Safety Risk Model: Risk Profile Report, version 7 · Safety Risk Model: Risk Profile Report,...

Issue 1.1 – Published June 2013

Safety Risk Model: Risk Profile Report, version 7.5

This report is issued by RSSB.

If you would like to give feedback on any of the material contained in this report,

please contact:

Marcus DacreRSSBBlock 2, Angel Square1 Torrens StreetLondon EC1V 1NY020 3142 [email protected]

© RAIL SAFETY AND STANDARDS BOARD LTD. 2013 ALL RIGHTS RESERVEDThis publication may be reproduced free of charge for research, private study or for internal circulation within an organisation.This is subject to it being reproduced and referenced accurately and not being used in a misleading context. The material mustbe acknowledged as the copyright of RSSB and the title of the publication specified accordingly. For any other use of thematerial please apply to RSSB for permission. This publication can be accessed via the RSSB Rail Risk Portal atwww.safetyriskmodel.co.uk.

This is Issue 1.1 of the report. It supersedes Issue 1.0, which was published in March 2013.

Issue 1.1 updates the High Level Output Specification safety metrics, primarily to incorporate

information from the 2012 RSSB survey of workforce hours, which has become available

since the report was initially published. The SRM risk estimates are unchanged.

ii Version 7.5 — June 2013

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Version 7.5 — June 2013 iii

Table of Contents

Executive Summary.......................................................................................................... vii

1 Introduction ............................................................................................................. 1

2 SRM Objectives and Overview ............................................................................... 3

2.1 Objectives .................................................................................................................... 3

2.2 Overview ...................................................................................................................... 3

2.3 Key assumptions and exclusions ............................................................................. 4

3 SRMv7.5 Update Strategy ....................................................................................... 5

3.1 Overview of the SRMv7.5 update .............................................................................. 5

3.2 Modelling and scope changes from SRMv6.5 to SRMv6.6 and SRMv7 toSRMv7.1 ....................................................................................................................... 6

3.3 Update from SRMv7.1 to SRMv7.5 ............................................................................ 6

4 Total Risk on the Mainline Railway ........................................................................ 8

4.1 Overall profile .............................................................................................................. 8

4.2 Risk by ASPR hazard categorisation ...................................................................... 12

4.2.1 Discussion .................................................................................................... 13

5 HLOS Safety Metrics ............................................................................................. 17

5.1 Background ............................................................................................................... 17

5.2 Changes to the baseline HLOS safety metrics ...................................................... 17

5.3 Progress against the HLOS safety metrics ............................................................ 18

6 Uncertainty in the SRM risk estimates................................................................. 20

6.1 Introduction ............................................................................................................... 20

6.2 Uncertainty Methodology......................................................................................... 20

6.3 SRM Model Uncertainty Results.............................................................................. 21

6.4 Next steps .................................................................................................................. 24

7 SRM Governance and SRM Updates.................................................................... 25

7.1 SRM Practitioners Working Group.......................................................................... 25

7.2 Update history ........................................................................................................... 25

7.3 Updates to the SRM during CP4.............................................................................. 27

8 RSSB Rail Risk Portal ........................................................................................... 28

8.1 SRM Risk Profile Bulletins/ Risk Profile Report .................................................... 28

8.2 Yards, Depots and Sidings SRM Risk Profile Report............................................ 28

8.3 Risk assessment guidance ...................................................................................... 28

Contents

iv Version 7.5 — June 2013

8.4 SRM Risk Profile Tool............................................................................................... 28

8.5 Taking Safe Decisions Analysis Tool ..................................................................... 29

8.6 Fixed Lineside Telephony Analysis Tool ............................................................... 29

8.7 SPAD Risk Ranking Tool.......................................................................................... 29

8.8 Risk Management Forum ......................................................................................... 29

8.9 Assistance and training ........................................................................................... 30

9 Injury Weightings .................................................................................................. 31

10 Contributors........................................................................................................... 32

11 Acronyms and Glossary ....................................................................................... 33

11.1 Acronyms................................................................................................................... 33

11.2 Glossary..................................................................................................................... 34

12 References............................................................................................................. 40

Contents

Version 7.5 — June 2013 v

List of Tables

Table 1: Risk, normalisers and normalised risk by person type ....................................... viii

Table 2: Risk by accident type......................................................................................... viii

Table 3: System boundaries .............................................................................................. 4

Table 4: Total risk by accident category............................................................................. 8

Table 5: Total risk by person category............................................................................... 9

Table 6: Total risk to each person category from each accident category........................ 10

Table 7: ASPR hazardous event groupings ..................................................................... 12

Table 8: Summary of the revised estimates for the baseline HLOS safety metrics .......... 18

Table 9: Summary of the progress against the HLOS safety metrics ............................... 19

Table 10: Summary of risk by person type......................................................................... 19

Table 11: SRM update history ........................................................................................... 26

Table 12: Injury degrees and weightings ........................................................................... 31

Contents

vi Version 7.5 — June 2013

List of Charts & Figures

Figure 1: Summary of the SRM modelling and data updates................................................ 5

Chart 1: Total risk profile for passengers, the workforce and members of the public —

% of total FWI/year ............................................................................................ 11

Chart 2: Combined risk profile (FWI/year) — includes % change from SRMv7.1............. 14

Chart 3: Combined risk profile (fatalities/year) — includes % change from SRMv7.1 ...... 16

Chart 4: Chart showing risk distribution and the 95% confidence interval for the total

SRMv7.5 HEM/HEN risk. ................................................................................... 21

Chart 5: Charts showing the risk distribution and the 95% confidence interval for the

SRMv7.5 HEM and HEN risk separately. ........................................................... 22


SRMv7.5 passenger, workforce and public risk separately. ............................... 23

Chart 7: Timeline for updates of the SRM and the SRM-RPB for CP4............................. 27

Executive Summary

vii Version 7.5 — June 2013

Executive Summary

The Safety Risk Model (SRM) consists of a series of fault tree and event tree models

representing 121 hazardous events (HEs) that collectively define the overall level of risk on

the mainline railway. It provides a structured representation of the causes and

consequences of potential accidents arising from railway operations and maintenance. The

reported risk estimates relate to the network-wide risk and they indicate the current level of

residual risk (i.e. the level of risk remaining with the current risk control measures in place

and with their current degree of effectiveness).

The Department for Transport and the Office of Rail Regulation are using outputs from the

SRM as the primary means of measuring the performance of the industry against the High

Level Output Specification (HLOS) safety metrics. The risk estimates in version 6 of the

SRM (SRMv6) provided the initial baseline against which safety performance through

Control Period 4 (CP4, April 2009 to March 2014) will be compared. SRMv7.5 provides the

second comparison against the baseline HLOS safety metrics.

To enable this comparison to be meaningful, the update of the SRM to version 7.5 has been

split into two distinct stages. The first stage was to revise earlier risk estimates by

incorporating all modelling changes and error corrections: SRMv6.5 (a previous update to

the SRMv6 figures) was thus updated to SRMv6.6 and SRMv7 was updated to SRMv7.1.

These interim versions represent the risk as it would have been calculated for SRMv6 and

SRMv7, had the modelling changes in SRMv7.5 been implemented at the time these

versions were produced. The second stage was then a refresh of selected HE models using

data up to the 30 June 2012. Train accidents HEs have not been updated in SRMv7.5.

In addition to presenting the results for SRMv7.5 and the updated HLOS safety metrics, this

report outlines the methodology being developed for quantifying uncertainty in the SRM

results.

Headlines

Overall Risk

SRMv7.5 estimates that the overall level of risk (excluding the direct risk from suicide

events) for the railway is 139.2 FWI/year. This represents a decrease of 1.3% from the

figure of 141.0 FWI/year estimated by SRMv7.1 (the revised SRMv7 overall risk).

Contents

viii Version 7.5 — June 2013

Risk by Person Type

The overall figures for SRMv7.5 and SRMv7.1 can be broken down by each exposed group

and compared with their normalisers as shown in Table 1.

Table 1: Risk, normalisers and normalised risk by person type

Absolute passenger risk has increased by 4.9% since SRMv7.1. However, over the same

period passenger journeys have increased by 19.2% and passenger kilometres have

increased by 8.6% (from 53.1 billion passenger km in SRMv7.1 to 57.7 billion passenger km

in SRMv7.5). The main reason for the increase in passenger risk is that there has been a

real increase in the risk from HEN-14: Passenger slips, trips and falls. This is due to an

increase in the frequency of events seen for this HE in the last two years. However, the risk

per passenger journey has decreased, from 42.1 FWI/billion passenger journeys in SRMv7.1

to 37.1 FWI/billion passenger journeys in SRMv7.5.

Workforce risk is now 26.9 FWI/year, representing a 0.3% reduction since SRMv7.1.

Risk to the public has decreased by 6.9% when compared with the SRMv7.1 figure. Given

the uncertainty associated with this risk estimate (which is dominated by trespasser

fatalities), this is not considered to indicate any significant change in the underlying risk.

Risk by Accident Type

Alternatively, the overall risk figure of 139.2 FWI/year can be broken down by accident type

as shown in Table 2.

Table 2: Risk by accident type

v7.5 Risk (FWI/year) v7.1 Risk (FWI/year)

Train accidents (HETs) 8.2 8.2

Movement accidents (HEMs) 55.9 59.8

Non-movement accidents (HENs) 75.1 73.1

HEMs have seen a reduction of 6.5% and HENs have seen an increase of 2.8%. The

reduction in estimated trespasser fatality risk explains much of the fall in HEM risk, and the

increase in the risk from slips, trips and falls influences the change in HEN risk. The risk from

HETs has not changed from SRMv7.1 because none of the HET models were updated with

new incident data for SRMv7.5.

v7.5 v7.1 Unit of exposure v7.5 v7.1 v7.5 v7.1

billion passenger km 57.7 53.1 0.947 0.981

billion passenger journeys 1.47 1.24 37.1 42.1

26.9 27.0 million workforce hours 213 207 0.126 0.130

57.7 62.0 [No normaliser used] - - - -

Risk (FWI/unit of exposure)NormaliserRisk (FWI/year)

54.7 52.1

Contents

Version 7.5 — June 2013 ix

HLOS Safety Metrics

The SRMv7.5 figures have been used to demonstrate progress against the HLOS safety

metrics. These have been calculated as follows:

SRMv7.5 passenger safety metric — 0.941 FWI per billion passenger kilometres.

SRMv7.5 workforce safety metric — 0.119 FWI per million worker hours.

When compared to SRMv6.6, representing the start of CP4, the SRMv7.5 results represent

a 5.7% decrease in the HLOS passenger safety metric and an 11.6% decrease in the HLOS

workforce safety metric. These should be compared against the target of at least a 3%

reduction in both of these safety metrics over CP4.

The risk results from SRMv7.5 are presented in this report as a measure of the absolute risk

on the mainline railway. As with any quantified risk assessment, the results are estimates

and are dependent on modelling assumptions and limitations of the available data.

Quantified risk estimates can be a useful input to the decision making process, but should

not be the only input, and their inherent uncertainty must be taken into account.

Version 7.5 — June 2013 1

1 Introduction

RSSB works with its members to support the development of safety strategies, develop

standards and monitor and report on the safety performance of the industry. An

understanding of the overall risk level and risk profile of the railway is a key foundation for

this role. RSSB supports its members — who comprise the railway industry — by providing

risk information to help them understand their own risk profile and benchmark their

performance. This in turn helps them formulate their own safety policies, plans and

measures. The Safety Risk Model (SRM) provides the network-wide risk profile and this

information is communicated to the industry in a range of ways, the primary one being the

SRM Risk Profile Bulletin (SRM-RPB).

Version 7.5 of the SRM consists of a series of fault tree and event tree models representing

121 hazardous events (HEs), which collectively define the overall level of risk on the

mainline railway. It provides a structured representation of the causes and consequences of

potential accidents arising from railway operations and maintenance on railway infrastructure

as well as other areas where the industry has a commitment to record and report accidents.

The SRM has been designed to take account of both high-frequency, low-consequence

events (occurring routinely, and for which there is a significant quantity of recorded data) and

low-frequency, high-consequence events (occurring rarely, and for which there is little

recorded data). The results for each HE are presented in terms of the frequency of

occurrence (number of events per year) and the risk (number of fatalities and weighted

injuries (FWI) per year). The FWI weightings equate injuries of differing degree with a

fatality event, which allows all of the risk on the railway to be totalled and contrasted in

comparable units. These weightings are shown in Section 9.

The risk estimates presented can be used to support risk assessments and for judging how

the risk relating to particular operations compares with and contributes to the network-wide

risk.

The information contained in this document relates to the network-wide risk on railway

infrastructure covering all running lines, rolling stock types and stations currently in use.

Risk associated with areas away from the operational railway, such as yards, depots, sidings

(YD&S), or station car parks, is not included (with the exception of workforce involved in road

traffic accidents). Work to extend the scope to include YD&S is ongoing and initial risk

estimates for depots, yards and sidings are available in the Yards, Depots and Sidings Risk

Profile Report [Ref. 1]. The system boundaries for SRMv7.5 are detailed in Section 2.2. The

risk estimates in SRMv7.5 are for the current level of residual risk on the mainline railway,

which is the level of risk remaining with the current risk control measures in place and with

their current degree of effectiveness. The cut-off date for incident data used to inform

SRMv7.5 was 30 June 2012.1

Because of the network-wide nature of the SRM, it is necessary to make average

assumptions that represent the general characteristics of the network. The model also

hinges on the definitions of the HEs and precursors by which risk estimates are reported.

1There are four hazardous event models that are exceptions to this data cut-off: HEM-12, HEM-25, HEM-31 and

HEN-77. The mapping of incidents to these HEs is influenced by coroners’ reports, which may not be availableuntil sometime after the event. Therefore, to ensure there is confidence in the data used to analyse them, anearlier cut-off date (30 June 2011) was used.

Introduction

2 Version 7.5 — June 2013

These definitions will soon be provided on the RSSB Rail Risk Portal at

www.safetyriskmodel.co.uk (see Section 8.10), and a thorough understanding of them is

essential to the correct interpretation and use of the risk information reported here. The

SRM does not provide risk profiles for specific lines of route and train operating companies

(TOCs), although a Risk Profile Tool is also available from the Rail Risk Portal to help scale

the results for this purpose. The information in this report should not be considered to be

representative of the risk for any particular line of route or TOC, without further localised

analysis.

The SRM Practitioners Working Group (SRM-PWG) is the industry governance body for the

SRM. It was formed under the authority of the Safety Policy Group (SPG) to engage

stakeholders in the development and control of future versions of the SRM and its related

outputs. Section 7.1 contains more information regarding this group and its aims.

The modelling changes implemented as part of the update of the SRM to version 7.5 have

been endorsed by the SRM-PWG. The revised version 6 figures (SRMv6.6) and the revised

version 7 figures (SRMv7.1) were presented to the group and approved in January 2013.

The Department for Transport (DfT) is using the outputs from the SRM as the primary means

of measuring the performance of the industry against the High Level Output Specification

(HLOS) safety metrics, rather than using a measure of safety performance based solely on

accident statistics. The risk estimates derived from SRMv6 provided the initial baseline

against which to compare safety performance through Control Period 4 (CP4, April 2009 to

March 2014). This is achieved by comparing the risk metrics derived from SRMv7.5 and

future versions against the baseline safety metrics determined from SRMv6 (and

subsequently updated to SRMv6.6).

The main part of the SRM-RPR sets out:

The objectives of the SRM (Section 2.1)

System boundaries (Section 2.2)

Overview of the SRMv7.5 update (Section 3)

Total risk on the mainline railway (Section 4)

Details of progress against the HLOS safety metrics (Section 5)

Additional appendices for this document may be downloaded from the RSSB Rail Risk Portal

at http://www.safetyriskmodel.co.uk (in Excel format).

Appendix A contains frequency, consequence and risk estimates for each HE (Table A1),

and describes the changes from SRMv6.5 to SRMv6.6 (Table A2), from SRMv7 to SRMv7.1

(Table A3), and from SRMv7.1 to SRMv7.5 (Table A4) in detail.

Appendix B contains frequency and risk contributions for all precursors leading to each HE

(Table B1).


2 SRM Objectives and Overview

2.1 Objectives

The primary objectives of the SRM are:

To provide an estimate of the extent of the current risk on the mainline railway.

To provide risk information and risk profiles relating to the mainline railway.

The SRM has been developed and published to support RSSB members. Its specific

purpose is to provide risk estimates for use in risk assessments, appraisals and decisions

throughout the railway industry. This includes:

To enable risk-informed assessments and cost-benefit analyses (CBAs) to be carried

out to support decisions taken about:

Whether changes to the railway can be made safely

Which control measures should be applied on the railway

Where current risk control measures can be relaxed or changed.

Technical modifications and upgrades such as new infrastructure investment.

Revision of Railway Group Standards (RGS), in terms of their contribution to

risk mitigation (including development of impact assessments for proposed

changes to the RGS).

To provide risk information to support:

The development of priorities for the Industry Strategic Business Plans

20014–2019 [Ref. 2].

Prioritisation of areas for research on the railway.

Transport operator risk assessments, as required by The Railways and Other

Guided Transport Systems (Safety) Regulations 2006.

Significant changes which require application of the Common Safety Method

on Risk Evaluation and Assessment.

Identification and prioritisation of issues for audit.

To provide an understanding about the contribution of a particular item of equipment

or failure mode to the overall risk.

To provide risk estimates to be used as the basis of the HLOS safety metrics.

2.2 Overview

The SRM includes the safety risk from incidents which could occur during the operation and

maintenance of the mainline railway within the boundaries defined in Table 3. For SRMv7.5

there have been no changes to the system boundary scope, however one new HE within this

scope has been identified and this is discussed further in Section 3. Appendix G of [Ref. 3]

contains a more detailed discussion of the SRM scope and the system boundaries and gives

specific guidance as to what aspects of the operation and maintenance of the railway are

within scope of the SRM.

SRM Overview


Table 3: System boundaries

In SRM Scope Not in SRM Scope

People Pasengers on trains

Pasengers at stations within areas to which they havelegitimate access.

Railway workers on trains

Railway workers in public areas at stations

Railway workers working on or near the line

Railway workers in signal boxes, signalling centres, orelectrical control offices

Railway workers involved in road traffic accidents whileon duty.

Members of Public (not passengers) outside themainline railway or legitimately crossing the mainlinerailway (i.e. on level crossings).

Members of Public who enter the mainline railway withno legitimate purpose (e.g. tresspassers includingpassengers who enter areas for which they have nolegitimate access).

Events associated with vandalism and Members ofPublic falling or trespassing on the mainline railway arealso included.

Injuries directly associated with suicides or attemptedsuicide are quantified but not included in the overallresults discussion.

On trains All on-train events.

Events on the mainline railway which affect trainsincluding level crossings.

All accidents related to the movement of OTP that occurwithin possessions.

In stations

All public areas associated with the movement ofpassengers and staff inside the physical boundaries ofstations.

People The SRM does not quantify the

risk to staff due to long-termoccupational health issues.

Risk associated with terroristactivity is excluded.

Yards, sidings and depots Events occurring within yards,

sidings and depots are notincluded within the SRM (this isbeing developed).

However, those events relatingto the movement of trainsentering and leaving yards,sidings and depots, and eventsrelating to the condition of trainsjoining the system from thedepots have been included.

In stations Non-public areas at stations, i.e.

the work side of a ticket office(however, where a member ofthe workforce is assaulted by aMember of Public who is on thepublic side of the office, this hasbeen included).

Retail outlets within stations.

Station toilets.

Everything roadside of a statione.g. car parks, access roads,forecourts, taxi ranks etc.

Offices.

2.3 Key assumptions and exclusions

Appendix F of version 7 of SRM-RPB [Ref. 3] lists key assumptions that are applicable to the

SRM. Further clarity on the definitions and assumptions applicable to individual HEs can be

provided on request.


3 SRMv7.5 Update Strategy

3.1 Overview of the SRMv7.5 update

The SRM is being used by the DfT as the primary means of measuring the performance of

the industry against the HLOS safety metrics. As a result of this it is now necessary to be

able to distinguish between changes in risk arising from genuine changes in the underlying

data and changes due to refined modelling of HEs.

To enable this comparison to be meaningful, the update of the SRM to version 7.5 has been

split into two distinct stages. The first stage was to incorporate all changes and error

corrections into the model and produce revised versions of the previous models — SRMv6.6

and SRMv7.1. These interim versions represent the risk as would have been calculated for

SRMv6 and SRMv7, had the modelling changes implemented in version 7.5 been

implemented at the time the previous versions were created. The second stage was then a

data refresh of selected HE models with data up to 30 June 2012.

Risk estimates from SRMv7.1 to SRMv7.5 can therefore be meaningfully compared; the

difference between them represents the estimated change in risk due to a refresh of the data

up to June 2012 (compared to September 2010 for version 7.1). This is the second time the

SRM has been updated in this fashion, the other occasion being SRMv7. The aim is to be

able to provide a framework that is compatible with the requirements for monitoring the

HLOS metrics and to provide risk estimates for different points in time that are calculated on

a like-for-like basis.

Figure 1 below summarises the different SRM versions and how they have been derived.

For HLOS comparative purposes, the horizontal arrows show valid comparisons based

solely on changes in data between the different versions of model.

Figure 1: Summary of the SRM modelling and data updates.

SRMv6 Baseline

-------------Remodelled

to

SRMv6.5 Data

refreshed to SRMv7 First comparison

-------------Remodelled

toRemodelled

to

SRMv6.6 Data

refreshed to SRMv7.1

Datarefreshed to

SRMv7.5 Second comparison

-------------------------------------------------------------------------------------

----------------------------------------------------------------------------------------------------------------------------------

--------------------------

SRMv7.5 Update


3.2 Modelling and scope changes from SRMv6.5 to SRMv6.6and SRMv7 to SRMv7.1

The significant changes from SRMv6.5 to SRMv6.6 can be split into two main categories —

the first is the introduction of new hazardous events (usually to provide better event

classification/understanding) and the second is modelling changes. Changes that fall under

the first category include:

The creation of a new HE in SRMv6.6 and SRMv7.1, namely: Member of public (non-

trespasser) fall from platform and struck by train (HEM-49). This was introduced in

response to a recent incident.

In the second category a number of modelling changes were identified for the update from

SRMv6 to SRMv6.5. The main changes are:

A number of modelling changes have been made to the derailment models (HET-12,

HET-13) for SRMv6.6 and v7.1. The main change is a remodelling of derailments on

bridges to account for the fact that a train will not always fall from the bridge (as had

previously been assumed).

The estimates for HET-04 (collisions of trains with objects not resulting in derailment)

in SRMv7.1 have been corrected to account for an error identified in the analysis.

The frequency and consequences for a number of HEs in SRMv6.6 and SRMv7.1

have been re-examined in light of the version 7.5 update in order to incorporate

improved modelling assumptions and make them comparable between versions.

See Table A2 (for SRMv6.5 to SRMv6.6) and Table A3 (for SRMv7 to SRMv7.1) for a

full discussion of these.

3.3 Update from SRMv7.1 to SRMv7.5

The update from SRMv7.1 to SRMv7.5 comprises a partial update of the model. None of

the train accidents (HETs) were updated. A total of 53 movement accidents (HEMs) and

non-movement accidents (HENs) were identified to be updated based on an analysis of the

most recent injury data and a comparison with the SRMv7 estimates. The criteria for

updating a HE were:

Where overall risk for a HE had significantly changed from the SRMv7 estimate. This

was determined by looking at the 95% confidence interval for the SRMv7 estimates

and testing if the most recent data would result in a new risk estimate outside these

limits.

Where the overall risk for a HE has changed appreciably. There is a trade-off to be

made in defining what is meant by appreciable. If the limit is set low, then every HE

will change appreciably. If it is set too high, then very few HEs will have changed

appreciably and therefore warrant updating. An absolute risk change of 0.1 FWI/year

was selected as being an appropriate level to set as being an appreciable change in

risk.

In addition to this, a review of the HEs selected for update was also carried out to

identify further HEs for update, either because similar HEs were being updated and it

made sense to update them as well or because it was felt that the HE was of

particular significance and should be updated.

SRMv7.5 Update


The aim of these criteria was to identify HEs that warranted updating in order to accurately

reflect the overall change in the risk profile while ensuring that the update could be carried

out as efficiently as possible. The updated HEs accounted for around 85% of the overall risk

profile.

The 53 HEs identified were updated using data from incidents occurring up to and including

30 June 20122. For a full discussion and explanation of the significant and appreciable

differences between SRMv7.1 and SRMv7.5 see Table A4.

2There are four hazardous event models that are exceptions to this data cut-off: HEM-12, HEM-25, HEM-31 and

HEN-77. The mapping of incidents to these HEs is influenced by coroners’ reports, which may not be availableuntil some time after the event. Therefore, to ensure there is confidence in the data used to analyse them, anearlier cut-off date was used (30 June 2011).


4 Total Risk on the Mainline Railway

4.1 Overall profile

This section presents the overall risk for the 121 HEs on the mainline railway which are

considered within the SRM. Risk is presented in terms of: injury severity by accident

category (see Table 4); injury severity by person category (see Table 5); and person injured

by accident category (see Table 6).

It should be noted that the totals presented exclude the direct risk due to suicide and

attempted suicide. However, all secondary risk (e.g. the shock/trauma that can arise when

drivers witness suicides) associated with these events has been included.

The total risk from the 121 HEs is assessed to be 139.2 FWI/year. This is made up of

approximately:

67 fatalities per year

484 major injuries per year

2107 Class 1 reportable minor injuries per year

10542 Class 2 reportable minor injuries per year

1764 cases of shock/trauma per year

This compares to 141.0 FWI/year as calculated in SRMv7.1 (reported in SRM-RPB version 7

as 140.9 FWI/year). These total risk estimates are broken down by accident category and

injury type in Table 4: Total risk by accident category below.

Table 4: Total risk by accident category

Accident category FWI /year

Fata

liti

es

/ye

ar

Majo

rin

juri

es

/year

Cla

ss

1m

ino

rin

juri

es

/y

ear

Cla

ss

2m

ino

rin

juri

es

/y

ear

Cla

ss

1sh

ock/t

rau

ma

/year

Cla

ss

2sh

ock/t

rau

ma

/year

(POS = inside possession)

Train accidents (excl. POS) 7.9 6.0 14.6 74.1 9.2 1.3 3.0

Movement accidents(excl. POS and trespass)

22.2 11.2 61.9 359.4 1751.3 214.4 194.7

Non-movement accidents(excl. POS and trespass)

56.0 6.1 330.9 1539.1 7796.3 12.3 1296.1

Inside possession (POS) 8.6 1.7 53.6 116.3 975.7 2.7 4.8

Trespass 44.4 41.8 23.2 18.2 9.7 33.8 0.5

Total 139.2 66.8 484.3 2107.1 10542.2 264.6 1499.2

Note 1: The direct risk from suicide and attempted suicide has been excluded, however all secondary riskassociated with suicide has been included.

Note 2: Some totals may not appear to add up correctly within the table due to the effects of rounding.

Total Risk on the Mainline Railway


Table 5 shows the risk to each person category on the railway. Risk to the public forms the

greatest proportion of the total risk, at 57.7 FWI/year (a decrease of 6.9% from SRMv7.1).

This is mainly due to a large number of fatalities from trespassing events. Given the

uncertainty associated with this risk estimate, the 6.9% decrease is not considered to

indicate a significant change in the underlying risk.

Absolute passenger risk has increased by 4.9% since SRMv7.1. However, over the same

period passenger journeys have increased by 19.2% and passenger kilometres have

increased by 8.6% (from 53.1 billion to 57.7 billion passenger km). The main reason for the

increase in passenger risk is from HEN-14: Passenger slips, trips and falls. This is due to an

increase in the frequency of this HE in the last two years. However, after the passenger risk

is normalised by passenger journeys, it can be seen that risk has actually decreased, as the

absolute risk increase (4.9%) is less than the increase in the normaliser (19.2%).

The risk to the workforce is now 26.9 FWI/year which represents a 0.3% reduction from

SRMv7.1. This small change is the aggregated effect of reductions in the risk from some

HEs and increases in the risk from others. Notable reductions were seen for the following

event types:

Workforce struck by / contact with / trapped by object not at a station

Workforce electric shock (conductor rail)

Workforce assault

The following event types showed increases:

Witnessing a traumatic event (movement)

Workforce electric shock (overhead line equipment)

Witnessing a traumatic event (non-movement)

Table 5: Total risk by person category

Personcategory

SRMv7.5 SRMv7.1

FW

I/y

ear

Fata

liti

es

/ye

ar

Majo

rin

juri

es

/year

Cla

ss

1m

ino

rin

juri

es

/y

ear

Cla

ss

2m

ino

rin

juri

es

/y

ear

Cla

ss

1sh

ock/t

rau

ma

/year

Cla

ss

2sh

ock/t

rau

ma

/year

FW

I/y

ear

%C

han

ge

fro

mS

RM

v7.1

toS

RM

v7.5

Passenger 54.7 10.5 308.6 1416.8 5578.6 1.4 637.2 52.1 +4.9%

Workforce 26.9 3.9 129.7 614.4 4763.1 262.5 824.2 27.0 -0.3%

Public 57.7 52.4 46.0 75.9 200.6 0.6 37.7 62.0 -6.9%

Total 139.2 66.8 484.3 2107.1 10542.2 264.6 1499.2 141.0 -1.3%

Note: The direct risk from suicide and attempted suicide has been excluded, however all secondary riskassociated with suicide has been included.

Note 2: Some totals may not appear to add up correctly within the table due to effects of rounding.



Table 6 presents the risk broken down into person category and accident categories. The

table shows that risk due to train accidents (HETs) has not changed as it has not been

updated for SRMv7.5. Movement accidents (HEMs) have seen a 6.5% decrease in risk,

whereas non-movement accidents (HENs) have seen an increase of 2.8%. Overall, the total

decrease in risk from SRMv7.1 to SRMv7.5 is 1.3%.

Table 6: Total risk to each person category from each accident category

Hazardousevent

SRMv7.5 SRMv7.1

TotalFWI/year

PassengerFWI/year

WorkforceFWI/year

PublicFWI/year

TotalFWI/year

% Changefrom v7.1

to v7.5

HET 8.2 3.1 1.2 3.9 8.2 0%

HEM 55.9 10.8 6.3 38.8 59.8 -6.5%

HEN 75.1 40.7 19.4 14.9 73.1 +2.8%

Total 139.2 54.7 26.9 57.7 141.0 -1.3%




Chart 1: Total risk profile for passengers, the workforce and members of the public — %

of total FWI/year




Chart 1 presents the total risk profile for passengers, the workforce and the public. It shows

that the bulk of the risk is split between passengers and the public, with 39.2% and 41.4%

respectively — the remaining proportion (19.4%) is attributed to workforce incidents. The

profile of injury across person categories has remained similar to SRMv7, with approximately

50% of the risk to passengers and the workforce resulting from major injuries. Fatalities still

dominate the risk to the public, comprising 90.9% of the overall risk to the public per year.

Most of these fatalities are trespassers (41.8 fatalities per year).

4.2 Risk by ASPR hazard categorisation

In this section, the HEs have been grouped into 22 accident types,3 consistent with the

groupings used in the Annual Safety Performance Report (ASPR) [Ref. 4]. Combining the

HEs in this manner allows identification of the types of accidents that contribute the greatest

proportion of risk to the overall figure. The HEs have been grouped as shown in Table 7.

Table 7: ASPR hazardous event groupings

Event type Hazardous events

Assault and abuse HEN-64, HEN-65, HEN-66

Contact with object HEM-20, HEM-32, HEM-42, HEN-21, HEN-23, HEN-26,HEN-44, HEN-55, HEN-56, HEN-59, HEN-76

Contact with person HEN-55, HEN-56

Falls from height HEN-15, HEN-25, HEN-45

Fires and explosions (not involvingtrains)

HEN-01, HEN-02, HEN-03, HEN-04, HEN-05, HEN-48,HEN-49

Lean or fall from train in running HEM-03, HEM-07, HEM-15, HEM-17

Machinery/tool operation HEN-22, HEN-27, HEN-56

Manual handling / awkward movement HEN-73, HEN-74, HEN-82, HEN-83

On-board injuries HEM-38, HEM-39, HEN-62, HEN-63

Platform-train interface(boarding/alighting)

HEM-05, HEM-06, HEM-09, HEM-16, HEM-21, HEM-22,HEM-23, HEM-43

Platform edge incidents (notboarding/alighting)

HEM-06, HEM-08, HEM-10, HEM-21, HEM-40, HEM-41,HEM-49, HEN-09, HEN-10, HEN-13, HEN-52, HEN-67

Road traffic accident HEN-35

Slips, trips and falls HEN-14, HEN-16, HEN-24, HEN-25, HEN-46, HEN-68

Struck/crushed by train HEM-11, HEM-14, HEM-19, HEM-27

Suicide HEM-31, HEN-77

3Some HEs have been split across two or more accident types.



Table 7: ASPR hazardous event groupings (cntd)

Event type Hazardous events

Train accidents: collisions andderailments

HET-01, HET-02NP, HET-02P, HET-03, HET-06, HET-09,HET-12, HET-13, HET-26

Train accidents: collisions with objects HET-04

Train accidents: collisions with roadvehicles at level crossings

HET-10, HET-11

Train accidents: other HET-17, HET-20, HET-21, HET-22, HET-23, HET-24,HET-25

Trespass HEM-12, HEM-25, HEM-30, HEM-44, HEN-36, HEN-37,HEN-38, HEN-39, HEN-40, HEN-41, HEN-42, HEN-43,HEN-71, HEN-72

Workforce electric shock HEN-27, HEN-30, HEN-31, HEN-32

Other HEM-01, HEM-50, HEN-07, HEN-08, HEN-11, HEN-27,HEN-28, HEN-29, HEN-33, HEN-50, HEN-51, HEN-53,HEN-54, HEN-57, HEN-58, HEN-60, HEN-61, HEN-70,HEN-75

4.2.1 Discussion

Chart 2 presents the risk profile in FWI/year and indicates the percentage change in risk

between SRMv7.1 and SRMv7.5 for each of the 22 HE categories listed above. The

greatest overall risk contribution results from Trespass with 44.4 FWI/year, which is

dominated by fatality risk. The next-highest risk contribution results from Slips, trips and falls

with 33.1 FWI/year, an increase of 8.1% compared with SRMv7.1.

The majority of risk from Slips, trips and falls occurs to passengers, contributing

25.6 FWI/year, which represents 46.8% of the overall risk to passengers. After Slips, trips

and falls, the category which contributes most to the overall risk to passengers is Assault

and abuse, representing 8.4 FWI/year, followed by Platform edge incidents (both

boarding/alighting and non-boarding/alighting). Considered together, these four categories

account for over 80% of the risk to passengers.

The greatest workforce risk also comes from the Slips, trips and falls category

(6.3 FWI/year), with the second-highest contribution coming from Contact with object

(4.2 FWI/year). Together these categories represent 38.9% of the risk to the workforce.

A large proportion of the risk to the public results from Trespass (44.3 FWI/year), followed by

Struck/crushed by train (not trespass) with 5.9 FWI/year. Together they represent 86.9% of

the risk to the public.



Chart 2: Combined risk profile (FWI/year) — includes % change from SRMv7.1



Chart 3 shows the combined risk by event type in fatalities per year (excluding the

contribution from non-fatal injuries, shock and trauma). Fatality risk is dominated by

Trespass accidents, accounting for more than half, with 41.8 fatalities per year — down

8.4% on the SRMv7.1 figure. The accident type contributing the second-highest number of

fatalities is Struck/crushed by train4 with 8.3 fatalities per year (the majority of these

occurring at level crossings), suggesting a decrease of 0.6% compared with SRMv7.1.

Together, these two categories account for 75.0% of fatalities.

The highest contribution to passenger fatalities is Platform edge incidents (excluding

boarding/alighting), which accounts for 3.6 fatalities per year (representing 34.5% of

passenger fatality risk).

The most significant contributor to workforce fatalities is Struck/crushed by train, accounting

for 1.9 fatalities per year (48.4% of the workforce fatality risk total). The 41.8 fatalities per

year due to public Trespass represent 79.8% of public fatality risk.

4This excludes trespassers struck by trains, as well as people struck by trains at the platform edge or as a result

of boarding or alighting accidents



Chart 3: Combined risk profile (fatalities/year) — includes % change from SRMv7.1


5 HLOS Safety Metrics

5.1 Background

The government’s white paper Delivering a Sustainable Railway [Ref. 5] sets out the HLOS.

This describes the improvements in safety, reliability and capacity that the industry is

committed to deliver during CP4 (April 2009 to March 2014) and the Statement of Funds

Available to secure these improvements.

The improvements in safety are quoted in terms of a reduction in two safety metrics. These

state that there should be a 3% reduction in the national level of risk for both passengers

and the workforce over CP4. The passenger risk is expressed as FWI per billion passenger

kilometres, whilst the workforce risk is expressed as FWI per million employee hours.

The DfT is using the SRM as the primary means of measuring the performance of the

industry against these safety metrics, rather than using a measure of safety performance

based on accident statistics. This is because, for rare high-consequence events, the rate of

occurrence of accidents over any given period does not provide a good measure of

underlying safety performance. The risk estimates from SRMv6 were used in order to

calculate the baseline risk from which the 3% reduction will be measured.

5.2 Changes to the baseline HLOS safety metrics

As discussed in Section 3, for the purposes of calculating progress against the HLOS safety

metrics, the update for SRMv7.5 has been split into two separate and distinct stages. The

first stage was to incorporate all changes and error corrections into the model and produce

revised versions of the previous models — SRMv6.6 and SRMv7.1. These versions

represent the risk as would have been calculated for SRMv6 and SRMv7, had the modelling

changes implemented in version 7.5 been implemented at the time the previous versions

were created. This creates a revised and more accurate baseline for HLOS monitoring. The

second stage was then a data refresh of selected HE models with data up to 30 June 2012.

The changes from SRMv6.6 to SRMv7.5 represent the latest estimate of risk changes since

the beginning of CP4.

In 2010 RSSB was commissioned by Network Rail to undertake an independent review of

compliance with The Reporting of Injuries, Diseases and Dangerous Occurrences

Regulations 1995 (RIDDOR) by Network Rail staff and its contractors [Ref. 6]. The review

concluded that a number of minor injury events had not been reported into the industry’s

Safety Management Information System (and hence are missing from the SRM data). Based

on the estimated level of under-reporting agreed with Network Rail, for SRMv6.6 an

additional contribution of 0.463 FWI per year has been added to the overall workforce risk to

account for the under-reported RIDDOR-reportable minor injury events. For SRMv7.1 and

SRMv7.5 additional contributions of 0.663 and 0.179 per year FWI, respectively, have been

added to the overall workforce risk to account for the under-reported RIDDOR-reportable

minor injury events during the period used to calculate the risk estimates.

Table 8 below summarises the revised baseline HLOS safety metrics and compares them

with the previously calculated values from version 6.5 of the SRM. Note that there are two

workforce figures: one with the under-reported RIDDOR reportable minor injuries and one

HLOS Safety Metrics


without. These revised safety metrics also incorporate the revised normaliser figures for the

baseline period.

Table 8: Summary of the revised estimates for the baseline HLOS safety metrics

PassengerFWI / billion

passenger km

Workforce FWI / million workforce hours

Excluding under-reported minor injuries

Including under-reported minor injuries

v6.5 HLOS safety metric 0.988 0.133 0.135


% change +0.9% -0.2% -0.2%

It should be noted that the baseline HLOS safety metric figures are subject to change as

modelling refinements are identified which necessitate a recalculation of the SRM figures.

There are therefore likely to be further changes to these numbers in the future when SRMv8

is completed in 2014.

5.3 Progress against the HLOS safety metrics

The passenger and workforce risk figures have been used along with the relevant

normalisation data to calculate the progress HLOS safety metrics and a comparison is then

made against the baseline figures to determine progress against the HLOS target5.

As agreed with the DfT and ORR the HLOS metrics exclude three areas of SRM risk

because of concerns about the reliability and consistency of reporting. The exclusions are:

Non-physical assaults

Workforce involved in road traffic accident whilst on duty6

Witnessing a traumatic event

The passenger km normalisation figure has been taken from the ORR’s National Rail Trends

(Jul 2011 to Jun 2012) [Ref. 7]. This figure aligns with the data cut-off for SRMv7.5 (30 June

2012). The total number of passenger km for this period is 57.73 billion, which is an

increase of 15% from the passenger km figure used for SRMv6.6 (50.4 billion).

The workforce hours normalisation data has been collected as agreed by SPG. The

workforce hours estimate has been based on industry responses received by RSSB. This

issue of the report uses the 2012 numbers. It updates Issue 1.0, which was based on 2011

figures. The total number of workforce hours in the relevant period is 213.0 million, which is

an increase of 1.6% from the workforce hours estimate used for SRMv6.6 (209.6 million).

Table 9 summarises the progress HLOS safety metrics and the comparison of them with the

baseline safety metrics.

5The risk figures and normalisation data used to calculate the metrics exclude the contributions from HS1 which

are outside the scope of the HLOS safety metrics but are inside the scope of the SRM.6

An initiative is currently underway to enable better data collection of these events.

HLOS Safety Metrics


Table 9: Summary of the progress against the HLOS safety metrics7

PassengerFWI / billion

passenger km

Workforce FWI / million workforce hours

Excluding under-reported minor injuries

Including under-reported minor injuries



% change -5.7% -10.8% -11.6%

From Table 9 it can be seen that there has been a decrease in the passenger safety metric

of around 5.7% since the start of Control Period 4 and a larger decrease of around 11.6% in

the workforce metric.

Table 10 provides a summary of the estimated risk for SRMv6.6 and v7.5 and the

differences between them. It also shows this risk broken down by person type (excluding the

under-reported RIDDOR reportable minor injuries).

Table 10: Summary of risk by person type

Person category SRMv7.5 (FWI/year) SRMv6.6 (FWI/year) % Change

Passenger 54.7 50.9 +7.4%

Workforce 26.9 29.5 -9.0%

Public 57.7 60.8 -5.1%

Total 139.2 141.2 -1.4%

Table 10 shows the change in absolute risk (FWI per year) between the HLOS baseline

(SRMv6.6) and the latest risk estimates (SRMv7.5). The passenger metric is showing a

decrease despite the increase in absolute risk (shown in Table 10) due to the number of

passenger km increasing by a greater percentage than the absolute risk increase. The

workforce safety metric shows a decrease that is broadly in line with the observed decrease

in absolute workforce risk shown in Table 10.

7Note that the normalised risk figures presented in Table 9 do not match those in Table 1 because some

elements of SRM risk are excluded from the HLOS calculation, as described at the start of Section 5.3.


6 Uncertainty in the SRM risk estimates

6.1 Introduction

The SRM risk estimates represent the underlying level of risk on the GB rail network. They

are based on an analysis of data reported to SMIS, which is classified according to the HE

and precursor structure of the SRM. The amount of data for each precursor in the SRM can

vary quite considerably. In some cases, there is a lot of data to base a precursor estimate

on, in other cases there is little or very little, and in some cases there is none.

The SRM precursor/HE estimates represent the best estimate of risk based on the available

data for that precursor/HE. Where there are a lot of data, there is a high level of confidence

in the estimate, however where there are few data there is less confidence in the estimate.

It has been a long standing aim to quantify this level of uncertainty and to develop a

framework that can determine selected confidence intervals around the SRM estimates.

This section will give some background to the work that has been undertaken in this area,

outline the methodology that is currently being developed and finally present some results

based on the version 7.5 update.

6.2 Uncertainty Methodology

In 2003, RSSB funded research at Strathclyde University to investigate quantification of the

uncertainty in a risk assessment model, using the SRM as an example. This research

formed R&D project T306 [Ref. 8]. While methods investigated apply primarily to the train

accident (HET) models (as they are built using fault and event tree models), the principles

can be equally applied to the other models of the SRM.

The main difference between the HET models and the HEM/HEN models is that in general

the HEM/HEN models are based on significant amounts of actual injury-related data, while

the HET models are not. This means that the HET uncertainty methodology is mainly aimed

at quantifying model uncertainty in conjunction with statistical uncertainty due to the lack of

data. The HEM/HEN methodology focus, however, can be aimed more at quantifying

statistical uncertainty, as there is ample data.

The main idea behind the methodology for quantifying the uncertainty in the HEM/HEN

estimates is to construct a framework whereby the uncertainty in the frequency and

consequence estimates for each HE can be quantified and combined to give an overall

confidence interval for the risk for each precursor. This will involve constructing distributions

to model the frequency and the average consequence estimates of each precursor. These

distributions could be constructed either from data or expert judgement, or a mixture of the

two. Once these have been set, a simulation can be run, where frequency and

consequence estimates are sampled from the distributions many thousands of times and

combined to give a distribution of the risk estimates for each precursor. These can then in

turn be sampled from to give distributions of the risk at HE level, HEM/HEN level or at the

overall SRM system risk level.

Taking Safe Decisions


6.3 SRM Model Uncertainty Results

The uncertainty methodology currently in development has been applied to the version 7.5

HEM/HEN risk estimates. The HET risk has been excluded from this analysis along with the

additional workforce risk from the under-reported RIDDOR injuries. Excluding these

contributions gives an overall SRM combined HEM/HEN risk of 131 FWIyear.

Chart 4 below shows the 95% confidence interval8 around the overall HEM/HEN risk of 131

FW/year. The boxes above the chart show some properties of the distribution of the risk that

has been constructed. The central white box gives the mean (average) value of the

distribution and it can be seen that this corresponds9 with the overall SRM HEM/HEN risk

estimate. The other two white boxes either side show the extent of the 95% confidence

interval, with a lower limit (LL) of 124.6 FWI/year and an upper limit (UL) of 137.7 FWI/year.

The blue boxes show the absolute risk difference between the LL/UL and the mean. In this

case it can be seen that the UL is 6.7 FWI/year above the mean risk, while the LL is 6.4

FWI/year below the mean risk.

Chart 4: Chart showing risk distribution and the 95% confidence interval for the total

SRMv7.5 HEM/HEN risk.

Chart 5 below shows the 95% confidence interval for HEM risk and HEN risk consideredseparately, while Chart 6 below shows the 95% confidence interval for passenger, workforceand public risk considered separately. Figures for the mean risk of each of thesedistributions along with the LL and UL of the 95% confidence interval can be read from thewhite and blue boxes as before.

8A confidence interval indicates the range of values an estimate is likely to lie in given a specified level of

confidence. In this case a 95% confidence interval means that if we were to rerun (if this was possible) the wholeoperation of the railway again, as it was over the SRMv7.5 data period, collect the data and calculate a 95%confidence interval for the overall HEM/HEN risk, we would expect in 19 out of 20 occasions (ie 95% of the time)the confidence interval would contain the true underlying level of risk.9

This is to be expected from the way the HEM/HEN uncertainty model has been constructed. It is notnecessarily always the case and depends on the assumptions made to construct the model.

LL 124.6 -6.4 Mean 131.0 UL 137.7 6.7SRM

119 121 123 125 127 129 131 133 135 137 139 141 143




SRMv7.5 HEM and HEN risk separately.

There is more uncertainty in the estimate of HEM risk even though it has a lower mean. This

is because HEM risk tends to be dominated by a relatively small number of fatalities

(somewhat under 150 over the three-year period that is typically used for frequency

estimates), whereas HEN risk tends to be dominated by a greater number of lower

consequence events. The same reasoning explains why there is more uncertainty in the

estimate of public risk than in the estimates of risk to passengers or members of the

workforce, see Chart 6 which follows.

LL 50.6 -5.3 Mean 55.9 UL 61.5 5.6

HEM

46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66

LL 71.5 -3.5 Mean 75.0 UL 78.7 3.7HEN

65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85




SRMv7.5 passenger, workforce and public risk separately.

LL 49.7 -2.5 Mean 52.2 UL 54.8 2.6Passenger

42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62

LL 24.1 -1.4 Mean 25.5 UL 26.8 1.3Workforce

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

LL 47.2 -5.9 Mean 53.1 UL 59.4 6.3Member of Public

43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63



6.4 Next steps

The work presented in this chapter is on-going and the results should be treated as

preliminary findings, however they do illustrate what the eventual aim of the work is and how

the results can be presented. The next steps are to finalise the HEN/HEM uncertainty

methodology and to continue to develop the HET methodology. The eventual aim is to

construct a framework that can be used to assess the uncertainty in the SRM risk estimates

at any level that is required and to present the information in a format that is accessible and

understandable.

SRM Governance


7 SRM Governance and SRM Updates

7.1 SRM Practitioners Working Group

The SRM-PWG is the industry governance body of the SRM. It was set up to facilitate a

structured process for eliciting the industry’s views on the development and use of the SRM.

The SRM-PWG provides governance for changes to the SRM.

The SRM-PWG was formed under the authority of the industry’s Safety Policy Group

(SPG)10 to engage stakeholders in the development and control of future versions of the

SRM and its related outputs which include the SRM-RPB, SRM-RPT and documents such

as Guidance on the Preparation and Use of Company Risk Assessment Profiles for

Transport Operators (see Section 8.3). It comprises a range of industry representatives

including Network Rail, train operators, rolling stock manufacturers, infrastructure

maintenance companies and the ORR. The aims of the group are:

To ensure that the SRM and its outputs meet the needs of the industry.

To provide stakeholders with a formal opportunity to contribute to, oversee and

recommend developments to the SRM, and to provide transparency for any

development activities carried out by RSSB.

To create a forum for the industry to inform RSSB of changes to the network that

should be reflected in the SRM, thus ensuring that the SRM provides the best

possible representation of the underlying level of risk on the railway.

To enhance the channels through which RSSB delivers, promotes and supports SRM

risk information.

The modelling changes implemented as part of the update of the SRM to version 7.5 have

been endorsed by SRM-PWG. The revised version 6 figures (SRMv6.6) and the SRMv7.5

figures were presented to the group in January 2013 and recommended for approval by

SPG. Following this meeting the results were then presented to SPG and approved in

February 2013.

7.2 Update history

Since version 1 in 2001, the SRM-RPB has been updated regularly so that the risk profile

remains as current as possible. Since version 2, the SRM-RPB has been issued

approximately every 18–24 months. The version 7.5 results are reported in a shorter version

of the Risk Profile Bulletin, the Risk Profile Report. Version 7.5 is actually the ninth release

and covers SRMv6.6, SRMv7.1 and SRMv7.5. The update history up to and including this

version is shown in Table 11 below.

10SPG no longer exists and the System Safety Review Group (SSRG) has now become the SRM-PWG’s parent

group.



Table 11: SRM update history

Version Issue Date Major Change (from previous version)

1 January 2001 First version

2 July 2001 Re-release of SRMv1

3 February 2003 Full data update and model enhancements

Inclusion of TPWS

4 January 2005 Full data update and model enhancements

5 August 2006 Full data update and model enhancements

Removal of Mk1 slam-door rolling stock from models

Inclusion of OTP risk model

5.5 May 2008 Interim partial data update

Change in FWI weightings

6 June 2009 Full data update and model enhancementsCP4 HLOS benchmark version

6.5 January 2011 Enhanced version 6

7 June 2011 Full data update

6.6 March 2013 Enhanced version 6.5

7.1 March 2013 Enhanced version 7

7.5 March 2013 Interim partial data update



7.3 Updates to the SRM during CP4

After version 7.5, a further, full update of the SRM will be produced in March 2014 so that

the change in risk over CP4 can be measured and compared with the benchmark SRMv6

figures. Chart 7 illustrates the timeline for updates of the SRM during CP4.

Chart 7: Timeline for updates of the SRM and the SRM-RPB for CP4

As part of any future updates it may be necessary to incorporate some modelling changes

into the update process and this may be due to a number of reasons, namely:

New analyses or analysis methods are incorporated into the SRM or the SRM is

extended to cover new HEs.

A significant change in the risk profile becomes apparent due to the introduction of a

new control measure or a significant deterioration in the application of one or more

existing control measures is identified.

As was necessary in order to produce the HLOS progress metrics associated with this

update, any update to the modelling approach applied to the SRM during the remainder of

CP4 will require SRMv6.6 to be recalculated to allow the risk profile over CP4 to be

calculated consistently and on a like-for-like basis.

The next full update of the SRM will be version 8 in 2014.


8 RSSB Rail Risk Portal

The SRM-RPB is one of the outputs from the SRM, which has been developed as a

resource for the railway industry. RSSB is committed to providing support to our members,

and have produced a range of products and services, all derived from the SRM.

All products are currently available on the RSSB Rail Risk Portal at

www.safetyriskmodel.co.uk.

8.1 SRM Risk Profile Bulletins/ Risk Profile Report11

The outputs from the SRM are presented in the SRM-RPR, along with analyses of important

risk profiles and discussion of these in the wider context of the rail industry.

To assist the industry in conducting risk assessments, the SRM-RPR provides national risk

estimates for the mainline railway in GB. These are provided as Excel spreadsheets and

can be freely downloaded from the RSSB Rail Risk Portal at www.safetyriskmodel.co.uk.

8.2 Yards, Depots and Sidings SRM Risk Profile Report

The Yards, Depots & Sidings (YD&S) project involves extending the scope of the SRM, to

incorporate the risk from hazardous events in YD&S sites away from the operational

railway. This means that accident frequency and consequence data will be available for

YD&S sites for companies to use to help improve their understanding and management of

risk on these sites.

YD&S-SRM-RPR version 1 was released in November 2012, and provides national risk

estimates for YD&S in GB. These are provided in tabular form in the YD&S-SRM-RPR and

can be freely downloaded from the RSSB Rail Risk Portal at www.safetyriskmodel.co.uk.

8.3 Risk assessment guidance

RSSB has produced Guidance on the Preparation and Use of Company Risk Assessment

Profiles for Transport Operators [Ref. 9], which provides guidance to transport operators on

how to prepare and maintain risk assessments covering their operations.

The principles in this document are designed to facilitate a consistent and robust approach

to risk assessment throughout the rail industry. The document also suggests how to make

the best use of the tools provided by RSSB, such as the SRM-RPB and the SRM-RPT (see

Section 8.4).

8.4 SRM Risk Profile Tool

The SRM Risk Profile Tool, formerly known as the SRM Templates Tool, can be used to

estimate the risk contribution from a portion of the GB network, for example, the risk profile

of a given transport operator.

11A Risk Profile Bulletin would usually be produced with outputs from the SRM, however due to the selected

nature of the data updated in the development of the SRMv7.5, a Risk Profile Report has been produced instead

RSSB Rail Risk Portal


The SRM is used as a starting point, representing the total risk to the whole GB network.

The user enters data into the SRM-RPT in order to scale the national average risk, to make

it more representative of the risk profile of their own operation.

Please note that the SRM-RPT was not updated for SRMv7.5.

8.5 Taking Safe Decisions Analysis Tool

The law in the UK requires the railway to reduce safety risk to a level that is ALARP. A

judgement about whether or not safety risk has been reduced to a level that is ALARP is

based on the consideration of the costs and safety benefits of the different options; this can

involve both subjective judgement and objective analysis. In its most detailed form, for a

subset of complex decisions, the ALARP judgement can be supported by a quantified CBA.

Taking Safe Decisions (see Section 11 of version 7 of SRM-RPB [Ref. 3]) contains a

framework that describes how to put these principles into practice. The Taking Safe

Decisions – Analysis Tool, in turn, supports safety decision taking by facilitating the

construction of a CBA that is compatible with Taking Safe Decisions, in circumstances where

this is necessary.

8.6 Fixed Lineside Telephony Analysis Tool

In the wake of the rollout of GSM-R across GB, RSSB have produced guidance note

GO/GN3677 Guidance on Operational Criteria for the Provision of Lineside Telephony

Following GSM-R Introduction [Ref. 10], which recommends a risk-based appraisal process.

The Fixed Lineside Telephony Analysis Tool (FLAT) has been produced to support this

process.

FLAT is intended to assist users in deciding whether to provide, renew, retain or remove

lineside telephony at a specific location. It uses risk estimates from the SRM to perform a

CBA which is consistent with the legal framework in the UK.

8.7 SPAD Risk Ranking Tool

The SPAD Risk Ranking Tool was developed in 2002 to:

Estimate the probability of the SPAD escalating to an accident and the potential

accident severity.

Estimate changes to overall potential risk from SPADs.

Identify those SPADs that are potentially significant.

Inform the SPAD investigation process.

8.8 Risk Management Forum

The annual Risk Management Forum (RMF) exists to promote, develop and steer good

practice in risk management for Britain’s railways. RSSB has been hosting the RMF on

behalf of the industry for a number of years.

RMF presentations are available on www.safetyriskmodel.co.uk.



8.9 Assistance and training

RSSB provides training on risk assessment tools and techniques for groups or individuals.

We also offer a hot desk at our offices where we can work closely with you on any risk

problem.

For more information, please contact us on 020 3142 5464 or [email protected].



9 Injury Weightings

Table 12 shows the different injury classifications and their associated weightings. The

figures in the ratio column represent the number of injuries of each type that are regarded as

‘statistically equivalent’ to one fatality.

Table 12: Injury degrees and weightings

Injury degree Definition Weighting Ratio

Fatality Death occurs within one year of the accident. 1 1

Major injury

Injuries to passengers, staff or members of the public asdefined in schedule 1 to RIDDOR 1995. This includeslosing consciousness, most fractures, major dislocations,loss of sight (temporary or permanent) and other injuriesthat resulted in hospital attendance for more than 24 hours.

0.1 10

Class 1minor injury

Injuries to passengers, staff or members of the public, thatare neither fatalities nor major injuries, and are defined asreportable in RIDDOR 1995

12amended April 2012, plus:

Workforce injuries, where the injured person isincapacitated for their normal duties for more thanthree consecutive calendar days, not including the dayof the injury.

0.005 200

Class 2minor injury

All other physical injuries. 0.001 1000

Class 1shock/trauma

Shock or trauma resulting from being involved in, orwitnessing, events that have serious potential of a fataloutcome e.g. train accidents such as collisions andderailments, or a person being struck by train.

0.005 200

Class 2shock/trauma

Shock or trauma resulting from other causes, such asverbal abuse and near misses, or personal accidents of atypically non-fatal outcome.

0.001 1000

12RIDDOR refers to the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995: a set of

health and safety regulations that mandates the reporting of, inter alia, work-related accidents.


10 Contributors

Details of the preparation and approval of the SRM-RPR are given below:

Prepared by: Steven Burke

Stuart Carpenter

Ben Gilmartin

David Griffin

Steven Grima

Chris Harrison

Jay Heavisides

Anna Holloway

Matt Hunt

Rachael Johnson

Albert Law

Reuben McDonald

Wayne Murphy

Paul Murray

Kevin Thompson

Reviewed by: George Bearfield

Marcus Dacre

SRMv7.5 scope and update changes from previous versions were endorsed by:

SRM Practitioners Working Group on behalf of Safety Policy Group

Approved by: George Bearfield

Release date: March 2013

Correspondence may be sent to: RSSBBlock 2, Angel Square1 Torrens StLondon EC1V 1NYUK

or: [email protected]


11 Acronyms and Glossary

11.1 Acronyms

ALARP As Low As Reasonably Practicable

CBA Cost-Benefit Analysis

CP4 Control Period 4

DfT Department for Transport

FLAT Fixed Lineside Telephony Analysis Tool

FOC Freight Operating Company

FTE Full-Time Equivalent

FWI Fatalities and Weighted Injuries

GB Great Britain

HE Hazardous Event

HLOS High-Level Output Specification

HSE Health and Safety Executive

LUL London Underground Ltd

NPT Non-Passenger Train

NR Network Rail

ORR The Office of Rail Regulation

POS inside Possession

RGS Railway Group Standards

RIDDOR The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations

1995

RMF Risk Management Forum

RSSB Rail Safety and Standards Board

RU Railway Undertaking

SFAIRP So Far As Is Reasonably Practicable

SMIS Safety Management Information System

SMS Safety Management System

SPG Safety Policy Group

SRM Safety Risk Model

SRM-PWG Safety Risk Model Practitioners Working Group

SRM-RPB Safety Risk Model: Risk Profile Bulletin

Acronyms & Glossary


SRM-RPR Safety Risk Model: Risk Profile Report

SRM-RPT Safety Risk Model: Risk Profile Tool

SSP Strategic Safety Plan

TOC Train Operating Company

YD&S Yards, Depots and Sidings

11.2 Glossary

The following list describes terms as they are used in the SRM.

ALARP/SFAIRP The Health and Safety at Work Act 1974 (HSWA) places

duties on employers in the UK to ensure safety ‘so far as is

reasonably practicable’ (SFAIRP). When these duties are

considered in relation to risk management the duty is

sometimes described as a requirement to reduce risk to a

level that is ‘as low as is reasonably practicable’ (ALARP).

These terms therefore express the same concept in

different contexts and should be considered to be

synonymous.

awkward movement An injury caused by a body movement, eg twisting or

stretching. This excludes injuries related to manual

handling.

child A person under 16 years of age.

collective risk The aggregate risk, possibly for a range of different groups,

associated with their exposure to a particular scenario or

hazardous event. The SRM calculates collective risk as

the average number of fatalities, or FWI/year that would

be expected to occur from a hazardous event, or group of

hazardous events. When undertaking an assessment of

whether or not a measure is necessary to reduce risk to a

level that is ALARP, the change in risk associated with the

measure is a collective risk estimate.

common safety method on

risk evaluation and

assessment

A mandatory risk assessment process that forms part of a

wide-ranging programme of work aimed at bringing about

an open, competitive and safe European railway. It

provides a framework for assessing and evaluating the risk

associated with significant safety-related changes using

one or more of the following risk acceptance principles: (i)

application of codes of practice, (ii) comparison with

reference systems, (iii) explicit risk estimation.

consequence/s The number of fatalities, major and minor injuries, shock

and trauma resulting from the occurrence of a particular

hazardous event outcome.

Acronyms & Glossary


control measure Any means to reduce the frequency of a hazardous

event and/or minimise the consequence following its

occurrence.

Control measures may be physical devices, procedures, or

a system of both.

escalation factor Any failure which significantly increases, or ‘escalates’, the

consequence from a hazardous event.

For instance, a train derailment (the hazardous event)

could escalate into;

a bridge collapse onto the train,

the outbreak of a fire

a release of hazardous substances from a train.

An escalation factor may be:

a system failure,

sub-system failure,

component failure,

human error,

physical effect,

operational condition.

It may occur individually, or in combination with other

escalation factors.

fatalities and weighted

injuries (FWI)

The aggregate amount of safety harm. One FWI is

equivalent to:

one fatality, or

10 major injuries, or

200 Class 1 minor injuries, or

200 Class 1 shock/trauma events, or

1,000 Class 2 minor injuries, or

1,000 Class 2 shock/trauma events.

fatality Death within one year of the causal accident, this includes

subsequent death from the causes of a railway accident.

All are RIDDOR-reportable.

frequency The rate of occurrence (eg the number of events per year).

hazardous event (HE) An incident that has the potential to be the direct cause of

safety harm.

Acronyms & Glossary


hazardous event - movement

accident (HEM)

An accident causing injury to people, involving trains (in

motion or stationary) but excluding injuries sustained in

hazardous event - train accident (HET).

hazardous event - non-

movement accident (HEN)

An accident causing injury to people, unconnected with the

movement of trains.

hazardous event – train

accident (HET)

The SRM definition is based on that of train accidents as

defined in RIDDOR, but includes a wider set of incidents.

There are additional criteria for different types of accident

(e.g. buffer stop strikes, train derailment), and they depend

on whether the accident involves a passenger train or not.

Not all these criteria (which may, for example, relate to

damage) are used in the SRM definition, which means that

more incidents fall under the SRM definition of a train

accident than the RIDDOR definition.

individual risk The probability of fatality per year to which an individual

is exposed from the operation of the railway. Individual risk

is a useful notion when organisations are seeking to

benchmark their risk profile and to prioritise safety

management effort. The ORR categorises individual risk

as “unacceptable”, “tolerable” and “broadly acceptable” for

the purposes of prioritising its enforcement activity.

infrastructure worker A member of workforce whose responsibilities include

engineering or technical activities associated with railway

infrastructure. This includes track maintenance, civil

structure inspection and maintenance, S&T

renewal/upgrade, engineering supervision, acting as a

controller of site safety (COSS), hand signaller or lookout

and machine operation.

level crossing This is a ground-level interface between a road and therailway.

It provides a means of access over the railway line and hasvarious forms of protection including two main categories:

Active crossings– where the road vehicle user orpedestrian is given warning of a train’s approach (eithermanually by railway staff i.e. manual crossings orautomatically i.e. automatic crossings)

Passive crossing – where no warning system is provided,the onus being on the road user or pedestrian to determineif it is safe to cross the line. This includes, using atelephone to call the signaller.

major injury An injury to any person as defined in schedule 1 of

RIDDOR 1995, or where the injury resulted in hospital

attendance for more than 24 hours.

Acronyms & Glossary


minor injury Any other physical injury to any person that is neither a

fatality nor a major injury.

operational railway All railway lines for which the IM has been granted a safety

authorisation, and the RU has been granted a safety

certificate by the ORR (under European Safety Directive

2004/49/EC [Ref. 11]). This provides evidence that there is

a suitable SMS in place, and that operations are being

conducted in accordance with that SMS.

Ovenstone criteria An explicit set of criteria, adapted for the railway, which

provides an objective assessment of suicide if a coroner’s

verdict is not available. The criteria are based on the

findings of a 1970 research project into rail suicides and

cover aspects such as the presence (or not) of a suicide

note, the clear intent to commit suicide, behavioural

patterns, previous suicide attempts, prolonged bouts of

depression and instability levels [Ref. 12].

passenger A person on railway infrastructure, who either intends to

travel on a train, is travelling on a train or has travelled on

a train. This does not include passengers who are

trespassing or who commit suicide — they are included

in the SRM as members of public.

possession (POS) Used for the protection of engineering work. The line is

handed over to a Person in Charge of Possession (PICOP)

who is responsible for the protection arrangements. The

actual work is done within work sites which are under the

control of an Engineering Supervisor (ES). Any type of

work may be undertaken and engineering trains, OTM and

OTP may be present. Rule Book module T3 refers.

precursor A system failure, sub-system failure, component failure,

human error or operational condition which could,

individually or in combination with other precursors, result

in the occurrence of a hazardous event.

public, members of (MOP) Persons other than passengers or workforce members.

This includes passengers who are trespassing (eg when

crossing tracks between platforms) and anyone who

commits, or attempts to commit suicide.

railway infrastructure Railway infrastructure includes all associated railway

assets, including public areas at stations.

residual risk The level of risk remaining with the current risk control

measures in place and with their current degree of

effectiveness.

Acronyms & Glossary


RIDDOR The Reporting of Injuries, Diseases and Dangerous

Occurrences Regulations 1995 is a set of health and safety

regulations that require any major injuries, illnesses or

accidents occurring in the workplace to be formally

reported to the enforcing authority. It defines major

injuries and lists notifiable diseases — many of which can

be occupational in origin. It also defines notifiable

dangerous occurrences, such as collisions and

derailments.

running line A line shown in Table A of the Sectional Appendix as a

passenger line or as a non-passenger line.

Safety Management

Information System (SMIS)

A national database used by RUs and IMs to record any

safety-related events that occur on the railway. SMIS data

is accessible to all of the companies who use the system,

so that it may be used to analyse risk, predict trends and

focus action on major areas of safety concern.

Safety Risk Model (SRM) A quantitative representation of the safety risk that can

result from the operation and maintenance of the GB rail

network. It comprises 121 individual models, each

representing a type of hazardous event.

shock/trauma Shock or traumatic stress affecting any person who has

been involved in, or a witness to, an event, and not

suffered any physical injury.

Shock and trauma is measured by the SRM and reported

on in safety performance reporting; it is within the scope of

what must be reported into SMIS. However, it is never

RIDDOR-reportable.

Class 1 Shock/trauma events relate to witnessing a

fatality, incidents and train accidents (collisions,

derailments and fires).

Class 2 Shock/trauma events relate to all other

causes of shock/trauma such as verbal assaults,

witnessing physical assaults, witnessing non-fatality

incidents and near misses.

suicide and suspected

suicide

A fatality is classified as a suicide according to a coroner’s

verdict. It is classified as a suspected suicide where the

coroner has yet to return a verdict or returns an open

verdict, but where objective evidence of suicide exists

based on the application of the Ovenstone criteria.

train Any self-powered vehicle, or vehicles hauled by a self-

powered vehicle, with flanged wheels on guided rails.

Acronyms & Glossary


trespass ‘Trespassing’ has occurred when people intentionally go

where they are never authorised to be.

This includes:

Passengers crossing tracks at a station, other than

at a defined crossing.

Public using the railway as a short cut.

Passengers accessing track area at station to

retrieve dropped items

Public using the running lines as a playground.

Public committing acts of vandalism / crime on the

lineside.

Passenger / public accessing the tracks via station

ramps.

Public inappropriate behaviour on other

infrastructure resulting in a fall onto the railway.

Public jumping onto railway infrastructure.

On train passengers accessing unauthorised areas

of the train (interior or exterior).

Note: Level crossing users are never counted as

trespassers, providing they are not using the crossing as

an access point into a permanently unauthorised area,

such as the trackside.

workforce Persons working for the industry on railway operations,

either as direct employees or under contract.


12 References

[Ref. 1] RSSB (2012) Yards, Depots & Sidings Risk Profile Report, version 1.

www.safetyriskmodel.co.uk

[Ref. 2] Network Rail (2012) Strategic Business Plans 2014-2019.http://www.networkrail.co.uk/publications/strategic-business-plan-for-cp5/

[Ref. 3] RSSB (2011) Safety Risk Model Risk Profile Bulletin, version 7.

www.safetyriskmodel.co.uk

[Ref. 4] RSSB (2012) Annual Safety Performance Report 2011/12.http://www.rssb.co.uk/SPR/REPORTS/Pages/default.aspx

[Ref. 5] Department for Transport (2007) Delivering a Sustainable Railway, CM-7176.

http://www.dft.gov.uk/pgr/rail/whitepapercm7176/

[Ref. 6] RSSB (2011) Independent Review of RIDDOR Reporting by Network Rail and its

Contractors. http://www.rssb.co.uk/Pages/RIDDORReview.aspx

[Ref. 7] The Office of Rail Regulation (2010) National Rail Trends.

http://dataportal.orr.gov.uk/

[Ref. 8] Cheng D., 2009, Uncertainty Analysis of Large Risk Assessment Models with

Applications to the Rail Safety & Standards Board Safety Risk Model. Glasgow:

Strathclyde University (http://strathprints.strath.ac.uk/13400/).

[Ref. 9] RSSB (2009) Guidance on the Preparation and Use of Company Risk

Assessment Profiles for Transport Operators. http://www.safetyriskmodel.co.uk

[Ref. 10] RSSB (2010) Rail Industry Guidance Note GO/GN3677: Guidance on

Operational Criteria for the Provision of Lineside Telephony Following GSM-R

Introduction. http://www.rgsonline.co.uk

[Ref. 11] European Railway Safety Directive 2004/49/EC.http://www.dft.gov.uk/pgr/rail/Safety/ersd

[Ref. 12] Ovenstone, I.M. (1973) A psychiatric approach to the diagnosis on suicide.

British Journal of Psychiatry, 123 (572), pp15–21.

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