areas suggested that the predominant types of error that would be encountered would be perception, action and memory errors. Most tasks do not provide the opportunity for decision-making errors, although these were also predicted. Expert opinion suggested that decision-making errors would be more likely in planning and management tasks than in manual tasks.
In the majority of cases, applying the rules laid down in either RT/E/S/29987 or GO/RT3091 will result in specific risk assessment of the task and a safe system of work to be developed thereby lowering the risk to a tolerable level.
The identification of risks in third rail areas was initiated following the introduction of Issue 3 of GO/RT3091 but this work stalled upon its withdrawal. It is recommended that this work is re-initiated.
A number of recent innovations in the process of being developed or at a point where a development would enhance safety or efficiency are presented at Section 8. Further work should be undertaken in Phase 2 of this project to introduce developments that will offer improvement. An area of concern in the introduction of innovation or development is the apparent lack of change management culture within the industry, which delays introduction of good ideas and does not make them visible.
Contents
EXECUTIVE SUMMARY... 1
1 INTRODUCTION ... 6
2 BACKGROUND ... 7
3 REVIEW OF PERTINENT DOCUMENTATION ... 8
3.1 Railway Group Standards ... 8
3.2 Network Rail Company Standards ... 9
3.3 Other documentation considered ... 9
3.4 Legislation ... 9
4 EVOLUTION OF 25 KV OLE ISOLATION AND EARTHING PROCESSES ... 11
4.1 Introduction... 11
4.2 The Isolation & Earthing Process ... 12
4.3 Isolation Process Flowchart ... 14
4.4 Isolation and Earthing Process – Control Measures ... 15
4.5 Issue of Overhead Line Permits... 16
4.6 Hazard from 25kV overhead line equipment... 17
4.7 Typical residual 25kV hazards ... 17
4.8 Planning and 25kV Residual Hazards... 21
4.9 Hazard and Risk-Based Briefing ... 21
4.10 PTS Electrification Training... 22
4.11 COSS Electrification Training... 22
4.12 Nominated and Authorised Persons Competence... 22
4.13 Compliance with Isolation Procedures ... 22
4.14 Isolation Planning ... 23
4.15 Alternative Methods of Issuing Overhead Line Permits... 23
4.16 Identification of Overhead Line Permit Recipients ... 24
4.17 Over Issue of Overhead Line Permits... 24
4.18 The Origin and Purpose of the ‘9 foot rule’ (sic)... 25
4.19 25kv Electrical Clearances to Members of the Public on Station Platforms ... 26
4.20 Clearances to Members of the Workforce and Public in EN 50122-1... 28
4.21 Electrical Clearances to Earth... 29
4.22 25kV electrical clearances to earth summarised:... 30
5 CONSIDERATION OF DC THIRD RAIL ISOLATION AND EARTHING PROCESSES ... 31
6 HUMAN FACTOR ANALYSIS... 32
6.1 Introduction... 32
6.2 Literature Review ... 32
6.3 Review of Historical Incident Data ... 36
6.4 Results of Review of Historical Incident Data ... 39
6.5 Conclusions... 49
6.6 Recommendations... 53
6.7 Predictive Error Analysis... 56
7 TASK IDENTIFICATION AND RISK ANALYSIS ... 67
7.1 Methodology... 67
7.2 Example of Task Identification and Risk Assessment Process... 69
7.3 Summary... 70
8 DEVELOPMENTS... 73
8.2 Specific Developments ... 73
9 CONCLUSIONS ... 78
10 RECOMMENDATIONS... 81
10.1 Introduction... 81
10.2 Recommendation 1 – Communications... 81
10.3 Recommendation 2 – Vertical Slice Audits... 81
10.4 Recommendation 3 – National Database of DEP Locations ... 81
10.5 Recommendation 4 – PTS and COSS Training... 81
10.6 Recommendation 5 – Electrical Clearances to Earth... 81
10.7 Recommendation 6 - Safety Observation Schemes ... 81
10.8 Recommendation 7 - Greater Emphasis on Supervisory Checks ... 82
10.9 Recommendation 8 - Introduce Safety Communications Training ... 82
10.10 Recommendation 9 - Checking the Planning Process ... 82
10.11 Recommendation 10 - Further Analysis... 82
10.12 Recommendation 11 - Incident Reporting... 82
10.13 Recommendation 12 – RIMINI Approach ... 82
10.14 Recommendation 13 – Tasks on the DC Third Rail... 82
10.15 Recommendation 14 – Development - Live Line Indicators... 83
10.16 Recommendation 15 – Development - Live Line Testers... 83
10.17 Recommendation 16 – Development - Live Line Data Loggers... 83
10.18 Recommendation 17 – Development - Conductor Rail Gauging... 83
10.19 Recommendation 18 – Mandated use of PPE in DC Conductor Rail Areas ... 83
1 Introduction
The Rail Safety and Standards Board's (RSSB's) Research Programme is responsible for the development and delivery of the railway industry’s safety-related research and development. RSSB have awarded a contract to Balfour Beatty Rail Projects under this programme for the Review and Development of Safe Working Practices in Electrified Areas.
The project aims to review the basis on which practices for isolation and earthing during construction, renewals, commissioning and maintenance have evolved, and to make recommendations for revised standards that will lead to greater safety for workers as well as more effective maintenance possessions. It also looks at issues related to working on functioning electrification systems, such as touch voltages and live line indication.
The project is delivered in the form of two separate reports. This report (Report No. 2) addresses the issues of: how isolation and earthing practices have evolved; incidents where human contact with a live conductor have occurred, including human factors analysis; tasks undertaken in an electrified railway and the risks associated with them; and training in respect of working on electrical equipment. It also discusses some developments with processes, standards and equipment, which can lead to enhanced safety and, in addition, efficiency without compromise to safety.
Report No. 1 considers some fundamental electrical issues that impact on safety. In particular, it focuses on the voltages that appear on the running rails, and on connected non-live conductive structures, under a variety of conditions. It also considers the influence of the protection system in determining the length of time for which elevated rail voltages may persist during a short circuit. The study has focussed on 25 kV AC systems because potentials that are high enough to present a safety risk are much more likely to occur, when compared with DC third rail systems.
2 Background
The electrification system and the associated operating procedures have been designed for safe operation. Many changes have occurred over recent years, which include:
Infrastructure changes, including new auto transformer systems, switchgear, protection devices, etc
New rolling stock, with greater power demand Increased traffic density, requiring higher fault levels
Operational changes that have affected the management of both infrastructure and trains Disaggregation of the rail industry into many smaller service providers, many with little
history of railway working and in particular electrification systems
Although it is generally recognised that change is effectively managed by the Safety Case requirements and that standards and procedures are amended to reflect the change, concern remains within the industry regarding both workforce and passenger safety.
The risk of electrocution from contact with an energised conductor remains high, and any mitigation of this risk is desirable.
The move to privatisation resulted in a massive loss of skill and expertise at all levels in the rail industry. In many cases, the people who were lost were the people who set the standards that form the basis of what is in place today. When these people moved on they took with them the corporate memory which formed the decision making criteria of what was done and why. The corporate memory issue is further compounded by the disaggregation brought about by privatisation with no one body holding all the information.
The disaggregation of the rail industry has resulted in a need for many independent organisations providing discrete services to interface with each other. This demands much better controls and communications to be applied to ensure safety for both the workforce and the travelling public. The desire to achieve increased passenger growth has seen an increase in traffic density, which in turn limits the availability for access to the infrastructure for maintenance and renewal purposes. Improvements in efficiency in taking isolations and applying earths is seen as key in ensuring the future condition of the rail network as a whole, although this must be achieved without compromise to safety in taking the isolation or provision of a safe system of work.
3 Review of Pertinent Documentation
There is a plethora of documents which cover the subject matter contained within this research ranging from railway safety principles and guidance produced by the HSE, other legislative documents, Railway Group Standards, Network Rail Company Standards and European Standards. The standards listed below were used as the basis for this research.
3.1
Railway Group Standards
Document no Date/ Issue Title Synopsis
GL/RT1252 Apr-00/1 Production & Management of Electrification Isolation Documents
Defines the requirements for the production & management of isolation documents for all electrified lines
GL/RT1254 Apr-00/1 Electrified Lines Traction Bonding Mandates the requirements for electrified lines traction bonding GM/RT1040 Aug-96/1 Safe Working on or Near Electrical Equipment The requirements for providing a safe system of work
GI/RT7007 Jun-02/1 Low Voltage Electrical Installations Defines the requirements for low voltage installations on Network Rail controlled infrastructure
GI/RT7033 Jun-03/1 Lineside Operational Safety Signs
This document mandates the arrangements for the management & specification of lineside operational safety signs in order to provide consistency of form and presentation throughout the network.
GE/RT8024 Oct 2000/1 Persons Working on or near to AC Electrified Lines
Defines the requirements for the production of safe systems of work to prevent injury for electrical causes to persons working on or near to Network Rails AC Overhead line equipment that danger may arise.
GE/RT8025 Oct 2001/1 Electrical Protective Provisions for Electrified Lines
Mandates the design requirements for the avoidance of direct contact between persons and live parts of electrification equipment and of electrical equipment on trains
GO/RT3091 Apr 1998/2 DC Electrified Lines Instructions
These instructions set out the actions to be taken to avoid danger from DC electrified lines or the process to be followed to determine the actions to be taken to avoid such danger.
GO/RT3093 Dec 1999/2
The Planning Requirements for Operational Safety of Engineering Work
The minimum requirements for planning
engineering work to ensure the risks to operational safety are effectively controlled to be as low as reasonably practicable.
GO/RT3260 Aug 1998/2 Competence Management for Safety Critical Work
Clarifies the application of the Railways (Safety Critical Work) Regulations to Network Rail controlled infrastructure, and defines requirements for systems for managing the competence and fitness of persons required to undertake such work. GO/RT3279 Dec 1999/5 High Visibility Clothing Sets out the minimum requirements for high visibility clothing GO/RC3560 Aug 1998/1 Code of Practice - Competence Assessment
The recommended components of a competence assessment system to assist compliance with GO/RT3260 Competence Management for Safety Critical Work
3.2
Network Rail Company Standards
Document No. Date/Issue Title
NR./SP/ELP/27154 Procedure for the use and care of BR Type Testers
NR./SP/ELP/27150 Procedure for use of Permaquip Scissors type platform machine and HighCapacity Trolleys as used for OHL Maintenance NR./SP/ELP/27214 Maintenance of Mark IIIB Overhead line equipment (formerlyEHQ/ST/O/003) NR./SP/ELP/27171 Procedure for the Issue, Storage, Routine Inspection and Testing ofRubber Gloves NR./SP/ELP/27203 Specification for the provision of isolation, earthing and indicationfacilities where local isolations are permitted on AC Electrified Lines EHQ/SP/S/030 Specification for the preparation of isolation diagrams and instructionsfor AC Electrified Lines
RT/CE/C/033 Historical Competence requirements for safety critical permanent way work NR/GN/ELP/00004 AC Electrified Lines Earthing and Bonding
NR/SP/ELP/24009 Competence requirements for Electrical Control Room Operators RT/E/S/20000 Historical Index of Railtrack documents relating to Electromechanical plantengineering activities NR/SP/ELP/21067 Instruction for making out, issuing and cancelling HV Permits to work,sanctions to test and circuit state certificates NR/SP/ELP/21070 Competence of persons working on or having access to Electrical Powersupply equipment NR/SP/ELP/24001 Appointment, Training & Assessment of Persons Working On or havingaccess to Electrical Power Supply Equipment for Railway Traction NR/SP/ELP/21085 Design of earthing and bonding systems for 25 kV AC electrified lines NR/SP/ELP/21131 Warning and other signs for AC & DC Electrified Lines
NR/SP/ELP /29987 Working on or about 25kV AC Electrified Lines (formerlyRT/E/S/29987) RT/LS/P/006 Maintenance and contents of the National Hazard Directory
EHQ/SP/S/030 Jan 1992 Specification for the preparation of Isolation Diagrams and Instructions NR/WI/ELP/2708 Dec 2004 Instruction for the Layout of Overhead line equipment
Table 2 Network Rail Company Standards
3.3
Other documentation considered
Railway Safety Principles and Guidance Part 2 Section C - Guidance on Electric Traction Systems
BS EN 50122-1 1998 Railway Applications – Fixed Installations, Part 1 – Protective Provisions Relating to Electrical Safety and Earthing
Network Rail Safety Information Bulletin No IMM/GE/001; August 2004 Traction Return Circuit Continuity Bonds
BR 12034/16 Railway Electrification 25kV a.c. Design on B.R. (historical document)
3.4 Legislation
This section is not an exhaustive review of pertinent legislation, rather it picks out the headlines as they influence the people and equipment involved in the isolation process.
As far as employers and employees conduct themselves relating to particular activities in the isolation process, the Health and Safety at Work etc Act 1974 (HASAW) requires that:
‘It shall be the duty of every employer to ensure, so far as is reasonably practicable, the health, safety and welfare at work of all his/her employees.
It shall be the duty of every employee while at work:
To take reasonable care for the health and safety of himself and of other persons who may be affected by his acts or omissions at work; and
To co-operate with the employer as far is necessary in order for statutory obligations to be met.’
As far as employers and employees discharge their responsibilities regarding competence within the isolation process, the Railways (Safety Critical Work) Regulations 1994 Approved Code of Practice and Guidance states:
‘The HASAW (Health and Safety at Work etc Act 1974) and MHSWR (Management of Health and Safety at Work Regulations 1999) combine to require all employers to ensure that employees are competent to carry out their tasks without risk to the health and safety of themselves and others. ‘Competence’ means that employees must have the necessary skills, experience, knowledge and personal qualities. Employers must specify essential requirements and ensure, through selection criteria for personnel, and by the provision of necessary information, instruction, training and supervision, that the demands of a task do not exceed the individual’s ability to carry it out without undue risk.’
As far as the system requirements are concerned relating to the isolation activity, the Electricity at Work Regulations (1989) require that (abridged extracts):
‘Suitable means (including, where appropriate, methods of identifying circuits) shall be available for:
Cutting off the supply of electrical energy to any electrical equipment The isolation of any electrical equipment
Isolation means the disconnection and separation of electrical equipment from every source of electrical energy in such a way that this disconnection and separation is secure
Adequate precautions shall be taken to prevent electrical equipment, which has been made dead in order to prevent danger while work is carried out on or near that equipment, from becoming electrically charged during that work if danger may thereby arise’
4 Evolution of 25 kV OLE Isolation and Earthing Processes
4.1 Introduction
This section of the report is aimed at people who already have a basic knowledge of 25 kV AC isolation procedures and terminology.
Experience with main line electrification started just before the Second World War with LNER projects to electrify the GE lines between Liverpool Street and Shenfield, and the MSW or ‘Woodhead Line’ from Manchester. After nationalisation in 1948, British Rail continued to electrify the network, and various documents for individual schemes and regions were produced, until the British Railways Board produced BR 29987 ‘Working Instructions for 25 kV AC
Electrified Lines’ in 1967. Electrification staff know this publication as the ‘Green Book’, an
informal title that persists to this day. This document has been revised numerous times, and was re-written into modular format by Railtrack as Company Specification RT/E/S/29987 in 1998. The isolation process prescribed in RT/E/S/29987 is a well-proven, methodical way to achieve safe working on or adjacent to 25kV overhead line equipment. Over time, it has proved itself suitable for the task, based on the relatively low number of incidents that have occurred, and general satisfaction with the time taken to issue an overhead line permit. Network Rail continues regular and ongoing review of this document and it remains the electrification document for risk assessment, planning, and delivery of 25kV AC isolations.
The actions described are well established and universally applied to effect isolation. However they were developed for British Rail maintenance and renewal activities, rather than the need to issue numerous (25+) overhead line permits on a current major work site. It is this latter, now common, requirement that stretches the suitability of the standard method of issuing overhead line permits.
An alternative method of issuing overhead line permits was introduced as an option in RT/E/S/29987 from February 2005. The likelihood of this alternative option being selected can be low if:
The high number of overhead line permits required is only revealed on the night when the nominated person actually has to issue them. It is therefore too late to plan and implement an alternative method of issuing permits (which could safely speed up the process).
The high number of permits that require issuing may be due to the following bad practice:
The issue of overhead line permits to every COSS and Machine Controller regardless of whether their work activity requires it (which takes extra time and undermines the value of the permit)
These two issues are detailed further on in the text.
While the infrastructure and planned isolation involves manual switching and application of portable earths on-site, the issue of overhead line permits will always take a finite time, but it can be as short as thirty minutes if planned and implemented properly.
It is recommended that when changes to the rules occur, enhanced communication to publicise the changes be effected. This could take the form of industry wide alerts to re-iterate the requirement of the Rulebook; poster campaign; cascade briefing to industry through Safety Net or other suitable media.
It is also recommended that vertical slice audits of the isolation process be undertaken to determine the effectiveness of the Standard and the process. The vertical slice audit should start with GE/RT 8024 compliance including the requirements of RT/E/S/29987.
There are various parts of the process, which are not implemented thoroughly or fall into place later than is ideal:
Whilst isolation planning occurs as far out as 40 to 26 weeks before implementation, the detailed possession planning and submission of the Isolation Details Form (IDF) to the Electrical Control Room occurs in the week preceding the isolation, compressing the planning process considerably at the end. This is due to the associated possession meetings (sometimes referred to as the ‘PICOP’ meeting) occurring in the week immediately preceding the isolation.
A complete list of overhead line permit recipients should be available to the Nominated Person prior to the isolation being implemented, but it is often incomplete or omitted to the disadvantage of the Nominated Person. This is not due to the lack of clarity of the requirement, rather that the company requiring the Overhead line permits has not identified the total list of named COSSs requiring permits. This can be supplied at the final pre-possession meeting or at the latest in the final two days before the isolation. Many companies and projects have demonstrated that this requirement can be achieved, but it remains a frustrating and ongoing omission in some parts of the UK network.
4.2
The Isolation & Earthing Process
Please refer to the Isolation Process Flowchart in section 4.3
The method of switching off and isolating the traction supply to overhead line equipment is a standard process using remotely controlled circuit breakers to switch off the traction supply. Where isolation of complete electrical sections is required, the circuit breakers remain open and form the point-of-isolation. Where part-sections are required, structure mounted overhead line isolators are also operated, either manually or at certain locations, remotely. After operation, they form the point of isolation, and the circuit breakers may be re-closed to energise adjacent part sections that are not part of the isolation. In each case a lock or inhibit is applied to prevent unauthorised operation during the period of the isolation.
The method of earthing OLE was standardised from the mid 1980s by the introduction of designated earthing points (DEPs) with defined earth application points (EAPs). These enabled short, pole-applied earths to be applied at high level, which in normal use the operator cannot make contact with, regardless of any irregularity with the isolation. It is also by design less susceptible to being removed or damaged by the passage of trains or on-track machines. The long earth that it superseded for general use relies on operator competence to ensure that the earth end is always applied first and removed last and tied back to prevent collision with trains or on track machines. When applied in the correct sequence there is no danger to the operator, but if the earth end is applied last or removed first, the operator will be exposed to whatever voltage is present on the overhead line equipment. There are many permutations of this irregularity, but one such example is the fatal accident at Ranskill (ECML) in 1998.
Long earths are still in regular use for certain applications, but should be subject to defined methods of use and control (local management instructions or M&EE COP 1001). Long earths may be required because:
Historically, the installation of DEPs was not completed The EAP may be broken
In each case, a plan of action is required to avoid the continued use of long earths. A database of DEP locations is very useful in checking and monitoring any corrective action required and to support isolation planning or walkouts. We recommend that a national database of DEP locations be progressed in Phase 2 of this study. Some regional information already exists, and it would be beneficial to gather this information and, using best practice, turn it into a national database.
4.4
Isolation and Earthing Process – Control Measures
The isolation process is robust in that several control measures prevent access to energised equipment. The likelihood of an incident increases if any control measures are stripped away. There is always a set pattern of events after the line has been blocked to electric traction, which is: ISOLATE-TEST-EARTH. The following is not intended to describe this process in detail, rather to examine the control measures and consider the hazardous conditions that can arise if they are not applied.
ISOLATING involves switching, as described previously, to disconnect the section of overhead line from all sources of supply. This relies on the electrical control room operator following
written documentation to remotely, or manually switch circuit breakers and isolators to remove all sources of electrical supply. If there was a switching error (either human error or equipment fault),
and apparently de-energised equipment was in fact still energised, the LIVE-LINE TESTER (LLT) applied to the overhead line equipment (OLE) before the EARTHS were applied would indicate that the line was still energised. The same result would occur if the TESTER were applied to energised OLE outside of the isolated area (i.e. wrong side of section insulation or wrong road). This irregularity (a live reading on the LLT) would immediately be communicated back to the electrical control room for investigation and the isolation suspended until a de-energised reading was obtained. If the mandated TESTING control measure were omitted, the
energised condition of the OLE would not be identified until the application of the EARTH. There
are two possible results when omitting this control measure:
Scenario A: No adverse reaction - the remaining part of the isolation proceeds normally. Scenario B: The instant circuit breaker trips thereby creating the potential for danger to life. Scenario A will occur if switching has been carried out correctly removing all electrical supply to the OLE sections and the earths are being applied at the correct locations recorded on the Isolation Detail Form (IDF). Whilst no adverse reaction has occurred, stripping the testing control measure away is not compliant with procedure or training, and leaves no defence against a switching or earth-application point error described next. It is fundamentally a bad practice.
Scenario B will result if the electrical supply to the OLE at the earth application point has not been disconnected or the earth is being applied to OLE that is not part of the isolation. Testing prevents Scenario B occurring by ensuring that these activities are carried out correctly BEFORE the earth is applied. The circuit breaker tripping would result in the isolation being cancelled or delayed, a subsequent inquiry, and possible disciplinary action. Where, however, short earths are being applied at a DEP location, tools and equipment are subject to electrical stress and not a member of staff (it is not completely risk free but the short circuit occurs at high level away from the individual applying the earth as described in the previous section). Where these incidents do occur this is the most likely conclusion as short earths are in more common use than long earths. There is the greatest potential danger to life within Scenario B if a long earth is used and applied incorrectly. If wrongly applied live end first, the unsecured earth end at ground level would be live at 25kV. This most dangerous situation would only occur if training was ignored, but it is physically possible (see development section for an improvement to this).
All NPs and APs are rigorously trained and assessed to apply the earth end first when using long earths. Short earths applied at DEPs have removed this hazard to the operator, a key reason why they were introduced. It should be emphasised that this section has examined failures of control measures. The practice of not testing a section of overhead line equipment at all before applying earths, AND a switching error OR applying earths in the wrong location or manner is far from the norm, and has no place in a well managed and delivered isolation. When the live-line tester indicates de-energised overhead line equipment, EARTHS will be erected at the locations detailed
Several companies have improved the control of these activities with the use of Switching Testing and Earthing Details (STED) forms. In addition to the Nominated Person (NP) verbally instructing the Authorised Person (AP) of the required manual switching, testing and earthing activities, they are also recorded on a STED form that serves as a written instruction from the NP to the AP. It is currently considered best practice and is included in the Network Rail NP&AP training package. During 2005, use of the STED form became mandatory when it was included in Network Rail Company Standard RT/E/S/29987.
4.5
Issue of Overhead Line Permits
The briefing and issue of overhead line permits is intended to safeguard the electrical safety of the recipient. The nominated person must make sure that the COSS understands the following, extracted from Module AC2, section 7 of GE/RT8000:
The working limits on the overhead line permit;
Where live equipment is adjacent to, or crosses over earthed equipment, exactly which equipment is live and which is earthed;
The issue of the overhead line permit does not mean that train movements are stopped on the lines concerned.
There is need for time, maturity and professionalism in this process, both by the Nominated Person giving the initial briefing to the COSS, and by the COSS to his/her work group. Factors that influence the efficacy of this information transfer include:
Maturity of personnel Role specific competence Number of persons being briefed
Number of overhead line permits to be issued
Speed – driven by time available and operational pressures Thoroughness of pre-work planning:
o Were the number and recipients of Permits identified in advance? o Had an isolation walkout taken place? 1
o Had a pre-possession site meeting taken place? 2
Does the COSS understand the briefing that he is given? It is the duty of the Nominated Person to ensure that the COSS fully understands it; but the knowledge of the COSS together with the factors above, directly affects whether information is absorbed and understood or only a façade of understanding is thrown up by the COSS:
o Whether the COSS includes the permit details in the briefing of his/her work group. o Whether the relieving COSS is briefed thoroughly and effectively by the COSS he is
relieving. There is a risk of the details and importance being diluted or even lost at this secondary and ongoing transfer.
1 The Nominated Person should undertake an isolation walkout in daylight hours to check access arrangements, earth locations and switching locations, and to identify 25 kV residual hazards at least once before any series of isolations in the same area.
2 A pre-possession site meeting enables the isolation provider to meet a representative(s) of the parties requiring Overhead Line Permits, confirm contact details, times and meeting points and if possible show the COSSs the 25kV residual hazards in daylight hours.
4.6
Hazard from 25kV overhead line equipment
The hazard presented by live overhead line equipment is always life threatening and this hazard remains whilst working in an isolated area, but the briefing, understanding and compliance with an overhead line permit reduces the risk to an acceptable level. The reduction or elimination of residual 25kV hazards is a practical step in reducing the overall risk, regardless of the quality of the overall briefing process. The residual risk from equipment remaining ‘live’ is a factor of the physical arrangement of electrification equipment within, and adjacent to the isolated area, and the coverage of the planned isolation
4.7
Typical residual 25kV hazards
Adjacent overhead line equipment remaining alive Section insulators
Span wire insulators
Back-to-back registration insulators
25kV feeds approaching or crossing over the isolated equipment
The live overhead line equipment that abuts the extremities of the isolated area
Note: The Nominated Person does not usually include Red Bonds in his brief, as they are a day-to-day electrical hazard included in PTS/COSS courses, not a residual 25kV hazard. Disconnection of Red Bonds and other traction bonding MUST be considered when planning track renewals or modifications in order to maintain the integrity of the OLE earthing.
These are the hazards that the Nominated Person should brief and make aware to the COSS, but the need to brief these items depends entirely on whether they are present. Each COSS will have an accepted method statement and risk assessment for his work, but these documents will generally only consider the basic need for overhead line isolation, and not include the danger from specific residual 25kV hazards. This fact indicates the particular importance of the Nominated Persons brief, and the COSS in turn briefing his workgroup. The overriding principal to be employed is to remove the person as far as is practicable away from the hazard, rather than understanding the hazard explicitly and keeping clear of it. This is an important point as it demonstrates safe conditions may appear to be robustly achieved but in reality are much less robust, being reliant on the work activity of the COSS. To measure this reliance, a practical check would be to ask any individual on-site:
• What overhead line equipment adjacent to this isolation is still live at 25kV?
Only face-to-face questioning can prove whether the individual has received and retained this information. Expanding on each 25kV residual hazard listed above:
4.7.1 Adjacent overhead line equipment remaining live
In a multi-track area, all roads are not necessarily isolated simultaneously just to allow work on a single road. Other tracks may remain energised for operational requirements. Therefore, at some stage work will be carried out with the adjacent road alive. This is particularly true on sections of two-track railway where rules-of-the-route only allow single road possession and isolation. In multi-track areas it may be possible to work on an outer road and have the adjacent road de-energised only (isolated but no permits issued), but for maintenance work it would be more likely to take advantage of this availability and issue overhead line permits for both roads enabling work on each. That would mean personnel were again working adjacent to a live road. It should be stressed that it is possible to work with all roads isolated where this is planned with sufficient
require an abnormal possession and isolation. In the latter case significant notice periods have to be given, typically 26 weeks or more.
4.7.2 Section Insulators
If there is a wired crossover with a section insulator in the isolated area and the adjacent road is not part of the isolation, one side of the section insulator will be de-energised and the other side will be energised at 25 kV. It is not usually possible to quote an overhead line structure for this cross-track isolation limit. The nominated person is required to reach a clear understanding with the COSS regarding this residual 25kV hazard. If the job can be planned so that both roads and electrical sections are included then this hazard can be removed but as previously stated, this may lead to the introduction of other residual 25kV hazards.
Example of High Speed Section rise to live 25kV equipment approaching isolated Insulator (HSSI), giving
area
Figure 1 HSSI 25kV residual hazard
Back-to-back registrations and span wire insulators are other physical overhead line features that will approach the isolated area in the across track direction that need to be considered within the NP briefing to the COSS, and the COSS briefing his own work group.
4.7.3 Back-to-back registrations
Example of back-to-back registration giving rise to live 25kV equipment approaching isolated area
4.7.4 Span wire insulators
Figure 3 Span wire insulator 25kV residual hazard 4.7.5 Live feeds crossing the isolated area
It is common for structure-mounted transformers to be fed from a different road than that to which the structure is adjacent, where each road is a separate electrical section. In practice that means a section of overhead line can be isolated and earthed with live 25kV feeds crossing over the top of it. In headspan construction the demarcation provided by the boom or twin track cantilever (TTC) is absent. Modern designs ensure that the cross track feed is screened and/or 2.75m above the catenary of any separately sectioned OLE. It remains a 25kV residual hazard, particularly the area around the transformer bushings and older types of electrification equipment that were not constructed with the above safety considerations.
Example of live feed able to cross an isolated area giving rise to live 25kV equipment being above and adjacent to the isolated area
Example of span wire insulation live 25kV equipment adjacent to isolated area (The outer span wire insulators have been moved away from the structure face to the platform edge to remove live equipment from above the platform).
4.7.6 Live equipment that abuts the extremities of the isolation
At one or both ends of the isolated area, live equipment at 25kV will abut. The isolation instructions are written so that it is never possible to work right up to live equipment in the along track direction, there is always an area that is de-energised (minimum 2.75m typically 50m-75m) that will never be included in the limits of the Overhead Line Permit.
For instance:
At a switched insulated overlap, the limits for the adjacent electrical sections should be one span inside the isolated area, away from the twin cantilever structures forming the overlap
Limit of isolation Limit of
isolation
To work in this area, both electrical sections are required to be isolated and earthed and an overhead line permit issued.
Insulated overlap
Figure 5 Insulated overlap isolation limits
At a neutral section the isolation limit is not the centre of the neutral section, it should be one span inside the isolated area in both directions.
Neutral Section
To work in this area, both electrical sections are required to be isolated and earthed and an overhead line permit issued.
Limit of isolation
Limit of isolation
Figure 6 Neutral Section isolation limit
At a switching structure with section insulator, the switching structure is not quoted as the isolation limit it should be one span inside the isolated area in both directions.
As a minimum, live equipment must not approach closer than 2.75m to the isolation limit structure, in the along track direction.
A particular along track hazard occurs when adjacent roads are not sectioned at the same point in the along track direction, and it is possible to quote a different isolation limit for each road. The affect is that an overhead line permit may safely include one road, whilst the same along track point on the adjacent road will be live at 25kV and therefore not included in the working limits of
the permit. It is not standard practice to construct or section the overhead line in this way but instances do occur. To avoid this dangerous situation it is normal practice to foreshorten the longer isolated section in the isolation instructions so that the isolation limits are the same on both roads. Any lack of uniformity or clarity with adjacent along track limits raises the likelihood of misunderstanding and an injury or fatality to staff.
4.8
Planning and 25kV Residual Hazards
Standard possessions are in accordance with the rules of the plan/rules of the route. The resultant isolations and 25kV residual hazards are a function of this, rather than the reduction of 25kV hazards being the driving force. This may be a realistic position to take based on train movements being the overriding need, but it leaves a disconnection between regular possession planning and the reduction of 25kV hazards. Based on the low number of fatalities or serious injuries to staff due to electrocution this stance has not triggered numerous electrical accidents. Notwithstanding that, rules-of-the-route possessions (and the isolations matched to them) should still be reviewed periodically to assess the residual 25kV hazards. Abnormal possessions should be booked only after considering which overhead line equipment needs to be made safe for the programmed work, including the reduction or elimination of 25kV residual hazards.
4.9
Hazard and Risk-Based Briefing
The nominated persons briefing should include the electrical hazards present as described in the previous sections. The particular risk of any uncontrolled event happening should be covered in each COSS’s risk assessment attached to the method statement or work planning package for any particular work activity. The NP will not have been involved in the preparation of these risk
assessments, nor will he generally have visibility of them. The practical way to avoid this disconnection is to have a pre-possession site meeting to understand the proposed work activity and to match the extent of the isolation to it.
A nominated persons briefing for an isolation adjacent to an energised road will have several 25kV residual hazards to brief out. This should attract the highest standard of briefing and level of understanding reached with the COSS, and from the COSS to the individuals in his workgroup. In contrast, a two-track railway with both roads isolated and no residual 25kV hazards presents few electrical hazards to brief out. The standard of the briefing should be of no lesser standard, but fundamentally, there is less electrical hazard information to convey. An obvious but important fact is that the hazard is lower if work is being undertaken in an area completely isolated and earthed. This last condition is rarely reached as there will still be equipment energised at 25kV at one or both ends of the outer track limits of the isolation, but this can be achieved where the limits on the o line permit are several spans within the overall isolated area in all directions. The reduction or elimination of residual 25kV hazards is a practical step in reducing the overall risk, regardless of the efficacy of the overall briefing process.
There is an associated risk that staff working for extended periods in isolated areas where no residual 25kV hazards are present, will become complacent to that danger. If they move to work in an isolated area where there are numerous residual 25kV hazards present, any complacency will modify their perception and reduce awareness of the hazard that equipment remaining live at 25kV represents. The Nominated Person will strive to deliver a thorough and effective brief in a professional manner, but has no influence on the selection of COSSs who work in his/her isolation.
4.10 PTS Electrification Training
The electrification content in the AC module of personal track safety training should be sufficient to arm the successful candidate with basic knowledge of overhead line terminology and safety. This content has been similar for many years. A review should be undertaken of what the candidates are expected to know compared to the suitability of the training material to convey this.
4.11 COSS Electrification Training
Any person(s) identified to receive overhead line permits must hold current COSS competence. Experience has shown that the depth and content of the electrification training within the COSS course can be bettered, particularly in the area of understanding, controlling, and briefing the overhead line permit. The COSS is required to include the permit details in his own brief to his workgroup and furthermore each COSS (when and if relieved) is responsible for briefing the relieving COSS. This requires complete understanding of the overhead line permit in order to brief the next COSS accurately and confidently. There is a risk of the detail and importance being diluted or even lost at this secondary and ongoing transfer. Several companies have run local training sessions to reinforce the roles and responsibilities of a COSS when receiving an overhead Line Permit. Network Rail is in the process of enhancing COSS training in the areas highlighted above. An implementation date should be published.
4.12 Nominated and Authorised Persons Competence
From 2003, Network Rail and industry wide stakeholder groups overhauled Nominated and Authorised Persons training and assessment completely. Individual company training plans with numerous examining and issuing officers appointed regionally by Railtrack or Network Rail have been replaced with one national scheme. Licensed trainers deliver universal and comprehensive training material and examinations, followed by a formal mentoring period during which the successful candidate has probationary status only, and must be accompanied whilst undertaking AP or NP duties.
The assessment process commences with an initial assessment during the probationary period, which, if satisfactory, enables the candidate to achieve full status and work without being accompanied. Ongoing workplace assessment, refresher training, and recertification are then embarked upon. In between assessments, the candidate has to demonstrate that he or she is actually undertaking the duties of a Nominated or Authorised Person by keeping a logbook of completed isolation duties. This has been successfully implemented since 2004 and is subject to regular review. It has raised the profile of the Isolation activity and the overall quality of training and assessment. All candidates are subject to ongoing assessment, refresher training and recertification training. This is a positive practical step to improving and maintaining the competence of Nominated and Authorised Persons.
4.13 Compliance with Isolation Procedures
Management of workforce competence is connected to minimising the gap between 100% compliance with standards or procedures, and actual operational practices. Human factors in this equation are looked at elsewhere within this project. The safety and professional culture of any organisation driven from top-to-bottom affects the actions of the workforce delivering the activity. This is underpinned by high standards of initial training and assessment, and managers, supervisors, and peers reinforcing this culture. In other words, other workers and their supervisors do not tolerate malpractice - malpractice is eradicated. In order to identify variations with laid down procedure, the whole isolation process should be subject to regular vertical audits across several territories. Each audit should start with the isolation request through planning to the issue and understanding of the overhead line permit(s) on site.
Network Rail undertook a national audit of operational isolation procedures for AC & DC electrified lines in 2005, the summary of which was published in October 2005. Minor differences to the isolation forms and electrical control room procedures remain but Network Rail is aware of these issues and is positively working towards standardised electrical control room instructions and forms across the network.
4.14 Isolation
Planning
RT/E/S/29987 Module 6 states that the Network Rail isolation planner shall record each overhead line permit requested and allocate each one a unique reference number on an Isolation Planning Form (IPF). A proforma IPF is printed in Module 6 but as this activity is normally PC based and an ongoing activity, it will probably be customised in some way.
Whilst it may be possible to identify the number of permits required from the outset, this information is typically not identified until much later in the planning process. This is often in the few weeks preceding the isolation (see Appendix A Possession Pack WON 38, Item 117) or in some cases may not be provided at all (see Appendix B Possession Pack WON 47, Item 05). This non-compliance requires the purpose of the IPF to be reviewed. For example instead of allocating a unique reference number to individual permits, allocate a reference number to each worksite limits/Form B requested and then the permits identified later to be issued from any one of the Form B’s will share the same reference number. That would stop long-term non-compliance with, but still meet the spirit of Module 6. The key issue is to build on this by identifying the total number and recipients of permits before the isolation is effected. To ensure compliance with Module 6 it is important that the layout of the IPF and IDF forms are correctly structured to avoid the need for repeated hand written information detailing limits, lines, structure numbers, electrical sections etc. Current layout suggests that the IPF and IDF are biased towards recording working limits rather than numerous individual permits in any case.
In June 2005, Network Rail established a sub-group of the 29987 User Group to review Module 6 thoroughly, including the Isolation Planning and Details Forms (IPF and IDF). The group will have a broad range of personnel involved in the planning and delivery of isolations including the author. The requirements of the IPF need to be made clear, and then compliance checked against those clear requirements.
In the final production stage of this document, good progress is being made in this area of isolation planning on parts of the West Coast Main Line (WCML) and the Great Eastern (GE) lines from London Liverpool Street. The 29987 User Group is re-writing many parts of Module 6, considering the removal of the IPF as a paper form ready to be re-issued during 2006. It is essential to understand that many of the issues highlighted in this report are current and ongoing.
4.15 Alternative Methods of Issuing Overhead Line Permits
(RT/E/S/29987 Module 6, section 4.8 February 2005 refers)
On major railway renewal or project sites, more than twenty-five COSSs may require overhead line permits, typically within thirty to sixty minutes of the possession being taken. The standard method of issuing permits was not written around that required volume. Notwithstanding that fact, it is the challenge regularly presented to many overhead line Nominated Persons. To ease this demand some individuals explored headroom available in the definition of ‘blockade working’ (pre February 2005 revision of RT/E/S/29987) and only issued an overhead line permit to the Engineering Supervisor (ES).
issued to the Engineering Supervisor only. He was generally the supervisor of the overhead line works as well.
This was undertaken safely on one particular site in East Anglia (see Her Majesty’s Railway Inspectorates (HMRI) report 220002878/RSC/03-04/5.1, which contains much useful information on the management and observation of isolation procedures).
At Marston Green on the WCML near Birmingham, the management of the overhead line permit was linked to an electric shock injury and a Prohibition Notice (serial number P/UA/20030702a July 2003) was issued on the construction joint venture alliance comprising Balfour Beatty Rail Projects and Carillion. Network Rail was issued with an Improvement Notice (serial number 1/0782004 dated 7th June 2004) in connection with the same incident.
The effect of the Prohibition Notice was to stop the issue of an overhead line permit to the ES only as this was in contravention to the rulebook, then GO/RT4100 (section Z part 1). The Improvement Notice required that any Network Rail Company Standard specifying safe systems of work at or near 25kV OLE is clear and unambiguous with respect to people’s roles, responsibilities and all arrangements for issuing overhead line permit. Furthermore, the procedure described should be robust to prevent abuse and allow for monitoring to check effectiveness, and be able to be practically implemented on-site. Planning was required to be in accordance with Module 6, or if alternative methods were applied, they had to meet the requirements of the previous two sentences.
This led to Network Rail introducing Module 6 section 4.8 with respect to alternative methods of issuing overhead line permit. This does allow for the single issue of an overhead line permit but the planning and implementation of this method is particularly stringent. The electrical safety of all individuals on site must be ensured. Please refer to RT/E/S/29987 Module 6 section 4.8.
4.16 Identification of Overhead Line Permit Recipients
This topic was introduced in Isolation Planning. If actioned correctly, it ensures that the Nominated Person knows in advance the total number of permits he has to issue, and enables the NP to establish contact with all the COSSs identified. The early identification of the number of permits is also required to consider whether an alternative method of issuing the permits is selected and implemented. If the number of permits is not identified the trigger to consider whether an alternative method of issuing the permits is selected and implemented will be missed, thus eliminating the chance of planning an effective ‘alternative’ method of issuing the permit. The Nominated Person on the night is then faced with issuing a previously unidentified high number of permits expected in the usual short time to enable work groups to start. Something will flex, namely the chance for the Nominated Person to give an effective individual briefing to each COSS. It is for that express reason that the alternative option has been introduced. It is entirely appropriate to plan how twenty-five COSSs and their workgroups will be effectively briefed in half an hour for instance, rather than hoping the Nominated Person will somehow achieve that on the night. Not identifying all COSS names is a serious omission.
4.17 Over Issue of Overhead Line Permits
This problem relates to the erroneous issue of permits to either COSSs whose work activity does not require an isolation, or to Machine Controllers who are members of a COSS workgroup and not undertaking the COSS role themselves. It seriously devalues the permit process as it destroys the link of proper risk assessment of the work activity driving the need for a permit, and in the latter case can confuse the responsibility of the COSS to brief his group regarding the contents of the permit. He should not expect Machine Controller(s) for whom he is responsible to be in
possession of a separate permit! In plain terms, it can also render the permit ‘as just another piece
of paper’, for those that did not need it in the first place. Factors that have contributed to this practice include:
Misinterpretation of GE/RT 8000 (Module AC2, 7.1) - ‘…. the nominated person will hand to each COSS of each work group requiring the isolation, a separate overhead line permit…’ - Inexplicably the words ‘requiring the isolation’ appear to be ignored by some readers leaving ‘each COSS’
Confusion with a Machine Controller always requiring COSS competence but not necessarily undertaking COSS duties on any given worksite
The Prohibition notice issued to the construction joint venture alliance comprising Balfour Beatty Rail Projects and Carillion (serial number P/UA/20030702a) which prohibited - ‘Work on or near overhead line equipment that requires an isolation, unless every Machine Controller/Controller of Site Safety in charge of an affected work group is provided with a separate overhead line permit (Form C) by the Nominated Person as detailed in the Rulebook GO/RT 4100 (section Z part I)’. This was applied by issuing every Machine Controller with a permit, regardless of whether they were undertaking COSS duties or were already in a COSS’s workgroup
Lack of proper identification of permit recipients either because this activity was missed altogether, or not based on risk assessment: both leading to a ‘cover all’ over-issue approach being adopted. The Nominated Person would have to issue more permits than necessary either on a planned basis or in the worst case having to issue permits as required to an unknown number of recipients ‘on the night’. Issuing a high number of permits in a timely fashion severely stretches the ability to use, whilst remaining compliant, the traditional method of briefing and issuing to individual COSSs, adding staff that in fact did not require a permit only makes this problem worse! The option of applying an alternative method of issuing the permits is now included in the Feb 05 revision of RT/E/S/29987. It will require the number of permit recipients to be identified well in advance and the alternative option deliberately selected and implemented.
4.18 The Origin and Purpose of the ‘9 foot rule’ (sic)
In recent history, the distance of 2.75 metres or 9 feet has been used as a safe limit of approach towards live OLE without reference to the electrification department. The selection of this
particular distance is now difficult to substantiate but as an example, the following is an extract
from the 1975 version of BR 29987 Working Instructions for A.C. Electrified Lines:
‘Work may also be performed in situations other than those referred to above, without reference to the Electric Traction Engineer or equivalent officer, provided the work does not require any part of a workman or any tool or materials which he has to use to approach nearer than 9 feet (2.75 metres) to the live equipment, or provided the work is to be performed by specifically authorised staff.’
It should therefore not be considered as an electrical clearance as such, but a formulaic distance judged to be a safe working distance to allow a worker to approach live OLE without reference to the local overhead line depot. On this criterion, any reduction to less than 2.75m would be
difficult to substantiate 3.
The ‘9 foot rule’ should not be read in isolation as other text describes how this distance may be infringed with other controls applied. BR 29987 allowed this form of working through the ETE
department assessing all factors and nature of the work, and then prescribing one of three solutions:
Specified demarcation line (to work up to) Temporary screening (a rigid barrier)
Only work under the protection of an overhead line permit (OLE isolated and earthed) Under no circumstance could work take place within 600mm of live OLE.
RT/E/S/29987 Modules 2 and 3 developed this principle further with written method statements and risk assessments required, based on whether work was to take place up to 2.75m, or within 2.75m up to 600mm. Authorisation of the method of working is prescribed in Module 3. The COSS must be in possession of the accepted method statement and risk assessment, understand them and critically enact the mitigation measures described. (Railway Group Standard GE/RT 8024 “Persons Working On or Near to AC Electrified Lines” refers.)
Considering the 9 feet dimension in electrification schemes pre-1967, working instructions generally forbade staff to climb higher than the footplate of a steam locomotive. The distance from the footplate (the ‘standing surface’) to the overhead line contact wire (at minimum height) is approximately 9 feet. This standing surface clearance to live 25kV equipment is in EN 50122-1 (see section 4.20 of this report) and in RT/E/S/29987, relating to the unloading of wagons (module 3 section 9). In this latter application, 9 feet is not specifically quoted, rather the maximum height of the wagon floor above rail level (1.4 metres). Adding 2.75 metres (approx 9 feet) to this dimension results in a very close approximation to minimum allowable contact wire height. Thus, the 1.4m dimension appears to have been derived from minimum contact wire height minus 9 feet. Ultimately, 9 feet (2.75 metres) has been and continues to be applied in two different ways. There is no direct link between each application. The application to risk assessment in RT/E/S/29987, derived from the previous BR instructions, is the more widely held understanding of what the 9 feet rule means.
