Research Programme
Engineering Review and Development of Safe Working Practices in Electrified Areas - Report No. 2
Balfour Beatty
Issue: 1.0 Date: 1st December 2006
Project 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
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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.
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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.
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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 reinitiated. 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.
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Contents EXECUTIVE SUMMARY............................................................................................................................ 1 1
INTRODUCTION ................................................................................................................................ 6
2
BACKGROUND ................................................................................................................................... 7
3
REVIEW OF PERTINENT DOCUMENTATION ........................................................................... 8
3.1 3.2 3.3 3.4 4
Railway Group Standards ................................................................................................ 8 Network Rail Company Standards .................................................................................. 9 Other documentation considered ..................................................................................... 9 Legislation ....................................................................................................................... 9
EVOLUTION OF 25 KV OLE ISOLATION AND EARTHING PROCESSES .......................... 11
4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10 4.11 4.12 4.13 4.14 4.15 4.16 4.17 4.18 4.19 4.20 4.21 4.22
Introduction.................................................................................................................... 11 The Isolation & Earthing Process .................................................................................. 12 Isolation Process Flowchart ........................................................................................... 14 Isolation and Earthing Process – Control Measures ...................................................... 15 Issue of Overhead Line Permits..................................................................................... 16 Hazard from 25kV overhead line equipment................................................................. 17 Typical residual 25kV hazards ...................................................................................... 17 Planning and 25kV Residual Hazards............................................................................ 21 Hazard and Risk-Based Briefing ................................................................................... 21 PTS Electrification Training.......................................................................................... 22 COSS Electrification Training....................................................................................... 22 Nominated and Authorised Persons Competence.......................................................... 22 Compliance with Isolation Procedures .......................................................................... 22 Isolation Planning .......................................................................................................... 23 Alternative Methods of Issuing Overhead Line Permits................................................ 23 Identification of Overhead Line Permit Recipients ....................................................... 24 Over Issue of Overhead Line Permits............................................................................ 24 The Origin and Purpose of the ‘9 foot rule’ (sic)........................................................... 25 25kv Electrical Clearances to Members of the Public on Station Platforms ................. 26 Clearances to Members of the Workforce and Public in EN 50122-1........................... 28 Electrical Clearances to Earth........................................................................................ 29 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 6.2 6.3 6.4 6.5 6.6 6.7 7
TASK IDENTIFICATION AND RISK ANALYSIS ....................................................................... 67
7.1 7.2 7.3 8
Introduction.................................................................................................................... 32 Literature Review .......................................................................................................... 32 Review of Historical Incident Data ............................................................................... 36 Results of Review of Historical Incident Data .............................................................. 39 Conclusions.................................................................................................................... 49 Recommendations.......................................................................................................... 53 Predictive Error Analysis............................................................................................... 56 Methodology.................................................................................................................. 67 Example of Task Identification and Risk Assessment Process...................................... 69 Summary........................................................................................................................ 70
DEVELOPMENTS............................................................................................................................. 73
8.1
Report No. 2
Introduction.................................................................................................................... 73
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8.2
Specific Developments .................................................................................................. 73
9
CONCLUSIONS ................................................................................................................................. 78
10
RECOMMENDATIONS.................................................................................................................... 81
10.1 10.2 10.3 10.4 10.5 10.6 10.7 10.8 10.9 10.10 10.11 10.12 10.13 10.14 10.15 10.16 10.17 10.18 10.19 11
Introduction.................................................................................................................... 81 Recommendation 1 – Communications ......................................................................... 81 Recommendation 2 – Vertical Slice Audits................................................................... 81 Recommendation 3 – National Database of DEP Locations ......................................... 81 Recommendation 4 – PTS and COSS Training............................................................. 81 Recommendation 5 – Electrical Clearances to Earth..................................................... 81 Recommendation 6 - Safety Observation Schemes ....................................................... 81 Recommendation 7 - Greater Emphasis on Supervisory Checks .................................. 82 Recommendation 8 - Introduce Safety Communications Training ............................... 82 Recommendation 9 - Checking the Planning Process ............................................... 82 Recommendation 10 - Further Analysis.................................................................... 82 Recommendation 11 - Incident Reporting................................................................. 82 Recommendation 12 – RIMINI Approach ................................................................ 82 Recommendation 13 – Tasks on the DC Third Rail.................................................. 82 Recommendation 14 – Development - Live Line Indicators..................................... 83 Recommendation 15 – Development - Live Line Testers ......................................... 83 Recommendation 16 – Development - Live Line Data Loggers............................... 83 Recommendation 17 – Development - Conductor Rail Gauging.............................. 83 Recommendation 18 – Mandated use of PPE in DC Conductor Rail Areas ............. 83
REFERENCES ................................................................................................................................... 84
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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.
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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.
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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 GL/RT1252
Apr-00/1
GL/RT1254
Apr-00/1
GM/RT1040
Aug-96/1
GI/RT7007
Jun-02/1
GI/RT7033
Jun-03/1
GE/RT8024
Oct 2000/1
GE/RT8025
Oct 2001/1
GO/RT3091
Apr 1998/2
GO/RT3093
Dec 1999/2
GO/RT3260
Aug 1998/2
GO/RT3279
Dec 1999/5
GO/RC3560
Aug 1998/1
Title
Synopsis
Production & Management of Electrification Isolation Documents Electrified Lines Traction Bonding Safe Working on or Near Electrical Equipment
Defines the requirements for the production & management of isolation documents for all electrified lines Mandates the requirements for electrified lines traction bonding The requirements for providing a safe system of work Defines the requirements for low voltage Low Voltage Electrical installations on Network Rail controlled Installations infrastructure This document mandates the arrangements for the management & specification of lineside operational Lineside Operational Safety Signs safety signs in order to provide consistency of form and presentation throughout the network. Defines the requirements for the production of safe systems of work to prevent injury for electrical Persons Working on or near to AC causes to persons working on or near to Network Electrified Lines Rails AC Overhead line equipment that danger may arise. Mandates the design requirements for the avoidance Electrical Protective Provisions of direct contact between persons and live parts of for Electrified Lines electrification equipment and of electrical equipment on trains These instructions set out the actions to be taken to avoid danger from DC electrified lines or the DC Electrified Lines Instructions process to be followed to determine the actions to be taken to avoid such danger. The minimum requirements for planning The Planning Requirements for engineering work to ensure the risks to operational Operational Safety of Engineering safety are effectively controlled to be as low as Work reasonably practicable. Clarifies the application of the Railways (Safety Critical Work) Regulations to Network Rail Competence Management for controlled infrastructure, and defines requirements Safety Critical Work for systems for managing the competence and fitness of persons required to undertake such work. Sets out the minimum requirements for high High Visibility Clothing visibility clothing The recommended components of a competence Code of Practice - Competence assessment system to assist compliance with Assessment GO/RT3260 Competence Management for Safety Critical Work
Table 1 Railway Group Standards
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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 Procedure for use of Permaquip Scissors type platform machine and High NR./SP/ELP/27150 Capacity Trolleys as used for OHL Maintenance Maintenance of Mark IIIB Overhead line equipment (formerly NR./SP/ELP/27214 EHQ/ST/O/003) Procedure for the Issue, Storage, Routine Inspection and Testing of NR./SP/ELP/27171 Rubber Gloves Specification for the provision of isolation, earthing and indication NR./SP/ELP/27203 facilities where local isolations are permitted on AC Electrified Lines Specification for the preparation of isolation diagrams and instructions EHQ/SP/S/030 for 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 Index of Railtrack documents relating to Electromechanical plant RT/E/S/20000 Historical engineering activities Instruction for making out, issuing and cancelling HV Permits to work, NR/SP/ELP/21067 sanctions to test and circuit state certificates Competence of persons working on or having access to Electrical Power NR/SP/ELP/21070 supply equipment Appointment, Training & Assessment of Persons Working On or having NR/SP/ELP/24001 access 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 Working on or about 25kV AC Electrified Lines (formerly NR/SP/ELP /29987 RT/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:
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‘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’
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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.
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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 prepossession 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.
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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.
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4.3
Isolation Process Flowchart
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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 deenergised 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: Scenario B:
No adverse reaction - the remaining part of the isolation proceeds normally. 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 on the IDF, before the Nominated Person issues individual overhead line permits to each COSS in charge of each workgroup.
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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 o o
Were the number and recipients of Permits identified in advance? Had an isolation walkout taken place? 1 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 o
Whether the COSS includes the permit details in the briefing of his/her work group. 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.
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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 dayto-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 deenergised 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 notice. Depending on area and line, this may be allowed under the rules-of-the-route or may
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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 crosstrack 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 Insulator (HSSI), giving rise to live 25kV equipment approaching isolated 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
Figure 2 Back to back registration 25kV residual hazard
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4.7.4
Span wire insulators
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).
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
Figure 4 Live feed crossing isolated area 25kV residual hazard
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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
Insulated 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. 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.
Limit of isolation
Neutral Section
Limit of isolation
To work in this area, both electrical sections are required to be isolated and earthed and an overhead line permit issued.
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
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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.
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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.
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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). It is worth noting that during the British Rail era (before the creation of the COSS role), if the overhead line function was carrying work out alone, it was common that the permit would be
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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
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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 3 European Standard Technical Report – Annex CLC SC9XC WG 14, dated April 2005 has considered the dimensions equivalent to 2.75m and 600mm in the UK and has derived them to be 1500mm and 500mm using objective criteria. The author has commented on this document and ‘Clearances and screening of live parts, according to EN 50122-1’ to RSSB separately.
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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.
4.19
25kv Electrical Clearances to Members of the Public on Station Platforms
This previous section detailed the misconception that it is forbidden for any member of the workforce to approach within 2.75m of live OLE, where in reality they can, with the appropriate control measures. Drawing number CH/EMP/05/001 considers 25kV electrical clearances to members of the public on station platforms. The individual sketches are based on nominal and normal minimum contact wire height (lower contact wire heights exist on certain routes but normal minimum is representative for the UK rail network). There is no special criterion for contact wire height in station platforms. It can be seen that unless passengers stand back from the platform edge as shown in column three, the 2.75m dimension is infringed in each case, perhaps surprisingly so in some of the scenarios shown. In contrast, analysis of electrical injuries to members of the public in 25kV electrified station areas should occur before considering these clearances as unacceptably small.
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4.20
Clearances to Members of the Workforce and Public in EN 50122-1
The following extracts from EN 50122-1:1997 section 5, ‘Protective provisions against electric shock in installations for nominal voltages in excess of 1kV a.c/1.5kV DC up to 25kV AC. or DC to earth’ should be related to the previous two sections: Extract 5.1.2.1-Standing surface ‘For standing surfaces, accessible to persons, clearance for touching in a straight line shown in figure 14, shall be provided against direct contact with live parts of an overhead contact line system as well as any live parts on the outside of a vehicle (e.g. current collectors, roof conductors, resistors). The clearances given in the following clauses are minimum values, which shall be maintained at all temperatures and with additional and exceptional line loading. Due to national or regional existing practises, greater clearances or smaller mesh sizes may be prescribed by the relevant railway authority.’ Extract 5.1.2.2-Standing surfaces for working persons ‘The clearances to be observed for persons working nearby energised overhead contact line systems shall be defined in the operational specifications. If operational specifications do not exist, clearances shown in figure 14 or the clearances according to 5.1.3 shall be used.’ As operational specifications do exist in the United Kingdom these would be expected to take precedence. Figure 14 in EN 50122-1 illustrates vertical and horizontal clearances all round the standing surface. Considering the vertical component only, 2.75m is used but rather than the distance from the extremities of the person, tool or material to the extremity of the live OLE, to be maintained unless other control measures are applied, it is the distance from the standing surface to the nearest live OLE. Whilst that distance is maintained therefore, a worker* may safely stand on that surface according to this standard. Figure 7 below illustrates this. It appears to allow a clearance without further control measures, which in the UK may only be allowed after a method statement, and risk assessment has been authorised and applied on-site. The universal application and compliance with RT/E/S/29987 (module 2 and 3) across all UK railway functions should be checked before judging this ostensibly less onerous approach. *It is surprising that the UK special national condition quoted in figure 7 allows the 2.75m dimension to be applied to members of the public in the case stated. Her Majesty’s Railway Inspectorate would not permit any live equipment over a platform surface whether at 2.75m or 3.5m (the standard vertical clearance for members of the public stated in EN 50122-1). Insulation would be inserted so that cantilevers or span wires are at traction earth potential over the platform surface, or the support structure may be sited other than in the station platform. This clause may therefore have been sought in consideration of clearance from members of the public to roof equipment (pantograph horn, bushings or bus-bars), but would not be applied in the UK to live OLE over the platform standing surface. (Please refer again to CH/EMP/05/001.) Nearest
live
25kV *
920 mm (indicative) 2.75m 1.83m Standing surface
EN 50122-1:1997 Annex G (normative) Special national conditions Clause 5.1.2.1 ‘The dimension of R3.5 mm (sic) clearance in public areas shown in figure 14 shall be amended to R2.75 (sic) minimum for use in the case of future electrification of existing railway lines with restricted infrastructure clearances
Figure 7 Vertical clearances to accessible live parts up to 25kV (based on EN 50122-1)
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Note:
The dimensions of 1.83 m and 920 mm have been added as an example based on the typical height of a male individual.
4.21
Electrical Clearances to Earth
Electrical clearances to earth for single-phase 25kV AC OLE are detailed in many separate UK documents including: Railway Safety Principles and Guidance Part 2 section C Railway Group Standard GE/RT 8025 Electrical Protective Provisions for Electrified Lines Network Rail Company Standard NR/SP/ELP/27214 Maintenance of Mark IIIB Overhead line equipment (formerly EHQ/ST/O/003) BR 12034/16 Railway Electrification 25kV AC Design on B.R. (historical document) The latter document states: ‘British Railways electrical clearances were originally based on the UIC* recommendation and for 25kV were 270mm static clearance and 200mm passing clearance, requiring total headroom above kinematic load gauge at a support point of 680mm’. *International Union of Railways In 1962, following tests and service experience, the statutory clearance requirements on BR were revised and reduced clearances of 200mm static and 150mm passing as were introduced for 25kV operation. These reduced requirements, together with modifications to the design of the overhead equipment, meant that the minimum headroom could be reduced by 175mm and this significantly reduced the costs of obtaining electrification clearances. Research and development work had also established that where insufficient headroom is available to allow the normal catenary/contact wire arrangement, a “twin contact wire” arrangement where the catenary is replaced by contact wire and the two contact wires are supported side-by-side, gave good current collection even with the most restricted clearance arrangement at bridges. A key factor in perfecting the twin-contact wire arrangement and so reducing the headroom for 25kV equipment was the development of large resin-bonded glass fibre rods with track resistant surface covering, which provided a flexible and virtually indestructible combined insulator and support for the twin-contact wires. In 1974, design effort was concentrated on the investigation of possible further reductions in electrical clearance. The objective set was that any improved arrangement must not degrade the surge and 50Hz voltage withstand levels achieved with the existing arrangements. It was found that these levels were governed by the electrical stress between the live end fitting on the equipment support arm and the roof of the bridge or tunnel. This fitting was re-designed to a semicircular shape, to distribute the stress evenly. The re-design of the fitting has enabled the clearance above the live end fitting of the support assembly to be reduced to 95mm static and 70mm passing. At the same time, the passing clearance from the contact wire to kinematic load gauge was reduced to 125mm. These “Special reduced clearance” arrangements mean that a total of only 375mm of headroom is required above kinematic load gauge for 25kV equipment, an additional 25mm being allowed for increased uplift of the contact wire at speeds above 60km/h. Special reduced clearances are adopted in all cases of exceptional difficulty or expense in obtaining greater headroom’
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4.22
25kV electrical clearances to earth summarised:
These clearances are shown in all the documents listed in 4.21, but with some variation, as shown in the tables below: Network Rail Company Standard & BR historical document Category
Static
Passing
Normal
270 mm
200 mm
Reduced
200 mm
150 mm*
Special reduced
150 mm+
125 mm*+
Document NR/SP/ELP/27214 BR 12034/16 NR/SP/ELP/27214 BR 12034/16 NR/SP/ELP/27214 BR 12034/16
* A passing clearance of 80 mm applies to brick and masonry overbridges and tunnels between pantograph and bridge only (not between equipment and bridge) and each case is subject to special dispensation by the Department of Transport. + Where stress-graded glass-fibre bridge arms are used, a static clearance of 95 mm and a passing clearance of 70 mm between the insulator live end casting and bridge are allowable, with special dispensation from the Department of Transport. Group Standard Category Enhanced Normal Reduced Special reduced*
Static 600 mm or greater 599 - 270 mm 269 -200 mm 150 mm
Passing 600 mm or greater 200 mm or greater 199 - 150 mm 149 - 125 mm
Document GE/RT8025 GE/RT8025 GE/RT8025 GE/RT8025
*The values for pantograph to masonry and stress-graded arms are not explicitly stated. Railway Safety Principles and Guidance Part 2 Section C Category
Static
Passing
Document
Normal
200 mm
150 mm
RSP&G ‘C’
Special reduced
150 mm
125 mm
RSP&G ‘C’
Only two categories are explicitly stated.
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5 Consideration of DC Third Rail Isolation and Earthing Processes The original remit and scope of this study was to consider all types of electrification in use on the network of Britain’s railways. However, the situation in respect of isolation and earthing processes on the DC third rail system remains in a state of flux whilst discussion and agreement on the most suitable way forward are resolved between the HMRI, Network Rail, and RSSB. The current standard covering the requirements for isolation and earthing are covered by DC Electrified Lines Instructions GO/RT3091 Issue 2 1998. This standard was developed following the issue of an improvement notice on the then Network South East Division of British Rail by HMRI. In the period from August 1998 to August 2001, much work was done on the production of a new revised document Issue 3. The main differences between Issue 2 and Issue 3 were enhanced requirements to undertake risk assessments of any proposed work in relation to the danger from exposed live parts of electrical equipment. The standard placed an increased emphasis on any work that was likely to come within 300mm of any exposed live parts of the electrical equipment and called for a method statement to be produced by a competent person who must be a member of an organisation holding a valid Safety Case or a valid Contractors Assurance Case. The competent person was required to describe in the method statement how the intended work was to be carried out, without coming into contact with live parts of the electrical equipment. The standard also set down the requirements to submit the method statement for review and acceptance to a competent organisation approved by the Zone Electrification and Plant Engineer (ZEPE). Other principal changes from Issue 2 included: Isolation Agents Temporary Isolations Protective Switch Outs Machine Switch Outs Revised Strapping Arrangements The revised strapping arrangements potentially involved the requirement to fit additional straps and/or straps being placed in close proximity to junctions and incoming supply. Issue 3 of the standard was issued in August 2001 but was withdrawn shortly after issue due to concern from the industry over the increased risk to personnel applying straps from moving vehicles. Much debate has taken place in the intervening period and discussions between HMRI, Network Rail, and RSSB throughout 2006 were aimed at resolving these issues and determining the best way forward. In view of this, it was agreed with RSSB that no further effort would be placed on this aspect of the study.
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6 Human Factor Analysis 6.1
Introduction
This section of the report concentrates on the Human Factors study undertaken as part of the research. It covers the human factor issues and focuses on the human being and their role in electrical safety. 6.1.1
Remit of Human Factors Study
The human factors 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 i.e. intentionally, unintentionally or because of the influence of company safety culture. Prior to gaining access to incident reports, it was anticipated that some time would be available to interview witnesses and persons involved in the incidents to gain a deeper understanding of the behaviours involved. However, due to the volume of information in the reports received and the consequent analysis time required, this was not achieved. It would have been possible to conduct interviews at the expense of the analysis of some of the incidents, but it was considered more important to gather data from as wide a range of sources as possible; Predict the types of human error that could feasibly occur considering the tasks that personnel are required to perform in and around electrified areas.
6.2
Literature Review
A trawl of the human factors literature revealed no previous work explicitly directed towards understanding the human factors issues associated with working in electrified areas in the rail industry. However, some papers covered human factors considerations for railway work in general, including trackside or on-track work. By virtue of the fact that the tasks described in these references could be carried out in electrified areas, they are therefore considered applicable to this project. That is not to say that such tasks would be conducted in exactly the same way in electrified areas (for example, personnel may exercise additional caution whilst maintaining rail in a DC electrified area, and the procedures in place will take account of the additional hazards), however the basics of the task would be very similar. The results of the literature review identified work on the following topics that would be applicable to this project: Safety critical rule compliance; Team-working in the railway industry; Communications errors during track maintenance; Judging distances near overhead power lines. Sections 6.2.1, 6.2.2, 6.2.3, and 6.2.4 provide a brief review of each of these pieces of work, along with their implications for the current project. 6.2.1
Safety Critical Rule Compliance
This work, conducted by Greenstreet Berman for RSSB in June 2004 to address the question of why, although the majority of personnel are conscientious with respect to rules and procedures, incidents have occurred through failure to comply with them. The research investigated the factors
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affecting compliance, the prevalence of non-compliance in the industry, and methods likely to succeed in improving compliance. It also developed a toolkit of practical methods, procedures, and guidance that the railway industry can readily use to improve compliance. The study identified the key influences on safety critical rule compliance as: Organisational factors (e.g. a participative supervisory style was found to produce greater compliance amongst workers, and giving workers health and safety duties was also found to improve compliance levels). Environmental factors (e.g. it was found that the weather and rail conditions can influence whether or not a driver complies with driving rules). Individual differences (e.g. workers were found to differ in terms of their views, for example, on the occurrence of signals passed at danger (SPADs). Some believed they can control SPADs, others believed that SPADs are inevitable, such differences could influence the extent to which individuals are likely to attempt to comply with rules). Cognitive factors (e.g. sometimes tasks can be too demanding for an individual, and hence encourage individuals to decide to ‘cut corners’). Motivations and behaviour (e.g., motivators include performance pressures and peer pressures). Attitudes and beliefs (e.g. individuals may not believe that they are able to comply with formal rules, or they may believe that they do not need to comply with certain rules). Workplace design (e.g., the design of workplaces may provide the opportunity to use equipment in ways that were not intended or may otherwise encourage non-compliance). It was clear from the research performed that non-compliance can be an intentional act (i.e. a ‘violation’ of procedure) or unintentional (i.e. an error). The research resulted in the development of a toolkit for the classification of non-compliance with procedures and understanding why such non-compliances take place. The toolkit also provided users with generic solutions to help encourage compliance, which fell under the following general headings: Enhancing safety leadership behaviours Setting clear standards Making rule & compliance important Supervising & monitoring Applying rewards, sanctions & discipline Improving the rules Making compliance easier / making non-compliance more difficult Education Modifying behaviour Involving staff in rule implementation In terms of the implications for the present study, this work covers both intentional and unintentional behaviours that could result in incidents. It will be beneficial to the project to use the generic solutions to specific types of non-compliance when formulating recommendations during the review of previous railway incidents in electrified areas. The work under the present project is directed towards understanding the reasons for the behaviour that led to a violation or an error, as opposed to understanding the reasons for non-compliance, however, the difference between the two approaches is subtle. It is anticipated that the types of generic corrective actions identified from the previous research into rule compliance will also be applicable to the results of this study.
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6.2.2
Team-working in the Railway Industry
Gregory Harland Limited conducted a 15-month study for RSSB during 2003 and 2004 to develop best practice team-working guidance for the rail industry. The remit of this work was to: Identify areas where teamwork is most critical within the rail industry Determine best practice for teamwork across the rail industry Identify ways of effectively promoting team-working best practice across the rail industry The research work involved studying team-working within the rail industry and identifying important lessons that could be learned from other industries. Using these sources of information as the starting point, the study then worked on the identification of measures of team performance and preliminary guidance on best practice for team-working. The preliminary guidance for teamworking best practice was subjected to a pilot study using a sample of railway group members, prior to being finalised. The study resulted in the development of 20 guidelines for team-working best practice, covering things that individual team members should do as well as things that the organisations should do. The study also resulted in the development of a methodology for assessing both teamwork and the organisational support for teamwork to identify any deficiencies at the individual and organisational levels. The best practice guidelines are easily translated into recommendations for action in order to address any deficiencies identified. A pilot trial of the assessment process and guidelines conducted as part of the study found that the process was readily understood by the participants and provided valuable insights into the current state of teamwork and what was needed to improve it. This study into human factor issues in electrified areas will be focussing on incident reports involving teams of track workers. If any of these incidents indicate a failure in team-working practices, then the best practice guidelines developed under the Gregory Harland study will provide the basis for recommendations for the improvement of team-working. 6.2.3
Communications Errors During Track Maintenance
Gibson et al (2004) used an analysis of recorded voice communications to identify the number of communications errors occurring during track maintenance activities between PICOP / COSS and the signalman. Two types of error were identified: Failure to implement general communications procedures Deviations in information content Each of these error types was sub-divided into a number of specific errors observed during the study (e.g. ‘omission or failure to use the phonetic alphabet’). For each specific error reported, the authors provide an estimate of human error probability (HEP) which is based upon the number of errors observed divided by the number of opportunities for error (based on the total number of times that the relevant task was completed over the course of the period of recording). The results suggested a very high frequency of failures to implement general communications procedures (e.g. failure to use the phonetic alphabet in 78% of cases, not using specific terms (e.g. ‘over’, ‘negative’, ‘disregard’) in 100% of cases.
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The authors suggest that this high failure rate is at least in part due to personnel needing to deviate from the procedures as depicted in the Rulebook, but without support on how best to do this. For example, the Rulebook states that all numerals communicated verbally should be spoken singly (e.g. ‘one’ ‘two’ ‘zero’ as opposed to ‘one hundred and twenty’), but operators find this difficult and confusing when working with longer numerical strings. In addition, the standard terms required in the Rulebook are based upon radio communication, and do not apply to telephone communications (e.g. ‘over’ and ‘out’) hence in communications between PICOP or COSS and signaller, they are not used. Errors of deviation from information content were classified in terms of slips of the tongue. Their frequency was much lower than deviations from procedure. Un-recovered critical slips involving numerical information accounted for only 0.4% of opportunities for error during the observations. The researchers provide evidence from air traffic-control studies to suggest that this figure is consistent with natural human variability in relation to the communication of numerical information. A CIRAS analysis bulletin covering an analysis between June 2000 and February 2002 reports 27 cases of driver-signaller communications failure, approximately 18 of these related to signallers and drivers not responding to each other’s communication. The bulletin cites as a common cause of these errors ‘poor procedures’. This information may provide further evidence for the need to review communications procedures. The Gibson report is relevant to this study in that it is specifically focussed on human errors made during track maintenance tasks. The authors of the reported study state that it would be beneficial to their ongoing research into human error probabilities to examine the occurrence of communication errors that are involved in incident reports. Although this study aims to examine incident reports relating to electrified areas only, the analysis may yield information that is of benefit to continued RSSB research into communications errors. The research by Gibson et al also provides a number of insights into the reasons for noncompliance with communication procedures that could be useful during the investigation of the human factors causes of historical incidents. 6.2.4
Judging Distances Near Overhead Power Lines
There are growing concerns in North America about the risks associated with operating cranes adjacent to overhead power lines. The National Institute for Occupational Safety and Health estimate that around 15 electrocutions every year are caused by contacts between cranes and overhead power lines (mostly power distribution lines as opposed to railway systems, but the principle is the same). A number of standards are quoted which provide precautions or operations near overhead power lines, including OSHA regulations, ANSI standard and the Construction Safety Association of Ontario, Canada’s recommendations for safe working practices when adjacent to overhead power cables. The recommendations from such standards do not provide a great deal of insight into additional means of risk reduction over and above those taken in the UK rail industry. However, some of the suggestions could provide the basis for some recommendations on mitigating risks identified because of the reviewed incident reports, for example: Use of independent insulated barriers to prevent physical contact with overhead cables; Require crane operation at slower than normal speed when under power cables; Raise awareness of the fact that in strong winds cables could sway and reduce clearance between the cable and the vehicle;
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Raise awareness of the need for caution when moving over uneven ground that could reduce separation between the vehicle and the power line. Imbeau et al (1996) also conducted some research into the judgement of clearance between cranes and overhead power cables. A group of 16 trained and experienced crane operators were asked to move their crane hook to the edge of the danger zone around an overhead power cable. They were asked to do this under two conditions: one in which they used no visual aids at all, and simply judged their proximity to the cable. In the second condition, they were presented with fluorescent markers laid on the ground at a distance from the crane representative of the maximum safe extent of the boom in that location. The results of the study revealed that operators were unreliable in judging distance without any reference markers, but when reference markers were provided, operators were much more precise and reliable in judging the edge of the danger zone. As this study involved crane drivers working at a distance of 3 Metres from the nearest live cable it was deemed that this study was appropriate to the research undertaken on this project. The results of this work will be borne in mind whilst reviewing incident reports to determine whether any of the recommendations listed above could be used to help prevent recurrence of incidents involving cranes or other similar vehicles with extendable apparatus.
6.3
Review of Historical Incident Data
This section documents the analysis of 19 incidents involving electrocution or potential electrocution of members of the workforce carrying out work within electrified areas (both conductor rail and overhead line equipment). This work has been supplemented by a predictive analysis of human error risk conducted using the task-based risk assessment in electrified areas conducted for this project and detailed in section 7 of this report. This supplementary exercise of predicting human error aimed to identify all forms of human error that could conceivably occur whilst conducting those tasks represented in the risk assessment. As such, the analysis is less focussed than the analysis of previous incidents included in this section. The results are intended to provide the reader with an indication of what could occur, and the various ways in which these events could come about. A number of recommendations have been made due to the predictive analysis, and because some predicted errors could happen in a number of different ways, these recommendations need to cover all possible ways in which an error could occur. Because the events are predicted, and not identified through the analysis of actual events, these recommendations need to be very high-level, indicating the types of mitigation that could be implemented to prevent the predicted errors, but would need to be put into context to solve specific problems. For all of these reasons we have elected to include this analysis as an appendix to the report, as the recommendations are less focussed than those resulting from the analysis of historical incident data.
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The focus of the work reported here was to identify the human factors lessons that could be learned from previous incidents, and so it is this work which forms the main body of this section of the report. Recommendations emerging from the historical analysis are more directed towards preventing a specific type of event from occurring again, or at least reducing the impact of the event if it does occur. The remainder of this section concentrates on the historical analysis of 19 of serious incidents involving electric shock, electrocution or near misses. These were as follows:
Location
Date
Paddington, Acton East
21 January 2000
Adwick
2 August 2000
Hither Green
25 July 1995
Dock Junction
10 February 2002
Doncaster Belmont Yard
2 December 2001
East Croydon
8 September 2002
Handsworth
5 March 2002
Harlow Mill
5 May 2002
Hemel Hempstead
8 August 2001
Liverpool Street
7 November 1999
Marston Green
1 July 2003
Oakley
7 August 2003
Ranskill
19 October 1998
West Croydon
10 October 2001
Tollerton
2 May 2001
Hooton
5 March 2003
Leighton Buzzard
14 June 1985
Euston
12 November 1988
Hett
14 April 1998
The reports were reviewed using three forms of human factors analysis: human error analysis, ABC analysis of violations, and safety culture analysis. Each of these forms of analysis is described in Appendix C. In a number of cases, incidents did not include just one type of human failure; they tended to have involved both errors and violations, or a combination of errors, or a combination of violations. In some cases, there was evidence to suggest that the safety culture of the organisation that employed the worker had some influence on the incident. Because of project time and budget limitations, given the volume of information included in the 19 reports analysed, this analysis has had to focus on those human failures directly relating to the incident, rather than the indirect failures. Additionally, many indirect failures are not explicitly described in the incident reports. The primary focus is on the immediate cause of the incident, with some description of other causes, but not in sufficient detail to perform a human factors analysis. For example, an incident may involve a violation on the part of a worker who did not follow the required procedure for checking whether a line was de-energised. This would be considered the direct failure in relation to the incident. However, it is also possible that planning errors could have contributed to the incident, but whilst such an error would be acknowledged as having contributed to the incident, these would not be thoroughly analysed.
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This report provides details of the analysis for each incident reviewed, which includes recommendations for addressing similar human factors issues in the future. 6.3.1
Incident Analysis Procedure
The procedure followed when analysing each of the incidents was as follows: 1. Review the incident report and identify the behaviours that were exhibited leading up to the incident. 2. From the evidence available, decide whether the behaviour was intentional or unintentional. 3. When the behaviour was intentional, apply the ABC analysis tool to determine the triggers and consequences for the behaviour, and specify the alternative, safe, behaviour along with required triggers and consequences. 4. When the behaviour was unintentional, apply the human error analysis tool to determine the underlying psychological causes and formulate recommendations for preventing recurrence or reducing the impact of future similar errors. 5. Use the safety culture analysis-tool to determine any possible safety culture influences on the behaviour in question and recommend action as appropriate. In some cases, there was insufficient evidence to identify specific behaviours involved in the incident. In such cases, this was reported as the outcome of the analysis. In several cases, there was evidence of failure in the planning process, and other works management processes that occurred well in advance of the incident itself. In such cases, the nature of these failures could rarely be determined, as the investigations tended to focus on the reasons for the incident itself. However, where possible these problems have been highlighted although it has not been possible to analyse them in any depth. The following sections of this report provide the reader with a synopsis of each incident, the form of human factors analysis applied (i.e. human error analysis, ABC analysis or safety culture analysis) and the recommendations resulting from the analysis of the individual incident. Full transcripts of the human factors analyses conducted for each of the incidents are included at Appendix D. 6.3.2
Difficulties in Analysis of Historical Data
Re-analysing incident reports after the event is often difficult because the analyst is constrained by the information contained within the report, and occasionally has to base analysis on assumptions made by the original investigators. This study was no exception. Information regarding human factors issues associated with incidents tends to require a high level of detail to be reported in the incident report. In some cases, the reports that were available for this study contained little detail; some comprised only a Coroner’s report, which did not provide any information on what actually happened at the time of the accident. In cases such as this, where there was plainly insufficient information to conduct an analysis, this is stated in this section of the report.
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6.4
Results of Review of Historical Incident Data
This section contains a summary of the review of the 19 incidents used in this project. For each incident, a synopsis is provided which summarises the incident and the human factors analyses conducted. Following each synopsis there is a summary of the recommendations resulting from the human factors analysis of that specific incident. These recommendations are analysed to identify common themes in Section 6.5, and the resulting key recommendations are included at Section 6.6. 6.4.1
Acton East 21st January 2000
Synopsis The nominated person (NP) for the isolation was applying earths to an isolated section at a designated earthing point (DEP) when there was arcing across and the earth blew, indicating that the section was in fact still live. It was later found that a switch that was normally open was in fact closed. The NP had conducted live line testing to confirm that the power had been isolated prior to applying the earths, but the tester was found to have been defective. The Live-Dead-Live procedure for live line testing had not been applied. In this procedure, the user tests a known live line, followed by the dead line, followed by a live line. This allows the user to confirm the different deflections of the needle for live and dead lines. The formal investigation report finds that this incident included a trend of failing to follow the Live-Dead-Live testing procedure, resulting in arcing and a blown earth. The human factors analysis of this behaviour suggested that it was possible, given the evidence, that this could have been either intentional or unintentional, and therefore both ABC analysis and human error analysis were applied. It was also noted that what appears to have been a switching error had occurred that resulted in the line, which was expected to be de-energised, being energised. However, the incident report states that the investigation into this error was unable to identify how the switch became closed, and that it could have been closed for up to three months prior to the incident without detection. It was not therefore possible to perform any analysis on this error. The contents of the incident report state that had the Live-Dead-Live procedure been followed, the switching error would have been detected. Analysis Recommendations Raise awareness of the existing procedure that ensures that all live line testing equipment is tested using signage and briefings prior to leaving the depot. Increase the frequency of routine testing. Publicise the results of this incident to illustrate to personnel the potential consequences of not following the correct procedure. Engage some of the personnel involved in relaying their experience of what it was actually like. Apply a label to a prominent position on the live line tester to remind users of the correct procedure. Implement a safety observation scheme to provide praise for personnel seen to be consistently working safely to act as positive reinforcement, and explore the reasons why people do not follow the procedures. These can be used to introduce negative reinforcement for unsafe behaviours. Provide training to all personnel who will act as on-the-job instructors. This should include an assessment of a person’s ability to train another person (it does not always follow that a person good at doing the job will be good at training someone else to do it). Procedure should include detailed information on what to do, and why to do it – procedures often focus only on what is required, knowing why it is required often helps to encourage compliance.
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Instil in workers the importance of checking all information available before coming to a decision. Decision-making training may be appropriate for NP level personnel. Another high potential risk scenario was introduced when the NP was supervising a trainee. There are a number of examples of historical incidents where this situation has been shown to contribute to poor performance of a primary task. For example, research in air traffic control revealed a higher than average number of incidents when experienced air traffic controllers were mentoring a trainee controller. In such cases, the underlying causes were to do with a need to divide attention between a primary task and a similar secondary task, and the effectiveness of training provided for mentors. Taken in conjunction with the ongoing maintenance work, these two factors may have had a significant impact on performance at the time of the incident. Awareness should be raised of the conditions where performance and communications can break down, and when to pay more attention to the procedures. 6.4.2
Adwick, 2nd August 2000
Synopsis Whilst cutting back a bush, which was getting close to the return conductor, a worker carried cut branches to an overgrown area and threw one from above his head to get it well into the overgrown area. The tip of the branch brushed the tail wire on the OLE, resulting in a mild electric shock. Review of the incident as part of the human factors analysis revealed little in the way of detailed information to make a clear distinction between intentional and unintentional behaviour, hence both ABC analysis and human error analysis were applied. The absence of briefing on the electrical hazards associated with the work was also a factor, but details of the COSS actions are not available to allow any analysis of the associated behaviour. A formal investigation report was not available for this incident. A copy of a three-page internal fax, which contains the internal investigation report (a brief description of the incident and the investigation conclusions and recommendations), was used. Analysis Recommendations Provide all OLE workers with a safety induction briefing or formal training in the hazards associated with overhead lines. Provide a rule of thumb to workers to indicate what is a safe distance from the line (i.e. nothing to be held above head height). Check the effectiveness of training and mentoring to ensure that workers are going onto the railway line with the necessary information, paying particular attention to new recruits. Use videos to show graphically the consequences of contact with the OLE. 6.4.3
Hither Green, 25 July 1995
Synopsis A track worker fell with his chest across the conductor rail with no protective equipment worn above the waist. The result was electrocution. Witnesses were unable to explain the actions of the deceased immediately prior to the accident, so the behaviours concerned could not be examined in detail. However, the behaviour of not wearing full PPE, which, had it been worn may have reduced the severity of the accident, can be analysed. The deceased was naked above the waist, having removed his high-visibility vest and T-shirt and tied the vest around his waist. Assuming that the victim was aware of the requirement to wear the vest, this was clearly an intentional violation, and was therefore analysed using ABC analysis. Note that direct exposure to the third rail is not considered intentional; there was clearly some unintentional activity which led to contact.
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Additional factors identified in the incident report involve failures to introduce safe systems of work and insufficient planning. In both cases, there will have been behaviours that could have been further analysed, but since they are contributory factors, they are not covered in detail in the incident report. Analysis Recommendations Provide training for how to intervene and accept intervention constructively. Many people have a problem with this, and this is required if people are to feel comfortable intervening. Identify suppliers of more comfortable PPE under all weather conditions and conduct usability trial. Assess safety culture to identify why people do not intervene and encourage managers, COSS, etc to lead by example. Some of these problems may be addressed through training on intervention. 6.4.4
Dock Junction, 10 February 2002
Synopsis A gang of sub-contractors was due to dismantle and remove scaffolding from an area in proximity to OLE under T3 protection. The duration of the possession and isolation were shortened such that there would only be 2 hours to complete the job rather than 4 ½ hours. Three hours were required to do the job safely. Due to the lack of contingency arrangements, the COSS decided to amend the method statement to allow removal of the scaffold before the possession/isolation was granted. This involves contractors carrying scaffold poles above head height. The deputy possession manager intervened to stop this activity until the possession/isolation was confirmed. There were no injuries. This incident clearly involves a violation of the procedures by the COSS and hence ABC analysis only has been used to analyse it. Analysis Recommendations All similar work to be completed only under T3 conditions – reinforce the right to stop work in the event that COSS believes that safety is compromised. If one is not already in place, introduce a scheme similar to “Time Out For Safety” – TOFS) which empowers employees to stop work should they feel that there are any threats to safety. Priority to be given to safety over productivity - managers need to lead by example and not punish the workers if they are unable to complete a job because of safety constraints. 6.4.5
Doncaster Belmont, 2 December 2001
Synopsis A worker was asked to go and find a tank wagon in the yard, which was carrying fuel for the central heating system. He found the tank wagon, which was properly labelled. There were no witnesses to the accident, but the worker had climbed onto the top of the tank wagon and was fatally electrocuted either by contact with or by arcing from the OLE. Due to the lack of witnesses, the report contains a number of assumptions. It is by no means certain whether this behaviour of climbing on to the tank wagon was intentional or unintentional, although it is conceivable that the worker made some form of error in judgement regarding climbing onto the tank wagon. The human factors analysis has proceeded on this assumption. The report suggests that there may have been a lack of awareness of electrical hazards due to the deceased not being issued with Section Z of the Rulebook. There would have been a behaviour
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associated with this failing, but there is insufficient information in the report to analyse this further. The full incident report was not available for review. The information reviewed appears to come from two different sources, and provides a summary of the inquiry and the conclusions and recommendations of the investigation only. Analysis Recommendations All personnel whose work could bring them into an area where live overhead lines are present should be briefed on the dangers of Overhead Line equipment, and should have a copy of the relevant rules and procedures for their personal use. Introduce a procedure for a situational risk assessment when an individual or team of workers come across a task with which they are not familiar. All personnel who may encounter labelling used on goods wagons of any description to be provided with training on their location and meaning. 6.4.6
East Croydon 8 September 2002
Synopsis Whilst fitting plastic tubes around traction current cables with the conductor rail live and the line open to trains, the COSS made contact with the conductor rail and the running rail, resulting in fatal electric shock. There was no evidence to indicate what the COSS had been doing immediately prior to the accident. Given the lack of evidence of the COSS’s actions prior to the accident, detailed analysis has not been possible. However, the fact that a conductor rail shield was not taken to the worksite and that there was no method statement for the job suggests that violations of procedure had occurred, and hence an ABC analysis has been conducted on the incident in general, rather than on the undetermined behaviour of the COSS. The report also indicated behaviours associated with the short-term rather than long-term planning of work. Although these are acknowledged as factors that affected this incident, there is insufficient detail in the incident report to analyse these further. Analysis Recommendations Clarify through procedures, briefings, etc. that method statements for all tasks that bear the risk of electrocution are a requirement, regardless of how simple the task may appear. Introduce a safety observation scheme where an NP would tour worksites on a scheduled basis and provide positive feedback for safe performance, to reinforce safe behaviour. Teams that perform consistently safely could receive some form of positive feedback that is meaningful to them (for example a monthly prize – a night out for example that they can all partake of as a team) or even just recognition through publicising their successes in a popular company journal, on a notice board that is often used, etc. Introducing incentives for meeting safety targets should be discouraged, as it encourages workers to behave safely only when there is something in it for them, rather than triggering a change in their beliefs and values relating to safety. What is recommended here is a reinforcement of safe behaviour rather than an incentive scheme. Introduce regular work audits to allow managers to identify and actively discourage unsafe behaviours, involving those involved in unsafe acts in developing a safer way of working.
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6.4.7
Handsworth, 5 March 2002
Synopsis Whilst erecting fencing in the West Midlands and Chilterns area, and having conducted a CAT scan which indicated the presence of a buried metal object, two workers ruptured a 132kv buried cable, resulting in an explosion and burns to both men. This accident seems, on review of the evidence, to have been the result of an error on the part of the two workers brought about by a number of factors to do with their expectations, the reliability of equipment, and the efficiency of the planning process. A human error analysis was conducted, which is reported below. The formal incident report acknowledges several factors relating to planning of the job, lack of resource, sub-contractor safety assessment, and chain of command all contributed to the incident. All of these will have had behaviours associated with them, but they are not investigated in-depth in the report, hence human factors analysis was not possible. Analysis Recommendations Provide additional methodical checking of the planning documentation and information passed to the work site regarding location of hazards. Introduce procedures to proceed with caution when resistance is encountered when digging, until the source of resistance has been identified. 6.4.8
Harlow Mill, 5 May 2002
Synopsis Two members of staff involved in the renewal of sleepers and ballast were asked to redistribute the loads in three wagons of spoil. The two men climbed into the wagons to redistribute the loads, and on reaching the second wagon, one of the men received an electric shock after coming into contact with live OLE. The human factors analysis of this accident focuses on the behaviours of the engineering supervisors involved, which led to a failure in briefing personnel on the safety aspects of the work. Two behaviours were identified which, based on the evidence presented, appeared to be unintentional, and hence human error analysis has been used to analyse this incident. Other relevant factors included the decision to control a risk using ‘briefing by the COSS’ and the inconsistent recording of the isolation limits in the documentation for the work. Both factors will have involved a human failure or failures, but there is insufficient detail in the investigation report to analyse these further. Analysis Recommendations Conduct regular audits of COSS briefings to determine their quality and provide coaching and development for those that require it. Introduce a procedure that requires systematic checks to be made of the limits of all work areas prior to briefing other personnel. Provide coaching and / or training in how to communicate safety information effectively. Provide guidance on high-risk handovers, and how to reduce the associated risks – this may involve using a checklist, if this is appropriate. Ideally, the procedure for Form ‘C’ acceptance and briefing of COSSs should be consistent across organisations working in rail. To account for the fact that this is unlikely to be the case in practice, site briefings should be provided to ensure that local procedures are briefed to any personnel that have not worked on site before. This should be treated as a site safety induction.
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Indications in this report that there may have been multiple violations on site in failing to follow the procedure to formally brief on the Form ‘C’ contents to COSSs, but insufficient evidence to pursue. 6.4.9
Hemel Hempstead, 8th August 2001
Synopsis A group of workers were performing overhead line maintenance from the top of an overhead line train. A crossover section insulator was close to the train, and workers were warned of this being live equipment. The victim was attempting to clean a section insulator rod when he received an electric shock. He was thrown backwards, onto the train roof, ablaze. It was later stated that no one had asked the victim to clean the section insulator, and that at least one other member of the crew did not know that the section insulator in question was live. The review of the incident suggested that the victim did not intentionally reach out for a live piece of equipment, suggesting that this was an error. It is also possible that an error was made on the part of the person briefing the victim on his tasks; hence, error analyses have been conducted for both possibilities. It is also clear that some form of human behaviour was also associated with the lack of formal training, lack of a method statement and failure to cover electrical hazards fully in the work procedure. However, although these are highlighted as contributory factors in the incident report, there is insufficient detail for more detailed analysis of the associated behaviours. Analysis Recommendations Provide safety communications training to personnel, providing workers with guidance and practice on how to convey safety-related information most effectively in the least ambiguous manner, and to encourage workers on the receiving end of information to check their understanding and clarify any issues they are not 100% comfortable with. See also the recommendations made by Gibson et al (2004) on reducing safety communications errors, which includes a recommendation to improve the usability of existing communications procedures to improve compliance levels. When work is conducted in an area where the complexity of the overhead lines is high, determine the potential benefits of conducting line testing procedures whenever moving to a new piece of overhead equipment. 6.4.10 Liverpool Street, 7th November 1999 Synopsis Whilst climbing scaffolding at Liverpool Street Station in order to dismantle it, a contractor made contact with the overhead line equipment. This resulted in the contractor being thrown backwards onto the track and sustaining injuries due to electric shock and the fall onto the tracks. The human factors review of this incident suggested that the contractors involved might have made an error based upon the manner and content of information provided to them regarding the job. The COSS did not receive face-to-face communication regarding the job, but was briefed over the telephone regarding the track arrangements, and did not gain sufficient understanding of the isolation arrangements from the NP. This was seen primarily as a planning and control of contract issue, and has been analysed using the human error analysis tool. The formal investigation report identifies a number of factors that were not investigated in detail which relate to a failure to follow briefing procedures and differing isolation and possession limits. As these are raised as ‘factors for consideration’, there is insufficient detail to perform human factors analysis on the associated behaviours.
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Analysis Recommendations Worksite and isolation limits to coincide to reduce the risk of confusion. Audits by site safety authority on regular basis to identify problems with briefings or the physical conduct of work 6.4.11 Marston Green, 1st July 2003 Synopsis Overhead line prep work was underway at the accident location. The COSSs had briefed the workers that the overhead lines were not yet isolated and that the Form C had not been received. Road rail vehicles (RRV) were driven onto the road rail access point (RRAP) under live OLE to await the Form C. The isolation was delayed, but some men did not know whether to begin ground-level work under OLE or stay in the cab. One vehicle was set up for control from the basket, when it was necessary to raise the basket slightly to see over the cab. At some point shortly thereafter, a flashover occurred and both men in the basket jumped out of the basket. A human factors review of the incident report suggested that the vehicle was driven down the line whilst the line was still live, indicating an intentional behaviour on the part of the crew. An ABC analysis has, therefore, been conducted. Several other issues were highlighted in the report associated with behaviours prior to the incident. These were the shortening of the isolation limits prior to start of work, documentation references being outdated, poorly written procedures, and poor briefing from the COSS. Although there will have been specific behaviours associated with these events that could have been subjected to human factors analysis, there was insufficient detail in the report to do so. The version of the report reviewed was a draft produced on 18 July 2003, not a formal investigation report. Analysis Recommendations Procedure to state that baskets, or other exterior elevated structures on vehicles, will not be used under live OLE, with a possible extension to this procedure to leave interlock keys for basket operation with an NP or a person who will not be working under OLE and to have them handed back when the Form C is issued. Provide handover and safety communications training to all personnel working in electrified areas to cover principles of accurate and safe communication, including two-way checking of understanding, etc. Some workers reported they were not sure whether they were authorised to start groundwork on arrival (some were instructed to do so by supervisors). Situation not clear, led to assumptions being made. Include in training the importance of use of positive statements in providing information – i.e. state whether or not Form C is present, not that it is expected – either the permit is in force or it is not. 6.4.12 Oakley, 7 August 2003 Synopsis While a gang was replacing broken insulator pots, repositioning displaced pots, and changing pot fixings, etc. a lookout on the job was seen to bend down as if to do some work. Shortly afterwards the lookout made contact with the conductor rail, resulting in a fatal electric shock. A review of the incident suggested that there was some form of violation on behalf of the lookout engaging in work other than the duties assigned to him, and hence an ABC analysis was done. There was also some evidence to suggest that the safety culture of the organisation could have had an impact on the behaviour of the individual, and a safety culture analysis has also been
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completed. It was also noted that a lack of formal training, checking for possessions only one week ahead, and an inadequate method statement were also factors for which there would be a corresponding human behaviour. However, although these are acknowledged in the incident report, there is insufficient detail to analyse them further. Analysis Recommendations
•
•
Conduct regular audits of risk assessments to identify those that focus on high-level risks or hazards, rather than those specific to the job. Work without an adequate risk assessment along these lines should not be allowed. Management to make their expectations clear regarding the quality of risk assessments, and these should be included in the risk assessment procedure. Assess the safety culture of the organisation to determine the impact on safety practices within the workforce. If issues are identified, develop improvement actions to enhance safety culture with the involvement of the workforce. Explicitly state in procedures when a particular method of conducting work is not permitted under company policy, i.e. do not rely on implication. On-the-job training should be conducted either by COSS or by another member of the gang not involved in other duties that could detract from the quality of training provided, or draw them away from other duties, which require their attention. Use a sign-off system similar to the safety briefing to record who provided the training and the confirmation from the trainee that the training has been received. Work planning for electrical work to identify first available T3 possession – planners to be encouraged to look further ahead. Provide negative feedback if T3 possessions were available but not used due to perceived time pressure.
6.4.13 Ranskill, 19 October 1998 Synopsis At about 04:50 on the day of the accident, while disconnecting local earths from an overhead line structure towards the end of an isolation, a linesman received a fatal electric shock because he disconnected the earth end before the line end was clear. Long earths had to be used instead of short earths because the expected DEP was not present at the expected structure. A human factors review of the incident suggests that the most plausible explanation for this behaviour was that it was unintended, and hence a human error analysis has been applied. The lack of a control measure to prevent the possibility of a person applying or removing earths in the wrong sequence, and the absence of a formal audit and inspection system to observe the isolation process were cited as potential underlying causes of this incident. However, there is insufficient information in the report to analyse these in any more detail. Analysis Recommendations Introduce a procedure, which states that when removing long earths, one man removes both the line end and the rail end of the earth. It seems that communication on who was doing which part of the task broke down in this case. Workforce should receive training on effective communication and co-ordination strategies for safety-related activities. See also Gibson et al (2004) recommendations on modification of procedures for safety communication. The workers were trained in the use of long earths, but experience of actually applying them was limited. For safety-related tasks, ensure that practical experience is received within one month of initial training. If the task is not performed for an extended period of time (for example 6 months) then refresher training should be provided, which need not be in the same format as the original training.
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The worker who died had worked 21 consecutive shifts, with two 84-hour weeks immediately prior to the incident. It seems highly likely that this contributed to his performance on the day of the accident. Working hours should be monitored and action taken when an individual worker has exposed themselves to high levels of fatigue that could endanger themselves and their co-workers. Frequent auditing of records should be used to identify problem cases. 6.4.14 West Croydon, 10 October 2001 Synopsis During the course of maintaining a rail flange lubricator, an uninsulated, open-ended spanner contacted the energised conductor rail. This resulted in an arc that caused the grease in the vicinity to ignite, and injure two workers. Human factors review of the incident suggested that this behaviour was unintentional, it was difficult to conceive why someone would do this intentionally and hence human error analysis was conducted. It is recognised, however, that the use of uninsulated tools could be considered a violation, although there was insufficient information in the report to allow full analysis of this. The formal incident report identifies a number of underlying causes, all of which involve human behaviours, many of which involve unsafe behaviour on the part of management. They were: Not providing suitable tools Lack of suitable training in risk identification Failure to enforce procurement policy Conductor rail shield applied incorrectly Failure to obtain method statements and risk assessments Failing to monitor contractors All of these factors involved human behaviour, but there is insufficient detail in the report to analyse them further. Analysis Recommendations The work was carried out without an isolation, which would have prevented the accident. Recommend that where possible, electrical work is conducted under T3 isolation Ensure that properly insulated tools are used in electrified areas. Where T3 isolation is not possible, conductor rail shields must be used as a matter of course. 6.4.15 Tollerton, 2 May 2001 Synopsis As part of maintenance work in the area, a group of contract staff were to unload track from a HIAB crane. The area for unloading the crane was under live OLE, and the HIAB fouled the OLE, resulting in electric shock to some of the men on board. A human factors review of the accident suggested that the crane operator had intentionally raised the crane arm, and hence an ABC analysis was conducted. The formal incident report states that inadequate planning and resourcing of the job was an underlying factor in the incident, but details of the behaviours of those involved in these activities were not included in the report, precluding more detailed human factors analysis.
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Analysis Recommendations Conduct regular audits of work planning to ensure that work, involving vehicles with extending parts, takes place wherever possible under T3 possession. Introduce procedure disallowing any movement of crane arms, etc. when the vehicle is beneath live OLE. Note:
In the formal incident report there is no transcript of an interview with the crane driver, as it is stated that no interview had been achieved prior to publication of the report. The evidence in the report as it stands suggests a violation; however, it would be useful to have had access to more detailed information to determine whether there was also an error involved. Previous work reviewed during this project suggests possible simple systems to help improve the judgement of distance when operating cranes near overhead power cables. If an error in judgement was involved, then these recommendations would also be pertinent (See Imbeau et al, 1996).
6.4.16 Hooton, 5 March 2000 Insufficient information on the actions of the injured party was available for the conduct of human factors analysis. It was not clear whether the behaviour was intentional or unintentional. The lack of clarity is because only information contained in the original incident recording forms and SMIS was available, which lacked sufficient detail to analyse the behaviours involved. 6.4.17 Leighton Buzzard 14 June 1985 Insufficient information was available on what the victim was doing at the time of the accident to conduct any detailed analysis. It is known that the branch that was being cut made contact with OLE because the worker had to cut from one side, then the other with the chainsaw in order to cut through it. Witnesses stated that the saw sounded as if it was labouring, but that the deceased had stated that it was always like that. This suggests inappropriate tools and equipment to do the job. It is possible the incident could have been prevented if the saw was capable of cutting through the branch without having to change position and bend the branch to remove it. Information for this incident came not from a formal incident report, but from a copy of the inquest along with hand-written and typed witness statements, providing little in the way of detail on the behaviour of the deceased or others within the organisation. 6.4.18 Euston, 12 November 1988 The worker did not appear to have been briefed of the hazards associated with trains or overhead lines prior to starting work, and work did not seem to have been monitored. The worker took a shortcut that meant that the metal pole he was carrying made contact with OLE. The deceased was working at the station for the first time, was not an OLE operator, and should have received a comprehensive briefing. Information on this incident came from a copy of the post-mortem examination and a typed transcript of the inquest. 6.4.19 Hett, 14 April 1998 There is no evidence in the report to indicate how this incident happened, as the only witness was the injured party, who was in hospital at the time of the inquiry. None of his co-workers saw what happened. It is therefore not possible to complete a human factors analysis on this incident.
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6.5
Conclusions
The review of incident reports identified a range of behaviours involved in a sample of incidents spanning the last 15 years. The number of intentional behaviours (violations) and the number of unintentional behaviours (errors) were approximately equal with a few more errors identified than violations. In many cases due to the individual dying because of the incident, one can never be positive about the level of intent involved. 6.5.1
Common Causes of Behaviours
The review and analysis of the incidents revealed a wide range of causes for the behaviours that were exhibited, ranging from the physical (e.g. poor lighting) to the psychological (e.g. seeking approval from a manager or colleague). However, there were a number of causes, which were common to many of the behaviours that contributed to, or triggered these accidents, as described in the table below: No. of Behaviours Exhibiting Factor 4
Common Cause Poor risk awareness (including lack of awareness training, or ineffective awareness training) Insufficient briefing (includes not following prescribed briefing procedure) Complacency (for example during longterm non-standard activities such as maintenance or when workers are highly experienced with a task) Working under perceived time pressure, leading to the perceived need to get the job done quickly Seeking approval for getting the job done, or seeking to avoid ridicule for not joining in with custom and practice Lack of (or accessibility of) a specific method statement, risk assessment or procedure for the job Lack of suitable tools and equipment to do the job (including lack of interlocks, poor ergonomic design)
9 8 7
5 5
Associated Recommendation Safety Communications Training Supervisory Checks Safety Communications Training Safety Communications Training Safety Observation Scheme Checking the Planning Process Supervisory Checks Safety Observation Scheme Safety Culture Supervisory Checks
4
Safety Observation Scheme Supervisory Checks
4
Safety Observation Scheme
These common causes should be used to raise awareness within the organisations working on the railways of the conditions and situations under which the risk of a human failure could be increased. The following section provides details of the recommendations that were generated because of the analyses in order to combat the common causes in the preceding table, and provides some indications as to those that are likely to have the greatest effect in improving safe working
4 This is the number of behaviours identified during the incident review and analysis, not the number of incidents. Some incidents involved more than one unsafe behaviour that was the subject of the human factors analyses.
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practices in electrified areas. The links between the recommendations and the common causes are indicated in the above table. 6.5.2
Summary of All Analyses
In coming to conclusions regarding the incidents reviewed, the first stage was to consolidate the number of recommendations made for all of the incidents into a more manageable list. Some recommendations were very specific to one incident; others were applicable to several of the incidents reviewed. Where the latter was the case, these have been merged into a single recommendation that would be applicable to the incidents reviewed. To track this process, a table was created showing all of the incidents reviewed along the top, the recommendations down the side, and tick marks indicating which recommendations were applicable to which incidents. The recommendations have been listed in descending order of the number of incidents to which they apply. In the table, the descriptions of the recommendations have been summarised – for details of the recommendations for each incident please refer to the relevant part of the previous section of this report.
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Hett
Leighton Buzzard Euston
Hooton
West Croydon Tollerton
Ranskill
Hemel Hempstead Liverpool Street Marston Green Oakley
Harlow Mill
Handsworth
Dock Junction Doncaster Belmont East Croydon
Hither Green
Adwick
Acton
Recommendation
Safety communication training to include handovers and how to intervene effectively Safety observation scheme to praise safe behaviour and discourage unsafe behaviour, audit briefings, etc. More methodical checks of planning process, scheduled for T3, limits of isolation Monitor line testing procedures Publicise incident consequences using videos, briefings, etc. Training and procedures for on-the-job trainers Safety inductions that cover generic issues plus dangers of electrical equipment Assess Safety Culture (as required by RGSP). Procedures to discourage extending parts under OHLE
use
of
vehicle
Attach procedural aide mémoire to equipment Rules of thumb for distance judgement Audit training improvements
effectiveness
and
identify
Identify more comfortable PPE for all conditions Introduce a Time-Out For Safety scheme Managers to demonstrate safety more important than productivity
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Hett
Leighton Buzzard Euston
Hooton
West Croydon Tollerton
Ranskill
Hemel Hempstead Liverpool Street Marston Green Oakley
Harlow Mill
Handsworth
Dock Junction Doncaster Belmont East Croydon
Hither Green
Adwick
Acton
Recommendation
Introduce situational RA procedure Make staff aware of goods labelling and location Emphasise requirement for method statements for all jobs Procedure for verifying CAT scan Consistency of Form C acceptance procedure between organisations Formal audit or risk assessments All procedures to be explicit, not implicit Procedure for earth removal Provide opportunity for practice following training Monitor working hours. Provide properly isolated tools Rail shield always used when rail live.
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6.6
Recommendations
Summarising the recommendations from all analyses in this way provides an indication of the human factors interventions that have the potential to have the greatest impact on incidents involving contact with a live conductor. From what was found out about the sample of incidents reviewed, it would seem that safety observation schemes, greater emphasis on supervisory checks, safety communication training and more methodical checks of the planning process are the four interventions that would prove most fruitful in reducing incidents. In addition, it is felt that further analyses of the incident reports to find out how effective they have been in reducing the occurrence of incidents in electrified areas is undertaken. The information presented in the Formal Inquiry Reports lacked in detail and consistency. 6.6.1
Implement Safety Observation Schemes
Safety observation schemes are designed to aid behavioural change by using the principles of providing feedback to reinforce the required behaviours. They revolve around management or employee observations of work areas to identify both safe and unsafe behaviours taking place. The concept then is to provide positive reinforcement for the desired (i.e. safe) behaviour whenever it is observed. The idea is that workers get to know that behaving safely brings recognition and will therefore tend to join in. When an undesired behaviour is observed, rather than punishing the individual, the concept is to sit down with the individual and get them to: (a) (b) (c) (d)
explain what they did explain why they did it describe what the consequences could have been (what’s the worst that could happen) come up with the suggestions for how to do the same job more safely the next time.
The aim should be to get the individual committed to doing the job more safely next time. This process has two objectives – the first is to provide positive feedback on the desired behaviour to reinforce that behaviour. The second is to engage the individual in coming up with a better way of doing that task, to gain their buy-in and commitment to change. We recommend that the concept of Safety Observation Schemes be further researched under Phase 2 of this Project. Benefits In terms of the common causes identified in the previous section, this recommendation would help to identify situations where perceived time pressure is a particular influence, and allow managers and supervisors to re-define their expectations. It would also identify situations where personnel work unsafely due to lack of a formal method statement, risk assessment, or procedure, and allow workers and supervisors the opportunity to define solutions for such cases. It would highlight situations where workers seek the approval of colleagues and managers, allowing the setting of more helpful expectations and examples. Finally, it could provide the opportunity to identify cases where workers are required to implement makeshift adaptations to equipment due to a lack of suitability of the original equipment, and for the workers themselves to highlight any problems. However, this should not be seen as a replacement to sound human factors engineering involvement in the procurement and design of equipment to ensure suitability and usability. The introduction of schemes of this nature will not be easy in today’s disaggregated railway; this however, should not prevent the promotion of what is seen as a valuable tool in improving safety awareness. The use of this concept in many organizations has seen an improvement in safety
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performance. Organisations could be encouraged to do this by inclusions in The Railway Group Safety Plan (RGSP) and through acceptance of Contractor’s Assurance Cases. 6.6.2
Greater Emphasis on Supervisory Checks
Related to the previous recommendation, the evidence emanating from a number of the formal investigation reports seemed to suggest that the frequency of supervisory checks of worksites tended to be very low, and that when they did occur they were not very thorough. Organisations should be required to place a greater emphasis on supervisory checking, which should be used to check that work is being done according to plan and the prescribed procedures, but also helps to raise the level of visibility of the supervisors. Benefits Several of the common causes identified in the previous section would benefit from improved supervisory practices. For example, supervisors would be able to check that suitable method statements and risk assessments were in place and would be in a position to make sure that workers were sufficiently aware of the risks to which they would be exposed. It would also be possible for supervisors to demonstrate commitment to getting the job done safely, and hence help to avoid workers gaining the impression that they are under time pressure. More checks by supervisors would also have the effect of helping to set management expectations in terms of safety and getting the job done. This would help to reduce the number of instances where workers behave unsafely because they think they will get some from of reward for getting the job done, even though it was not a safe way of doing so. 6.6.3
Introduce Safety Communications Training
A number of incidents seemed to involve incomplete or ambiguous information being passed between team members. A great deal of work has been conducted in the recent past to develop guidelines for workers on how best to communicate safety information to make sure that the relevant information is correctly understood. A number of principles to do with giving a good handover are applicable to safety communications in general. These include: Communicating face-to-face whenever possible Using positive statements relating to safety issues (i.e. do not say, “The lever is not in the correct position” because if the middle part of that message were drowned out by noise the recipient might think that the lever was in the correct position. Do say, “The lever is in the wrong position”). Summarise the main points of the communication at the beginning. Where possible, supplement verbal information with written or another form of visual information so that there is redundancy of information to help avoid mistakes. Check that the other person has fully understood, do not take it for granted. Summarise main points at the end of the communication. Person you are communicating with should be actively listening, asking questions and confirming understanding, not just nodding their head. Safety communication training should not be classroom-based, it should provide delegates with the opportunity to practice these skills and go away a better communicator.
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Benefits This would help to tackle the issue of poor risk awareness by helping to ensure that critical information relating to hazards and risks is effectively communicated. However, it would not address the whole issue, and would need to be supplemented with a hazard awareness training and training effectiveness monitoring scheme. This training would need to raise awareness of the conditions under which complacency can impair safety performance, such as ongoing maintenance activities, as this complacency was another of the common causes listed in the previous section. This recommendation would also help to address another common cause, ineffective briefings. 6.6.4
Checking the Planning Process
On a number of occasions, there were failures in the planning process that contributed in some way to the incidents. For example, providing the wrong map of underground services, planning work for red-zone working when there is a T3 possession the following week, having work areas and isolations with different limits, etc. A checking (or auditing) process is required to identify these problems early when they arise, and try to find a safer alternative. There are clear barriers to be overcome – at present, there appears to be a culture in the rail industry that encourages a focus on keeping trains running and avoiding delay. A system that asked for all electrified area working to take place during a T3 possession would not fit within this culture. Some form of step-change is required, similar to the change that was initiated in the offshore industry following the Piper Alpha disaster. The petrochemical industry is living proof that this can be achieved, and the documentation that discusses how to go about ‘changing minds’ is available from the Step Change website (http://step.steelci.org/publications/main_publications_fs.htm). A parallel to the change that is required can be drawn from the implementation of the RIMINI approach for protection of lineside workers. Rather than determine what work can be done under live conditions have a hierarchical approach that looks at the safest possible option first. 6.6.5
Recommended Further Analysis
It would be useful at some later date to perform an analysis of the recommendations generated by the incident reports to find out how effective they have been in reducing the occurrence of incidents in electrified areas. This should involve making contact with the organisations involved in the incidents and finding out how well the recommendations were received, and whether they have been implemented. This would also provide the opportunity to perform a reality-check of the recommendations from this report with these organisations, and obtain impressions of the value added by human factors analysis. The Railway Group Safety Plan (RGSP) already contains a recommendation for Railway Group members to assess safety culture. Reviewing these incidents suggests that to some extent behaviours of workers are being influenced by a ‘can-do’ culture that seems prevalent within the rail industry. This is resulting in workers taking risks in the belief that they will gain acceptance from their colleagues and managers for getting the job done. It would therefore seem that the RGSP recommendation is much needed, and that the assessment of safety culture within the rail industry should be heartily encouraged. An obstacle in the preparation of this report has been the availability and inconsistency of information contained within Formal Inquiry Reports. It is recommended that a review of Standards covering this requirement is undertaken.
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6.7
Predictive Error Analysis
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 objective of this exercise was to predict the types of human error, which could occur whilst working in AC, or DC electrified areas. The method used to conduct this analysis was a predictive form of the technique used to examine the occurrence of error retrospectively, based upon TRACEr Lite, that was applied to the incidents described in the main body of this report. The technique is driven by a task analysis, which in this case was substituted for the risk assessment referred to above. The process for the assessment is as follows for each task in the task analysis: (i) (ii) (iii) (iv) (v) (vi)
Determine the performance shaping factors associated with that task; Predict the observable errors that might occur (see below for detail); Predict the types of error (perception, memory, decision or action) that might lead to the error as described in (ii); For the chosen error type, determine the most likely error mode (a definition of how the error type manifested itself); Determine the opportunities for recovery from the error described in stages (i) to (iv); Where stage (v) indicates that there are recovery opportunities, determine how likely it is that recovery will be successful;
Once this process was complete, references were made to the severity ratings assigned to tasks in the original risk assessment. In order to tie the assessment results to the analysis of incidents reported earlier, each task was checked against the incident data to determine whether human performance of that task had been a causal or contributory factor in any of the incidents that were analysed. On completion of the analysis, the results were reviewed by electrification specialists from Balfour Beatty Rail over a period of two days to check the feasibility of the errors predicted. An initial meeting was held at The Keil Centre’s Edinburgh office to thoroughly explain the rationale behind the results and ensure that the electrification specialists were comfortable with interpreting the data. Although this form of analysis is based upon the same model as the methodology used for retrospective analysis in the main body of the report, there are some notable differences that the reader needs to be aware of to avoid confusion. Firstly, ‘observable error type’ refers to what indication there would be to a third party that an error had been made (for example, missing a step out of a procedure). This is used in addition to the ‘error type’, which describes what happens in terms of the human information processing system of the person making the error. Secondly, predictive error analysis is also concerned with the opportunities which exist to recover from the error, and how likely successful recovery would be. In order to do this, there needs to be some indication of how the error would manifest itself to a third party (i.e. the observable error type), because it is clearly necessary to be able to detect an error in order to be able to recover from it. Errors, which do not manifest themselves in any way (i.e. they remain inside the head of the person making the error), are clearly more difficult to recover from because detection and recovery
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are in the hands of the person making the error. Errors that do manifest themselves such that others (or electronic systems) stand more of a chance of being recovered. Finally, the term ‘extraneous act’ describes an action that is not required within the task sequence, but which has nevertheless occurred. An extraneous act is not necessarily an incorrect thing to do in itself, but within the context of the task in hand it is inappropriate. An extraneous act can be observed by a bystander, in that an action would be seen that could be recognised as being surplus to requirements for the task. 6.7.1
Results of Predictive Error Analysis
In all, 205 tasks carried out in electrified areas (both AC and DC) were analysed. They comprised tasks involved in inspection of equipment and facilities (i.e. those that do not involve physical contact with energised equipment), those tasks that involve working in close proximity to electrical equipment that may or may not be energised, and those tasks that involve intrusive maintenance of electrical equipment. The initial results of the analysis revealed that the tasks could be divided into three different groups based on the types of error that could occur when performing the tasks. These groups of tasks were examined to identify any common themes in order to allow them to be identified in this report. The following classification system was adopted: 1. Inspection and Servicing – tasks involving only visual inspection of equipment or servicing equipment; 2. Inspection and maintenance in proximity to electrical source – inspections of components of electrified systems (e.g. conductor rail) and maintenance work in the vicinity of the track (e.g. vegetation clearance, boundary maintenance); 3. Maintenance – intrusive maintenance of electrical equipment or working in close proximity to energised electrical equipment. Each of these classifications will now be examined in more detail to provide: an indication of the types of errors predicted in each case an indication of the severity ratings associated with the tasks that make up each class of task whether or not any of the incidents reviewed for the main body of this report involved any of the tasks included within the classification. 6.7.2
Interpreting the Results of the Predictive Error Analysis
In the pages that follow, the results of the predictive analysis are presented in a series of tables accompanied by explanations of the data. This information should be interpreted in the following way: 1.
Review the list of tasks associated with each group. These are located in Appendix E.
2.
Review the list of performance shaping factors for each group. interfere with performance of the tasks in this group.
3.
Review the details of predicted errors. This section begins by providing an indication of the types of error that might be observed (e.g. an extraneous act). For each observable error type predicted, there is then a table, which describes how human information processing might break down and result in the predicted observable error. In each table the error type is listed first (e.g. action error) followed by the error mode – how this error might occur (e.g. selection error). Note that in some cases, there are several ways in which the observable error could come about (e.g. by action, perception or action error). In such
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cases, all feasible ways in which the error could be generated are explained in the table5. The table then goes on to show whether or not the analysis predicts that recovery from the error would be possible, if so the assessed likelihood that recovery from the error would be successful, and a comments field to provide additional explanation. 4.
Following the table there is a list of incidents reviewed for this study, which involved relevant tasks from the risk assessment, and a brief explanation of what happened in each case.
6.7.3
Inspection and Servicing
List of Tasks See list at Appendix E. All tasks in this group received risk rating of “5” or less in the risk assessment (i.e. low risk). Performance Shaping Factors The tasks covered by this classification were most likely to be affected by the following factors: Weather Noise and distraction Alertness / concentration / fatigue
Lighting Familiarity with the task
Details of Predicted Errors The most likely way that an observer would be able to tell that an error had occurred would be observation of an unrequired and incorrect action (i.e. an extraneous act). The following table describes how this could occur: Extraneous Act (unintentionally taking action that is not required) Error Type
Error Mode
Selection error Action (unintended physical action)
Recovery Is Recovery Success Possible? Likelihood Yes
Low – may not have time to intervene
Comments Action error or incorrect positioning of a hand, or tool, results in contact with energized equipment - special consideration should be given to this task, including isolation
None of these tasks was involved in the incidents that were reviewed for this project. 6.7.4
Inspection and Maintenance in Proximity to Electrical Source
List of Tasks See list at Appendix E. The tasks in this group received a risk rating between 10 and 20 in the risk assessment (i.e. they are moderate to high risk).
5 This means that any of the error types could result in the observable error, not that all of them would occur together to produce the observable error.
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Performance Shaping Factors The tasks covered by this classification were most likely to be affected by the following factors: Weather Noise and distraction Alertness / concentration / fatigue
Lighting Familiarity with the task
Details of Predicted Errors As with the inspection and servicing tasks, one of the most likely ways in which errors would manifest themselves would be in extraneous acts (unrequired actions that are also incorrect). In addition to this, errors within this group of tasks are also likely to manifest themselves by operators taking more action than is required to perform the task (e.g. getting too close to live equipment) a type of error expressed as ‘action too much’. The following tables describe how these situations could occur: Extraneous Act (unintentionally taking action that is not required) Error Type Error Mode
Action
Is Recovery Recovery Success Possible? Likelihood
Selection error (unintended Yes physical action)
Low – may not have time to intervene
Comments
Action error or incorrect positioning of a hand, or tool, results in contact with energized equipment - special consideration should be given to this task, including isolation
Action Too Much Error Type Error Mode
Is Recovery Recovery Success Possible? Likelihood
Perception No Perception Yes
Comments
Low to Moderate – more time to intervene Going too close to the energized if a worker is seen to equipment because of failure to be getting too close to perceive proximity to it energized equipment
Two of the incidents reviewed for this project were related to one of the tasks from this group – manual vegetation clearance. Adwick in August 2000 involved vegetation clearance but involved a violation by one of the workers rather than a human error. The Leighton Buzzard incident of June 1985 also involved vegetation clearance, but there was insufficient information in the investigation report to determine the human factors cause.
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6.7.5
Maintenance
List of Tasks See list at Appendix E. All tasks in this group were rated above 20 in the risk assessment (i.e. high risk). Performance Shaping Factors This was by far the largest group of tasks identified, covering a range of tasks involving maintenance work on or around electrical equipment. This includes intrusive maintenance of electrical equipment or maintenance in close proximity to energised electrical equipment. Due to the range of tasks involved the factors likely to affect the performance of those carrying out the tasks is extensive, as shown in the following list: Time pressure;
Non-standard activities;
Procedure availability/access/location;
Weather;
Lighting;
Temperature;
Familiarity with task;
Level of experience;
Recency of training;
Training quality;
Competence testing;
Mentoring quality;
Alertness/concentration/fatigue;
Complacency;
Team co-ordination quality;
Handover/take-over;
Team maturity;
Supervision;
Staff availability;
Details of Predicted Errors Many of the tasks in this group were more complex than in the previous two groups, and therefore presented more opportunities for error. The following list describes the ways in which errors could manifest themselves in this type of task: Action Too Much – doing more than is required, e.g. getting too close to an energised electrical source; Extraneous Act – action that is not required and is incorrect, e.g. unintentionally touching a wrench to the energised conductor rail. Action too Early – action that occurs at the wrong time, e.g. driving a vehicle off before all of the workers are on board; Right Action on Wrong Object – the choice of action is correct but the selection of object is incorrect, e.g. cleaning one of several section insulators, but selecting a live one by mistake; Action in Wrong Order – an action is conducted at the wrong point in a sequence, e.g. unintentionally starting work before testing has been completed; Omission – an action that should have been taken is missed out, e.g. failing to conduct live line testing prior to commencing work. The analysis suggested that there were a number of types of error, which could lead to the occurrence of these observable errors. The following tables describe the predicted errors in more detail, including the likelihood of recovery.
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Action Too Much Error Type Error Mode
No Perception Perception
Is Recovery Possible?
Recovery Success Likelihood
Comments
Yes
Low to Moderate – more time to intervene if a worker is seen to be getting too close to energized equipment
Going too close to the energized equipment because of failure to perceive proximity to it
Extraneous Act (unintentionally taking action that is not required) Error Type Error Mode
Action
Selection error (unintended physical action)
Is Recovery Possible?
Recovery Success Likelihood
Comments
Yes
Low – may not have time to intervene
Action error or incorrect positioning of a hand, or tool, results in contact with energized equipment - special consideration should be given to this task, including isolation
Is Recovery Possible?
Recovery Success Likelihood
Comments
Action Too Early Error Type Error Mode
Perception Misperception Yes
Memory
Forget information
Decision
Misjudgement Yes
Yes
E.g. Accessing equipment too Low – could be difficult if early because equipment the misperceived status information has been information is credible misperceived Accessing equipment too early because the checking Low – difficult for others procedure or other to detect a memory failure information relating to equipment status is forgotten Low – difficult to recover Making a judgment about the is basis of judgment is safety of working around live credible, also difficult for equipment, which is in some co-workers to detect a way lacking decision failure.
Right Action on Wrong Object Error Type Error Mode
Is Recovery Possible?
Recovery Success Likelihood
Perception Misperception Yes
Low to moderate– relies on further checks by individual or detection of mistake by co-workers
Memory
Low to moderate– relies
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Yes
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Comments
Action taken on a live piece of equipment instead of the intended de-energised or nonelectrified equipment due to perceptual confusion between pieces of equipment Action taken on a live piece
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on further checks by individual or detection of mistake by co-workers
of equipment instead of the intended de-energised or nonelectrified equipment due to misrecall of the equipment reference number, location, isolation limits, etc. Action taken on a live piece of equipment instead of the intended de-energised or nonelectrified equipment due to action error resulting in inappropriate selection of equipment
Yes
Low – difficult to intervene in time to prevent harm
Error Type Error Mode
Is Recovery Possible?
Recovery Success Likelihood
Comments
Memory
Yes
Low
Misrecall of work procedure leads to a step in a procedure being taken out of sequence
Is Recovery Possible?
Recovery Success Likelihood
Comments
Action
Selection error
Action in Wrong Order
Misrecall
Omission Error Type Error Mode
Memory
Late/missing Yes action
Forget Information Misrecall
Decision
Failure to confirm isolation in place (e.g. live line testing) or check equipment status prior Low to Moderate – reliant to commencing work. Could on co-worker to spot the be due to memory failure omission before harm or stemming from a late or last minute realization by missing action, information the worker being forgotten (e.g. forgetting procedure) or misrecall of information
Yes
As above
As above
Yes
As above
Poor decision Yes / plan
As above
As above Failure to check of equipment status, or confirm isolation caused by a poor decision or plan, which does not include provision for standard checks, leading to work commencing with equipment energized
Twelve of the incidents reviewed for this project involved tasks that fall into this group. Of these, seven were classified as errors and the remaining five were violations. Further details of these incidents are provided below:
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At East Croydon in September 2002, a worker was electrocuted whilst replacing cable tubing near the rails. The analysis of this incident indicated that this was a violation rather than an error. At Oakley in August 2003, a lookout was electrocuted when he joined in with the replacement of insulator pots. This was found to be a violation rather than an error. At West Croydon in October 2001, two workers were injured whilst maintaining a rail flange lubricator when an uninsulated spanner contacted the energised conductor rail. A human error analysis was performed which suggested that this was an action error (specifically a selection error because it was a physical action) and that this was most likely due to human variability in physical performance (i.e. the same person does not always perform to the same level of precision, their performance will naturally vary). This is in line with the predicted action (selection) error leading to an observed extraneous act. The most effective solutions to prevent such errors of action involve removing the hazard or physically separating the worker from the hazard. In the analysis of this incident, the recommendations covered working under T3 conditions, ensuring properly insulated tools are used, and the use of rail shields. At Doncaster Belmont in December 2001, a worker died when he climbed on top of a wagon, presumably to check its contents. The worker was alone at the time and so the circumstances behind the accident are unclear. However, a human error analysis suggested that the most likely course of events were that the worker made a poor decision regarding climbing on top of the wagon due to a lack of knowledge. The knowledge that was most likely missing was that he could check the contents from the label (or perhaps where the label was located), and there may have been a lack of knowledge regarding the dangers of overhead lines. Recommendations covered the provision of training on the hazards associated with AC equipment, the use of situational risk assessments, and familiarity with goods wagon labelling. At Harlow Mill on the 5th May 2002, a worker received an electric shock when redistributing the load on top of a wagon. This was an error on behalf of the Engineering Supervisor, who had made a poor decision based on a faulty mindset. Recommendations covered effective communication training, guidance on high-risk handovers, checking procedures and audits of COSS briefings. At Tollerton in May 2001, several workers received electric shocks during the unloading of track by a crane that fouled the overhead line during a renewals project. Investigation of the incident suggested that this was a violation rather than an error. At Hemel Hempstead in August 2001, a worker received an electric shock when cleaning a section insulator. Two errors were identified, one on behalf of the worker and one on behalf of the person giving the briefing. One was an action error (unclear information on location of live equipment); the other was a perception error where information was misperceived due to confusion. Recommendations covered the conduct of line testing in complex areas and provision of safety communications training. At Marston Green in July 2003, workers received electric shocks during preparation for work on the OLE. Analysis of the incident revealed that this involved a violation rather than an error. At Ranskill in October 1998, a worker was killed when he removed the earth end of a long earth before the line end. Analysis revealed that this was a perception error stemming from a misperception that a colleague had removed the line end. Recommendations covered a oneman procedure for removing earths, effective communications training, refresher training and opportunities to develop skills, and auditing of records of working hours.
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At Liverpool Street in November 1999, a worker was injured when he made contact with the OLE whilst climbing some scaffolding. Analysis suggested that this was a perception error (misperception of correct location by the contractor) caused by confusion between different locations on the station that looked similar. Recommendations covered coinciding worksite and isolation limits, and regular audits by the site safety authority. An incident at Dock Junction in February 2002 involved workers trying to dismantle a scaffold under OLE following a shortening of the possession which meant that there was not time to complete the job safely. This was classified as a violation rather than an error. At Handsworth in March 2002, two workers were burned when they ruptured a buried 132Kv oil-filled HV cable. The analysis suggested that this was due to an error of perception (failure to perceive information), caused by their expectations regarding what was buried at the worksite. Recommendations included planning documentation with enhanced detail and procedures for encounters with buried objects. 6.7.6
Summary
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. It was felt that decision-making errors would be more likely in planning and management tasks than in manual tasks. The review of previous incidents reported in the main body of this document suggested that the most common form of error was the perception error, which occurred four times in those incidents reviewed. There were also two action errors and two decision-making errors. None of the incidents reviewed included memory errors. The incidents that were reviewed were, largely, associated with tasks that have been classified under the higher risk classification categories in the risk analysis (i.e. those that have a rating of 20 or 25 on a 5 x 5 scale). A number of incidents have involved error types that have also been predicted for other tasks that so far, and to the best of our knowledge, have not been involved in incidents. It is therefore important that means of reducing the likelihood that such errors will occur in future, or if they do their impact can be lessened, should be afforded a high level of importance. In the main body of this report, the analysis of the sample of electrification incidents resulted in a series of recommendations directed towards preventing or mitigating similar events in the future. The results of this predictive analysis can be used to generate more generic recommendations that can be applied to a greater range of tasks. Based upon the output from the predictive analysis, the following section documents some generic recommendations, which should be considered for reducing the likelihood and impact of errors for all tasks that receive higher risk classifications in the first instance. It is not recommended that such error-reduction measures only be applied to the higher-risk tasks, although these should receive priority attention. Other tasks should be given similar attention once the higher-risk tasks have been addressed. 6.7.7
Generic Recommendations
These recommendations are presented grouped by the type of error (perception, memory, decision or action) that they are designed to address. These recommendations are generic; to apply them they should be interpreted in the context of the specific task (or tasks) to which they are to be applied. They are intended to provide a starting point from which to develop a specific recommendation to fit a particular situation.
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Perception Error Recommendations 1. Introduce checking procedures to be followed by people operating in the more risky conditions to trap errors prior to incidents. 2. Raise awareness of conditions under which tunnel vision (focussing on one piece of information at the expense of others) can cause difficulties (e.g. emergency conditions and other high-stress situations). 3. Train and educate personnel to develop situational awareness skills to reduce the likelihood that they will distract others during performance of critical tasks and increase the likelihood that errors caused through distraction will be identified early. 4. Raise awareness of the influence of distraction and preoccupation on error rates and encourage personnel to consider these as part of a personal risk assessment prior to conducting work. Personnel should feel able to raise preoccupations and distractions that they feel could affect safety through programmes such as “Time Out for Safety”. 5. Provide means of clearly distinguishing de-energised equipment from energised equipment (e.g. marker boards, brightly coloured isolation permits, etc).
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Memory Error Recommendations 1. Design training to include a period of practice prior to returning to the job. 2. Raise awareness throughout the workforce of the safety impact of lack of learning and encourage the reporting of instances where they feel risks exist (e.g. through existing open reporting systems, Time Out for Safety, etc.). 3. Provide aides mémoire for critical tasks to reduce memory load. 4. Provide regular emergency training to reduce the probability of memory failure. 5. Ensure that multiple team members have the information required for critical tasks to introduce redundancy. 6. Review procedures regularly with members of the workforce to reduce ambiguity and complexity and ensure that they are fit for purpose, effective and easy to use and remember. Decision Error Recommendations 1. Provide training in decision making in order to increase skills in integrating several information sources, considering potential side effects of actions, checking the validity of plans as the situation unfolds. 2. Introduce procedural checks by other personnel to detect errors in time to correct them. 3. For critical actions, use multiple personnel in the decision-making process to increase the probability that decision-making failures will be identified early. 4. Ensure that newly trained personnel receive mentoring or supervision for a period of time to ensure that training has been successful 5. Introduce a formal training evaluation procedure to identify shortcomings in existing training interventions. 6. Ensure that all personnel receive the training required to enable them to fulfil their duties safely and reliably. 7. Introduce situational awareness training to help ensure that all team members are aware of all stages of the decision-making process and are able to intervene should there be a problem. Action Error Recommendations 1. Design the working environment to account for variation in body size and inaccuracy of positioning (e.g. make steps wide enough to accommodate 5th percentile female shoe size up to 95th percentile male shoe size). 2. Ensure that all personnel are provided with adequate practical skills training to meet operational requirements. 3. Ensure that training is in place to overcome potential confusion associated with habits from previous jobs or changes to equipment. 4. Raise awareness of conditions under which thoughts and habits can intrude and encourage team members to be more vigilant under such conditions.
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7 7.1
Task Identification and Risk Analysis Methodology
This element of the research has included the identification of tasks that are undertaken by maintenance and renewal teams on the electrified railway. The scope of tasks examined included Permanent Way; Signals; Telecommunications; Contact Systems (both AC and DC); Power Distribution and Off Track activities, which include vegetation clearance and drain cleaning. In excess of 600 tasks performed on the operational railway were identified and risk assessed. The breakdown of tasks against each function is shown in the table below: Function Permanent Way Signalling Telecommunications 750 V DC Conductor Rail 25 kV AC Overhead Line Power Distribution Off Track Activities Total
No. of Tasks Identified Overhead Line DC Conductor Rail 62 62 88 83 43 47 N/A 36 49 N/A 23 24 51 61 316 313
Having identified the various tasks, a panel of experienced personnel from within the Balfour Beatty Rail Group of Companies was formed. The panel reviewed the risk associated with undertaking each task and ranked it in terms of likelihood and severity assuming that only base line controls were in place. The base line controls included basic competence e.g. PTS and any specific competence requirement required for the task such as Level A, B or C Competency for working on or near live electrical equipment. RT/E/S/21070, RT/E/P/24001 and RT/E/C/27018 refer. Risk assessments were carried out in accordance with a risk rating approach using a 5 x 5 matrix. Degree of risk (rating) = likelihood x severity. Numerical Value 1 2 3 4 5
Likelihood Improbable Remote Occasional Probable Frequent
Definition Extremely unlikely to occur Unlikely to occur Likely to occur once Likely to occur more than once Extremely likely to occur
Numerical Value 1
Severity Negligible
2
Minor
3 4 5
Noticeable Major Fatal
Definition Little risk of injury or disease Minor injury that may result in less then one shift loss time Lost time injury of more then one shift Accident or Incident reportable under RIDDOR Loss of life
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The above values are then multiplied together to give a risk ranking as follows: Likelihood 1 1 2 3 4 5
1 2 3 4 5
Risk Rating
Class
1 to 3
Negligible
4 to 5
Low
6 to 9
Medium
10 to 14
High
15 to 25
Unacceptable
2 2 4 6 8 10
Severity 3 3 6 9 12 15
4 4 8 12 16 20
5 5 10 15 20 25
Control Action Ensure identified controls are in place. Monitor work to ensure no increase in risk Ensure identified controls are in place. Monitor work to ensure no increase in risk Ensure controls are in place. Monitor and review work methods to further reduce risk Action required to control risk. Review work methods to reduce risk. Monitor situation Action required to modify work methods and introduce controls to reduce risk rating
Having followed the format detailed above across the range of tasks identified in both an overhead line and DC electrified railway scenario, 202 of the tasks assessed fell into the red risk category with only base line controls applied. Shown in the chart at 7.2 is an example of the process adopted for a number of tasks undertaken in the category of Permanent Way Engineering. As can be seen for these tasks, only two falls into the red risk category and requires additional control measures to be applied to bring the risk down to a tolerable level. Additional control measures for these activities could include additional training, using surveying equipment in OLE areas that is non-conductive, physical stops on the telescopic poles to restrict their height or in the extreme, only undertaking this activity when the overhead line has been isolated and earthed. In view of the number of tasks identified, it was decided to concentrate on those, which fell into the red risk category. The charts shown at Appendices F1 to F10 inclusive detail the tasks, which came out as red risks with only basic controls being applied. The column on the extreme right of the charts highlights areas where additional control measures could be applied to bring the risk down to a tolerable level. This may mean in some instances only doing those tasks under isolated and earthed conditions. The degree and extent of the additional control measures should reduce the residual risk down to one that does not put employees at undue risk.
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7.2
Example of Task Identification and Risk Assessment Process
Task List and Risk Assessment for Permanent Way Engineering in OLE Area Proximity to OLE Task
Description
Key Electrical Risk
>2.75 600mm <600mm M 2.75M
RA Basic Control Measures L
S
Total
None Identified
1
5
5
None Identified
1
5
5
None Identified
1
5
5
None Identified
1
5
5
None Identified
1
5
5
None Identified
1
5
5
None Identified
1
5
5
None Identified
1
5
5
None Identified
1
5
5
Possible Mitigation
Inspections Patrolling S&C Inspections Ultrasonic Inspection (Manual) Ultrasonic Inspection (Manual) Formation Structures Fencing Tunnels Longitudinal Timbers
Foot Patrol and Visual Inspection of the P Way Foot Patrol and Visual Inspection of S & C Staff undertaking NDT using hand trolley Staff undertaking NDT using hand probe Foot Patrol and Visual Inspection of the P Way Structures examination by staff from Rail Level Fencing inspection from track or cess Foot Patrol and Visual Inspection of tunnels Foot Patrol and Visual Inspection of timbers
Clearances
Foot Patrol and Visual Inspection of the P Way
None Identified
3
5
15
Surveying using levelling equipment
Staff undertaking optical survey of track
Equipment coming into contact with live OLE
4
5
20
Rail lubricator servicing
Staff working at rail level
None identified
1
5
5
Rail lubricator replacement
Staff working at rail level
None identified
1
5
5
Fishplate oiling
Staff working at rail level
None identified
1
5
5
All staff undertaking these tasks have been trained and certificated to PTS requirements All staff undertaking these tasks have been trained and certificated to PTS requirements All staff undertaking these tasks have been trained and certificated to PTS requirements All staff undertaking these tasks have been trained and certificated to PTS requirements All staff undertaking these tasks have been trained and certificated to PTS requirements All staff undertaking these tasks have been trained and certificated to PTS requirements All staff undertaking these tasks have been trained and certificated to PTS requirements All staff undertaking these tasks have been trained and certificated to PTS requirements All staff undertaking these tasks have been trained and certificated to PTS requirements This subject to be given further consideration especially where gauges are used which could come into contact with live OLE Telescopic staffs can come into contact with OLE
Rails All staff undertaking these tasks have been trained and certificated to PTS requirements All staff undertaking these tasks have been trained and certificated to PTS requirements All staff undertaking these tasks have been trained and certificated to PTS requirements
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level.
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7.3
Summary
7.3.1
Overhead Line Areas
In the majority of cases the red risks can be managed down to a tolerable level by the application of the requirements of RT/E/S/29987 Module 3 which details the requirements for the management of electrical risks involved when work is to be carried out on or about 25 kV A.C. Electrified Lines. The document states that before any work is carried out on or about the electrified lines, the work shall be subjected to risk assessment in relation to the danger from the live parts of the OLE, and live pantographs and other roof mounted electrical equipment on trains. It is a requirement of the document to produce a risk assessment and a written method of working. Dependent on the proximity to the OLE of the intended work the levels of preparation, review and authorisation vary. From discussions with personnel who undertake both maintenance and renewal activity it has become apparent that the requirements of RT/E/S/29987 are not as widely understood as they should be, and that the availability of the document to all pertinent employees working on or near to electrified lines is often restricted. RT/E/S/29987 is quite specific regarding the responsibilities of Employers and states in Module 1: ‘Responsibilities of Employers Employers are responsible for ensuring that persons under their supervision who are required to work on, or so near to, electrified lines that danger may arise are supplied with, trained and where required certificated in meeting the requirements contained within, the relevant Modules forming Network Rail Company Specification RT/E/S/29987 and that all such persons: a) fully understand the requirements relating to their personal safety; b) fully understand the requirements relating to obtaining an emergency isolation; c)
understand the requirements which apply specifically to them and that they shall make themselves acquainted with, and will be held responsible for the observance of such requirements.’
Whilst the ‘Green Book’ (RT/E/S/29987) has been the ‘bible’ of electrification staff for many years and they afforded some degree of protection and overseeing in the pre-privatised railway industry to other functional groups, the same cannot be said in today’s disaggregated railway. Electrification poses many hazards but the premise of ‘work within the rules and you will be safe’ rings true. It is recommended that the application of RT/E/S/29987 is further investigated and that Network Rail undertake targeted audits to confirm that Employers are adequately discharging their responsibilities in accordance with the clause highlighted above. Full application of the ‘Green Book’ including the requirement to undertake risk assessment will mitigate the risk to personnel from contact with a live conductor. Consideration needs to be given to activities where the ‘less than 2.75 Metre’ rule is likely to be breached in respect of identifying the need for an isolation or other safe system of work employing the use of PPE, Insulated tools etc. Special consideration should be given where the distance is likely to be less than 600mm. In both cases, strict adherence to the requirements as detailed in RT/E/S/29987 regarding safe systems of work should be observed. Planning is seen as key in mitigating risk and careful consideration needs to be given when undertaking activities such as renewals involving plant and equipment. A number of incidents
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have occurred where lifting machines located outside the area defined as being ‘on or near’ have made contact with the live overhead line, putting people’s safety at risk. (See Tollerton Incident May 2001 Section 6.4.15). Changes to the planned activity should not take place unless the changes are re-planned and the risks re-assessed. The incidents at Harlow Mill and Marston Green (See Sections 6.4.8 and 6.4.11) are typical where late notice change was effected without re-planning and re-assessing the risk. Off track activities, especially vegetation clearance is another area where there have been a number of incidents (See Adwick 2nd August 2000 Section 6.4.2). Once again, the activity should be fully risk assessed at the planning stage and the need for a suitable ‘Safe System of Work’ identified. There is some merit in looking at the approach the industry has taken to the safety of people working on or near the line as defined in RT/LS/S/019. It is recommended that consideration be given to undertaking further research that examines the merits of mandating a hierarchical approach to safety of persons working on or about the electrified line such that the first consideration is always the safest possible way (isolation). In the event that it is not possible to secure an isolation then the next consideration should be to adopt alternative safe systems of work. No activity should be performed on the electrification equipment itself without first obtaining an isolation and following the requirement for a ‘Permit to Work’ (Form C). 7.3.2
DC Conductor Rail Areas
In DC conductor rail areas, the likelihood of contact with an energised conductor is greatly increased due to it being at ground level and adjacent to the running rail. Many of the red risks can be managed down to a tolerable level if the requirements of GO/RT3091 Issue 2 are followed. GO/RT3091 states that every person working on or near a line electrified by the DC conductor rail system must be supplied with a copy of the instructions relevant to their duties. It further states that Employers and Persons in charge are responsible for ensuring that all persons under their supervision including contractors, are supplied with and are competent in the use of these instructions and that each person: (a) Understands which of the instructions apply to them and that they must make themselves acquainted with, and will be held responsible for, the observance of all such instructions; (b) Fully understands the instructions relating to their personal safety. As stated in the section relating to the OLE it is further recommended that Network Rail establish the application of the requirements of GO/RT3091 across the industry. GO/RT3091 further states that ‘Work on near the conductor rail shall be carried out under the protection of a Conductor Rail Permit except as shown in instruction 2.1.3’ Instruction 2.1.3 states that ‘Certain activities, for example those shown in Instruction 43 can be carried out with the conductor rail live subject to the establishment of a safe system of work. Instruction 43.2 states ‘Where it is not reasonably practicable to isolate the conductor rail and issue a conductor rail permit certain activities may be carried out with the conductor rail live. In these circumstances, a safe system of work for each activity must be established.
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The problem arises in the interpretation ‘reasonably practicable’ and who actually determines and authorises work on or near the live conductor rail. Much work has been undertaken in the past on enhancing GO/RT3091, which culminated in the production and issue of ‘Issue 3’, which went into some depth on the requirements of safe systems of work related to the proximity of the activity to the conductor rail. Issue 3 was subsequently withdrawn due to other circumstances and the industry was slow to react to continuing with the other benefits that it contained. It is known that some work was undertaken by maintenance contractors working in the Wessex, Kent and Sussex areas on the identification of tasks that were performed on or near to the electrified DC line and the establishment of safe systems of work. It is recommended that this work is revisited and mandates issued as to which activities are allowed to be performed with the conductor rail live and which are not. The incidents at East Croydon in September 2002 and Oakley in August 2003 involved undertaking work on the conductor rail under live conditions. The question of whether it was not reasonably practicable to take an isolation has to be answered. Once again the planning process is key to the establishment of a safe system of work and the recommendations for a RIMINI approach to planning work in respect of danger to electrocution is re-emphasised.
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8 Developments 8.1
Introduction
This section of the report looks at some of the developments that are either available, in the process of being developed or where benefit is seen from undertaking development to enhance safety or improve efficiencies without compromise to safety. Although there has been much work done already in the development of safety enhancing devices the industry has been slow to respond in their introduction and as a result use has been extremely limited. Phase 2 of this project is seen as an ideal vehicle to progress worthy items in a logical and controlled way such that their introduction and availability is improved.
8.2
Specific Developments
8.2.1
Personal Live-Line Indicators (LLI)
These devices are intended to warn individuals of the proximity of 25kV live equipment. They do not replace Live-Line testers as part of the isolation process. The particular device reviewed in this report is the CoTEC Technology ‘Cricket’. It is a small battery powered device, the size of a normal key fob. It should be attached to hard hats or only offered towards the OLE on an as required basis. It will start to alarm (beep) from approximately 2.75m increasing the rate of beeps as that dimension decreases. Further operating details are available from the manufacturer. Early trials by Balfour Beatty Rail Projects (mid 2005) shows that the device performs as described; in particular NOT giving spurious results beyond 2.75m from 25kV equipment. This clear discrimination ability is essential and commends this device for further operational trials. Product acceptance must be considered as the warning given could clearly be considered as safety critical but may be tempered by the fact that it is an additional control measure, not intended to be the first line of defence or to supplant any of the existing control measures applied in the Isolation process. Whenever a new device is considered the risks it may import must be considered as well as the benefits it brings (table below). Any device that warns of the presence of live OLE has to strike a balance between warning early enough and becoming a nuisance. Where overhead line personnel are working adjacent to live OLE concern remains that any LLI would alarm too frequently. This is not an inherent fault of the device but shows the nature of working adjacent to live equipment. If the right balance could not be found for this application, consideration could be given to fitting to baskets or platforms on OLE rail mounted maintenance machines. It could be argued that had such a device been available and in use at the time of the Marston Green incident in July 2003 the staff who were preparing to work on the OLE would have received a warning and stopped work. It is recognised however, that the introduction of such devices has to be undertaken in a controlled and rigorous manner that looks at all facets of safety. It is recognised that devices of this nature could lead to improved safety and it recommended that a full review with HAZOP and field trials be undertaken in Phase 2 of the project.
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Hazard: Contact with OLE energised at 25kV. Consequence: Death or serious injury Mitigation
Mitigation failure mode:
Factors:
Competence and Person
Control measure
professionalism of Nominated
1) Nominated Person does not give effective briefing Nominated Person briefing and issuing of Overhead Line Permit to each COSS whose work activity requires isolation. Briefing covers safe working limits and residual 25kV hazards.
Too many Permits to be issued within a given time to deliver effective individual briefings
2) COSS does not understand briefing COSS does not brief his own workgroup COSS does not brief relieving COSS
COSS training will be enhanced by Network Rail to include extra content and emphasis on the receipt and briefing of OHL Permits. RT/E/S/29987 (Feb 05) has new section enabling alternative methods of issuing OHL Permits to be considered and implemented.
All of the above in this column can be factors in this most critical residual risk, exacerbated by late changes to plan, work content or personnel.
All of the above in this column are trying to prevent this situation occurring but ultimately, there is no physical last line of defence.
4) Personnel will ignore Nominated Persons briefing and rely on LLI
Wearing of LLI must not affect or detract from NP reaching clear understanding with COSS.
Site audit of all Permit holders to test understanding of safe working limits. (This should occur whether LLI’s are in use or not).
5) LLI not worn correctly and fails to warn at safe distance
Familiarity with new piece of kit LLIs being passed to individuals who have not received training in its use
Identified personnel must be trained and records kept. Consider numbering individual LLIs and issuing to named staff.
Provide clip that is specifically designed to fit a hard hat
6) LLI alarms frequently and is considered a nuisance
As cell above plus has the work been planned to reduce or eliminate residual 25kV hazards?
As above plus challenge the planning of the isolation
Keep in pocket and only use on specific occasions
Not first line of protection
Battery test facility. CE compliant
7) LLI fails completely
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LLI will warn individuals or RMMM that they are approaching live 25kV equipment. LLI does not remove or change the responsibility of the NP to reach clear understanding with the COSS regarding safe working limits
Knowledge of COSS regarding OLE and Permits Content and efficacy of COSS training Time identified for briefing Poor practices may have become the norm. Alternative method of issuing Permit not considered
3) Group or individual fail to follow briefing and stray beyond safe working limits
Wear personal Live-Line Indicator
Nominated Person competence training and assessment regime has been thoroughly overhauled by Network Rail into national package. Number of Permits to be issued MUST be identified at planning stage, and decision made regarding alternative method of issuing Permit to ensure timely effective briefing of safe working limits to all COSSs.
LLI control measure
Issue 1.
LLI gives warning before individual touches live equipment
LLI gives warning before individual touches live equipment
Consider wearing two
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8.2.2
Live Line Testers
There are many variants of live-line testers in use on the rail network, ranging from testers that were developed and manufactured by Regional Electrification Depots, through to testers that have been adapted from those used in other industries. The older BR devices were designed and manufactured prior to the introduction of the Machinery’s Directive and do not carry CE marking. It is doubtful whether they would meet the requirements to gain appropriate certification today. A further complication is the ongoing maintenance and repair. Newly introduced testers have not been without their problems and there have been instances of failure, which could have resulted in injury. Discussions with one leading manufacturer of testers for the Electrical Supply Industry has indicated a reluctance on their part to enter into development because of the relatively small numbers involved and the uncertainty of product acceptance. It is recommended that the specification and development of live line testers be pursued in Phase 2 of this project. 8.2.3
Data Logging in Live-Line testers
Live-Line testers are used to check that overhead line equipment has been removed from all sources of electrical supply. The consequences of not testing have previously been described. That can happen because testing is not interlocked with circuit breakers, switches or isolators. It relies on the competence and discipline of the Nominated or Authorised person to carry it out correctly, as per their training, sustained by a safe professional culture in their workplace. Compliance with testing on every occasion is impossible to check at present. The innovation of data logging in the live-line tester can improve that, and if managed properly would discourage future non-compliance. The author has discussed this with Co-TEC: Existing C31 testers can be modified to carry out data logging. The microcontroller on these testers can tell whether the line voltage is high or low (i.e. above 11kV or below 10.9kV). The tester will log the date and time the tester was applied to an overhead line carrying high voltage, and also when it was removed from the line (or the line de-energised). Depending upon memory available, the tester would be able to store the last 10 to 20 tests. The tester will write over the oldest test in the log when the memory is full and a new test is carried out. It will not be able to log a de-energised check only. The latest C31 tester can store hundreds of tests. It can log the precise measured voltage, the date and time the tester was applied to the energised line and the time it was removed (or the line de-energised). It may be used to record a de-energised check so long as there is at least some residual voltage left in the line to measure (because it can measure actual voltage rather than just high or low). The memory will take much longer to fill compared to the modified testers, but once it is full, the tester will write over the oldest data first just as before. Existing C31 testers may have the complete control boards replaced to give full functionality but that will be more costly, nevertheless it is an option. In both cases, CoTEC can supply a communication device that plugs into the existing socket at the back of the tester so that owners can interrogate their C31 testers as desired. The benefits will be to spot check the activities of Overhead Line staff with regard to correct isolation procedure. In the event of an incident, the tester should be immediately quarantined so that the logs can be retrieved and, if necessary, returned to CoTEC for independent verification. Although introduction of this facility will not in itself prevent an incident occurring, it will encourage personnel to follow the procedures and thereby improve safety.
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It is recognised that devices of this nature could lead to improved safety and it recommended that a full review with HAZOP and field trials be undertaken in Phase 2 of the project. 8.2.4
Interlocked long earths
P&B Weir has introduced interlocked long earths. They provide a positive deterrent to applying the earth end last. The principle is that the earth end clamp does not have a tommy bar, only a collar that will spin without turning the spindle/clamp. In order to tighten the earth clamp the tommy bar and spindle from the live-end must be offered up to the earth clamp, engaging with the spindle of the earth clamp and enabling it to be tightened. To prevent the enterprising Lineman cutting off the Live-end tommy bar for permanent ready use, there are 20 different live-end and earth-end combinations that must match to successfully engage. The interlocked long earth is a similar price to the standard long earth dependant on quantity. Whilst this system is not an absolute barrier to applying the live-end first, it does introduce a real need for the authorised person to apply the earth end first. That habit-forming need is a powerful addition in ensuring the earth is applied in the correct order. Use of interlocked long earths would contribute to avoiding incidents such as Ranskill in October 1998 where a fatality occurred when the earth end of a long earth was removed first. 8.2.5
Earthing devices
This report has considered pole applied portable earths. Modern switchgear includes the option of earthing the OLE that it is connected to, and at certain locations on the network, specific earthing circuit breakers are provided to perform this function. In this latter case, they are used to reduce the area affected by an emergency isolation by enabling adjacent OLE sections to be energised. The earth that it provides has never been included on a Form B in connection with the issue of an Overhead Line Permit. This is because the current UK edict is that an Overhead Line Permit can only be issued after a Form B has been completed with portable earths applied. This statement as an absolute requirement should be checked before developing the equipment or business case for a section of Overhead Line having fixed remotely controlled earths for the issue of issue of Overhead Line Permits. In addition to this overarching reason, there is long-standing concern of how to prove in absolute terms that a remotely controlled device has moved into the earth position. The current accepted practice is to use circuit breakers as their integrity is considered high enough to guarantee that a circuit has been connected to earth (for the application stated above). If extra assurance were required for Form B earths then an engineering solution would be required, some work has already taken place on a solution. Micro-switches on actuator (Morris Line Equipment) RF injection & detection (AEA technology & Network Rail) At present, the process of switching off, isolating, testing and earthing electrification equipment relies on verbal and written communications, both face-to-face and by telephone. Information exchanged is recorded on paper forms and telephone conversations with the Electrical Control Room (ECR) are recorded to tape or digitally. The process can be speeded up if all switching required is carried out remotely but the extent of the planned isolation and nature of the fixed infrastructure often means that manual switching is required on-site. Notwithstanding the issues described above, fixed isolation facilities in certain specific locations would bring tangible benefits: Nominated Person competence tailored to that installation (simpler, less broad range of knowledge required). Fewer personnel required (no portable earths to erect or manual switching to carry out) Personnel removed from the hazard of erecting portable earths or manual switching Less time taken to issue an Overhead Line Permit
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Possible to have discrete areas where all residual 25kV hazards are eliminated Isolations do not have to be bought in. For a fixed installation where the output and risks are clearly defined there is further opportunity for communication to be replaced or reinforced with digital outputs, whether that is interlocking in SCADA preventing out-out-sequence operations, panel indications for energized and earthed status of the OLE or indications communicated digitally to hand-held devices. The requirement for new fixed infrastructure, the required safety case, the change of culture and, of course, compliance with legislation makes this area of work particularly onerous. 8.2.6
DC Isolation and Earthing
There has been much concern regarding the ergonomics of transporting and applying short circuiting straps and other equipment on the DC railway when effecting an isolation. RSSB have awarded a separate research project, which is looking specifically at the design of short circuiting straps in respect of transportation, application and security of electrical connection. This project both recognises and supports that work. 8.2.7
DC Test Equipment
The equipment traditionally used to test the status of the DC conductor rail (box of eggs) is both primitive and cumbersome. There have been numerous failures which could have resulted in direct injury or providing a wrong indication of status. New devices, developed by London Underground, are currently undergoing a trial on the network. Initial feedback indicates that these new devices are also unwieldy and that the indicator lights are not as visible as they should be in daylight. This project supports the need for a better test instrument that affords operatives with a useable and reliable piece of equipment. We recommend that further work be undertaken in Phase 2 of the project to develop a tester that is both useable and reliable. 8.2.8
Conductor Rail Gauging
Following the incident at Oakley in 2003, Balfour Beatty Rail Maintenance took a decision to ban live working on DC conductor rail equipment. At that time, it was felt that work on the conductor rail equipment could be planned within a full possession and isolation. However, as the availability and likelihood of securing an isolation within daylight hours was remote the task of both spatial and profile gauging of the conductor rail could not be done effectively. The present design of gauges requires the operative to be within 300mm of the live conductor rail thereby placing him in a position of danger. It is recommended that the task of gauging of the conductor rail is looked at in Phase 2 of this project with the objective of defining a suitable design of gauge (non contact) that enable effective gauging to be undertaken without putting the operative at undue risk.
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9 Conclusions This project has reviewed working practices in electrified areas to identify where enhancements to working practices can be made in terms of safety and efficiency. It has looked at how isolation and earthing practices have evolved since the introduction of rail electrification. 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 OLE. Throughout the review, it has become evident that the isolation process is based on sound principles developed from the first electrification schemes. This development continues, in the main, under the guidance of the 29987 User Group. This project would like to commend the Group for the good work that they have done and continue to do. The continuation of this Group is seen as key in striving towards 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 is recommended that enhanced communication of rulebook requirements in this area is undertaken. The continued use of long earths in the absence of DEPs is a cause for concern especially when considering the Ranskill incident in October 1998 when a worker died whilst removing a long earth. We would 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. The publication could be used in NP/AP training and to raise awareness and understanding of these hazards to COSSs and PTS holders through their training and briefing. The level and content of electrification training on both PTS and COSS courses is a cause for concern and we recommend that a review is undertaken and improvements identified. Although several organisations have produced their own internal briefing material it is felt that the national training material should be enhanced. We therefore 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 Nominated and Authorized Persons. 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. During late 2005 into 2006 the competences of isolating DC 3rd Rail, and isolating/accessing railway distribution equipment have been added to the national Sentinel scheme. 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 is covered in clause 4.16 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.
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The origin of the nine-foot rule is discussed in clause 4.18 and concludes that this distance should be treat as a formulaic distance that is judged to be a safe working distance from the OLE rather than an electrical clearance. 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. It is recommended that a detailed review of electrical clearances in these documents takes place with the various stakeholders and a uniform approach agreed. The review has concluded that there are minor differences to the forms and procedures used in the isolation process driven by Electrical Control Room and Route. It is recognised that Network Rail are aware of these differences and are addressing the issue. The review recognised that GO/RT3091 remains in a state of flux whilst discussions on the most appropriate way forward are agreed between Network Rail, RSSB and the HSE. It is disappointing that the development of GO/RT3091 has now been going on for an inordinate amount of time and many of the benefits identified at Issue 3 have not been realised to the benefit of enhanced safety in third rail areas. 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, i.e. intentionally, unintentionally or because of the influence of company safety culture. Prior to gaining access to incident reports, it was anticipated that some time would be available to interview witnesses and persons involved in the incidents to gain a deeper understanding of the behaviours involved. However, due to the volume of information in the reports received and the consequent analysis time required, this was not achieved; 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. These results can be used to inform the analysis of previously reported incidents. Research into distance judgement suggests that even experienced crane operators find it very difficult to judge clearance from overhead lines accurately. 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.
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The objective of this exercise was to predict the types of human error, which could occur whilst working in AC, or DC electrified areas. The method used to conduct this analysis was a predictive form of the technique used to examine the occurrence of error retrospectively, based upon TRACEr Lite, that was applied to the incidents described in the main body of this report. The technique is driven by a task analysis, which in this case was substituted for the risk assessment referred to above. 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. It was felt that decision-making errors would be more likely in planning and management tasks than in manual tasks. Some 600 tasks performed across all disciplines were risk assessed as part of this review. Of these, some 200 fell into the high-risk category requiring additional control measures to be applied to bring the residual risk down to a tolerable level. 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. It is recognised that the identification of risks in third rail areas was initiated following the introduction of Issue three of GO/RT3091 but this work stalled upon its withdrawal. The fatality at Oakley in August 2003 gave this new impetus but progress has been slow. It is recommended that this work is re-initiated and tasks that cannot be performed under live conditions identified and people made aware. A number of innovations that have recently been developed, are in the process of being developed or where a development would enhance safety or efficiency without detriment to safety are presented at Section 8. It is recommended that further work be undertaken In Phase 2 of this project to introduce developments, which 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.
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10 Recommendations 10.1
Introduction
Recommendations identified whilst undertaking this review are detailed within the main body of the report. This section provides a brief summary of those recommendations, which it is felt appropriate to progress in Phase 2 of this project.
10.2
Recommendation 1 – Communications
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.
10.3
Recommendation 2 – Vertical Slice Audits
It is recommended that vertical slice audits of the isolation process be undertaken to determine the effectiveness of the Standard and the process. Each audit should start with the isolation request through planning to the issue and understanding of the Overhead Line Permit(s) on site. It should also determine compliance with GE/RT 8024 and include the requirements of RT/E/S/29987.
10.4
Recommendation 3 – National Database of DEP Locations
It is recommended that a national database of DEP locations be progressed. It is known that some Regional information already exists and it would be beneficial to gather this information and using best practice turn it into a national database for distribution to maintenance, renewal and project based organisations.
10.5
Recommendation 4 – PTS and COSS Training
It is recommended that a review of the level and content of electrification training on both COSS and PTS courses is undertaken and any enhancements identified. Although several organisations have produced their own internal briefing material, it is felt that the national standard should be enhanced. For this recommendation to be successful, it will require the collaboration of Network Rail and Sentinel to produce new slides, training plans and assessment tools.
10.6
Recommendation 5 – Electrical Clearances to Earth
A 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. It is recommended that a detailed review of electrical clearances in these documents takes place with the various stakeholders and a uniform approach agreed.
10.7
Recommendation 6 - Safety Observation Schemes
It is recommended that the concept of Safety Observation Schemes be further researched under Phase 2 of this Project. Safety observation schemes are designed to aid behavioural change by using the principles of providing feedback to reinforce the required behaviours. They revolve around management or employee observations of work areas to identify both safe and unsafe behaviours taking place. The concept then is to provide positive reinforcement for the desired (i.e. safe) behaviour whenever it is observed. The idea is that workers get to know that behaving safely brings recognition and will therefore tend to join in. When an undesired behaviour is observed, rather than punishing the individual, the concept is to: (a) (b) (c) (d)
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sit down with the individual and get them to explain what they did; why they did it; what the consequences could have been (what’s the worst that could happen) and get them to come up with the suggestions for how to do the same job more safely the next time. The aim should be to get the individual committed to doing the job more safely next time.
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10.8
Recommendation 7 - Greater Emphasis on Supervisory Checks
Related to the previous recommendation, the evidence emanating from a number of the formal investigation reports seemed to suggest that the frequency of supervisory checks of worksites tended to be very low, and that when they did occur they were not very thorough. Organisations should be required to place a greater emphasis on supervisory checking, which should be used to check that work is being done according to plan and the prescribed procedures, but also helps to raise the level of visibility of the supervisors.
10.9
Recommendation 8 - Introduce Safety Communications Training
A number of incidents seemed to involve incomplete or ambiguous information passed between team members. A great deal of work has been conducted in the recent past to develop guidelines for workers on how best to communicate safety information to make sure that the relevant information is correctly understood.
10.10 Recommendation 9 - Checking the Planning Process On a number of occasions, there were failures in the planning process that contributed in some way to the incidents. For example, providing the wrong map of underground services, planning work for red-zone working when there is a T3 possession the following week, having work areas and isolations with different limits, etc. A checking (or auditing) process is required to identify these problems early when they arise, and try to find a safer alternative. There are clear barriers to be overcome – at present, there appears to be a culture in the rail industry, which encourages a focus on keeping trains running and avoiding delay. A system, which asked for all electrified area working to take place during a T3 possession, would not fit within this culture. Some form of step-change is required, similar to the change that was initiated in the offshore industry following the Piper Alpha disaster.
10.11 Recommendation 10 - Further Analysis It is recommended that further analysis on the implementation of recommendations emanating from inquiry reports be undertaken to find out how effective they have been in reducing the occurrence of incidents in electrified areas. This should involve making contact with the organisations involved in the incidents and finding out how well the recommendations were received, and whether they have been implemented. This would also provide the opportunity to perform a reality-check of the recommendations from this report with these organisations, and obtain impressions of the value added by human factors analysis.
10.12 Recommendation 11 - Incident Reporting An obstacle in the preparation of this report has been the availability and inconsistency of information contained within Formal Inquiry Reports. It is recommended that a review of Standards covering this requirement is undertaken.
10.13 Recommendation 12 – RIMINI Approach It is recommended that consideration be given to undertaking further research that examines the merits of mandating a hierarchical approach to safety of persons working on or about the electrified line such that the first consideration is always the safest possible way (isolation). In the event that it is not possible to secure an isolation, then the next consideration should be to adopt alternative safe systems of work.
10.14 Recommendation 13 – Tasks on the DC Third Rail It is known that some work was undertaken by maintenance contractors working in the Wessex, Kent and Sussex areas on the identification of tasks that were performed on or near to the electrified DC line and the establishment of safe systems of work. It is recommended that this
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work is revisited and mandates issued as to which activities are allowed to be performed with the conductor rail live and which are not.
10.15 Recommendation 14 – Development - Live Line Indicators It is recognised that devices of this nature could lead to improved safety and it recommended that a full review with HAZOP and field trials be undertaken in Phase 2 of the project.
10.16 Recommendation 15 – Development - Live Line Testers It is recommended that the specification and development of live line testers be pursued in Phase 2 of this project.
10.17 Recommendation 16 – Development - Live Line Data Loggers It is recognised that devices of this nature could lead to improved safety and it recommended that a full review with HAZOP and field trials be undertaken in Phase 2 of the project.
10.18 Recommendation 17 – Development - Conductor Rail Gauging It is recommended that the task of gauging of the conductor rail is looked at in Phase 2 of this project with the objective of defining a suitable design of gauge (non contact) that enable effective gauging to be undertaken without putting the operative at undue risk. The Human Factors element of this review has also made individual recommendations against each incident and these are presented against each incident in the main body of the report.
10.19 Recommendation 18 – Mandated use of PPE in DC Conductor Rail Areas To minimise the risk of electrocution it is recommended that Network Rail mandate the use of appropriate PPE for all staff who work on or about a DC conductor rail area. Appropriate in this context means full covering of the torso, arms and legs. No working with exposed torso or legs (wearing of shorts) should be permitted.
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11 References NIOSH Alert May 1995 – Preventing Electrocutions of Crane Operators and Crew Members Working Near Overhead Power Lines Gibson, W. H., Megaw, E. D., Young, M. S. and Lowe, E; The Analysis of Communications Errors During Track Maintenance (undated copy via personal communication) Imbeau, D., Paques, J-J., Bergeron, S. and Bourbonnierre, R. (1996); Comparison of Two Methods for Judging Distances Near Overhead Power Lines. International Journal of Occupational Safety and Ergonomics, Vol. 2 No. 3 CIRAS Analysis Bulletin covering period June 2000 to February 2002 Team-working in the Rail Industry – The Journey Guide. RSSB 2004 Team-working in the Rail Industry Milestone 1 Report on Rail Industry Team-working Study. RSSB, 2003 Team-working in the Rail Industry Milestone 2 Report on Lessons Learned from Other Industries. RSSB 2003 Team-working in the Rail Industry Milestone 3 Report on Metrics for Measurement of Team Performance. RSSB, 2003 Team-working in the Rail Industry Milestone 4 Report on Definition of Preliminary Best Practice Guidelines. RSSB, 2003 Team-working in the Rail Industry Milestone 5 Report on the Study to Date. RSSB, 2003 Team-working in the Rail Industry Milestone 6 Report on Pilot Trial Setup. RSSB, 2003 Team-working in the Rail Industry Milestone 7 Report on Results of Pilot Trial. RSSB, 2003 Team-working in the Rail Industry Pilot Study Methodology. RSSB, 2003 Safety Critical Rule Compliance – The Solutions Toolkit – Part 3 Simplified Compliance Toolkit. RSSB, 2004 Safety Critical Rule Compliance – The Solutions Toolkit – Part 4 Examples. Version 1. RSSB, 2004 Safety Critical Rule Compliance – Toolkit Evaluation and Final Report RSSB, 2004 Daniels, A. C. (1999) Bringing out the Best in People. How to Apply the Astonishing Power of Positive Reinforcement. McGraw-Hill GL/RT1252 Production & Management of Electrification Isolation Documents 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
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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. GL/RT1254 Electrified Lines Traction Bonding GE/RT8024 Persons Working on or near to AC Electrified Lines GE/RT8025 Electrical Protective Provisions for Electrified Lines GO/RT3091 DC Electrified Lines Instructions RT/E/P/27154 Procedure for the use and care of BR Type Testers RT/E/S/27203 Specification for the provision of isolation, earthing and indication facilities where local isolations are permitted on AC Electrified Lines RT/E/C/27017 Competence Management Systems for work on Electrification and plant Systems RT/E/C/27018 Training of persons working on or having access to electrical power supply equipment RT/E/P/24009 Competence requirements for Electrical Control Room Operators RT/E/S/21067 Instruction for making out, issuing and cancelling HV Permits to work, sanctions to test and circuit state certificates RT/E/S/21070 Competence of persons working on or having access to Electrical Power supply equipment RT/E/S/21085 Design of earthing and bonding systems for 25kV AC electrified lines RT/E/S/29987 Working on or about 25kV AC Electrified Lines
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Appendix A
Possession Pack WON 38
Names omitted to ensure compliance with data protection act and security purposes.
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Appendix B
Possession Pack WON 47
POSSESSION PACK Possession Managed by Network Rail Liverpool Street To Bethnal Green / Bow / Cambridge Heath WON 47 Item No.05 (Saturday-Monday) Date: 08th February 2005
Held at: Romford
Note: The personnel listed below were present during the Co-ordination meeting and / or briefed and agree with the co-ordination of this possession. Name A N Other A N Other A N Other A N Other A N Other A N Other A N Other A N Other A N Other A N Other A N Other A N Other
Representing NWR Planning NWR NWR OHLTES NWR OHL NWR Track Services NWR S&T Liverpool St NWR NWR Rail Scape NWR S&T NWR NWR
Contact Number 00000 000000 00000 000000 00000 000000 00000 000000 00000 000000
Email Address / Fax Number / Hand
A N Other@nowhere. A N Other@nowhere. A N Other@nowhere. A N Other@nowhere. A N Other@nowhere.
00000 000000
A N Other@nowhere.
00000 000000 00000 000000 00000 000000 00000 000000 00000 000000 00000 000000
A N Other@nowhere. A N Other@nowhere. A N Other@nowhere. A N Other@nowhere. A N Other@nowhere. A N Other@nowhere.
Please ensure all staff park with consideration to local residents, keeping noise to a minimum and remove all litter. Failure to do so will result in staff being barred from site. Possession Pack prepared by : A N Other Date: 08th February 2005
Signature :
Worksite Limits:
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Work Site / Limits
Lines Affected
00m00ch to 00m60ch 00m00ch to 01m00ch 00m00ch to 00m60ch 00m00ch to 02m40ch 00m00ch to 02m40ch 00m00ch to 01m60ch
Up & Dn Subs Up & Dn Subs Up & Dn Subs Up & Dn Mains/Electrics Up & Dn mains/Electrics Up & Dn Fasts
Start Time 01.00 Sun 08.10 Sun 15.50 Sun 01.40 Sun 01.40 Mon 01.40 Mon
Finish Time 08.10 Sun 15.50 Sun 04.00 Mon 04.20 Sun 04.00 Mon 04.00 Mon
Isolation / Permit Issuing Part 1: Contractor NWR
305-306-303-304-311-312-
Start Time 01.00 Sun
Finish Time 04.00 Mon
Recipient
Contact no
Issued By
Lines Affected
Limits of Isolation
UP & Dn Mains/Electric/Fasts/Subs
Isolation / Permit Issuing Part 2: Contractor
Place of Issue
NWR Engineering Supervisor: Times 01.00 Sun to 08.00 Sun 08.00 Sun to 17.00 Sun 17.00 Sun to 04.00 Mon
Name A N Other A N Other A N Other
Telephone 00000 000000 00000 000000 00000 000000
Work Content Principal Contractor Work Content
Network Rail
PPS Ref
W2004/631597
Defect Rail
Site Times Actual Mileage
Isolation Req’d COSS(s) COSS(s) Access point Plant Site Manager Additional Info
N/A A N Other A N Other Norton Folgate Hand Tools
Principal Contractor
Network Rail
Work Content
S&T Maintenance
Isolation Req’d COSS(s)
N/A A N Other
00000 000000
01.00 – 08.00
COSS(s)
A N Other
00000 000000
08.00 – 20.00
COSS(s)
A N Other
00000 000000
20.00 – 04.00
Access point
Norton Folgate
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00000 000000 00000 000000
PPS Ref
01.00 Sun 18.00 Sun 00m00ch 01m00ch
01.00 to 08.00 08.00 to 18.00 Norton Folgate Egress point
W2004/864860
Site Times
01.00 Sun 04.00 Mon
Actual Mileage
Egress point
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Norton Folgate
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Appendix C
Human Factors Analysis Techniques Human Error Analysis The human error analysis technique is based upon a methodology called TRACEr (Technique for Retrospective Analysis of Cognitive Error) developed for use in Air Traffic Control to determine what the underlying causes of errors that contributed to incidents were. TRACEr was initially developed for use by human factors specialists to analyse incidents in parallel to, or following, the formal incident investigation. In order to allow human factors analysis to be conducted as part of the investigation process itself, the methodology was developed to be more usable by the nonspecialist and more practically focussed. The resulting methodology is known as TRACEr Lite, and has been used as the basis for the tool that is used in this study. The technique is focussed on determining why errors are made and what the organisation can do to defend against similar occurrences in the future, by either removing opportunities for error or reducing the impact of the error should it recur. Briefly, the procedure used first identifies all human errors that played a part in an incident, and then determines from the evidence available which part of the human information processing system malfunctioned resulting in the error. For the purposes of investigation, the human information processing system is divided into four key elements: perception, action, decision and memory as shown in Figure C1. Typically, when a person is completing a particular task, they perceive information from the world around them using their senses and compare the information they receive through this process to information held in memory. For example, if a person testing an overhead line with an analogue line tester sees the needle swing to 7kV, they recall information from their training, experience, etc. to help them to understand what this means. The person uses this information to make a decision on what to do next, and then performs some action in accordance with the decision (this might be a physical action such as opening or closing a switch, or a verbal action such as giving an instruction to someone else in the work party). Once the action has been completed, the outcome of the activity is stored in memory and can be recalled in terms of experience the next time they perform a similar task. For each of these there is a defined set of human error modes, which are a more detailed description of the error, and which indicate in what way the perception, memory, decision or action process broke down. Error modes, in turn, are also associated with a set of error mechanisms. Error mechanisms are descriptions of the ways in which the human mind works which can lead people to commit errors (e.g. expectation bias where someone expects to see or hear something and therefore assumes that they have done so when in fact they have not).
Memory of training, procedures, recent events, etc
Perceive information from outside world
Make decision based on perceptions and information from memory
Take action based on decision
Figure C1: Human Information Processing System
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The error modes associated with each of the four error types are shown in the following table: Error Type
Error Modes
Perception Misperception No perception
Memory Late/missing action Forget information Misrecall information
Decision Misjudgement Poor decision/plan Late decision/plan No decision/plan
Action Selection error Unclear information Incorrect information
Certain error mechanisms relate to certain error types. Therefore, if the analyst decides that an error is a form of perception error, there are only a certain number of error mechanisms that apply. Some mechanisms are relevant to more than one type of error. The relationships between error types and error modes are detailed in the following table – the ticks indicate which error mechanism is appropriate to which error type(s): Perception Error
Error Mechanisms
Memory Error
Decision Error
Action Error
Expectation Expect something to take place so strongly that you believe that it has occurred even if there is evidence to suggest otherwise Confusion Confusing information or objects of similar appearance, position or function or confusing information in memory that is similar. Signal Strength Failing to perceive something that is vague or of short duration. Tunnel Vision Fixating on one piece of information to the exclusion of other relevant information Overload A large amount of incoming information or too much information to retain in memory Distraction / Preoccupation Distraction by a momentary event or a longer term preoccupation Insufficient Learning A problem due to lack of experience or application of training Mental Block Inability to recall the required information Failure to integrate Failure to integrate several pieces of information, or a failure to calculate or understand information Considering Side-Effects Not foreseeing side effects or long-term effects of a decision Mind Set Sticking to a faulty plan, belief or interpretation, even despite evidence to the contrary Knowledge Problem Lacks required knowledge due to training Decision Freeze Decision 'freeze' due to complexity or emotion Human Variability Lack of manual precision, fluency or intonation
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Perception Error
Error Mechanisms
Memory Error
Decision Error
Action Error
Intrusive Thoughts / Habits Thoughts, habits or task interference effects cause a person to do or say something unintended Other Slip Other slip of the tongue, pen, action etc.
The process of breaking an error down in this way allows the investigator to identify the root cause of the error in psychological terms, i.e. why the error has occurred. The overriding benefit of using such a technique is that it allows the investigator to be very specific about the actions recommended to prevent recurrence in the future. For example, an error, which results in a switch that is usually open being left closed, may occur because the individual did not see that the blade of the switch had remained in the jaws, despite the handle at ground level being in the open position (i.e. a perception error). Alternatively, the individual may have forgotten that the switch had been closed for a specific reason and needs be opened again at the end of the job (i.e. a memory error). The action you would take would clearly be very different in each case, and conventional incident investigation techniques would not provide sufficient detail of the human errors involved to allow the investigator to define clearly the most appropriate course of action. All of the above deal with analysing the error in terms of a failure of information processing. This is an internal phenomenon, personal to the individual who made the error. Human performance, however, is strong influenced by the conditions under which we work, and so an assessment of the conditions that were likely to have affected performance (known as performance-shaping factors) is built into the analysis. These cover the following topics: The task - Workload, time pressure, etc. Communications - Language, quality, etc. Procedures & documentation - Number, clarity, etc. Environment - Noise, temperature, etc. Training & experience - Recency of training, etc. Human-machine interaction - Trust, accuracy, etc.Personal - Domestic issues, etc.Social & team - Handover, supervision, etc An investigator’s worksheet has been developed to ensure that we conduct a systematic analysis of human error covering all of the above aspects of human error, both internal and external to the individual who made the error. This is not included in the report because the analysis techniques themselves were not agreed as a deliverable on this project. ABC Analysis ABC analysis is a well-known form of behavioural analysis, which describes the Antecedents (or triggers) to a Behaviour and the Consequences of that behaviour from the point of view of the person behaving. ABC analysis forms the basis of many behavioural safety programmes used across industry sectors. An analysis tool has been developed to guide an investigator through the process of identifying what triggered a behaviour and what the consequences of the behaviour were to the individual involved. The first step of the analysis is to identify the antecedents that were either present, absent or inadequate and therefore triggered the behaviour. For example, driving over the speed limit may have occurred because there was no sign to indicate the speed limit. If the sign had been present, the intention would be to trigger the behaviour of driving within the speed limit, so in the example, the necessary trigger for the behaviour was missing.
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The next step of the analysis is to determine what the consequences of the behaviour were from the perspective of the person involved. For example, taking the example of exceeding the speed limit, the individual may have stated to their passenger that they were late for a meeting and needed to speed up. If this information were provided at interview, then the investigator has evidence to suggest that the consequences of the behaviour for the individual were to save time, get approval from the person holding the meeting, and the ever-present potential consequence of causing harm to themselves or others. A related stage in the analysis is to determine, from the point of view of the person behaving, whether the consequences identified were likely to be positive or negative, immediate or future, and certain or uncertain. To explain briefly the use of these terms in this context, firstly, positive and negative are self-explanatory. Immediate or future refers to whether the consequence occurs immediately after the behaviour or at some point in the future. Certain or uncertain refers to the subjective assessment of the person behaving of the likelihood of the consequence in question. In the example above, the first consequence – saving time – is likely to have been positive from their point of view. It would also have been seen to be a consequence that would be received at the time or shortly after the behaviour, so it would be immediate. A subjective assessment of certainty at the time would probably suggest that the consequence of saving time by speeding up would be almost certain to occur. Therefore, this consequence would be considered positive, immediate and certain. The second consequence – getting approval from the person holding the meeting – would be assessed in a similar way. The third consequence – causing harm to themselves or others – would be assessed as negative. However, most people who speed do not expect this consequence to occur at the time or shortly after the behaviour, they expect that it will not happen this time or that this is not something that will happen to them, therefore this would be a future consequence. Most people would also consider the subjective likelihood to be uncertain. This consequence would therefore be assessed as negative, future and uncertain. Behavioural research (e.g. Daniels, 1999) tells us that people find positive, immediate and certain consequences much more powerful reinforcers of behaviour than other classes of consequences. They tend to have a longer-lasting effect on behaviour than, for example, negative, immediate and certain consequences. For example, if a worker knows they will be punished for not wearing full PPE, (a negative, immediate and certain consequence) they will tend to comply with the rule when a supervisor is present, but not when the supervisor is absent. It is therefore providing effective reinforcement against the behaviour of not wearing PPE, but this is not continued once the trigger for the behaviour, the supervisor, is removed. Speed cameras are another example. If speed cameras provided positive, immediate and certain consequences of driving within the speed limit for your entire journey by calculating your average speed (e.g. reductions in road tax, vouchers for money off fuel) then this would reinforce the desired behaviour of driving within the speed limit more effectively than providing negative consequences. So in our example of the person exceeding the speed limit, the consequences that would discourage this violation were negative, the consequences for the violation were both positive, and so from the point of view of the person behaving, there were more good reasons to violate the procedure than there were to obey it. Having determined the triggers and consequences for the undesired behaviour, the analyst is then guided through the same process for the desired behaviour. Except in this case they are looking to identify the triggers that would help to encourage the behaviour in the first place, and the consequences that would provide reinforcement for it – positive ones to encourage uptake of the desired behaviour and negative ones to discourage the undesired behaviour. Where appropriate,
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the ABC analysis tool was used to conduct an analysis of the intentional procedural violations involved in the incidents under review. Safety Culture Analysis Based upon research conducted in the offshore oil and gas industry, a model of safety culture was developed which has since been refined and used in many diverse industries. This model has been developed into a simple matrix, which lists a number of different types of causal factors (e.g. skill level, following procedures, training) against the 10 elements of safety culture that form the basis of the model. Experience in applying the model in industry suggests that certain causal factors can indicate that there is a weakness in one or more of the elements of safety culture, and these have been mapped on the matrix. The matrix is used to identify whether or not a recommendation from the analysis should be to assess one or more elements of safety culture in the organisation concerned. Note that this is not a tool for assessing safety culture; it is a tool to indicate whether such an assessment should be conducted. The elements of safety culture in the model are as follows: Visible Management Commitment Safety Communications Productivity versus Safety Learning Organisation Health and Safety Resources Participation in Safety Risk Taking Behaviour Trust Between Management and Front Line Staff Industrial Relations and Job Satisfaction Competency The causal factors that they are mapped against are: Following procedures Use of tools or equipment Use of protective equipment Lack of awareness Work exposures Physical condition Behaviour Skill level Training etc Management etc Contractor etc Work planning Purchasing etc Work rules etc Communication
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Appendix D Transcripts of Human Factors Analyses of Historic Incidents This appendix contains details of the analyses referred to under Section 6.3.1 of the main body of this report. In each case, we indicate whether findings quoted are based upon the original analysis or on this human factors analysis. A finding from the original analysis is indicated by a (O) after the finding, and a finding from the human factors analysis is indicated by a (H) after the finding. In some cases, findings stem partly from the original analysis and partly from the application of human factors, where this was the case, this is clearly indicated. Where the human factors analysis has been based upon speculation or assumption on the part of the original investigators, this has also been highlighted in the results of the analysis. In some cases, it was necessary for the human factors analyst to make assumptions based upon the facts in the incident report. Again, this is clearly indicated in the reporting of results. Acton East 21st January 2000 ABC Analysis Behaviour: The NP, whilst preparing to apply earths to overhead line equipment, failed to follow the Live-Dead-Live procedure designed to test functioning of the line tester, resulting in arcing and a blown earth. Triggers: The tools and equipment at the time of the accident were present but inadequate for the task. (H) In terms of the NP’s awareness of hazards and risks, it is not clear whether the NP was aware of the additional risks associated with not conducting L-D-L testing. There were no signs to act as a reminder for the correct procedure. (H) The NP had all required knowledge, skills and competence to do this task. (H) Lack of training for on-the job trainers (the NP in this case was instructing a trainee at the time but had no formal training qualifications). (O) Consequences of behaviour: The potential consequence of causing injury to self or others, or other type of loss or damage would have been assessed as negative, future and uncertain. (H) Although it is clear that there must have been some perceived consequence of not following the prescribed procedure regarding testing of the line (e.g. to save time), there is insufficient information in the report to determine what this was. (H) Desired behaviour: All personnel are to apply the L-D-L procedure when testing overhead line equipment to ensure that the line is safe to work on. Required Triggers: Reminders (e.g. signs, briefings, posters) to ensure that all line testing equipment is serviceable before leaving the depot. (O) Briefings and/or training on the possible consequences of not using the correct procedure. (H) A reminder in the form of a label or sign on the line-tester of the correct procedure. (H) NPs to set good example for following procedures. (H) Explanation of the reasons for the procedure. (H) Required Consequences:
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Avoid injury to self or others, or other type of loss or damage would be assessed as positive, immediate and certain. (H) Praise for safe acts would be assessed as positive, immediate and certain. (H) If the worker were to believe that following procedure takes longer, this would be assessed as negative, immediate and certain. (H) Penalties if workers found not to be following correct procedure would be assessed as negative, immediate and certain. (H) Two of the proposed consequences are positive, immediate and certain from the point of view of the person, and these have a stronger influence on behaviour than other types of consequences. The consequences of the unsafe behaviour did not include any positive, immediate and certain consequences, hence, to the individual the proposed behaviour should be more attractive than the unsafe behaviour, and hence should be adopted in favour of the unsafe behaviour. (H) Human Error Analysis Behaviour: The NP, whilst preparing to apply earths to overhead line equipment, failed to follow the Live-Dead-Live procedure designed to test functioning of the line tester, resulting in arcing and a blown earth. Error Type: Decision error – Assumption: the NP appears to have judged that it was not necessary to use the full live-line testing procedure. (H) Error Mode: Poor decision or plan – The decision to apply the earths was inadequate and did not consider the possibilities of defective testing equipment or switching errors. (H) Error Mechanism: Mind Set (i.e. sticking to a faulty plan, belief or interpretation, even despite evidence to the contrary). The switch in question was normally open, therefore assumed to be so in this case. The live line test confirmed the earlier assumption. (H) Performance-Shaping Factors: These conditions, under which the NP was operating, could have influenced his performance and made the error more likely: The accuracy of information provided by the line tester was certainly a factor in this incident. If the tester had not been faulty, then the likelihood of this incident would have been reduced, and if the tester had been subjected to pre-use test before leaving the depot the defective equipment would not have been used. (O & H) In addition, the format of the information provided via the line tester (analogue information) may have meant that determining the status of line was more prone to error. The needle had stuck at 7kV and the dials were known to be prone to failure. (O & H) There appeared to be a high level of trust in the information provided by the line tester, leading to a willingness to believe the information in light of the expectation that the line was dead. (H) The fact that the NP was instructing a trainee at the time may have influenced performance. (H) Adwick, 2nd August 2000 ABC Analysis Behaviour: The OHLE worker, whilst cutting back a bush near OHLE equipment, lifted a branch above his head, causing contact with live OHLE and mild electric shock.
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Triggers: The victim did not appear to have had a full appreciation of the hazard (H). The briefing did not cover electrical hazards (O). Training does not seem to have been effective in relation to hazards and minimum clearances, etc (H). Procedure for the coverage of all hazards during COSS briefing does not seem to be adhered to (H). Consequences of behaviour: The potential consequence of causing injury to himself or others, or other type of loss or damage was perceived as negative, but not anticipated to be a direct result of the behaviour and not considered certain. (H) Assumption: It is possible that the worker felt that throwing the branch would save time over the alternative solution of carrying the branch into the undergrowth, which would have been a positive, immediate and certain consequence. (H) Assumption: The worker may also have been seeking approval from his supervisor for getting the job done quickly, and getting the branches well clear of the cess. This would have been viewed as a positive, immediate and certain consequence. Desired behaviour: All workers to refrain from lifting any object above head height when working underneath live OHLE. Required Triggers: Better training or mentoring for all staff working in OHLE areas on the hazards, minimum clearances, etc. (O& H) Include electrical hazards in COSS briefing. (O) Check that sufficient awareness of hazards has been developed. (H) Evaluate training to check effectiveness and modify if required. (O) Include information requirements for briefings in procedures. (H) Required Consequences: The consequence of avoiding injury to self or others, or other type of loss or damage would be associated with the desired behaviour, and assessed as positive, immediate and certain. (H) Providing feedback through mentoring on positive safety performance would act as positive reinforcement, and would be evaluated by the individual as positive, immediate and certain. (H) Any mentoring system or audit system could result in workers feeling they are being checked up on, which would be a negative, immediate and certain consequence. (H) These consequences would provide more positive reinforcement for the desired behaviour than negative, and therefore would be more likely to encourage this behaviour to be adopted. Human Error Analysis Behaviour: The OLE worker, whilst cutting back a bush near OHLE equipment, lifted a branch above his head, causing contact with live OLE and mild electric shock. Error Type: Decision error – Assumption: it is conceivable that the victim decided it was safe to throw the branch. Error Mode: Poor decision or plan – the decision to throw the branch did not take into account the proximity of the OLE. Error Mechanism: Knowledge problem (i.e. lacking the required knowledge due to training).
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Assumption: the incident report states that the worker had not been with the company long, and that the COSS had assumed that all members of the team were familiar with the hazards associated with OLE. Performance-Shaping Factors: Complacency - report states that workers took the dangers of working around live OLE for granted. Procedure availability, access or location – report states that COSS had never seen a method statement for vegetation clearance in OHLE areas. (O) Familiarity with task – Assumption: the victim may have been unfamiliar with the task. Hither Green, 25th July 1995 ABC Analysis Behaviour: A worker fell onto conductor rail without any PPE above the waist resulting in a fatal electric shock. There was no indication from report of what he was doing at the time. Triggers: Incorrect PPE – the hot, sunny, clear weather on the day of the accident may have led to inadequate use of PPE (O) Consequences of behaviour: The potential consequence of causing injury to himself or others, or other type of loss or damage was most likely assessed by the victim as negative, future and uncertain. (H) Avoiding discomfort (due to hot weather) associated with wearing PPE on the top half of the body could have been a positive, immediate and certain consequence of this behaviour. It is therefore probable that the assessment of risks associated with not wearing PPE was not sufficiently realistic to overcome the temptation of removing PPE to be more comfortable. (H) Desired behaviour: All workers to wear full PPE at all times when they are exposed to hazards and potential risks to avoid injury to themselves. Required Triggers: Identify whether there is more comfortable PPE available that would encourage use in all working conditions whilst still providing the same level of protection. (H) Workforce to intervene when colleagues fail to wear required PPE, set an example (H) Managers need to be seen to intervene to stop unsafe acts. (H) Required Consequences: Avoiding injury to self or others, or other type of loss or damage would be considered a positive, immediate and certain consequence of this behaviour. (H) Negative feedback for not wearing PPE would be assessed as negative, immediate and certain, and would help to discourage the unsafe behaviour. (H) Positive feedback for wearing correct PPE would be seen as positive, immediate and certain. (H) Positive feedback for intervening would be seen by workers as positive reinforcement and hence a positive, future (i.e. it will not occur at the time of intervention) and certain consequence. (H) Negative feedback for failing to intervene would be seen as a negative, future and certain consequence. (H) By introducing these consequences for the desired and undesired behaviour, the desired behaviour carries more possibilities for positive reinforcement, and the undesired behaviour carries more
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possibilities for negative reinforcement. This will have the effect of encouraging workers to behave as desired over time. Dock Junction, 10th February 2002 ABC Analysis Behaviour: The COSS intentionally violated procedures regarding working without an isolation, resulting in increased risk to personnel. Triggers: It is known that the COSS was aware of the risks involved in changing the method statement, although whether all workers were aware of the risks they were under seems unlikely, as they were not advised of the status of the adjacent OHLE, and signed to indicate their acceptance of the revised statement of work. When questioned, one member of the team stated that they were not aware of the electrical hazard. (O & H) The expectations of others - COSS knew the scaffolding was to be removed on the date of the incident, and when the isolation time was reduced, introducing time pressure, felt that this was still required even though the time available was one hour less than the time quoted for safe completion of the job. (O) There was not sufficient time to perform the required job safely. (O) Consequences of behaviour: The potential consequence of causing injury to self or others, or other type of loss or damage was likely to have been assessed as negative, but future and uncertain. (H) One consequence of changing the method statement was to save time in getting the job done, something that would have been seen as a positive, immediate and certain consequence. (H) Assumption: It is possible that by getting the job done on time, the COSS would have expected to get approval from his manager, something that would be seen as a positive, future and certain consequence. (H) In this case, there were more positive, immediate and certain consequences for behaving unsafely than there were negative consequences to discourage such behaviour. This will have reinforced the unsafe behaviour. Desired behaviour: All work of this or similar nature to be conducted under T3 possession/isolation conditions. Required Triggers: Management are to express their expectation that all work will be completed under T3 possession/isolation or postponed. Provide the strong message that no job is important enough to put workers at risk. (H) Required Consequences: Avoiding injury to self or others, or other type of loss or damage associated with the desired behaviour would be seen as a positive, immediate and certain consequence. (H) Receiving positive feedback for doing a safe job would be seen as a positive, immediate and certain consequence. (H) The possibility of having a wasted night due to not being able to commence or complete work could be seen as a negative, immediate and certain consequence of the desired behaviour. (H) Positive feedback when work has been planned for T3 possession would be seen as a positive, future and certain consequence. (H) Negative feedback when work is planned without T3 possession would be seen as a negative, future and certain consequence. (H)
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These consequences introduce more positive reinforcement for the desired behaviour than negative, and introduce negative reinforcement to discourage the undesired behaviour. From the perspective of a worker on site, the desired behaviour holds consequences that are more positive and is more likely to be adopted. Doncaster Belmont, 2nd December 2001 Human Error Analysis Behaviour: A worker climbed on top of a tank wagon to check the contents resulting in fatal electric shock from overhead line. Error Type: Decision error – Assumption: it is conceivable that the victim decided to check the contents of the tank manually. Error Mode: Poor decision or plan – to climb on top of a tank wagon positioned underneath live OLE. Error Mechanism: Knowledge problem (i.e. lacking the required knowledge due to training). Assumption: Conceivable that the victim did not know that he could have deduced the contents of the tank wagon from the label, and did not appreciate the dangers of overhead lines. Performance Shaping Factors: Communication quality (from the personnel at the two depots regarding the dangers of OHLE, where to check the contents of the tank, etc.) Procedure availability, access or location – The victim did not have access to documentation such as Section Z of the rulebook. (O) Familiarity with task – Assumption: the victim may have been unfamiliar with the task of determining the contents of a tank wagon. East Croydon 8 September 2002 ABC Analysis Behaviour: No specific behaviour for the COSS was identified. There were indications that a method statement had not been developed, and, more importantly, that a conductor rail shield had not been taken on the job, but one was collected from the depot after the accident. Triggers: A conductor rail shield, with the purpose of triggering safe behaviour by not working with the risk of exposure to energised equipment, was not present at the time of the accident. Note – the presence of a conductor rail shield would also act as a barrier to contact with the live rail. (O) The method statement, intended to promote the use of a safe means of achieving the job, was unavailable because one had never been written. (O) Consequences: The consequence of causing harm to themselves or others seems likely to have been considered a negative, future and uncertain consequence of events at the time of the accident. The gang were highly experienced in this task, their company having designed the process, therefore whilst injury would certainly be recognised as a negative outcome, it was not expected to happen because of the way the job was undertaken, it was also not considered particularly likely. (H) Assumption: Perhaps there was an expectation that not using the rail shield would have saved time, this would then have been a positive, immediate and certain consequence of the way work was undertaken. (H)
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Desired Behaviour: All risks associated with working around energised equipment to be identified, managed and minimised. Required Triggers: Produce method statements for all tasks that bear the risk of electrocution due to working in proximity to the conductor rail or OHLE (O) Required Consequences: Avoiding injury to self or others, or other type of loss or damage needs to be promoted and accepted as a positive, immediate and certain consequence of the desired way of conducting work. (H) Safety observation scheme to praise safe acts and remedy the situation – provide positive feedback for positive safety behaviour and ask those who behave unsafely to explain what the consequences of their actions could have been and how they would do the job more safely next time. This provides positive, immediate and certain consequences in the event of compliance with the desired behaviour. It has the benefit of involving teams in working out the solution to a problem. (H) Positive feedback for teams that perform consistently safely and publicise their success to other teams. This is a positive, future and certain consequence of adopting the desired behaviour. (H) Penalties if incomplete or improper equipment used – gangs will come to expect a negative, immediate and certain consequence of not using the correct set of tools and equipment. (H) Handsworth, 5th March 2002 Human Error Analysis Behaviour: Workers ruptured a 132kv cable buried under ballast whilst conducting fencing renewal work. This led to a hydrocarbon fire, which injured two men. Error Type: Perception error – the two men failed to identify the 132kV cable hazard. (O) Error Mode: No perception – Failure to perceive the hazard due to partially correct information presented from the planning process. (H & O) Error Mechanism: Expectation (i.e. expect something to take place so strongly that you believe that it has occurred even if there is evidence to suggest otherwise). Work planning and mapping had not identified the presence of buried services at the work site, so the gang expected the area to be free from electrical hazards. The gang had already experienced striking reinforced concrete slabs in the area on a number of occasions. When the CAT scan detected something, this confirmed expectations that the buried object was another piece of reinforced concrete, which was then tackled using heavy tools, leading to rupture. (O & H) Performance-Shaping Factors: Communication quality – Communications on the hazards present was not sufficiently effective, providing the workers with inaccurate information and no contact through whom to obtain a quick response on actions required. (O & H) Information accuracy / correctness – the provision of incorrect plans certainly appears to have had a strong bearing on the occurrence of this error. (O & H) Complacency – given the information these men were provided with, they were led to believe that there was no hazard associated with their actions. (O & H)
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Harlow Mill, 5th May 2002 Human Error Analysis 1 Behaviour: The nightshift ES failed to provide details to COSS’s on the isolation limits resulting in workers being exposed to live overhead line equipment. Error Type: Decision error - Based upon previous experience, decided to pin the Form ‘C’ to the wall in the SAM’s cabin. (O & H) Error Mode: Poor decision / plan - The nightshift ES was an experienced worker, it is therefore inconceivable that he did not know the potential consequences of not providing information on the isolation limits. This was a poor decision because there were additional sources of information that could have indicated that the isolation limits were not the same. (O & H) Error Mechanism: Mind-set (i.e. sticking to a faulty plan, belief or interpretation, even despite evidence to the contrary). The nightshift ES, based upon previous experience, believed that the isolation limits had not changed, even though there was evidence to the contrary available to him. (O & H) Performance-Shaping Factors: Non-standard activities- the circumstances surrounding the job had recently changed. (O & H) Time on the job – the ES had not been with the company for long (although he was very experienced). (O & H) Team co-ordination quality – the co-ordination of information and effort within the team lacked effectiveness. (O & H) Team communication quality – Assumption: communication within the team appeared to have broken down. (H) Handover / takeover – the handover between engineering supervisors did not appear to be systematic or structured. Handover when work is ongoing is particularly risky, there did not appear to be any consideration of the risks involved or highlighting them. (H) Human Error Analysis 2 Behaviour: The foreman, on receiving and signing the Form ‘C’, failed to advise the ES that he had received the Form ‘C’, resulting in relevant information on isolation limits not being briefed to other COSS’s Error Type: Decision error - Based upon previous experience, decided to pin the Form ‘C’ to the wall in the SAM’s cabin. (O & H) Error Mode: Poor decision / plan - The foreman’s plan was based on assumption, although there were other sources of information that could have been consulted that would have resulted in the correct decision. (O & H) Error Mechanism: Mind-set (i.e. sticking to a faulty plan, belief or interpretation, even despite evidence to the contrary). Assumed the ES would look at the Form C before briefing the COSS’s. (O & H)
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Performance-Shaping Factors: Time on the job – the ES had not been with the company for long (although he was very experienced). (O & H) Team co-ordination quality – the co-ordination of information and effort within the team lacked effectiveness. (O & H) Team communication quality – communication within the team appeared to have broken down. (O & H) Hemel Hempstead, 8th August 2001 Human Error Analysis 1 Behaviour: PS, whilst conducting overhead line maintenance duties, touched a live section insulator resulting in electrocution. Error Type: Action Error – Assumption: ED may have communicated information on the location of live equipment in an ambiguous fashion. (H) Error Mode: Unclear information - Ambiguity of communication regarding live equipment and / or the need to clean a section insulator. (H) Error Mechanism: Insufficient data to make a diagnosis. Performance-Shaping Factors: Communication quality –Assumption: manner in which information was relayed could have adversely affected performance. Information was passed verbally with no reference to supporting material (e.g. diagrams or the OHLE itself). (H) Familiarity with task – Assumption: level of familiarity with the task could have introduced complacency. (H) Team communication quality – manner of communicating between team members was open to error. (H) Human Error Analysis 2 Behaviour: PS, whilst conducting overhead line maintenance duties, touched a live section insulator resulting in electrocution. Error Type: Perception Error – Assumption: Difficult to say from the evidence, but it would appear possible that PS misheard an instruction indicating with section insulator required cleaning (this point is disputed in the report – i.e. ED states that he did not request any SI to be cleaned) or the location of the live equipment. Error Mode: Misperception – Assumption: Possible mishearing of instructions regarding areas of live equipment and / or which SI to clean (some dispute over the last issue) Error Mechanism: Confusion (i.e. confusing information or objects of similar appearance, position or function or confusing information in memory that is similar) – Assumption: Lack of evidence to support this, assumption made based upon knowledge of overhead line operations – could have been confused by proximity and similarity of appearance of live sections of OLE
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Performance – Shaping Factors: Communication quality – manner in which information was relayed could have adversely affected performance. Familiarity with task – level of familiarity with the task could have introduced complacency Team communication quality – manner of communicating between team members was open to error. Liverpool Street, 7th November 1999 Human Error Analysis Behaviour: Scaffolding was erected underneath live OLE by contractor, resulting in a member of the contractor’s staff sustaining an electric shock, which further resulted in a fall from height. Error Type: Perception error – Assumption: It appears that information regarding the correct positioning of the scaffold was misunderstood by contract personnel. (O & H) Error Mode: Misperception – The correct location for the scaffold was not correctly perceived by the contract personnel. (O & H) Error Mechanism: Confusion (i.e. confusing information or objects of similar appearance, position or function or confusing information in memory that is similar). There appears to have been confusion between different locations on the station that looked similar. Also, the isolation and worksite limits did not match, which may have caused confusion in itself, or contributed to overall confusion. Performance-Shaping Factors: Communication quality – in the communication of isolation limits, safety information and complacency in the briefing process. (O) Familiarity with the task – Staff had worked on the project for a number of months. (O) Complacency – high degree of familiarity with the project may have led to complacency. (O) Team communication quality – Assumption: communications within the team did not appear to be adequate as the isolation manager and the project manager were both unaware that work was to take place in the location in which it did. (O & H) Marston Green, 1st July 2003 ABC Analysis Behaviour: Workmen boarded and raised the basket underneath live 25kV OHLE, resulting in electrocution. Triggers: Tools and equipment – It was possible for the workers to operate the interlock that allowed the vehicle to be operated from the basket under live OHLE. (H) Awareness of hazards and risks – Given the experience of the workers involved there had to be an appreciation of the hazard of working in the area, but this was not enough to prevent them from putting themselves in danger. (O & H) Information – Assumption: Information regarding issue of the Form C potentially unclear did not explicitly state that Form C had not been issued at re-brief. (O & H) Accountability - COSS allowed men to enter the basket under live OHLE. (H) Other people’s expectations - Workers felt authorised to begin ground level work, message relating to lack of Form C not strong enough, insufficient control of situation by COSS. (H) Other people’s example - One worker got into basket for fear of being left behind. (O & H)
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Rules – Assumption: Rules regarding whether or not the workgroups should have been (a) on the track and (b) beginning ground level work seem to have been missing. (H) Procedures - Number of procedures are in place, but verification and compliance checking does not seem to be in place (Assumption). References to outdated procedures exist. (O & H) Consequences: Causing injury to self or others, or other type of loss or damage – this would have been seen as a negative, future and uncertain consequence, and hence weak reinforcement for avoiding this behaviour. (H) Save time in starting work – this would have been seen as a positive, immediate and certain consequence for the men, who had been informed of a delay to the isolation. (H) Avoid ridicule by co-workers for not getting into basket – this would have been seen as a positive, immediate and certain consequence for the individual concerned. (H) Avoid getting home late – a further positive, immediate and certain consequence to the men involved. (H) The consequences of this behaviour were predominantly positive, immediate and certain, thus would have strongly reinforced the behaviour. Desired behaviour: No personnel to ride in baskets or other exterior structures whilst under OLE power lines. Required Triggers: Tools and equipment –Key switch interlock operation prevented on vehicles with overhead platforms and platform steering until Form C issued (H) Awareness of risks and hazards - Clarify that raising basket even slightly underneath OLE increases the risk of flashover (H) Signs, displays - Notice next to interlock switch in RRV to discourage operation from the basket beneath OLE. (H) Other people’s expectations - Managers and supervisors to make clear safety expectations regarding OLE work. (H) Policies - Policy in place to prevent use of vehicles underneath OLE. (H) Procedures - Procedure for handover of information designed for clarity. (O & H) Required Consequences: Avoid injury to self or others, or other type of loss or damage – a positive, immediate and certain consequence that workers should already comprehend. (H) Praise correct individual behaviour – this provides positive, immediate and certain consequences for the individual for engaging in the desired behaviour. (H) Non-compliance results in a disciplinary action (a “three strikes and your out” policy) – Introduction of a negative, immediate and certain consequence of non-compliance. (H) Management observation scheme – depending on how this is managed, can be used to punish inappropriate behaviour, or positively reinforce desired behaviour. In both cases, the consequences are immediate and certain to the person behaving. (H)
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Oakley, 7th August 2003 ABC Analysis Behaviour: The lookout knelt down to engage in physical work, which led to his electrocution when he made contact with the conductor rail. Note – there is insufficient evidence to determine why the lookout disengaged from lookout duty to join in the work, but there are a number of factors that contributed to this, both at the time of the incident and during the planning process. These are recorded in this analysis. Triggers: Awareness of hazards and risks - The risk assessment only considered the high-level risk of the conductor rail – there was no specific assessment of the risks associated with this particular job. (O & H) Knowledge, skills, competence - One of the trackmen was inexperienced and there was no formal training for the work. This required COSS to provide on-the-job training, but it appears in this case that the lookout, as an experienced worker, was providing some of the training himself. (O & H) Other people’s expectations – Assumption: Mention made of the fact that the work had become urgent due to hot weather – was the implication that the workers felt under time pressure? In addition, the planning process for the possession looked only at the week ahead. This could also have been an effect of time-pressure to complete the work, as there were other slots further ahead that would have allowed the work to be carried out under T3 conditions. (O & H) Other people’s example - It had become custom and practice (routine violation) for this work to be conducted with the conductor rail energised. The safe worksite handbook does not include any activity covering this work with the conductor rail energised. It is therefore inferred that this is not officially condoned, but the rules on this are not made explicit. This could suggest to workers that management do not discourage such activity, and reflects on the commitment to safety of management as perceived by the workforce (link to safety culture) (H) Consequences: Causing injury to self or others, or other type of loss or damage – this would have been seen as negative, future and uncertain. (H) Save time – Assumption: it is possible that the lookout tried to join in work to save time, something that would have been seen as positive, immediate and certain. (H) Get approval from COSS for dealing with on-the-job training – something that would have been seen as positive, immediate and certain. (H) Get approval from trackman for helping with his training – Assumption: it is possible that the lookout felt that the trackman’s thanks for helping him would be a positive, immediate and certain consequence. (H) Desired Behaviour: 1. When on lookout duty, all personnel to refrain from engaging in work tasks. Note - this would not have resulted in an accident if the conductor rail had been de-energised. 2. All work involving changing pots and fixings to be planned for T3 possession. Note – this may involve a change in safety culture. Required Triggers: Risk assessments to include risks specific to the job in hand, rather than identifying hazards in the work area. (H) Training only to be provided by COSS when required on-the-job. (H)
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Procedure to state specifically that this work should not be conducted when the conductor rail is energised or adequate safeguards are in place. (H) Required Consequences: Avoid injury to self or others, or other type of loss or damage – positive, immediate and certain consequence. (H) Audit risk assessments and positive feedback on well-documented risk assessment, providing those involved with positive, immediate and certain consequences. (H) Provide negative feedback on any risk assessments that focus on hazards rather than risks – providing those involved with negative, immediate and certain consequences of noncompliance. (H) Positive feedback when work has been planned for T3 possession – positive, immediate and certain consequence. (H) Negative feedback when work is planned without T3 possession – negative, immediate and certain consequence. (H) Safety Culture Analysis The safety culture analysis suggested that two aspects of safety culture should be investigated in more depth. A number of the factors involved in this accident suggest possible weaknesses in the visibility of management’s commitment to safety and the level of risk-taking behaviour by employees. The analysis also suggested that communications relating to safety, the extent to which productivity or safety come first, and the competence of personnel in safety should be examined in addition. Ranskill, 19th October 1998 Human Error Analysis Behaviour: A linesman, whilst disconnecting earths from an overhead line, removed the earth end before the live end, resulting in fatal electric shock. Error Type: Perception error – Assumption: It appears that the men were working as a team to disconnect the earths and that the victim believed that the live end of the blue earth had been removed through observing his co-worker. (O & H) Error Mode: Misperception - Mistakenly perceived that the live end of the earth had been removed by his colleague. (H) Error Mechanism: Difficult to say from the evidence which one of signal strength (Failing to perceive something that is vague or of short duration.) and expectation (Expect something to take place so strongly that you believe that it has occurred even if there is evidence to suggest otherwise) is most likely to have been the mechanism. Either the victim expected that his colleague would have removed the top clamp, or he would have been unable to see clearly in the dark. Performance-Shaping Factors: Communication quality – the communication on progress of the job was poor and could have affected the performance of all team members. (O) Lighting – the fact that the task was being conducted in the dark with task lighting may have greatly affected performance. (O) Familiarity with the task – the gang were expecting to apply short earths and they were less familiar with long earths – this could have affected the performance of all involved. (O)
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Alertness, concentration and fatigue – the victim had worked 21 consecutive shifts before the accident, and booked 84 hours per week for the previous two weeks. (O) Team co-ordination quality – the co-ordination effort within the team could have been better. (O & H) Team communication quality – communications within the team could have been more frequent and may have had an effect on team performance. (H) West Croydon, 10th October 2001 Human Error Analysis Behaviour: Whilst maintaining a rail flange lubricator, an uninsulated spanner made contact with the conductor rail, causing ignition of grease and injury to two workers. Error Type: Action error - Tool unintentionally made contact with the energised conductor rail. (O & H) Error Mode: Selection error - Unintentionally positioned the spanner against the conductor rail. (H) Error Mechanism: Human variability - Temporary lack of precision. (H) Performance-Shaping Factors: Equipment ergonomics – the equipment was not insulated against electricity. (O) Alertness / concentration / fatigue – Assumption: it is possible that such factors caused a lapse in concentration. (H) Team co-ordination quality – Assumption: the co-ordination of effort between members of the team could have affected the performance of all team members. (H) Tollerton, 2nd May 2001 ABC Analysis Behaviour: The crane operator raises the crane arm whilst unloading, leading to contact with live OHLE. Triggers: Other people’s expectations - COSS expectations were not made clear to the crane operator (O & H) Other people’s example - The crane driver’s colleague did not intervene. (O) Consequences: Cause injury to self or others, or other type of loss or damage, would be seen as a negative, future and uncertain consequence. (H) Save time – Assumption: it is possible that the crane operator was trying to save some time, which would have been a positive, immediate and certain consequence of the behaviour. (H) Avoid ridicule from colleague for refusing to work without an isolation – a positive, immediate and certain consequence from the point of view of the crane operator. (H) Desired Behaviour: Crane operators not to operate arm in proximity to live OLE. Required Triggers: Audit of operations around OLE (H) COSS to remain with work party throughout operation (H)
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Required Consequences: Avoid injury to self or others, or other type of loss or damage, positive, immediate and certain. (H) Receive positive feedback for well-done method statements and risk assessments – to be seen as positive, immediate and certain from those involved. (H) Receive reprimand for poor work planning, a negative, future and certain consequence to discourage undesired behaviour. (H) Positive feedback when work has been planned for T3 possession, a positive, future and certain consequence. (H) Negative feedback when work is planned without T3 possession – a negative, future and certain consequence. (H)
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Appendix E
Task Lists for Predictive Human Error Analysis Inspection and Servicing Tasks Contact and catenary geometry inspection (crucifix gauge)
Contact and catenary geometry inspection (ultrasonic gauge)
Inspection of aerial feeds and jumpers (included in EO1)
Booster inspection
Bond testing (critical bonding)
Vegetation survey
transformer
Contact and catenary geometry inspection (laser gauge) Inspection of traction earthing and bonding (included in EO1)
Inspection and maintenance Tasks Inspection of conductor Rail
Inspection of fastenings
Inspection of cables
Inspection of continuity bonds
Catchpit clearance Patrolling (Risk only from con rail) Structures inspection only from con rail)
(Risk
Longitudinal timbers inspection (Risk only from con rail)
Switch heater maintenance monthly checks (Risk only from con rail) S & C inspections (Risk only from con rail) Vegetation clearance using flail mower mounted on 'on track' machine Ultrasonic inspection (manual) with hand trolley (Risk only from con rail)
Inspection of insulators Inspection of conductor rail equipment protection boarding Maintenance of ballast retention devices (Risk only from con rail) Formation inspection (Risk only from con rail) Vegetation clearance using manual methods Surveying using levelling equipment (Only risk from Con Rail)
Maintenance Tasks Maintenance of rails Maintenance of cables Removal and replacement of cables and tamper proof tubing from underneath rails Profile gauging of conductor rail Changing traction negative bonds Replacing conductor rail Tapping of pre-drilled holes in conductor rail to facilitate the connection of fittings Tripping of circuit breaker using short-circuiting bar Maintenance of switches and isolators Rail lubricator replacement (Risk only from con rail)
Maintenance of fastenings Maintenance of continuity bonds
Maintenance of insulators Maintenance of conductor rail protection boarding
Fitting cables
Drilling of running rail
of
terminations
Spatial gauging of conductor rail
Painting ramp ends
Changing insulator pots
Applying conductor rail wraps
Cutting and conductor rail
Fitting attachments to conductor rail Fitting and removal of conductor rail short-circuiting device
welding
Hookswitch changing Install glass-fibre shrouding under conductor rail Maintenance of cathodic protection systems Fishplate oiling (Risk only from con rail)
CWR stress management (Risk only from con rail)
Drilling conductor rail
CWR transpose
CWR Renewal
Rail welding (MMA)
Adjustment replacement
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switch
Fitting arc control shield Rail lubricator servicing (Risk only from con rail) Rail adjusting (Risk only from con rail) Restressing (elimination of non-compliances) (Risk only from con rail) Rail welding (thermic) (Risk only from con rail) Adjustment switch maintenance (Risk only from con rail)
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Rail changing (wear) IBJ maintenance (Risk only from con rail) Rail grinding (RMMM/RRV) Replacement of pads and nylons (Risk only from con rail)
Rail changing (defective) Check rail changing (Risk only from con rail) Rail grinding (trolley) Changing fastenings only from con rail)
(Risk
Longitudinal timber renewal
Longitudinal timber and fastening maintenance (Risk only from con rail)
Dynamic gauge maintenance (Risk only from con rail)
Complete resleepering
manual stone blowing (Risk only from con rail)
stone blowing using vehicle (Risk only from con rail)
Ballast unloading / levelling from on top of a wagon
Ballast profiling (Risk only from con rail)
Eradication of wet beds (manual) (Risk only from con rail) Renewals (reballasting or formation work) Retimbering (Risk only from con rail) Switch heater maintenance annual check (Risk only from con rail) Drainage clearance (highpressure water jetting) Catchpit maintenance Culvert maintenance (<450mm)
S&C tamping (Risk only from con rail) Manual maintenance of S&C (Risk only from con rail)
S&C Unit renewal (half-set switches or Xing) Electrical arc weld repairs Drainage clearance (manual rodding using long rods)
Renewals Ditch clearance
Section insulator maintenance
Insulator cleaning
Booster transformer maintenance Maintenance of mechanical barriers Maintenance of climbing equipment Painting of structures Localised contact wire renewal (circa 10 metre lengths) GN area bonding renewal (drilled and bolted) Panchex maintenance (changing potentiometers)
Power maintenance Maintenance notices
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Plain line tamping (Risk only from con rail) Manual correction to PL track geometry (Risk only from con rail) Maintenance of free-draining ballast and formation (Risk only from con rail) Maintenance of clearances (Risk only from con rail)
Maintenance of height restriction devices Signal control equipment replacement Maintenance of OLE in tunnels
Signals renewal
Direct fastening maintenance (Risk only from con rail)
Eradication of wet beds using on-track plant
Drainage maintenance Culvert (<450mm) repair and renewal Ultrasonic inspection (manual) using hand probe (Risk only from con rail) Level crossing equipment renewal Renewal of level crossing equipment Interlocking equipment replacement Removal of object from OLE (e.g. wind-blown debris)
Litter, spoil and debris clearance (outside stations)
IBJ renewal Guard rail maintenance (Risk only from con rail) Spot resleepering Sleeper retention device maintenance (Risk only from con rail)
Point machine / mechanism replacement Maintenance of level crossing CCTV and supports (fixed) Equipment housings replacement Inspect and maintain overhead line (EO2) Neutral section maintenance Maintenance of aerial feeds and jumpers (included in EO2)
transformer of
Culvert clearance (all diameters) Ditch maintenance Litter, spoil and debris clearance (inside stations)
warning
Isolator switch maintenance Maintenance of access ladders
Maintenance of platforms
Maintenance of guard rails
Bow wire anchor renewal Damaged area rectification (contact wire by tension length and droppers) GN Area butyl rubber insulator renewal Panchex maintenance (servo adjustments)
Dropper replacement
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Neutral section spreader bar replacement Dunted insulator renewal Maintenance of monitoring equipment
wind
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Replacement plastic dropper sleeves with stainless steel
High speed stirrups
Crossed contact assemblies
Maintenance of lineside signs
bridge
steady
arm
Maintenance of noise reduction barriers Driver only operation platform CCTV maintenance
Dropper saddles Catchpit clearance (mechanised) using on track plant Maintenance of structure and fabric of relay rooms Driver only operation mirrors and heaters maintenance Maintenance of structure and fabric of equipment rooms
Maintenance of lighting (fixed) Maintenance of structure and fabric of sub stations Maintenance of structure and fabric of TP huts Inspection, intrusive and nonintrusive maintenance of HSCB maintenance in sub station and TP hut Inspection, intrusive and nonintrusive maintenance of 11kV 3ph AC non traction substation Battery system maintenance (VRLA) Protection testing - DC
Harmonic filter maintenance
11kV / 750V DC transformer rectifier maintenance
Supervisory cable testing and maintenance
Outstation supervisory remote control
Motorised switch maintenance
Inspection, intrusive and nonintrusive maintenance of Voltage regulator
Main and standby supplies maintenance
LV wiring certification
650V mobile maintenance
415V SSP UPS maintenance
Inspection, intrusive and nonintrusive maintenance of HVCB in sub station (VCBs)
Maintenance of radio masts
Renewals of ladders, guard rails, etc.
Radio antennae (track side) Inspection, intrusive and nonintrusive maintenance of NCL frame leakage testing
Inspection, intrusive and nonintrusive maintenance of NCL 11kV OCB maintenance
Inspection, intrusive and nonintrusive maintenance of NCL LV CB / Panel maintenance
Inspection, intrusive and nonintrusive maintenance of traction derived supply point (supply changeover test)
Battery system maintenance (free vent)
Protection testing NCL Transformer maintenance (11kV / 440V) Control room supervisory remote control Inspection, intrusive and nonintrusive maintenance of SSP / Aux. HV transformer testing
and
Inspection, intrusive and nonintrusive maintenance of HVCB SMOS Painting of support structures Communications cable renewals
Lineside cable renewals Maintenance of elevated cable routes
Hookswitch operation
Oil pumping HV cables
Location cases and rooms - roof repairs
Straight post replacement
Brackets / gantry replacement
Roof work location cases/superlocs Brackets / gantry maintenance
Report No. 2
Signalling cable renewals Renewal of troughing units relay
Painting signal structures
Issue 1.
Page 112 of 127
Appendix F1
Task List and Risk Assessment for Permanent Way Engineering in OLE Area Showing Red Risks Proximity to OLE Task
Surveying using levelling equipment CWR transpose CWR renewal Rail grinding (RMMM/RRV) Rail Grinding (Trolley) Longitudinal timber renewal Complete resleepering Ballast unloading/levelling (manual)
Description
Staff undertaking optical survey of track
Key Electrical Risk
600mm >2.75M <600mm 2.75M
Equipment coming into contact with live OLE
Equipment/materials coming into contact with live OLE Laying out of new rail, Equipment/materials cutting old rail, repositioning coming into contact new rail, disposal of old rail. with live OLE Rail grinding using On Track On and off tracking of Plant machine Rail grinding using hand On/off loading from trolley vehicle Equipment/materials Major renewal activity coming into contact with live OLE Equipment/materials Major renewal activity coming into contact with live OLE Equipment/materials Staff stood on wagon coming into contact unloading/levelling ballast with live OLE Cutting of rails and turning them
Eradication of wet beds (using on track Wet spot eradication using On On and off tracking of plant) Track Plant machine Renewals (reballasting or formation work)
Major renewal activity
S&C unit renewal (half-set switches or Xing)
Major renewal activity
Renewals
Major renewal activity
Equipment/materials coming into contact with live OLE Equipment/materials coming into contact with live OLE Equipment/materials coming into contact with live OLE
RA Basic Control Measures L
S
Total
4
5
20
3
5
15
3
5
15
3
5
15
3
5
15
4
5
20
4
5
20
4
5
20
3
5
15
4
5
20
4
5
20
4
5
20
Possible Mitigations Possible Isolation Site-specific method statements, trained and competent staff. Suitable Equipment, PPE Probable Isolation Site specific method statements, trained and competent staff Probable Isolation Site specific method statements, trained and competent staff Compliance with relevant Engineering Acceptance Standards required. Site specific method statements, trained and competent staff Probable Isolation Site specific method statements, trained and competent staff Probable Isolation Site specific method statements, trained and competent staff Probable Isolation Site specific method statements, trained and competent staff Possible Isolation Site specific method statements, trained and competent staff Probable Isolation Site specific method statements, trained and competent staff Probable Isolation Site specific method statements, trained and competent staff Probable Isolation Site specific method statements, trained and competent staff
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level
Report No. 2
Issue 1.
Page 113 of 127
Appendix F2
Task List and Risk Assessment for Signalling Engineering in OLE Area Showing Red Risks
Task
Description
Proximity to OLE
Key Electrical Risk
RA Basic Control Measures
Possible Mitigations
600mm >2.75M <600mm L - 2.75M
S
Total
4
5
20
Site-specific method statements, trained and competent staff. Suitable Equipment, PPE
5
5
25
Isolation Required
5 5
5 5
25 25
Isolation Required Isolation Required
Roof Work location cases/superlocs Straight Post replacement
Renewal Activity
Equipment could come into contact with live OLE Persons and Equipment coming into contact with live OLE Ditto Ditto
Brackets/Gantries replacement
Renewal Activity
Ditto
5
5
25
Isolation Required
Brackets/Gantries maintenance
Intrusive Maintenance
Ditto
5
5
25
Isolation Required
Painting Signal Structures (all)
Renewal Activity
5
5
25
Point Machine/Mechanism replacement
Renewal Activity/Ground Mounted
4
5
20
Isolation Required Possible Isolation Site specific method statements, trained and competent staff
Signals
Renewal Activity
5
5
25
Isolation Required
Level Crossing equipment
Renewal Activity/Ground Mounted
Ditto Plant & Equipment could come into contact with live OLE Persons and Equipment coming into contact with live OLE Plant & Equipment could come into contact with live OLE
4
5
20
Isolation Required
Equipment Housings
Site Specific Replacement
Ditto
4
5
20
Isolation Required
Interlocking equipment Signal Control Equipment
Site Specific Replacement Site Specific Replacement
Ditto Ditto
4 4
5 5
20 20
Isolation Required Isolation Required
Signal sighting checks (New)
Site specific from ground could use periscope
Location cases and Relay Rooms - Roof Repairs
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level.
Report No. 2
Issue 1.
Page 114 of 127
Appendix F3
Task List and Risk Assessment for Telecommunications Engineering in OLE Area Showing Red Risks
Task
Description
Radio Antennae (Track Side)
Maintain or Replace
Lineside cables renewals
Ground Equipment
Signalling cable renewals
Site Specific
Communications cables renewals
Site Specific
Maintenance of cable routes
Elevated
Renewal of troughing units
Elevated
Proximity to OLE
Key Electrical Risk
>2.75M
Plant & Equipment could come into contact with live OLE Plant & Equipment could come into contact with live OLE Plant & Equipment could come into contact with live OLE Plant & Equipment could come into contact with live OLE Plant & Equipment could come into contact with live OLE Plant & Equipment could come into contact with live OLE
RA Basic Control Measures
Possible Mitigations
600mm <600mm L - 2.75M
S
Total
4
5
20
Possible Isolation Site specific method statements, trained and competent staff
4
5
20
Could require isolation dependent on cable routing
4
5
20
Could require isolation dependent on cable routing
4
5
20
Could require isolation dependent on cable routing
4
5
20
Could require isolation dependent on cable routing
4
5
20
Could require isolation dependent on cable routing
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level
Report No. 2
Issue 1.
Page 115 of 127
Appendix F4
Task List and Risk Assessment for Contact Systems Engineering in OLE Area Showing Red Risks Proximity to OLE Task
Description
Key Electrical Risk >2.75M
600mm <600mm 2.75M
RA Basic Control Measures L
S
Total
Possible Mitigations
Inspect and Maintain Overhead Line (EO2)
Intrusive maintenance of the OLE system
Staff or equipment coming into contact with live equipment
5
5
25
Isolation Required
Maintenance of OHLE in Tunnels
Intrusive maintenance of the OLE system
Ditto
5
5
25
Isolation Required
Removal of object from OLE
Staff removing objects e.g. wind blown debris from OLE
Ditto
4
5
20
Possible Isolation Site specific method statements, trained and competent staff
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Intrusive maintenance of the OLE system Intrusive maintenance of the Section Insulator Maintenance OLE system Intrusive maintenance of the Insulator Cleaning OLE system Maintenance of Aerial Feeds and Intrusive maintenance of the Jumpers (Included in EO2) OLE system Intrusive maintenance of the Booster Transformer Maintenance OLE system Intrusive maintenance of the Isolator Switch Maintenance OLE system Intrusive maintenance near to Maintenance of Mechanical Barriers the OLE system Intrusive maintenance near to Maintenance of Access Ladders the OLE system Intrusive maintenance near to Maintenance of Climbing Equipment the OLE system Intrusive maintenance near to Maintenance of Platforms the OLE system Intrusive activity near to live Painting of Structures OLE equipment Intrusive activity on or near to Bow Wire Anchor Renewal live OLE equipment Intrusive activity on or near to Dropper Replacement live OLE equipment Localised Contact Wire Renewal (Circa Intrusive activity on or near to 10 Metre Lengths) live OLE equipment Damaged Area Rectification (Contact Intrusive activity on or near to Wire by Tension Length + Droppers) live OLE equipment Neutral Section Maintenance
Report No. 2
Issue 1.
Page 116 of 127
Proximity to OLE Task
Description
Key Electrical Risk >2.75M
600mm <600mm 2.75M
RA Basic Control Measures L
S
Total
Possible Mitigations
Neutral Section Spreader Bar Replacement
Intrusive activity on or near to live OLE equipment
Ditto
5
5
25
Isolation Required
Bonding Renewal (Drilled and Bolted)
Intrusive activity on or near to live OLE equipment
Ditto
5
5
25
Possible Isolation Site specific method statements, trained and competent staff
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Butyl Rubber Insulator Renewal Dunted Insulator Renewal Panchex Maintenance (Changing Potentiometers) Panchex Maintenance (Servo Adjustments) Maintenance of Wind Monitoring Equipment
Intrusive activity on or near to live OLE equipment Intrusive activity on or near to live OLE equipment Intrusive activity on or near to live OLE equipment Intrusive activity on or near to live OLE equipment Intrusive activity on or near to live OLE equipment
Replacement of Plastic Dropper Sleeves Intrusive activity on or near to with Stainless Steel live OLE equipment Intrusive activity on or near to High Speed Steady arm Stirrups live OLE equipment Intrusive activity on or near to Dropper Saddles live OLE equipment Intrusive activity on or near to Cross Contact Bridge Assemblies live OLE equipment
Ditto
5
5
25
Possible Isolation Site specific method statements, trained and competent staff
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Ditto
5
5
25
Isolation Required
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level.
Report No. 2
Issue 1.
Page 117 of 127
Appendix F5
Task List and Risk Assessment for Power Distribution Engineering in OLE Area Showing Red Risks Proximity to OLE Task
Description
Key Electrical Risk >2.75M
600mm <600mm 2.75M
RA Basic Control Measures L
S
Total
Possible Mitigations Site-specific method statements, trained and competent staff. Certificated in accordance with NR standards. Permit to Work System. Management of Interface with Overhead line teams Site-specific method statements, trained and competent staff. Certificated in accordance with NR standards. Permit to Work System
HVCB maintenance SMOS
Inspection, non-intrusive and intrusive maintenance
Electrocution
4
5
20
Booster Transformer Maintenance
Inspection, non-intrusive and intrusive maintenance
Electrocution
4
5
20
Main & Standby Supplies Maintenance
Inspection, non-intrusive and intrusive maintenance
Electrocution
N/A
N/A
N/A
3
5
20
Site-specific method statements, trained and competent staff. Certificated in accordance with NR standards
650V Mobile maintenance
Inspection, non-intrusive and intrusive maintenance
Electrocution
N/A
N/A
N/A
3
5
20
Site-specific method statements, trained and competent staff. Certificated in accordance with NR standards
415v SSP UPS Maintenance
Inspection, non-intrusive and intrusive maintenance
Electrocution
N/A
N/A
N/A
3
5
20
Site-specific method statements, trained and competent staff. Certificated in accordance with NR standards
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level
Report No. 2
Issue 1.
Page 118 of 127
Appendix F6
Task List and Risk Assessment for Off Track Activities in OLE Area Showing Red Risks Proximity to OLE Task
Description
Key Electrical Risk >2.75M
Maintenance of fencing-Chain links
Maintenance of the railway boundary
Maintenance of fencing - Palisade Ditto Maintenance of fencing - Post and wire Ditto Maintenance of Boundary Walls Ditto Maintenance of Retaining Walls <1m Ditto high Maintenance of Retaining Walls provided for location of Signalling or electrical Ditto equipment Maintenance of Level Crossing CCTV Staff working at high level and supports (fixed) Maintenance of noise Maintenance of noise reduction barriers reduction barriers Maintenance of height restriction devices Ditto Renewal of Level Crossing Equipment
Major renewal activity
600mm <600mm 2.75M
RA Basic Control Measures L
S
Total
Possible Mitigations
Staff or equipment coming into contact with live OLE Ditto Ditto Ditto
3
5
15
3 3 3
5 5 5
15 15 15
Safe System of work required to ensure staff or equipment do not come with 2.75 metres. Use of trained and competent staff Ditto Ditto Ditto
Ditto
3
5
15
Ditto
Ditto
3
5
15
Ditto
Ditto
3
5
15
Ditto
Ditto
3
5
15
Ditto
Ditto
3
5
15
Ditto
Ditto
4
5
20
Ditto
3 3
5 5
15 15
Ditto Ditto
3
5
15
Ditto
3
5
15
Ditto
4
5
20
Possible Isolation Required
3
5
15
Possible Isolation Required
3
5
15
Possible Isolation Required
3 3 3 3
5 5 5 5
15 15 15 15
Could require isolation when working on roof Could require isolation when working on roof Could require isolation when working on roof Could require isolation when working on roof
Lineside signs Drainage clearance (manual rodding)
Staff working at high level Ditto Staff using long rods Ditto Catch pit clearance using On On and off tracking of Catchpit clearance (mechanised) Track Plant machine Maintenance of lighting (fixed) Staff working at high level Ditto Drainage clearance (high pressure water High pressure water jet Fine water spray on live jetting) machine OLE causing tracking Cutting back of lineside Vegetation clearance using flail mower vegetation using "on track" Ditto mounted on "on track" machine machine Vegetation clearance using manual Cutting back of lineside Ditto methods vegetation using hand tools Relay Rooms Building maintenance work Ditto Sub Stations Building maintenance work Ditto TP Huts Building maintenance work Ditto Equipment Rooms Building maintenance work Ditto
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level.
Report No. 2
Issue 1.
Page 119 of 127
Appendix F7
Task List and Risk Assessment for Permanent Way Engineering in DC Conductor Rail Area Showing Red Risks Task Ultrasonic Inspection (Manual) Surveying using levelling equipment
Description
Key Electrical Risk
Staff undertaking NDT using hand probe Staff undertaking optical survey of track
Staff or equipment coming into contact with live con rail Ditto
Proximity to Basic Control Measures Conductor Rail >300 mm < 300mm L S Total 4
5
20
4
5
20
Possible Mitigations Site-specific method statements, trained and competent staff. Use of PPE & Insulated Tools Ditto
Rail lubricator replacement
Intrusive maintenance
Ditto
4
5
20
Possible Isolation Site-specific method statements, trained and competent staff. Use of PPE & Insulated Tools Ditto
Fishplate oiling
Intrusive maintenance
Ditto
4
5
20
Ditto
Rail adjusting
Intrusive maintenance
Ditto
4
5
20
Ditto
CWR stress management
Intrusive maintenance
Ditto
5
5
25
Ditto
Restressing
Intrusive maintenance
Ditto
5
5
25
Ditto
CWR transpose
Ditto
5
5
25
Ditto
Ditto
5
5
25
Ditto
Rail welding (Thermic)
Cutting of rails and turning them Laying out of new rail, cutting old rail, repositioning new rail, disposal of old rail. Staff working at rail level
4
5
20
Ditto
Rail Welding (MMA)
Staff working at rail level
4
5
20
Ditto
Adjustment switch replacement
Intrusive maintenance
5
5
25
Ditto
Adjustment switch maintenance
Intrusive maintenance
Ditto Electric Shock due to earthing arrangement Staff or equipment coming into contact with live con rail Ditto
5
5
25
Ditto
Rail changing (wear)
Intrusive maintenance
Ditto
5
5
25
Ditto
Rail changing (defective)
Intrusive maintenance
Ditto
5
5
25
Ditto
IBJ renewal
Intrusive maintenance
Ditto
5
5
25
Ditto
IBJ maintenance
Intrusive maintenance
Ditto
4
5
20
Ditto
Check rail changing
Intrusive maintenance
Ditto
5
5
25
Ditto
Guard rail maintenance
Ditto
3
5
15
Ditto
None Identified
5
5
25
Ditto
Rail Grinding (Trolley)
Tightening of fastenings Rail grinding using vehicle in train formation Rail grinding using hand trolley
5
5
25
Ditto
Spot resleepering
Staff working at rail level
5
5
25
Ditto
Replacement of pads and nylons
Staff working at rail level
On/off loading from vehicle Manual Handling of sleeper and equipment in close proximity to live rail Staff using hand tools in close proximity to live rail
5
5
25
Ditto
Rail lubricator servicing
CWR renewal
Rail grinding (In train)
Report No. 2
Intrusive maintenance
Ditto
4
Issue 1.
5
20
Page 120 of 127
Task
Description
Key Electrical Risk
Proximity to Basic Control Measures Conductor Rail >300 mm < 300mm L S Total
Possible Mitigations
Changing fastenings Sleeper retention device maintenance
Staff working at rail level
Ditto
5
5
25
Ditto
Staff working at rail level
Ditto
5
5
25
Ditto
Longitudinal timber renewal
Major renewal activity
5
5
25
Ditto
5
5
25
Ditto
Longitudinal timber & fastening maintenance Direct fastening maintenance
Staff working at rail level Staff working at rail level
5
5
25
Ditto
5
5
25
Ditto
5
5
25
Ditto
Ditto
5
5
25
Ditto
Ditto
5
5
25
Ditto
Ditto
5
5
25
Ditto
Ditto
5
5
25
Ditto
Ditto
5
5
25
Ditto
Major Renewal Activity
Ditto
5
5
25
Ditto
Major renewal activity
Ditto
5
5
25
Ditto
Renewal Activity Measured Shovel Packing/Kango Packing Staff working at rail level
Ditto
5
5
25
Ditto
Ditto
5
5
25
Ditto
Ditto
4
5
20
Ditto
Intrusive Maintenance
Ditto
5
5
25
Ditto
Major renewal activity
Ditto
5
5
25
Ditto
Dynamic gauge maintenance
Staff working at rail level
Complete resleepering
Major renewal activity
Stoneblowing Manual correction to PL track geometry Eradication of wet beds (manual) Eradication of wet beds (using on track plant) Maintenance of clearances Renewals (reballasting or formation work) S&C unit renewal (half-set switches or Xing) Retimbering Manual maintenance of S&C Electric arc weld repairs Switch heater maintenance annual check Renewals
Equipment/materials coming into contact with live con rail Staff using hand tools in close proximity to live rail Ditto
Stone blowing using manual methods Measured Shovel Packing/Kango Packing Staff working at rail level Wet spot eradication using On Track Plant Staff undertaking track slews
Ditto Equipment/materials coming into contact with live con rail
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level.
Report No. 2
Issue 1.
Page 121 of 127
Task List and Risk Assessment for Signalling Engineering in DC Conductor Rail Area Showing Red Risks
Task
Description
Key Electrical Risk
Proximity to Conductor Rail
Basic Control Measures
Possible Mitigations
< L 300mm
S
Total
Staff or equipment coming into contact with Con rail
3
5
15
Possible Isolation Site-specific method statements, trained competent staff. Use of PPE & Insulated Tools
Point mechanism (all types inc back drives and supplementary detectors) - Ditto service
Ditto
3
5
15
Ditto
Electrical detector - service
Ditto
Ditto
3
5
15
Ditto
Mechanical detector - service
Ditto
Ditto
3
5
15
Ditto
Detonator placers - 12 week service
Ground Mounted
Ditto
3
5
15
Ditto
AWS, TPWS
Ground Mounted
Ditto
3
5
15
Ditto
Track Circuit - service
Ground Mounted
Ditto
4
5
20
Ditto
TCAID - annual service
Ground Mounted
Ditto
4
5
20
Ditto
Treadle - service
Ground Mounted
Ditto
3
5
15
Ditto
Facing point lock test
Staff working at Rail Level
>300 mm
Appendix F8
HABD maintenance
Ground Mounted
Ditto
3
5
15
Ditto
Wheel flat detection maintenance
Ground Mounted
Ditto
3
5
15
Ditto
3rd rail shoegear detection maintenance
Ground Mounted
Ditto
3
5
15
Ditto
Automatic trainstop protection
Ground Mounted
Ditto
3
5
15
Ditto
Ground Mounted
Ditto
3
5
15
Ditto
Dragging brake maintenance
gear
detector
and
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level.
Report No. 2
Issue 1.
Page 122 of 127
Appendix F9
Task List and Risk Assessment for Contact Systems Engineering in DC Conductor Rail Area Showing Red Risks
Task
Description
Key Electrical Risk
Proximity to Conductor Rail >300 < mm 300mm
Basic Control Measures
Possible Mitigations
L
S
Total
4
5
20
Isolation Required
Maintenance of Rails
Intrusive maintenance
Maintenance of Fastenings
Intrusive maintenance
Staff or equipment coming into contact with live con rail Ditto
4
5
20
Isolation Required
Maintenance of Insulators
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Maintenance of Cables
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Maintenance of Continuity Bonds Maintenance of Conductor Rail Equipment Protection Boarding Removal and replacement of cables and tamper proof tubing from underneath rails
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Ditto
4
5
20
Isolation Required
Ditto
4
5
20
Isolation Required
Ditto
4
5
20
Ditto
4
5
20
Isolation Required Safe System of Work required. development of new non contact gauge
Ditto
4
5
20
Ditto
Painting Ramp Ends
Intrusive maintenance Profile gauging using insulated gauge Spatial gauging using insulated gauge Intrusive maintenance
Ditto
4
5
20
Isolation Required
Changing Traction negative bonds
Intrusive maintenance
Ditto
4
5
20
Safe System of Work required
Changing Insulator Pots
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Applying Conductor Rail Wraps
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Replacing Conductor Rail Cutting and Welding Conductor Rail Fitting Attachments to Conductor Rail Tapping of pre drilled holes in conductor rail to facilitate the connection of fittings
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Fitting of terminations to cables Drilling Conductor Rail Drilling of running rail Profile Gauging of Conductor Rail Spatial Gauging of Conductor Rail
Hookswitch Changing
Report No. 2
Crimping cables using hydraulic crimping tool Intrusive maintenance
Issue 1.
Potential for
Page 123 of 127
Task Fitting and Removal of Third Rail Short Circuiting Device Tripping of Circuit Breaker using short circuiting bar Install glass fibre shrouding under conductor rail
Description
Key Electrical Risk
Proximity to Conductor Rail >300 < mm 300mm
Basic Control Measures L
S
Total
Possible Mitigations
Isolation Procedures
Ditto
4
5
20
Undertake task in accordance with GO/RT 3091
Isolation Procedures
Ditto
4
5
20
Undertake task in accordance with GO/RT 3091
Intrusive maintenance
Ditto
Fitting Arc Control Shield
Intrusive maintenance
Ditto
4
5
20
Isolation Required
Tunnel Patrol
Foot Patrol and Visual Inspection of the P Way
Ditto
3
5
15
All staff undertaking these tasks have been trained and certificated to PTS requirements
Intrusive maintenance
Ditto
4
5
20
Safe System of Work required
Intrusive maintenance
Ditto
4
5
20
Safe System of Work required
Maintenance of Switches and Isolators Maintenance of Cathodic Protection Systems
Isolation Required
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level.
Report No. 2
Issue 1.
Page 124 of 127
Appendix F10
Task List and Risk Assessment for Off Track Activities in DC Conductor Rail Area Showing Red Risks
Task
Description
Vegetation clearance using flail Cutting back of lineside vegetation mower mounted on "on track" using "on track" machine machine Vegetation clearance using manual Cutting back of lineside vegetation methods using hand tools Survey undertaken by staff from Vegetation Survey Cess or foot patrol from track Drainage clearance (manual Staff using long rods rodding) Drainage clearance (high pressure High pressure water jet machine water jetting)
Key Electrical Risk
Basic Control Measures
Proximity to Conductor Rail
>300 < L mm 300mm
S
Total
Staff or equipment coming into contact with live con rail
3
5
15
On/Off tracking needs to be considered
Ditto
3
5
15
Safe System of Work required to ensure activity is kept more than 300mm away from Con Rail
Staff or equipment coming into contact with live con rail
3
5
15
Activity is away from live con rail
Ditto
4
5
20
Possible Isolation required
Ditto
4
5
20
Possible Isolation required
Ditch clearance
Staff Working at Rail Level
Ditto
3
5
15
Culvert clearance (all diameters)
Staff Working at Rail Level
Ditto
3
5
15
Catchpit maintenance
Staff Working at Rail Level
Ditto
3
5
15
Drainage maintenance
Staff Working at Rail Level
Ditto
3
5
15
Ditch maintenance
Staff Working at Rail Level
Ditto
3
5
15
Culvert maintenance (<450mm)
Staff Working at Rail Level
Ditto
3
5
15
ditto but for repair and renewal
Staff Working at Rail Level
Ditto
3
5
15
Staff Working at Rail Level
Ditto
3
5
15
Staff Working at Rail Level
Staff or equipment coming into contact with live con rail
3
5
15
Litter, Spoil and Debris Clearance (inside stations) Litter, Spoil and Debris Clearance (outside stations)
Possible Mitigations
Safe System of Work required to ensure activity is kept more than 300mm away from Con Rail Safe System of Work required to ensure activity is kept more than 300mm away from Con Rail Safe System of Work required to ensure activity is kept more than 300mm away from Con Rail Safe System of Work required to ensure activity is kept more than 300mm away from Con Rail Safe System of Work required to ensure activity is kept more than 300mm away from Con Rail Safe System of Work required to ensure activity is kept more than 300mm away from Con Rail Safe System of Work required to ensure activity is kept more than 300mm away from Con Rail Safe System of Work required to ensure activity is kept more than 300mm away from Con Rail Safe System of Work required to ensure activity is kept more than 300mm away from Con Rail
Note: The possible mitigations are for consideration only. Where tasks indicate an unacceptable risk then appropriate control measures should be developed to bring the residual risk down to a tolerable level
Report No. 2
Issue 1.
Page 125 of 127
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Report No. 2
Issue 1.
Page 126 of 127
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