This report is issued by RSSB.
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RSSB
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020 3142 5476
© RAIL SAFETY AND STANDARDS BOARD LTD. 2013 ALL RIGHTS RESERVED
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This publication can be accessed via the RSSB Rail Risk Portal at www.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.
Issue 1.1 – Published June 2013

This page has been intentionally left blank ii Version 7.5 — June 2013

Executive Summary.......................................................................................................... vii
1 Introduction ............................................................................................................. 1
2
3
4
5
SRM Objectives and Overview ............................................................................... 3
2.1
2.2
2.3
Objectives .................................................................................................................... 3
Overview ...................................................................................................................... 3
Key assumptions and exclusions ............................................................................. 4
SRMv7.5 Update Strategy ....................................................................................... 5
3.1
3.2
3.3
Overview of the SRMv7.5 update .............................................................................. 5
Modelling and scope changes from SRMv6.5 to SRMv6.6 and SRMv7 to
SRMv7.1 ....................................................................................................................... 6
Update from SRMv7.1 to SRMv7.5 ............................................................................ 6
Total Risk on the Mainline Railway ........................................................................ 8
4.1
4.2
Overall profile .............................................................................................................. 8
Risk by ASPR hazard categorisation ...................................................................... 12
4.2.1
Discussion .................................................................................................... 13
HLOS Safety Metrics ............................................................................................. 17
5.1
5.2
5.3
Background ............................................................................................................... 17
Changes to the baseline HLOS safety metrics ...................................................... 17
Progress against the HLOS safety metrics ............................................................ 18
6
7
8
Uncertainty in the SRM risk estimates................................................................. 20
6.1
6.2
6.3
6.4
Introduction ............................................................................................................... 20
Uncertainty Methodology......................................................................................... 20
SRM Model Uncertainty Results.............................................................................. 21
Next steps .................................................................................................................. 24
SRM Governance and SRM Updates.................................................................... 25
7.1
7.2
7.3
SRM Practitioners Working Group.......................................................................... 25
Update history ........................................................................................................... 25
Updates to the SRM during CP4.............................................................................. 27
RSSB Rail Risk Portal ........................................................................................... 28
8.1
8.2
8.3
SRM Risk Profile Bulletins/ Risk Profile Report .................................................... 28
Yards, Depots and Sidings SRM Risk Profile Report............................................ 28
Risk assessment guidance ...................................................................................... 28
Version 7.5 — June 2013 iii

Contents
9
10
11
12
8.4
8.5
8.6
8.7
8.8
8.9
SRM Risk Profile Tool............................................................................................... 28
Taking Safe Decisions Analysis Tool ..................................................................... 29
Fixed Lineside Telephony Analysis Tool ............................................................... 29
SPAD Risk Ranking Tool.......................................................................................... 29
Risk Management Forum ......................................................................................... 29
Assistance and training ........................................................................................... 30
Injury Weightings .................................................................................................. 31
Contributors........................................................................................................... 32
Acronyms and Glossary ....................................................................................... 33
11.1
Acronyms................................................................................................................... 33
11.2
Glossary..................................................................................................................... 34
References............................................................................................................. 40 iv Version 7.5 — June 2013

Contents
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
Version 7.5 — June 2013 v

Contents
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
Chart 6: Charts showing the risk distribution and the 95% confidence interval for the
SRMv7.5 passenger, workforce and public risk separately. ............................... 23
Chart 7: Timeline for updates of the SRM and the SRM-RPB for CP4............................. 27 vi 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.
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).
vii Version 7.5 — June 2013

Contents
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
Risk (FWI/year) v7.5
v7.1
54.7
52.1
26.9
57.7
27.0
62.0
Normaliser
Unit of exposure billion passenger km billion passenger journeys million workforce hours
[No normaliser used] v7.5
57.7
1.47
213
v7.1
53.1
1.24
207
-
Risk (FWI/unit of exposure) v7.5
0.947
37.1
0.126
v7.1
0.981
42.1
0.130
-
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
Train accidents (HETs)
Movement accidents (HEMs)
Non-movement accidents (HENs) v7.5 Risk (FWI/year)
8.2
55.9
75.1
v7.1 Risk (FWI/year)
8.2
59.8
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.
viii Version 7.5 — June 2013

Contents
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 ix

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.
1
There 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 available until sometime after the event. Therefore, to ensure there is confidence in the data used to analyse them, an earlier cut-off date (30 June 2011) was used.
Version 7.5 — June 2013 1

Introduction
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 Version 7.5 — June 2013

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.
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.
3 Version 7.5 — June 2013

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 have legitimate 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, or electrical control offices
 Railway workers involved in road traffic accidents while on duty.
 Members of Public (not passengers) outside the mainline railway or legitimately crossing the mainline railway (i.e. on level crossings).
 Members of Public who enter the mainline railway with no legitimate purpose (e.g. tresspassers including passengers who enter areas for which they have no legitimate access).
 Events associated with vandalism and Members of
Public falling or trespassing on the mainline railway are also included.
 Injuries directly associated with suicides or attempted suicide are quantified but not included in the overall results discussion.
On trains
 All on-train events.
 Events on the mainline railway which affect trains including level crossings.
 All accidents related to the movement of OTP that occur within possessions.
In stations
 All public areas associated with the movement of passengers and staff inside the physical boundaries of stations.
People
 The SRM does not quantify the risk to staff due to long-term occupational health issues.
 Risk associated with terrorist activity is excluded.
Yards, sidings and depots
 Events occurring within yards, sidings and depots are not included within the SRM (this is being developed).
 However, those events relating to the movement of trains entering and leaving yards, sidings and depots, and events relating to the condition of trains joining the system from the depots have been included.
In stations
 Non-public areas at stations, i.e.
the work side of a ticket office
(however, where a member of the workforce is assaulted by a
Member of Public who is on the public side of the office, this has been included).
 Retail outlets within stations.
 Station toilets.
 Everything roadside of a station e.g. car parks, access roads, forecourts, taxi ranks etc.
 Offices.
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.
4 Version 7.5 — June 2013

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

Remodelled to


--------------------------
SRMv6.6

Data refreshed to

SRMv7

Remodelled to

SRMv7.1
-------------------------------------------------------------------------------------

Data refreshed to
 SRMv7.5
First comparison
Second comparison
5 Version 7.5 — June 2013

SRMv7.5 Update
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 (nontrespasser) 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.
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.
6 Version 7.5 — June 2013

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 2012 2 . For a full discussion and explanation of the significant and appreciable differences between SRMv7.1 and SRMv7.5 see Table A4.
2
There 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 available until some time after the event. Therefore, to ensure there is confidence in the data used to analyse them, an earlier cut-off date was used (30 June 2011).
Version 7.5 — June 2013 7

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
(POS = inside possession)
Train accidents (excl. POS)
Movement accidents
(excl. POS and trespass)
Non-movement accidents
(excl. POS and trespass)
7.9
22.2
56.0
6.0
11.2
6.1
14.6
61.9
330.9
74.1
359.4
1539.1
9.2
1751.3
7796.3
1.3
214.4
12.3
3.0
194.7
1296.1
Inside possession (POS)
Trespass
8.6
44.4
1.7
41.8
53.6
23.2
116.3
18.2
975.7
9.7
2.7
33.8
4.8
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 risk associated 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.
Version 7.5 — June 2013 8

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
SRMv7.5
SRMv7.1
Person category
Passenger
Workforce
Public
54.7
26.9
57.7
10.5
3.9
52.4
308.6
129.7
46.0
1416.8
614.4
75.9
5578.6
4763.1
200.6
1.4
262.5
0.6
637.2
824.2
37.7
52.1
27.0
62.0
+4.9%
-0.3%
-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 risk associated with suicide has been included.
Note 2: Some totals may not appear to add up correctly within the table due to effects of rounding.
Version 7.5 — June 2013 9

Total Risk on the Mainline Railway
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
Hazardous event Total
FWI/year
SRMv7.5
Passenger
FWI/year
Workforce
FWI/year
Public
FWI/year
Total
SRMv7.1
FWI/year
% Change from v7.1
to v7.5
HET
HEM
HEN
8.2
55.9
75.1
3.1
10.8
40.7
1.2
6.3
19.4
3.9
38.8
14.9
8.2
59.8
73.1
0%
-6.5%
+2.8%
Total 139.2
54.7
26.9
57.7
141.0
-1.3%
Note: The direct risk from suicide and attempted suicide has been excluded, however all secondary risk associated with suicide has been included.
10 Version 7.5 — June 2013

Total Risk on the Mainline Railway
Chart 1: Total risk profile for passengers, the workforce and members of the public — % of total FWI/year
Note: The direct risk from suicide and attempted suicide has been excluded, however all secondary risk associated with suicide has been included.
Version 7.5 — June 2013 11

Total Risk on the Mainline Railway
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).
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
Assault and abuse
Contact with object
Contact with person
Falls from height
Hazardous events
HEN-64, HEN-65, HEN-66
HEM-20, HEM-32, HEM-42, HEN-21, HEN-23, HEN-26,
HEN-44, HEN-55, HEN-56, HEN-59, HEN-76
HEN-55, HEN-56
HEN-15, HEN-25, HEN-45
Fires and explosions (not involving trains)
Lean or fall from train in running
Machinery/tool operation
HEN-01, HEN-02, HEN-03, HEN-04, HEN-05, HEN-48,
HEN-49
HEM-03, HEM-07, HEM-15, HEM-17
HEN-22, HEN-27, HEN-56
Manual handling / awkward movement HEN-73, HEN-74, HEN-82, HEN-83
On-board injuries
Platform-train interface
(boarding/alighting)
Platform edge incidents (not boarding/alighting)
Road traffic accident
Slips, trips and falls
Struck/crushed by train
Suicide
HEM-38, HEM-39, HEN-62, HEN-63
HEM-05, HEM-06, HEM-09, HEM-16, HEM-21, HEM-22,
HEM-23, HEM-43
HEM-06, HEM-08, HEM-10, HEM-21, HEM-40, HEM-41,
HEM-49, HEN-09, HEN-10, HEN-13, HEN-52, HEN-67
HEN-35
HEN-14, HEN-16, HEN-24, HEN-25, HEN-46, HEN-68
HEM-11, HEM-14, HEM-19, HEM-27
HEM-31, HEN-77
3
Some HEs have been split across two or more accident types.
12 Version 7.5 — June 2013

Total Risk on the Mainline Railway
Table 7: ASPR hazardous event groupings (cntd)
Event type
Train accidents: collisions and derailments
Train accidents: collisions with objects
Train accidents: collisions with road vehicles at level crossings
Train accidents: other
Hazardous events
HET-01, HET-02NP, HET-02P, HET-03, HET-06, HET-09,
HET-12, HET-13, HET-26
HET-04
HET-10, HET-11
Trespass
Workforce electric shock
Other
HET-17, HET-20, HET-21, HET-22, HET-23, HET-24,
HET-25
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
HEN-27, HEN-30, HEN-31, HEN-32
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.
Version 7.5 — June 2013 13

Total Risk on the Mainline Railway
Chart 2: Combined risk profile (FWI/year) — includes % change from SRMv7.1
14 Version 7.5 — June 2013

Total Risk on the Mainline Railway
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 train 4 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.
4
This 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
Version 7.5 — June 2013 15

Total Risk on the Mainline Railway
Chart 3: Combined risk profile (fatalities/year) — includes % change from SRMv7.1
16 Version 7.5 — June 2013

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.
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
17 Version 7.5 — June 2013

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 v6.5 HLOS safety metric v6.6 HLOS safety metric
% change
Passenger
FWI / billion passenger km
0.988
0.997
+0.9%
Workforce FWI / million workforce hours
Excluding underreported minor injuries
0.133
Including underreported minor injuries
0.135
0.133
-0.2%
0.135
-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.
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 target 5 .
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 duty 6
 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.
5
The 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.
18 Version 7.5 — June 2013

HLOS Safety Metrics
Table 9: Summary of the progress against the HLOS safety metrics 7 v6.6 HLOS safety metric v7.5 HLOS safety metric
% change
Passenger
FWI / billion passenger km
0.997
0.941
-5.7%
Workforce FWI / million workforce hours
Excluding underreported minor injuries
Including underreported minor injuries
0.133
0.118
-10.8%
0.135
0.119
-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
Passenger
Workforce
Public
Total
SRMv7.5 (FWI/year)
54.7
26.9
57.7
139.2
SRMv6.6 (FWI/year)
50.9
29.5
60.8
141.2
% Change
+7.4%
-9.0%
-5.1%
-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.
7
Note 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.
Version 7.5 — June 2013 19

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.
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.
20 Version 7.5 — June 2013

Taking Safe Decisions
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 interval 8 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 corresponds 9 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.
LL 124.6
-6.4
Mean
SRM
131.0
UL 137.7
6.7
119 121 123 125 127 129 131 133 135 137 139 141 143
Chart 5 below shows the 95% confidence interval for HEM risk and HEN risk considered separately, while Chart 6 below shows the 95% confidence interval for passenger, workforce and public risk considered separately.
Figures for the mean risk of each of these distributions along with the LL and UL of the 95% confidence interval can be read from the white and blue boxes as before.
8
A 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 whole operation 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 not necessarily always the case and depends on the assumptions made to construct the model.
Version 7.5 — June 2013 21

Taking Safe Decisions
Chart 5: Charts showing the risk distribution and the 95% confidence interval for the
SRMv7.5 HEM and HEN risk separately.
LL 50.6
-5.3
Mean
HEM
55.9
UL 61.5
5.6
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
HEN
75.0
UL 78.7
3.7
65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85
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.
22 Version 7.5 — June 2013

Taking Safe Decisions
Chart 6: Charts showing the risk distribution and the 95% confidence interval for the
SRMv7.5 passenger, workforce and public risk separately.
LL 49.7
-2.5
Passenger
Mean 52.2
UL 54.8
2.6
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
Workforce
Mean 25.5
UL 26.8
1.3
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
Member of Public
Mean 53.1
UL 59.4
6.3
43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63
Version 7.5 — June 2013 23

Taking Safe Decisions
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.
24 Version 7.5 — June 2013

SRM Governance
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.
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.
10
SPG no longer exists and the System Safety Review Group (SSRG) has now become the SRM-PWG’s parent group.
25 Version 7.5 — June 2013

5.5
6
6.5
7
6.6
7.1
7.5
Taking Safe Decisions
Table 11: SRM update history
Version
1
2
3
Issue Date
January 2001
July 2001
February 2003
4
5
January 2005
August 2006
May 2008
June 2009
January 2011
June 2011
March 2013
March 2013
March 2013
Major Change (from previous version)
First version
Re-release of SRMv1
Full data update and model enhancements
Inclusion of TPWS
Full data update and model enhancements
Full data update and model enhancements
Removal of Mk1 slam-door rolling stock from models
Inclusion of OTP risk model
Interim partial data update
Change in FWI weightings
Full data update and model enhancements
CP4 HLOS benchmark version
Enhanced version 6
Full data update
Enhanced version 6.5
Enhanced version 7
Interim partial data update
26 Version 7.5 — June 2013

Taking Safe Decisions
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.
Version 7.5 — June 2013 27

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
.
11
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
.
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
.
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).
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.
11
A 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
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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.
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.
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.
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.
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
.
Version 7.5 — June 2013 29

RSSB Rail Risk Portal
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 risk@rssb.co.uk
.
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RSSB Rail Risk Portal
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
Fatality Death occurs within one year of the accident.
Major injury
Class 1 minor injury
Injuries to passengers, staff or members of the public as defined in schedule 1 to RIDDOR 1995. This includes losing consciousness, most fractures, major dislocations, loss of sight (temporary or permanent) and other injuries that resulted in hospital attendance for more than 24 hours.
Injuries to passengers, staff or members of the public, that are neither fatalities nor major injuries, and are defined as reportable in RIDDOR 1995
12 amended April 2012, plus:
 Workforce injuries, where the injured person is incapacitated for their normal duties for more than three consecutive calendar days, not including the day of the injury.
Class 2 minor injury
All other physical injuries.
Class 1 shock/trauma
Class 2 shock/trauma
Shock or trauma resulting from being involved in, or witnessing, events that have serious potential of a fatal outcome e.g. train accidents such as collisions and derailments, or a person being struck by train.
Shock or trauma resulting from other causes, such as verbal abuse and near misses, or personal accidents of a typically non-fatal outcome.
Weighting Ratio
1 1
0.1
0.005
0.001
0.005
0.001
10
200
1000
200
1000
12
RIDDOR 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.
Version 7.5 — June 2013 31

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: RSSB
Block 2, Angel Square
1 Torrens St
London EC1V 1NY
UK or: risk@rssb.co.uk
Version 7.5 — June 2013 32

ALARP
CBA
CP4
DfT
FLAT
FOC
FTE
FWI
GB
HE
HLOS
HSE
LUL
NPT
NR
ORR
POS
RGS
RIDDOR
As Low As Reasonably Practicable
Cost-Benefit Analysis
Control Period 4
Department for Transport
Fixed Lineside Telephony Analysis Tool
Freight Operating Company
Full-Time Equivalent
Fatalities and Weighted Injuries
Great Britain
Hazardous Event
High-Level Output Specification
Health and Safety Executive
London Underground Ltd
Non-Passenger Train
Network Rail
The Office of Rail Regulation inside Possession
Railway Group Standards
The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations
1995
RMF
RSSB
RU
SFAIRP
SMIS
SMS
SPG
SRM
Risk Management Forum
Rail Safety and Standards Board
Railway Undertaking
So Far As Is Reasonably Practicable
Safety Management Information System
Safety Management System
Safety Policy Group
Safety Risk Model
SRM-PWG Safety Risk Model Practitioners Working Group
SRM-RPB Safety Risk Model: Risk Profile Bulletin
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Acronyms & Glossary
SRM-RPR Safety Risk Model: Risk Profile Report
SRM-RPT
SSP
Safety Risk Model: Risk Profile Tool
Strategic Safety Plan
TOC
YD&S
Train Operating Company
Yards, Depots and Sidings
The following list describes terms as they are used in the SRM.
ALARP/SFAIRP awkward movement child collective risk common safety method on risk evaluation and assessment consequence/s
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.
An injury caused by a body movement, eg twisting or stretching. This excludes injuries related to manual handling.
A person under 16 years of age.
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.
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.
The number of fatalities, major and minor injuries, shock and trauma resulting from the occurrence of a particular hazardous event outcome.
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control measure escalation factor fatalities and weighted injuries (FWI) fatality frequency hazardous event (HE)
Acronyms & Glossary
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.
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.
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.
Death within one year of the causal accident, this includes subsequent death from the causes of a railway accident.
All are RIDDOR-reportable.
The rate of occurrence (eg the number of events per year).
An incident that has the potential to be the direct cause of safety harm.
Version 7.5 — June 2013 35

Acronyms & Glossary hazardous event - movement accident (HEM) hazardous event - nonmovement accident (HEN) hazardous event – train accident (HET) individual risk infrastructure worker level crossing
An accident causing injury to people, involving trains (in motion or stationary) but excluding injuries sustained in hazardous event - train accident (HET).
An accident causing injury to people, unconnected with the movement of trains.
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.
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.
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.
This is a ground-level interface between a road and the railway .
It provides a means of access over the railway line and has various forms of protection including two main categories: major injury
Active crossings– where the road vehicle user or pedestrian is given warning of a train’s approach (either manually by railway staff i.e. manual crossings or automatically i.e. automatic crossings)
Passive crossing – where no warning system is provided, the onus being on the road user or pedestrian to determine if it is safe to cross the line. This includes, using a telephone to call the signaller.
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.
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Acronyms & Glossary minor injury operational railway
Ovenstone criteria passenger possession (POS) precursor public, members of (MOP) railway infrastructure residual risk
Any other physical injury to any person that is neither a fatality nor a major injury.
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.
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].
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 .
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.
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 .
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 includes all associated railway assets, including public areas at stations.
The level of risk remaining with the current risk control measures in place and with their current degree of effectiveness.
Version 7.5 — June 2013 37

Acronyms & Glossary
RIDDOR running line
Safety Management
Information System (SMIS)
Safety Risk Model (SRM) shock/trauma
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.
A line shown in Table A of the Sectional Appendix as a passenger line or as a non-passenger line.
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.
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 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 train
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 .
Any self-powered vehicle, or vehicles hauled by a selfpowered vehicle, with flanged wheels on guided rails.
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trespass workforce
Acronyms & Glossary
‘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.
Persons working for the industry on railway operations, either as direct employees or under contract.
Version 7.5 — June 2013 39

[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.
40 Version 7.5 — June 2013