Railway Safety Principles, Electrical Traction

Responsibility for the regulation of health and safety on the railways was

transferred from the Health and Safety Commission (HSC) and Health and

Safety Executive (HSE) to the Office of Rail Regulation (ORR) on 1 April

2006.

This document was originally produced by HSC/E but responsibility for the

subject/work area in the document has now moved to ORR.

If you would like any further information, please contact the ORR's

Correspondence Section - [email protected]

mailto:[email protected]

Railway safety principles andguidance

safety principles

RAILWAY

SAFETY

PRINCIPLES

and

GUIDANCE

part 2section CGuidance onelectric tractionsystems

HSEHealth & Safety ExecutiveHM Railway Inspectorate

HSE BOOKS

r a i l w a y s a f e t y p r i n c i p l e s a n d g u i d a n c e

i

CONTENTS

FOREWORD iii

1 INTRODUCTION 1

Electric traction system - definition 1

Application of the guidance 1

Approval procedures 2

Other regulations and standards 2

Structure of the guidance 3

Terminology 3

2 PROTECTION OF PEOPLE 4

Protection against unwanted access 4

At level crossings 4

Warning signs and notices 5

Equipment positioning 5

Anti-climbing protection 6

Safety screening 7

Earthing and bonding 7

Fire 7

Other considerations 7

3 ELECTRICAL CLEARANCES 8

Overhead systems 8

Conductor rail systems 9

4 SAFE MANAGEMENT AND OPERATION 10

Control and sectioning 10

Earthing and bonding 11

Fault protection 11

Conductor rail guarding 12

Precautions against contamination of insulators 13

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Precautions against electrolytic damage and electro-magnetic interference 13

APPENDIX A - ELECTRIC TRACTION SYSTEM PRINCIPLES 14

APPENDIX B - COMMON TERMS 18

Railway terms 18

People terms 18

Infrastructure terms 19

Station terms 19

Train terms 20

Electric traction system terms 20

Safety terms 20

Operational conditions or states 20


i i i

FOREWORD

This document is one of eight which provide guidance on specific aspects of railway construction. It

continues the tradition of providing written advice started by the Railway Inspectorate soon after

its formation in 1840.

This latest version of the guidance under its new title Railway safety principles and guidance revises

and updates the previous advice contained in the Railway construction and operation requirements

for passenger lines and recommendations for goods lines documents which became known throughout

the industry as ‘The Blue Book’ or simply the ‘Requirements’.

The guidance is now being published in two distinct ‘Parts’. Part 1 sets out the top level safety

principles and gives an indication of the factors which need to be taken into account in

implementing them.

Part 2 consists of eight separate sections dealing with specific aspects of railway construction.

It provides an expansion of the advice given in Part 1 and also gives examples of good practice

acceptable to the Inspectorate, for those who would find such advice of assistance.

The eight sections in Part 2 deal with specific aspects of railway construction:

A The infrastructure;

B Stations;

C Electric traction systems;

D Signalling;

E Level crossings;

F Trains;

G Tramways;

H Minor railways.

The RSPG series Parts 1 and 2 can be found on the HSE website at:

http://www.hse.gov.uk/railways/information.htm under Railway safety principles and guidance.

As with previous guidance, these documents are intended to give advice and not set an absolute

standard.

During the development of the new format and preparation of the principles and guidance, the

Railway Inspectorate has consulted extensively with the railway industry and other organisations

who could usefully contribute to the work. Much assistance and many constructive comments have

been received and the Inspectorate is most grateful for the time and help it has been given.

It is hoped that the railway industry of today will find this new guidance to be of as much help as

the Blue Book’s advice was in the past.

1 INTRODUCTION

1 Railway safety principles and guidance is intended to give guidance and advice to those involved

in the design and construction of new and altered works, plant and equipment (which includes

trains and other rail mounted vehicles) capable of affecting the safety of railways, tramways or

other guided transport systems, which require approval under the Railways and Other Transport

Systems (Approval of Works, Plant and Equipment) Regulations 1994.

2 This document is not intended to set out mandatory standards. It supports and amplifies the

Part 1 electric traction system safety principles by giving examples of established good practice

acceptable to the Inspectorate, for those who would find such advice of assistance. The full text of

these principles can be found in Appendix A - Electric traction system principles.

3 Specific guidance on the electric traction systems for tramways is contained in Part 2, Section G

Tramways which deals specifically with tramways.

Electric traction system - definition

4 The electric traction system (ETS) is used to mean the electrical equipment and conductors

necessary to power the trains on an electrified railway. It includes the incoming supply feeders,

switchgear and transformers which control and provide the electrical current at the traction

system’s line voltage, the distribution network and catenary or conductor rail systems. It does not

include the current collection equipment of the train or other on-board electrical equipment except

for the provision of electrical clearances between such equipment and the infrastructure.

Application of the guidance

5 Application of this guidance should provide a sufficient level of safety for approval to be given

by the Inspectorate, provided that it has been demonstrated that the use of the guidance is wholly

applicable to the works, plant or equipment.

6 If this is not the case, then the Inspectorate will wish to be satisfied that due consideration has

been given to implementing the safety principles in the Part 1 document Railway safety principles and

guidance in a way that ensures that all intolerable risks have been eliminated and that all remaining

risks have been reduced to be as low as reasonably practicable (known as ALARP).

Effects on existing works

7 Railway safety principles and guidance does not apply retrospectively to existing works, plant

and equipment. However, new or altered works, plant and equipment might introduce

incompatibilities or inconsistencies with the existing works, plant or equipment. In this case,

approval may only be given if appropriate arrangements have been made to address these safety

implications which may include modifications to the existing works, plant or equipment.

Operating conditions

8 The choice and design of the works, plant and equipment will depend not only on the guidance

expressed in this document but also on the operational requirements of the railway.


1

9 In assessing the suitability of any proposed safety measures or arrangements, it is important to

take into account:

(a) normal operating conditions;

(b) degraded conditions where any component or part of the railway system has failed;

(c) foreseeable abnormal conditions to which the system may be subjected; and

(d) emergency situations.

10 Where arrangements which differ from those set out in this guidance are proposed, those

responsible for submitting the works for approval will be expected to demonstrate that such

arrangements provide an equivalent level of safety.

11 The electrical clearances given are for overhead conductor systems with nominal voltages of

25 kV ac, 750 V dc and 1500 V dc, and for conductor rail systems with nominal voltages up to

750 V dc. Where different voltages or systems are proposed, the advice of the Inspectorate

concerning the appropriate clearances should be sought at the planning stage.

12 Where changes are proposed to works, plant or equipment already in use, it will be expected

that the changes should be in accordance with this guidance, where this is reasonably practicable,

rather than in accordance with earlier criteria under which the existing works, plant or equipment

were originally approved.

Design and building

13 The guidance applies to the finished works, plant or equipment but not to the processes of

designing or building. Designers and builders need to be aware of the responsibilities imposed upon

them by the Construction (Design and Management) Regulations 1994 made under the Health and

Safety at Work etc Act 1974.

Approval procedures

14 Guidance on the procedures to be adopted, and the format of the documents to be submitted by

those seeking approval of projects, is contained in the HSE publication Guide to the approval of

railway works, plant and equipment (second edition), is published on the HSE website at:

http://www.hse.gov.uk/railways/approval/approval.pdf.

15 The normal maintenance and repair of existing electric traction systems do not require approval.

The Guide also gives details of those works, plant and equipment not requiring approval.

Other regulations and standards

16 Works, plant or equipment may be subject to other specific regulations, for example, the Electricity at

Work Regulations 1989. In implementing the guidance in this document, compliance with these

regulations must be considered and specific reference is made to the more significant regulations.

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17 Similarly, any material or article used in the provision of works, plant or equipment may need

to comply with a specific standard. The guidance in this document does not make reference to these

numerous standards, however, an indication is provided where standards may be appropriate.

Note: Any reference in this guidance to any material or article complying with a specific standard should be

satisfied by compliance with any relevant standard recognised in any member state of the European Communities,

providing that the standard in question offers guarantees of safety, suitability and fitness for purpose equivalent to

those offered by the standard referred to in this guidance.

Structure of the guidance

18 The guidance is laid out, as far as is practicable, in a logical sequence which follows the main

elements of the electric traction system. This will best assist those responsible for the design of

works, plant or equipment.

19 A ‘Note’ is used to provide additional information which is relevant to the paragraph(s) of

guidance which precede it.

Terminology

20 Throughout the document, verbs with specific meanings are used:

(a) should - the primary verb for statements of guidance;

(b) may - where the guidance suggests options;

(c) must - only used where there is a legal/statutory requirement for the measures described to be

employed. Reference to the Act or Regulations will be provided;

(d) is (are) required - having decided upon a particular option or arrangements, some

consequential choices stem from that first decision. This expression is used to indicate those

consequential choices and where firmer guidance is considered appropriate.

21 Where possible the document has been written in plain English. However, some words or

expressions are used in a way which has a slightly wider meaning than their natural meaning.

These words are given in Appendix B - Common terms.


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2 PROTECTION OF PEOPLE

22 This chapter describes the measures which should be taken or considered to guard against the

dangers to people of exposed electric traction systems.

Protection against unwanted access

Fencing

23 All electrified railways should be suitably protected against inadvertent access and trespass.

Where necessary, additional or special fencing should be provided, eg near to public places such as

schools, recreation grounds etc.

Note: Guidance for boundary fencing is given in Part 2, Section A The infrastructure.

On bridges and other structures

24 Bridges which cross over a railway electrified with overhead line equipment should have

measures designed to deter access to the live equipment. Decks, stairways and parapets should be

solid and without gaps through which a wire could be passed. Uninsulated overhead line equipment

should not be located closer than 3000 mm to the outer end of any parapet.

25 At cuttings, wing walls, retaining walls or on other structures which make the live equipment

more readily accessible, further measures may be necessary.

Note: Guidance for bridges and other structures is given in Part 2, Section A The infrastructure.

At level crossings

With conductor rails

26 All level crossings accessible to the public and on lines electrified on a conductor rail system

should be protected by cattle-cum-trespass guards. Conductor rails should be terminated at least

300 mm from the outer edge of the cattle-cum-trespass guards.

27 If the level crossing is equipped with gates that afford suitable protection on their own, guards

may not be necessary.

With overhead line systems

28 At public road level crossings, the clearance between the crossing surface and the lowest

portion of the overhead line equipment should not be less than 5600 mm to provide a safe clearance

for road vehicles.

29 Where the Inspectorate has approved an overhead line equipment height below 5600 mm, a

height gauge to indicate the maximum safe height should be provided on each side of the crossing.

In calculating the safe height, due regard should be paid to the effect of the vertical profile of the

crossing on vehicles using it, including trailers, loads and equipment.

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30 At non-public level crossings, the clearance between the crossing surface and the lowest portion

of the overhead line equipment should be agreed between the railway and the occupier and is subject

to agreement by the Inspectorate. Height gauges should be provided if there is a risk of vehicles or

their loads coming into close proximity to overhead line equipment.

Note: For further details, including those of warning notices at level crossings and safe height calculations, see

Part 2, Section E Level crossings.

Warning signs and notices

31 Factors to consider about warning signs and notices:

(a) Places where passengers on foot have normal access at stations should not require signing.

(b) At all other authorised places of direct public or staff access to electrified lines or electrical

equipment locations and enclosures, signs giving suitable warning of the dangers from live

electrical equipment should be displayed.

(c) Particular attention should be given to signing at level crossings, platform ramps and work areas.

(d) Any access ladders or points of access to roofs and other places where people could foreseeably

approach live equipment in the course of their duties should carry warning signs.

(e) Consideration should be given to providing warning signs:

(i) where the railway is adjacent to public places such as schools or recreation areas;

(ii) at premises where cranes, or other equipment, are used and there is a risk of encroachment onto the

overhead line equipment. Other safeguards may also be necessary;

(iii) where bare traction feeders are used.

(f) Signs should be in accordance with the Health and Safety (Safety Signs and Signals)

Regulations 1996, the Traffic Signs Regulations and General Directions 1994, or as formally

agreed with the Inspectorate.

(g) Appropriate warning signs should also be provided on trains, mobile plant and road vehicles.

Equipment positioning

32 Factors to consider about equipment positioning:

(a) All electric traction conductors for overhead and conductor rail systems and all live equipment

associated with the operation of an electrified railway must* be positioned or protected so as to

minimise danger to people.


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* The Electricity at Work Regulations 1989

(b) Bare electric traction system feeder wires should be kept to a minimum. On electrified lines

where they run parallel to, or across the track they should be prominently signed unless

otherwise agreed by the Inspectorate. Where bare electric traction system feeders are provided

adjacent to non-electrified tracks, or such feeders have to cross non-electrified tracks the

clearances specified in Part 2, Section A The infrastructure should apply.

(c) Supporting structures for overhead line electric traction system conductors should be located

within the boundary of the infrastructure controller’s premises.

(d) Bare live equipment associated with overhead line traction systems should be kept to a

minimum and should be sited to minimise danger. Live equipment should not extend over non-

electrified lines, behind any buffer stop, over the platforms or any other public part of a station.

In cases of special difficulty, up to half the length of the earthed end of an insulator may extend

over such places.

(e) In goods yards and depots, live equipment should not normally be provided over working or

loading areas. Where this cannot be avoided, increased equipment height and other precautions

may be necessary.

(f) Return conductors should be insulated in areas of public and staff access where they are within

2750 mm of the standing point.

(g) Working or access platforms, walkways etc over live overhead equipment should have standing

surfaces, toe boards, screens/guardrails etc that afford suitable protection for people against the

risk of electric shock from foreseeable activities at the location.

Anti-climbing protection

33 Overhead equipment structures and supports should be of a design which cannot easily be

climbed. Where this is not achieved and either there is public access to the structure or trespass is

likely, anti-climbing protection should be provided.

34 Factors to consider about anti-climbing protection:

(a) Access to fixed ladders should be denied in areas prone to trespass.

(b) The means of access to any roof or other place which could allow people to approach live

equipment should be secured or otherwise protected.

(c) Structures outside or above railway property should be protected to minimise trespass or access

to overhead line equipment.

Safety screening

35 Suitable safety clearances should be achieved by positioning the overhead equipment at an

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appropriate distance from any accessible place. Where this cannot be achieved, a screen or other

suitable obstacle should be interposed between the accessible place and the live equipment.

36 Factors to consider about safety screening:

(a) Screens should extend so that the taut string distance from the standing point at the accessible

place, round the periphery of the screen, to any live equipment is not less than 2750 mm.

Imperforate screens are preferred, but any screen should not have holes with any dimension

greater than 30 mm.

(b) Conductor rail systems should be protected against accidental contact.

(c) Existing conductor rail systems that cannot be so protected should be fitted with guard

boarding where people are likely to be present and make accidental contact.

Earthing and bonding

37 The need to bond exposed metalwork to the appropriate electric traction return should be

considered.

Fire

38 The fire load of electric traction cables and equipment in areas where people are likely to be

present should be minimised.

Other considerations

39 Where airfields are situated adjacent to an electrified railway, special protection may be

necessary to minimise the risks posed to either system in the event of an aircraft emergency.


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3 ELECTRICAL CLEARANCES

40 This chapter describes the electrical clearances appropriate for different types of electric

traction systems and voltages.

Overhead systems

41 The design of the overhead line electrical equipment should include provision for the following:

(a) the safe electrical clearance between the earthed material of any structure and the live parts of

the overhead line equipment and pantograph taking account of dynamic effects;

(b) the safe electrical clearance between the live parts of the overhead line equipment and the

kinematic envelope taking into account the effects of horizontal and vertical curvature;

(c) the tolerances in the installation and maintenance of the overhead line equipment; and

(d) the tolerances in installation and maintenance of the alignment, height, and cross-level of the

track.

42 The clearances required are divided into two categories:

(a) Static clearance - defined as the safe distance between the earthed material of any structure

and the live parts of the overhead line equipment, under any permissible tolerance conditions.

(b) Passing clearance - defined as the safe distance between the earthed material of any structure

or rail vehicle and the live parts of the overhead line equipment, or between any earthed

material and the pantograph under any permissible conditions of operation and maintenance.

It takes into account dynamic effects including the uplift from a pantograph.

43 Values for the static and passing clearances are:

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FOR 25 kV ac SYSTEMS

Special reducedNormal

150 mm200 mm

125 mm*150 mm

* The passing clearance between a pantograph and a brick or masonry bridge ortunnel may be reduced to 80 mm, with the prior agreement of the Inspectorate

STATIC CLEARANCE

PASSING CLEARANCE

44 On existing railways:

(a) normal clearances should be achieved wherever reasonably practicable;

(b) special reduced clearances may only be used in cases of difficulty and should be notified to the

Inspectorate;

(c) exceptionally, special engineering solutions may be used in cases of extreme difficulty and with

the prior approval of the Inspectorate.

45 For new railways, better than normal clearances should be provided.

46 At structures crossing the line where the overhead line equipment is not attached to them or

supported immediately adjacent to them, not less than normal clearances should be provided.

47 Additional measures may be necessary to maintain special reduced clearances under all

conditions. These clearances should not be eroded by tolerances in any circumstances. Datum

marks to indicate the position of the track should be provided at any structures adjacent to places

where the overhead line equipment is installed using the special reduced clearances or other

reduced infrastructure clearances have been permitted.

Conductor rail systems

48 The clearance of any bare conductor rail, including bare metalwork attached to it, should not

be less than 75 mm from any other fixed metalwork, unless appropriate insulation is interposed

between the different potentials.

49 The clearance between any part of a collector shoe and any other fixed metalwork should be at

least 25 mm. On fourth rail systems where the collector potential does not exceed 250 V except

under fault conditions, this clearance may be reduced to 10 mm.

Note: For nominal voltages of up to 750 V dc, the minimum clearances result more from physical phenomena

than from electrical considerations.


9

FOR dc SYSTEMS


*75 mm

*25 mm

* For voltages up to 750 V dc nominal, the minimum clearances result more from physical phenomena than from electrical considerations so that smaller clearances are generally impractical

STATIC CLEARANCE

PASSING CLEARANCE


100 mm150 mm

80 mm100 mm

Up to and including 750 V dc Up to and including 1500 V dc

4 SAFE MANAGEMENT AND OPERATION

50 This chapter describes the facilities that should be provided for the safe management and

operation of the electric traction system.

51 Where different electric traction systems come into close proximity with one another,

consideration should be given to the need to provide protection against foreseeable effects from one

system to the other that might give rise to danger.

Control and sectioning

52 Factors to consider about control and sectioning:

(a) The electric traction system conductors should be sectioned electrically and provision should be

made to enable the electric traction supply to be disconnected. Where necessary, means should

be provided to permit the equipment to be earthed or otherwise made safe.

(b) On underground railway systems means should be provided throughout the tunnels and on

station platforms for the disconnection of traction current. In the case of overhead systems, this

may be on request to the control room by radio or tunnel telephone system. In the case of

conductor rail systems, adequate means of instantaneous discharge of current should be

provided. The same system of discharging the current should be used throughout the tunnels of

the underground railway.

(c) The electric traction system together with its feeder arrangements should be supervised from

one or more railway electrical control rooms where means should be provided to disconnect the

electric traction power from any part of the system. The railway electrical control room should

also be provided with a means of disconnecting the supply to incoming feeders to the electric

traction system.

(d) There should be efficient communications between the lineside and the railway electrical

control room to enable changes in the state of the electric traction system to be properly

undertaken and controlled.

(e) The electric traction system control arrangements should be located in the same room from

which the operation of the railway is controlled. Where this is not available, a prioritised,

secure and direct communications link is required between the two centres. A reliable

alternative should be available to cater for failure of the primary communications link.

(f) The track of any non-electrified siding, particularly if it serves private premises, should be

insulated from any electrified line to avoid dangers arising from electric traction currents.

Special precautions should be taken if flammable goods are handled and suitable warning

notices should be provided.

(g) Electrical equipment and structures should carry a unique means of identification.

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Earthing and bonding

53 Bridges which cross over a railway electrified with overhead line equipment should have

measures designed to prevent danger from touch potentials. Where there is exposed metalwork the

need to bond to the appropriate electric traction return should be considered.

54 Factors to consider about earthing and bonding:

(a) Consideration should be given to bonding metal structures adjacent to the line to the electric

traction return unless other measures are taken to avoid dangerous touch potentials arising.

Where equipment has to be connected to a different earthing system, precautions should be

taken to prevent danger arising from people touching both systems simultaneously.

(b) Leakage and circulating currents should be minimised.

(c) Appropriate measures should be taken on dc systems to avoid dangerous touch potentials.

(d) Where a railway electrical sub-station or switching station is adjacent to an electricity authority

supply station and a common earthing system cannot be provided, each of the installations,

including any fencing and gates surrounding it, may require its own earthing system. The

distance between the sub-station and supply station, or the fencing must* be sufficient to

prevent people from simultaneously touching any exposed metalwork connected to such

independent earthing systems.

(e) Consideration should be given to the effect of the movement of any gates or other means of access to

electrical switching or sub-stations to ensure clearances are not eroded during their operation.

(f) Where the running rails are used as an electric traction current return conductor, the arrangement

and frequency of rail and inter-track bonds must* be such that people cannot be subject to an electric

shock likely to cause them harm. Bonds which have been disconnected should be suitably placed and

safeguarded to prevent danger to people and damage to other equipment.

Fault protection

55 A system which employs separate electric traction supply and return conductors, with both

conductors insulated from earth and the running rails, should be provided with equipment to

indicate the detection and location of a fault to earth involving either conductor.

56 A direct short-circuit in the electric traction system must* cause the power supply to be

automatically disconnected. Equipment which differentiates between fault current characteristics

and those of normal loads is preferred.

Note: Where a conductor rail system is energised at other than full line voltage for maintenance or other special

purpose, it is to be treated as if it were normally energised, or special warning of its energisation given.


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* The Electricity at Work Regulations 1989

Conductor rail guarding

57 Conductor rail systems should have the proportion of exposed rail minimised, insulated or

shielded from accidental touch by people and tools on the track.

58 Where the conductor rail is not of a protected form, the guarding or other precautions specified

below may be necessary.

59 Factors to consider about conductor rail guarding:

(a) On double-track railways the conductor rails should be located in the interval between lines. This is

particularly important in tunnels and on long bridges. In stations, the conductor rails should be

located on the side of the track remote from the platform. Where this is impracticable, any

conductor rail adjacent to a platform should be shielded with protective boarding on each side.

(b) Where electrified sidings are adjacent to, and unfenced from, goods yards or places where staff

and people on business move freely over an area, the conductor rails should be on the side

remote from the area of activity. Where this is impracticable, the conductor rail should be

shielded with protective boarding on the outer or both sides, commensurate with the nature of

the activities at the location.

(c) At signal post telephones the conductor rail should be located on the side of the track remote

from the telephone. Where this is impracticable, protective boarding on each side needs to be

provided over a length commensurate with the stopping tolerances of the trains concerned and

the sighting of the signal.

(d) Where a person may be at risk from the conductor rail during carriage servicing, train

examination or coupling and uncoupling, local provisions should be made to isolate the

electrical supply. If this is impracticable, protective boarding should be provided on each side

of the conductor rail over an appropriate distance. Personal protective equipment may be used

by prior agreement with the Inspectorate.

(e) The layout, arrangements and means of local isolation of conductor rails through points and

crossings or past any equipment on the track needing regular maintenance should take account

of the need for safe access.

(f) Where signalling ground frames, equipment cubicles or other installations are close to the track

or where doors or steps from signal-boxes, lineside cabins or equipment rooms lead directly

towards the track, the conductor rail should be situated on the remote side of the track. Where

this is impracticable, other means of preventing accidental contact with the conductor rail

should be provided.

(g) The protective boarding should extend from at least 10 mm above the top of the conductor rail

to the lower edge of the rail. It need not be provided on any conductor rail which is bonded at

intervals to the running rails.

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Precautions against contamination of insulators

60 In areas of anticipated high contamination of electric traction insulators from industrial

pollution or from saline drips and sprays (eg in tunnels, near to the coast, road traffic on adjacent

highways etc) special consideration should be given to their protection. This may be by screening,

cleaning or other means to ensure the safety and reliability of the supply. Creepage distances over

insulation should be designed to minimise the effects of contamination.

Precautions against electrolytic damage and electro-magnetic interference

61 Details of the strategy to be taken against electrolytic damage and electro-magnetic

interference should be advised to the Inspectorate for agreement at the planning stage.

Note: It is difficult to predict all of the effects of electrolytic and electro-magnetic activity.


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S A F E T Y M I S S I O N

Principle 1

Principle 23

Level crossings

Safe for usersand trains

Stations andStablingAreas

Principles

TrainPrinciples

Electrictraction system

principles

Principle 19

Principle 17

Principle 18

Electric traction system

Safe for people


Interactions


Management

Electric traction system principles

Railway control system

principles

Infrastructureprinciples

14


APPENDIX A -

ELECTRIC TRACTION SYSTEM PRINCIPLES

Safe for people

An electric traction system should not present safety hazards to people.

Factors

The factors for consideration should include:

(a) the position and extent of live non-insulated components;

(b) the avoidance of dangerous touch potentials on structures within and adjacent to the railway;

(c) the arrangements at level crossings;

(d) the sectioning and isolation arrangements for normal operations, for maintenance and in

emergencies;

(e) in the case of on-street tramways, special arrangements for sectioning and isolating overhead

wires suspended over a highway;

(f) the arrangements to deter trespass and wilful acts that might give rise to danger;

(g) the display of warning signs; and

(h) the effects of wind, ice and lightning.

PRINCIPLE 17

Electric traction

system


15

16


Management

An electric traction system should provide for its safe management and operation.

Factors


(a) communications between the electrical control centre, the electricity supplier, the railway

control centre, the emergency services and trackside locations;

(b) the sectioning and isolating arrangements for normal operations, including for maintenance

and in emergencies;

(c) the continuity of power supply and the effect of its loss;

(d) the power supply and return configuration and its management;

(e) earth fault and short-circuit protection;

(f) the monitoring of the status of the electric traction system equipment;

(g) the marking of electric traction system equipment and structures for location purposes; and

(h) special circumstances for sub-surface railways.

PRINCIPLE 18

Electric traction

system


17

Interactions

An electric traction system should not give rise or be subject to dangerous interactions

within the railway or with other systems.

Factors


(a) the characteristics of the trains using the electric traction system;

(b) the compatibility and separation of different electric traction systems;

(c) the interfaces with trains or other plant and equipment;

(d) the structures on the railway and the electrical clearances;

(e) the siting of both conductor rails and overhead line equipment to allow sufficient clearance so

as not to foul the trains, other road vehicles or mobile plant in the case of an on-street

tramway, or interfere with other structures on the railway;

(f) the transfer of electro-magnetic fields which may be generated and their likely effects on other

plant and equipment on the railway or adjacent to it; and

(g) the transfer of electrical effects and their likely impact on other plant and equipment in use

on the railway or adjacent to it.

PRINCIPLE 19

Electric traction

system

APPENDIX B - COMMON TERMS

Where possible the document has been written in plain English and the use of technical expressions

or jargon has been avoided. However, to keep the document reasonably concise and to avoid the

repetition of phrases which only serve to provide an extended definition, some words or expressions

are used in a way which has a slightly wider meaning than their natural meaning, or a meaning that

is different to that accepted by disparate parts of the Railway Industry.

The following are terms used within the document:

Railway terms

‘Railway’ means all guided transport systems to which the Railway and Other Transport Systems

(Approval of Works, Plant and Equipment) Regulations 1994 apply. It includes main-line (heavy)

railways, mass transit, light rail, tramway and heritage systems.

‘Tramway’ means a system of transport used wholly or mainly for the carriage of passengers which:

(a) employs parallel rails which provide support and guidance for vehicles carried on flanged

wheels; and

(b) has been designed to have a significant element which operates on line-of-sight on a highway.

Note: In the context of tramways, ‘highway’ is used to mean any, or any combination of the following:

carriageway, bridleway, cycle track, footpath, land on the verge of the carriageway or between two carriageways

and any other place to which the public has access (including access only on making a payment).

‘Heritage system’ means a railway or tramway which has retained or has assumed the character

and appearance and, where appropriate, operating practices of railways or tramways of former

times. For example, it may replicate a railway branch line of former times, or may reflect no

particular era but demonstrates a wide variety of motive power and rolling stock at work,

irrespective of company (or country) of origin.

‘Other guided transport system’ means a system, other than a railway or tramway, where the

vehicles operating on it are guided by means external to the vehicles (whether or not the vehicles are

also capable of being operated in some other way). The term therefore includes monorails and

airport transit systems.

Note: Trolleybuses are excluded because they are not in any circumstances guided externally, and funiculars are

not included because they fall under the definitions of railway or tramway.

People terms

‘People’ means workers on the railway, passengers, emergency services personnel, people on

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business, level crossing users and trespassers (those who are on railway property when they have no

right to be there) on the railway.

There are four types of ‘people’:

(a) ‘Workers’ means staff and contractors directly employed on the railway (including the train

crew, station staff, signalling staff etc) and contractors employed in the supply industries,

maintenance facilities and disposal organisations. The workers may be employed at a fixed

location or move about the railway.

(b) ‘Passenger’ means any person who is on railway property and is travelling, or intends to travel,

or has recently completed travelling on the railway. Consideration should be given to a wide

range of passenger characteristics and classifications, for example:

• passengers who are disabled (visually, hearing or mobility impaired);

• children and unusually short and tall adults;

• passengers with heavy luggage, pushchairs, young children etc.

Passengers may be on the station premises (waiting to purchase a ticket, waiting on the

platform etc) or on a train.

(c) ‘People on business’ means people who:

• visit railway premises as non-travelling ‘passengers’ (people meeting or seeing off

passengers, train spotters, customers of station retail units etc);

• are official visitors to the railway.

(d) ‘Level crossing users’ means people crossing the railway on or at a level crossing. This includes

pedestrians, horse-riders and occupants of road and agricultural vehicles.

Infrastructure terms

‘Infrastructure’ means works, plant and equipment used for the operation of a railway including its

permanent way, and plant and equipment used for signalling or exclusively for supplying electricity for

operational purposes to the railway, but it does not include a station. It refers to track, structures

supporting it, signalling, and fixed electrical plant such as feeders, switchgear, sub-stations and the like.

Station terms

‘Station’ means a railway passenger station or terminal, but does not include any permanent way or

plant used for signalling or exclusively for supplying electricity for operational purposes to the


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railway. For tramways, ‘station’ is used to include a tramstop or platform. A station includes a halt,

terminal station and a station complex with or without retail units. ‘Station’ does not include areas

associated with station premises, such as car parks, which lie outside those premises.

‘Sub-surface station’ means a station of which more than half of any one platform is within a

tunnel or under a building.

Train terms

‘Train’ means any vehicle or combination of vehicles which run on the railway. Therefore, a train

may consist of a single vehicle or a number of vehicles coupled together including any locomotives

or power units. A train may be composed of one or more vehicles and vehicle inter-connections.

These can be passenger and freight, also maintenance and construction, vehicles. It also includes

on-track machines, engineers’ trolleys, cranes and other plant while operating on a railway

(commonly referred to as on-track plant or machines). For tramways ‘train’ means a tramcar or two

or more tramcars coupled together and includes non-passenger vehicles.

Electric traction system terms

‘Electric traction system’ means the electrical equipment and conductors necessary to power trains

on the railway. It includes the switchgear and transformers which control the electric current at line

voltage, the distribution network and overhead line or conductor rail equipment. It does not include

the collection equipment of the train or other on-board equipment.

Safety terms

‘Foreseeable’ means that which is likely or possible.

‘Hazard’ means a situation with the potential to cause harm including human injury, damage to

property, plant or equipment, damage to the environment, or economic loss.

‘Risk’ means the chance of something adverse happening and its severity. It is the combination of

the probability, or frequency, of the occurrence of a defined hazard and the magnitude of the

consequences of the occurrence.

‘Safety’ means the freedom from unacceptable risks of personal harm, ie the avoidance of accidents

and incidents.

Operational conditions or states

‘Normal conditions’ means the conditions which a part of the railway is designed to accommodate.

This would include the peaks, eg rush hours, and troughs in demand experienced during the day.

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‘Degraded conditions’ means the state of the part of the railway system when it continues to

operate in a restricted manner due to the failure of one or more components.

‘Abnormal conditions’ means extreme loading on a part of the railway system. For example, this

may be the result of extended delays on one part of the service impinging on another.

‘Emergency situation’ means a current unforeseen or unplanned event which has life threatening or

extreme loss implications and requires immediate attention, eg a fire.

FURTHER INFORMATION

HSE priced and free publications are available by mail order from HSE Books, PO Box 1999,

Sudbury, Suffolk CO10 2WA Tel: 01787 881165 Fax: 01787 313995 Website: www.hsebooks.co.uk

(HSE priced publications are also available from bookshops and free leaflets can be downloaded

from HSE’s website: www.hse.gov.uk.)

For information about health and safety ring HSE’s Infoline Tel: 08701 545500 Fax: 02920 859260

e-mail: [email protected] or write to HSE Information Services, Caerphilly

Business Park, Caerphilly CF83 3GG.

The Stationery Office publications are available from: The Stationery Office, PO Box 29, Norwich

NR3 1GN Tel: 0870 600 5522 Fax: 0870 600 5533 e-mail: [email protected] Website:

www.tso.co.uk (They are also available from bookshops.)

This document contains notes on good practice which are not compulsory but which you may

find helpful in considering what you need to do.

© Crown copyright This publication may be freely reproduced, except for advertising, endorsement

or commercial purposes. First published 7/96. Web version published 2005.

Please acknowledge the source as HSE.

01/05 Published by the Health and Safety Executive


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Railway Safety Principles, Electrical Traction

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