Safety Risk Model: Risk Profile Bulletin, version 8.1
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 Dacre
RSSB
Block 2, Angel Square
1 Torrens Street
London EC1V 1NY
020 3142 5476
risk@rssb.co.uk
© RAIL SAFETY AND STANDARDS BOARD LTD. 2014 ALL RIGHTS RESERVED
This 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 must
be acknowledged as the copyright of RSSB and the title of the publication specified accordingly. For any other use of the
material please apply to RSSB for permission. 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 details SRM version 8.1 and contains corrections to hours
worked by workforce groups and associated results.
Issue 1.1 – published December 2014
This page has been intentionally left blank
Version 8.1 - Issue 1.1 - December 2014
ii
Executive summary
Executive summary
The Safety Risk Model (SRM) consists of a series of fault tree and event tree models
representing 131 hazardous events (HEs) that collectively define the overall level of risk on
the 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 (ie
the level of risk remaining with the current risk control measures in place and with their current
degree of effectiveness).
Version 8 of the safety risk model has an extended scope to previous versions as it merges
mainline railway risk (as previously modelled in SRMv7.5) and risk on yards, depots and
sidings (previously modelled in the YDS-SRM). The version 8 SRM update also included a
number of modelling changes, precursor additions/restructurings and a refresh of data up to
the data cut-off date of 30th September 2013.
Following the completion of SRM v8 changes were made to the classification of a number of
suicide and trespass events. This resulted from improved liaison and data sharing between
RSSB and British Transport Police, which allowed for more accurate distinctions between
suicide and non-suicide events. Due to the magnitude of these data changes the risk
associated with affected hazardous events was recalculated to create a further version of the
SRM, version 8.1, using the same model structures and data cut-off date as version 8.
It is the results of version 8.1 that are reported on in this document. The risk results are
presented as a measure of the absolute risk on the 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.
Overall risk
SRMv8.1 estimates that the overall level of risk on the railway is 139.6 FWI/year1. This
represents a decrease of 4.8% from the figure of 146.6 FWI/year estimated by SRMv7.5 and
the YDS-SRM
Risk by person type
The overall figures for SRMv8.1 broken down by each exposed group are given in Table 1.
Table 1: SRMv8.1 results by person group
Person category
Passenger
Workforce
Public
Total
SRMv8.1 (FWI/yr)
58.4
33.4
47.8
139.6
Passenger risk is 58.4 FWI/year. The main contributors to this risk are slips trips and falls and
assaults.
1
Unless otherwise specified all risk figures quoted exclude the direct risk from suicide events. That is, injuries to
the suicidal person are excluded whilst secondary injuries, eg, train driver and crew shock/trauma injuries are
included.
Version 8.1 - Issue 1.1 - December 2014
iii
Executive summary
Workforce risk is 33.4 FWI/year. The main causes of workforce risk are slips, trips and falls
and contact with objects.
Risk to members of the public is 47.8 FWI/year. The majority of this risk is due to trespass.
Risk by accident type
Alternatively, the overall risk figure of 139.6 FWI/year can be broken down by accident type
as shown in Table 2.
Table 2: SRMv8.1 results by accident category
Accident category
HET
HEM
HEN
Total
SRMv8.1 (FWI/yr)
8.0
49.6
82.0
139.6
Where:

HET: Train accidents

HEM: Movement accidents

HEN: Non-movement accidents
Further information is available on the Rail Risk Portal: www.safetyriskmodel.co.uk.
Version 8.1 - Issue 1.1 - December 2014
iv
Contents
Table of contents
Executive summary .................................................................................................... iii
Table of contents ........................................................................................................ v
List of tables ........................................................................................................... vii
List of figures .......................................................................................................... viii
1 Introduction ......................................................................................................... 1
2 SRM objectives and overview ............................................................................. 3
2.1 Objectives ..................................................................................................... 3
3
2.2
Overview ....................................................................................................... 4
2.3
Key assumptions and exclusions .................................................................. 5
SRM update strategy .......................................................................................... 6
3.1 Overview of the SRMv8 update..................................................................... 6
3.2
4
Update to SRM version 8.1 ........................................................................... 7
Total risk on the railway ...................................................................................... 9
4.1 Overall profile ................................................................................................ 9
4.1.1
Mainline profile ..................................................................................... 12
4.1.2
Yards, depots and sidings .................................................................... 16
4.1.3
Estimation of YDS underreporting ........................................................ 19
4.2
Risk by ASPR hazard categorisation .......................................................... 20
4.2.1
Risk by annual FWI .............................................................................. 20
4.2.2
Risk by annual fatalities ........................................................................ 20
4.2.3
Detailed risk profiles ............................................................................. 20
5
Key risk areas ................................................................................................... 23
5.1 Other risk groupings .................................................................................... 25
6
7
SRM risk vs observed risk ................................................................................. 26
Uncertainty in the SRM risk estimates .............................................................. 28
7.1 Introduction ................................................................................................. 28
8
9
7.2
Uncertainty methodology ............................................................................ 28
7.3
SRM uncertainty results .............................................................................. 29
7.4
Uncertainty analysis next steps ................................................................... 32
Individual fatality risk ......................................................................................... 33
8.1 Introduction ................................................................................................. 33
8.2
Fatality risk .................................................................................................. 33
8.3
Passengers ................................................................................................. 34
8.4
Workforce .................................................................................................... 35
8.5
Members of the public ................................................................................. 37
Multiple fatality risk: the F-N Curve ................................................................... 39
9.1 F-N results................................................................................................... 39
9.2
F-N modelling approach .............................................................................. 43
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v
Contents
10 Remodelling risk at the platform-train interface ................................................. 44
10.1 Background and objectives ......................................................................... 44
10.2 The remodelling process ............................................................................. 44
10.2.1 Scope of changes ................................................................................. 44
10.2.2 Remodelling steps ................................................................................ 45
10.2.3 PTI structural changes .......................................................................... 45
10.3 Impact on the risk profile ............................................................................. 46
11 SRM governance and RPB updates ................................................................. 48
11.1 Data and Risk Strategy Group .................................................................... 48
11.1.1 SRM Practitioners Working Group ........................................................ 48
11.2 Update history ............................................................................................. 48
11.3 Updates to the SRM during CP4 ................................................................. 50
11.4 Future updates during CP5 ......................................................................... 50
12 Contributors ...................................................................................................... 51
13 Acronyms and glossary ..................................................................................... 52
13.1 Acronyms .................................................................................................... 52
13.2 Glossary ...................................................................................................... 53
14 References ........................................................................................................ 61
Appendix A. SRM outputs...................................................................................... 62
Appendix B. ASPR hazardous event groupings .................................................... 63
Appendix C. Individual fatality risk summary.......................................................... 65
Appendix D. Modelling approach ........................................................................... 66
D.1.
Key assumptions .................................................................................. 66
D.2.
Hazardous event definitions ................................................................. 67
D.3.
Normalisation data ................................................................................ 67
D.4.
Significant modelling changes for SRMv8 ............................................ 67
D.4.1. Inclusion of YDS-SRM risk ................................................................... 67
D.4.2. Remodelling of risk at the PTI............................................................... 67
D.4.3. Inclusion of MCB+OD and AOCL+B crossing types ............................. 67
D.4.4. New approach to assault data analysis ................................................ 67
Appendix E.
Railway lines in SRM scope .............................................................. 68
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vi
List of tables
List of tables
Table 1: SRMv8.1 results by person group ........................................................................... iii
Table 2: SRMv8.1 results by accident category.....................................................................iv
Table 3: Scope of the railway infrastructure .......................................................................... 4
Table 4: Exceptions to the physical boundary of the SRM ..................................................... 4
Table 5: Risk changes from SRMv8 to SRMv8.1 ................................................................... 8
Table 6: Total risk by accident category ................................................................................ 9
Table 7: Total risk by person category ................................................................................ 10
Table 8: Total risk to each person category from each accident category ........................... 10
Table 9: Total risk by accident category .............................................................................. 12
Table 10: Total risk by person category............................................................................... 13
Table 11: Total risk to each person category from each accident category ......................... 14
Table 12: Total risk by accident category ............................................................................ 16
Table 13: Total risk by person category............................................................................... 17
Table 14: Total risk to each person category from each accident category ......................... 17
Table 15: Grouped risk figures for SRMv8.1, not including YDS risk ................................... 23
Table 16: Selected SRMv8.1 risk groupings........................................................................ 25
Table 17: Comparison of SRM and uncertainty model risk estimates .................................. 29
Table 18: Total passenger individual fatality risk ................................................................. 35
Table 19: Workforce individual fatality risk breakdown ........................................................ 37
Table 20: Frequency of train-related incidents leading toRI multiple fatalities ...................... 39
Table 21: Return periods of train-related incidents leading to multiple fatalities ................... 39
Table 22: Remodelled PTI HE descriptions ......................................................................... 45
Table 23: Remodelled PTIHEs. Summary of changes......................................................... 46
Table 24: Summary of the changes in risk for PTI hazardous events .................................. 47
Table 25: SRM update history ............................................................................................. 49
Table 26: Accident groups used within the ASPR ............................................................... 63
Table 27: Workforce group individual fatality risk by cause classification. ........................... 65
Table 28: Key modelling assumptions in the SRM .............................................................. 66
Table 29: Railway lines in and out of scope of the SRM ...................................................... 68
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vii
List of figures
List of figures
Figure 1: Summary of the SRM remodelling and data updates. ............................................ 7
Figure 2: Total risk profile by person type (% of total FWI/year) .......................................... 11
Figure 3: Mainline railway risk profile by person type (% of total mainline FWI/year) ........... 15
Figure 4: YDS risk profile for workforce (% of total workforce FWI/year) ............................. 18
Figure 5: Risk profile in FWI/year (with % change from SRMv7.5+YDS) ............................. 21
Figure 6: Risk profile in fatalities/year (with % change from SRMv7.5+YDS ........................ 22
Figure 7: Breakdown of SRMv8.1 (excluding YDS risk) by risk area ................................... 24
Figure 8: Passenger observed FWI vs SRM FWI approximation ......................................... 27
Figure 9: Risk distribution for the total SRMv8.1 HEM/HEN risk .......................................... 29
Figure 10: Risk distribution for the SRMv8.1 risk for HEM and HEN separately .................. 30
Figure 11: Risk distribution for the SRMv8.1 risk by person type ......................................... 31
Figure 12: Fatality risk for each person category per year (SRMv8.1) ................................. 34
Figure 13: Causal breakdown of passenger fatality risk ...................................................... 34
Figure 14: Expected annual fatalities by workforce role....................................................... 36
Figure 15: Individual fatality risk by workforce role .............................................................. 36
Figure 16: Causal breakdown of MOP fatality risk ............................................................... 38
Figure 17: The F-N Curve – all person and train accident types. ......................................... 40
Figure 18: Estimated frequency of train accident-related fatality events .............................. 41
Figure 19: F-N curve – plotted separately for three categories of train accidents ................ 42
Figure 20: Contribution of key hazardous events to the F-N curve ...................................... 43
Figure 21: Timeline of updates of the SRM and RPB that occurred in CP4 ......................... 50
Version 8.1 - Issue 1.1 - December 2014
viii
Introduction
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).
The SRM consists of a series of fault tree and event tree models representing 131 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 lowfrequency, 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, which allows all of the
risk on the railway to be totalled and contrasted in comparable units. These FWI weightings
are shown in Section 13.2.
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, stations, yards, depots and sidings
currently in use. The system boundaries are detailed in Section 2.2. The risk estimates are for
the current level of residual risk on the railway, which is the level of risk remaining with the
current risk control measures in place and with their current degree of effectiveness.
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. These definitions
are available on the RSSB Rail Risk Portal at www.safetyriskmodel.co.uk, 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.
This risk profile bulletin details the risk estimates made for version 8.1 of the SRM. Version
8.1 is a partial update from SRM version 8 that came about as the result of significant changes
being made to the classification of suicide and trespass events (detailed in section 3.2). The
Version 8.1 - Issue 1.1 - December 2014
1
Introduction
cut-off date for incident data used to inform SRMv8.12 was 30 September 2013.3 Comparisons
are made against the combined SRMv7.5 and the Yards, Depots and Sidings SRM, referred
to throughout this document as SRMv7.5+YDS.
The main part of this report sets out:

An overview of the SRM and its objectives (Section 2.1)

The SRM update strategy (Section 3)

Total risk on the railway (Section 4)

Breakdown of risk by the Strategic Safety Plan (SSP) risk areas (Section 5)

A comparison of observed FWI with SRM risk estimates (Section 6)

Detail of the uncertainty involved in the SRM risk estimates (Section 7)

A summary of individual risk (Section 8)

A summary of multi-fatality risk (Section 9)

Modelling changes made for SRMv8.1 (Section 10)

SRM governance arrangements (Section 11)
The SRM Practitioners Working Group (SRM-PWG) was the industry governance body for the
SRM throughout Control Period 4 (CP4). 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. The modelling changes implemented as part of the update of the
SRM to version 8 have been endorsed by the SRM-PWG. The revised version 6 figures
(SRMv6.7) and the version 8 figures (SRMv8) were presented to the group and approved in
March 2014. As part of the modernisation of safety co-operation (MOSC) initiative, SPG and
SRM-PWG have been wound up and oversight for future SRM updates and developments will
be provided by the Data and Risk Strategy Group (DRSG) which is a subgroup of the System
Safety Risk Group (SSRG).
The Department for Transport (DfT) has been 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. The risk estimates derived from SRMv6 provided the
initial baseline against which to compare safety performance through CP4 (April 2009 to March
2014). This is achieved by comparing the risk metrics derived from SRMv8 against the
baseline safety metrics determined from SRMv6 (and subsequently updated to SRMv6.7). A
full report of the HLOS metric calculation is given in the report HLOS Safety Metrics – baseline
and progress metrics following completion of the update of the SRM to version 8 [Ref. 1] which
was delivered to SRM-PWG on the 27 March 2013.
Additional appendices for this document may be downloaded from the RSSB Rail Risk Portal
at http://www.safetyriskmodel.co.uk.
2
The term SRMv8.1 is used to refer to the full SRM scope of events including those events which did not need to
be recalculated in the partial update.
3 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 a considerable time after the event. Therefore, to ensure there is confidence in the data used to analyse them,
an earlier cut-off date (30 September 2012) was used.
Version 8.1 - Issue 1.1 - December 2014
2
SRM objectives and overview
2
SRM objectives and overview
2.1
Objectives
The SRM has been developed and published to support RSSB members. The primary
objectives of the SRM are:

To provide an estimate of the extent of the current risk on the railway.

To provide risk information and risk profiles relating to the railway.
This information is used for risk assessments, appraisals and to inform decision making
throughout the railway industry.
Taking Safe Decisions, [Ref. 2] sets out the rail industry’s consensus view on how safety is
taken into account when making decisions. The guidance was updated in 2014 to reflect
changes to the legal environment and evolving industry practice. In the Great Britain (GB) rail
industry, almost every policy, investment or operational decision has an impact on safety. In
order to make these decisions and to ensure that risk is acceptable, the rail industry needs to
understand safety risk, its causes and consequences. The SRM is one of the key tools used
to help support this decision making through:

Monitoring: are operations safe or might changes be required?

Analysing and selecting options: what (if anything) should I change and can it be done
safely?

Making a change: how do I make sure a change is safe?
This includes:


Enabling 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 risk control measures should be applied or 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).
Providing risk information to support:

The development of priorities for the Industry Strategic Business Plans 2014–
2019 [Ref. 3].

Transport operator risk assessments, as required by The Railways and Other
Guided Transport Systems (Safety) Regulations 2006.

Identification and prioritisation of issues for audit and/or research.

RSSB’s contributions and comments on the development of Technical
Standards for Interoperability (TSIs), National Technical Rules and National
Safety Rules.
Version 8.1 - Issue 1.1 - December 2014
3
SRM objectives and overview

2.2
Providing an understanding about the contribution of a particular item of equipment or
failure mode to the overall risk.
Overview
The SRM includes the safety risk from incidents which could occur during the operation and
maintenance of the railway. For SRMv8.1 the scope has been extended to include risk within
yards, depots and sidings, previously covered by the separate Yards, Depots and Sidings
(YDS) Risk Profile Report [Ref. 4].
For SRMv8.1 the extent of the railway infrastructure in question is defined below in Table 3.
Table 3: Scope of the railway infrastructure
Inclusions



The sections of the operational railway4
which are managed or operated by
Network Rail.
Any assets, structures, stations, yards,
depots and sidings associated with the
above.
Any yard, depot or siding that is
connected to but away from the
running lines on railway infrastructure,
where train maintenance, stabling,
marshalling and/or servicing (including
refuelling) takes place under the
management of other infrastructure
managers.
Exclusions










Station car parks.
Offices (except areas normally accessible by
MOP).
Mess rooms.
Training centres.
IECCs/SCCs.
Outside of the entrance to stations.
Station and site toilets.
Retail units and concessions in stations.
Construction sites which are completely
segregated from the public areas.
Track sections closed for long term
construction, maintenance, renewal or upgrade.
This defines the physical boundary of the SRM. Any incidents which occur inside this
boundary, and are listed in GE/RT8047, are included in the SRM. Conversely, any incidents
outside this boundary are excluded from the SRM.
The exceptions to this rule are listed below in Table 4.
Table 4: Exceptions to the physical boundary of the SRM
Inclusions outside the SRM boundary
Exclusions inside the SRM boundary



Injuries to people which are directly caused by
operations or maintenance inside the
boundary.
Injuries to railway staff who are on duty and
travelling between sites, except if their
destination is one of the excluded areas in
Table 3 (eg an office).5

Long-term occupational health issues.
Terrorist activity.
4
The operational railway includes all lines for which the infrastructure manager & railway undertaking have been
granted a safety authorisation & certificate respectively by the ORR (under European Safety Directive 2004/49/EC
[Ref 5]). This provides evidence that there is a suitable SMS in place, and that operations are being conducted in
accordance with that SMS.
5 For instance, this would include delivery of goods to a trackside location, but exclude travel to a training centre.
Version 8.1 - Issue 1.1 - December 2014
4
SRM objectives and overview
Appendix G of the YDS Risk Profile Report contains a more detailed discussion of the SRMYDS scope and the boundaries of yards, depots and sidings. It also gives specific guidance
as to what aspects of the operation and maintenance of the railway are within scope of the
SRM.
2.3
Key assumptions and exclusions
Appendix D.1 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.
Version 8.1 - Issue 1.1 - December 2014
5
SRM update strategy
3
SRM update strategy
3.1
Overview of the SRMv8 update
The SRM was used by the DfT as the primary means of measuring the performance of the
industry against the HLOS safety metrics throughout control period 4 (CP4). It was therefore
necessary to be able to distinguish between changes in estimated risk arising from genuine
changes in safety performance and changes due to modelling refinements (for SRM versions
6 through 8).
To incorporate YDS risk modelling and to enable the HLOS comparison to be meaningful, the
update of the SRM to version 8 has been split into three distinct stages.
1. Bring the YDS risk model into the main risk model framework.
2. Produce risk estimates for SRMv8 incorporating:
a. Changes to the model structure. This included:
i. Restructuring of the various platform-train interface (PTI) hazardous
events following industry requirements for greater understanding of
risk at the PTI (explanation of this remodelling is covered in detail in
Chapter 10).
ii. Extension of the seven level crossing hazardous events to include the
recently introduced crossing types: MCB with obstacle detection
(MCB+OD) and AOCL with half barriers (AOCL+B).
b. Changes to the calculation methods. This included:
i. Improved estimates of the risk from passenger and public assaults
utilising a refined matching of records between SMIS and the BTP
CRIME database.
ii. Correcting minor errors from previous SRM versions.
c. Changes to historical data (incidents which occurred prior to the data cut-off
for previous versions). This included:
i. Inclusion, exclusion or reclassification of incidents in the light of new
information.
ii. Inclusion of late reported incidents.
d. Inclusion of new data for incidents which occurred since the data cut-off for
the previous version and the SRMv8 data cut-off of 30 September 2013.
3. Apply step 2a) to 2c) above to SRMv6 to create SRMv6.7. This updated version
represents the risk as would have been calculated for SRMv6 had the modelling
changes for the mainline railway risk implemented in SRMv8 been implemented at
the time SRMv6 was first created.
The required comparisons between risk estimates can then be meaningfully made:
1. SRMv6.7 and SRMv8 can be compared to provide the estimated change in risk over
CP4 as required for HLOS.
Version 8.1 - Issue 1.1 - December 2014
6
SRM update strategy
2. SRMv7.5 and SRMv8 (without YDS) can be compared to give the estimated change
in risk due to remodelling and the refresh of the data up to 30 September 2013
(compared to 30 June 2012 for SRMv7.5).
3. The YDS-SRM and the YDS subsection of SRMv8 can be compared to give the
estimated change in YDS risk.
This is the third time the SRM update has required previous models to be simultaneously
updated. The other occasions being for SRMv7 and SRMv7.5. This has been necessary in
order 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 likefor-like basis.
Figure 1 summarises the different SRM versions and how they have been derived. For HLOS
comparative purposes, the light grey boxes show valid comparisons based solely on changes
in data between different versions of the model.
Figure 1: Summary of the SRM remodelling and data updates.
Date of version release
1st HLOS
comparison
Data cut-off date
SRM v6
SRMv6.5
SRMv7
KEY
Remodelling
YDS-SRM
2nd HLOS
comparison
SRMv6.6
Final HLOS
comparison
SRMv6.7
SRMv7.1
Partial
Update
SRMv7.5
Data refresh
Extension of scope
SRMv8
3.2
Update to SRM version 8.1
In 2013/14, BTP made more information about railway fatalities available to the rail industry
as a result of the enhanced co-operation effected by the National Suicide Prevention Strategy
Group. BTP provided additional information dating back to 2009/10, which has enabled the
industry to update the classification of a number of fatalities6.
6
Further information on the suicide/trespass data reclassification is available in the Annual Safety Performance
Report 2013/14.
Version 8.1 - Issue 1.1 - December 2014
7
SRM update strategy
The reclassified data only became available after the SRMv8 update had been completed.
However, due to the expected scale of the impact RSSB decided to update risk estimates for
the relatively small number of affected hazardous events and incorporate them in a partial
update to SRMv8 to create SRMv8.1.
The hazardous events for which data was recoded and the risk recalculated are:

HEM-31-Suicide (or attempted suicide) involving rolling stock in motion.

HEN-77-Suicide (or attempted suicide) not involving rolling stock in motion.

HEM-12-MOP (trespasser) struck/crushed by train while on tracks at station.

HEM-25-MOP (trespasser) struck/crushed by train while on railway infrastructure not
at station.

HEN-38-MOP (adult trespasser) electric shock (conductor rail).

HEN-71-MOP (adult trespasser) fall/jump onto railway infrastructure.
Other hazardous events were indirectly affected due to dependencies on the above, these
were:

HEM-31-YDS-Suicide or attempted suicide involving rolling stock in motion.

HEN-45-MOP (non-trespasser) fall onto railway infrastructure.

HEN-72-MOP (child trespasser) fall/jump onto railway infrastructure.

HEN-77-YDS-Suicide (or attempted suicide) not involving rolling stock in motion.
The overall effects of these changes are given in Table 5.
Table 5: Risk changes from SRMv8 to SRMv8.1
Change in FWI from v8 to v8.1
Absolute
Percentage
Suicide risk
7.97
3.4%
Other risk
-11.59
-27.1%
These changes only had a negligible impact on passenger and workforce risk so did not affect
the HLOS calculations.
Throughout this report all values, charts and tables reflect the SRMv8.1 results.
Version 8.1 - Issue 1.1 - December 2014
8
Total risk on the railway
4
Total risk on the railway
4.1
Overall profile
This section presents the overall risk on the railway for the 131 HEs which make up the SRM.
Risk is presented as:

Injury severity by accident category (Table 6)

Injury severity by person category (Table 7)

Person type injured by accident category ( Table 8)
The total risk from the 131 HEs is estimated to be 139.6 FWI/year7. This is made up of
approximately:

55 fatalities per year8

567 major injuries per year

2494 class 1 minor injuries per year

11833 class 2 minor injuries per year

1887 shock/trauma events per year
This compares to the 146.6 FWI/year calculated in SRMv7.5 and SRM-YDS9. These total risk
estimates are broken down by accident category and injury type in Table 6.
Class 1 minor
injuries/year
Class 2 minor
injuries/year
Class 2
shock/trauma/
year
Major injuries/
year
Train accidents
8.0
6.1
14
79
39
4
38
Movement accidents
(excl. trespass)
25.2
12.4
76
372
1822
253
217
Non-movement accidents
(excl. trespass)
72.8
5.6
457
2024
9964
9
1340
Trespass
33.6
31.3
21
19
9
26
0.4
Total
139.6
55
567
2494
11833
292
1595
Accident category
Class 1
shock/trauma/
year
FWI /
year
Fatalities/year
Table 6: Total risk by accident category
7
The values presented exclude direct risk due to suicide and attempted suicide. Indirect suicide risk (eg the
shock/trauma of witnesses) associated with these events is included.
8 Note that, due to rounding, values in tables and the text throughout this document may not match.
9 This version of the SRM is the first version that has included both mainline and yards, depots and sidings.
Consequentially comparisons have been made to the combined results from SRMv7.5 and the SRM-YDS.
Version 8.1 - Issue 1.1 - December 2014
9
Total risk on the railway
Table 7 shows the risk to each person category on the railway, broken down by person
category and accident category. Reasons for the changes in risk are explored in more detail
in section 4.1.1 (which focuses on the changes in mainline risk from SRMv7.5) and section
4.1.2 (which focuses on the changes in risk on YDS sites from the YDS-SRM).
Table 7: Total risk by person category
Class 2 minor
injuries/year
8.3
352
1616
6001
1.6
801
54.7
+6.9%
Workforce
33.4
4.2
173
798
5683
289
763
34.0
-2.0%
MOP
47.8
43
42
80
150
1.1
31
57.9
-17.5%
Total
139.6
55
567
2494
11833
292
1595
146.6
-4.8%
FWI/year
Class 1 minor
injuries/year
58.4
Class 2
shock/trauma/
year
Major injuries/
year
Passenger
Person
category
Class 1
shock/trauma/
year
Fatalities/year
% Change from
SRMv7.5+YDS to
SRMv8.1
SRMv7.5+YDS
FWI/year
SRMv8.1
Table 8: Total risk to each person category from each accident category
SRMv8.1
Accident
category
Total
FWI/year
SRMv7.5+YDS
Passenger
FWI/year
Workforce
FWI/year
MOP
FWI/year
Total
FWI/year
% change
from
SRMv7.5+
YDS to
SRMv8.1
HET
8.0
2.8
1.1
4.0
8.3
-4.4%
HEM
49.6
11.7
6.6
31.4
56.4
-12.0%
HEN
82.0
43.9
25.6
12.4
81.9
+0.1%
Total
139.6
58.4
33.4
47.8
146.6
-4.8%
The reclassification of suicide/trespass events has only been applied to this latest version of
the SRM. This means that those hazardous events that were reanalysed for SRM version 8.1
are no longer directly comparable to their SRMv7.5+YDS counterparts due to the significant
differences in the data. A significant proportion of the reduction in risk to both members of the
public and HEM events can be attributed to this.
Figure 2 presents the total risk profile for passengers, the workforce and members of the
public. It shows that the bulk of the risk is split between passengers and members of the public,
with 42% and 34% respectively — the remaining proportion (24%) is attributed to the
workforce. Fatalities still dominate the risk to the public, comprising 90% of the total risk to
members of the public (equivalent to 43 fatalities per year). Fatalities due to trespass make
up 73% of member of public fatalities (equivalent to 31 fatalities per year).
Version 8.1 - Issue 1.1 - December 2014
10
Version 8.1 - Issue 1.1 - December 2014
Class 1 minor injuries (12.0%)
Class 2 minor injuries
(17.0%)
Class 1 shock/trauma (4.3%)
Class 2 shock/trauma (2.3%)
Fatalities
(89.9%)
Major injuries (8.9%)
Class 1 minor injuries (0.8%)
Passenger
(42%)
Class 1 shock/trauma (0.01%)
Class 2 minor injuries
(10.3%)
Class 1 minor injuries
(13.8%)
Class 2 shock/trauma (1.4%)
Class 1 shock/trauma (0.01%)
Major injuries
(60.3%)
Total risk = 139.6 FWI/year
Class 2 shock/trauma (0.1%)
Fatalities (12.7%)
Major injuries
(51.7%)
Workforce
(24%)
Members of
the public
(34%)
Fatalities
(14.2%)
Class 2 minor injuries
(0.3%)
Total risk on the railway
Figure 2: Total risk profile by person type (% of total FWI/year)
11
Total risk on the railway
4.1.1
Mainline profile
This section presents the overall risk for the 122 hazardous events on the mainline railway
(that is, excluding all hazardous and sub-hazardous events referring to YDS risk), which are
considered within the SRM. Risk is presented as:

Injury severity by accident category (Table 9)

Injury severity by person category (Table 10)

Person type injured by accident category (Table 11)
The total risk from the 122 HEs for the mainline railway is assessed to be 132.0 FWI/year.
This is made up of approximately:

55 fatalities per year

520 major injuries per year

2314 class 1 minor injuries per year

10609 class 2 minor injuries per year

1874 shock/trauma events per year
These total risk estimates are broken down by accident category and injury type in Table 9.
Table 10 shows the risk to each person category on the railway. Risk to passengers forms the
greatest proportion of the total risk, at 58.4 FWI/year (an increase of 6.9% from SRMv7.5).
However, over the same period passenger journeys have increased by 2% and passenger
kilometres have increased by 3% (from 57.7 billion to 59.2 billion passenger km).
Class 1 minor
injuries/year
Class 2 minor
injuries/year
7.8
6.0
13
76
37
0.8
38
Movement accidents
(excl. trespass)
24.6
12.3
72
357
1760
253
216
Non-movement accidents
(excl. trespass)
66.2
5.3
414
1863
8803
9.2
1331
Trespass
33.4
31.1
20
19
9.1
26
0.4
Total
132.0
54.8
520
2314
10609
289
1585
FWI/
year
Version 8.1 - Issue 1.1 - December 2014
Class 2
shock/trauma/
year
Major injuries/year
Train accidents
Accident category
Class 1
shock/trauma/
year
Fatalities/year
Table 9: Total risk by accident category
12
Total risk on the railway
The increase in passenger risk is due to increases in several hazardous events, the top
contributors of which are HEN-14: Passenger slip, trip or fall and HEN-64: Passenger physical
assault. The rise in risk from HEN-14 is mainly driven by an increase in estimated frequency
due to a larger number of observed slips, trip or falls on stairs and escalators.
Absolute MOP risk decreased by 17.7% since SRMv7.5. This is due to a number of trespass
events being reclassified as suicides following further information from BTP. Trespass events
are still the largest contributor to MOP risk but following this reclassification, the trespass risk
has decreased by 10.9 FWI/year.
The risk to the workforce is now 26.1 FWI/year which represents a 2.9% reduction from
SRMv7.5. The decrease in workforce risk is due to a decrease in the risk from several
hazardous events, of which the top contributors are HEM-19: Infrastructure worker
struck/crushed by train in motion and HEN-65: Workforce physical assault.
Table 10: Total risk by person category
Class 2 minor
injuries/year
8.3
352
1616
6000
1.6
800
54.7
+6.9%
Workforce
26.1
3.8
126
620
4463
286
754
26.9
-2.9%
MOP
47.5
42.7
42
78
146
0.9
30
57.7
-17.7%
Total
132.0
54.8
520
2314
10609
289
1585
139.2
-5.2%
FWI/year
Class 1 minor
injuries/year
58.4
Class 2
shock/trauma/
year
Major injuries/
year
Passenger
Person
category
Class 1
shock/trauma/
year
Fatalities/year
% change from
SRMv7.5 to
SRMv8.1
SRMv7.5
FWI/year
SRMv8.1
Table 11 presents the risk on the mainline railway broken down by person and accident
category. As in the previous section, the table shows that overall risk due to train accidents
(HETs) has decreased by 4.6%, largely due to the decrease in estimated frequency of
derailments. Movement accidents (HEMs) have seen a 12.4% reduction in risk, whereas nonmovement accidents (HENs) have remained relatively constant. Overall, the total decrease in
risk from SRMv7.5 to SRMv8.1 is 5.2%.
Version 8.1 - Issue 1.1 - December 2014
13
Total risk on the railway
Table 11: Total risk to each person category from each accident category
SRMv8.1
Accident
category
Total
FWI/year
SRMv7.5
Passenger
FWI/year
Workforce
FWI/year
MOP
FWI/year
Total
FWI/year
% change
from
SRMv7.5 to
SRMv8.1
HET
7.8
2.8
1.0
4.0
8.2
-4.6%
HEM
49.0
11.7
6.0
31.3
55.9
-12.4%
HEN
75.2
43.9
19.1
12.2
75.1
+0.1%
Total
132.0
58.4
26.1
47.5
139.2
-5.2%
Figure 3 presents the total risk profile for passengers, workforce and public. It shows that the
bulk of the risk is split between passengers and public, with 44% and 36% respectively — the
remaining proportion (20%) is attributed to workforce incidents. Fatalities still dominate risk to
public, comprising 90.0%. This is due to public trespass events, contributing 31.3 fatalities per
year.
Version 8.1 - Issue 1.1 - December 2014
14
Version 7.1 — August 2011
Class 1 minor injuries (11.9%)
Class 2 minor injuries
(17.1%)
Class 1 shock/trauma (5.5%)
Class 2 shock/trauma (2.9%)
Fatalities
(90.0%)
Major injuries (8.8%)
Class 1 minor injuries
(0.8%)
Class 1 shock/trauma (0.01%)
Passenger
(44%)
Class 2 minor injuries
(10.3%)
Class 1 minor injuries
(13.8%)
Class 2 shock/trauma (1.4%)
Class 1 shock/trauma (0.01%)
Major injuries
(60.3%)
Total risk = 132.0 FWI/year
Class 2 shock/trauma (0.1%)
Fatalities (14.5%)
Major injuries
(48.1%)
Workforce
(20%)
Members of
the public
(36%)
Fatalities
(14.2%)
Class 2 minor injuries
(0.3%)
Total risk on the railway
Figure 3: Mainline railway risk profile by person type (% of total mainline FWI/year)
15
Total risk on the railway
4.1.2
Yards, depots and sidings
This section presents the overall risk for the nine hazardous events and 40 sub-hazardous
events related to YDS, which are considered within the SRM. Risk is presented as:

Injury severity by accident category (Table 12)

Injury severity by person category (Table 13)

Person type injured by accident category (Table 14)
The total risk from the 49 HEs for YDS is assessed to be 7.6 FWI/year. This is made up of
approximately:

0.7 fatalities per year

47.6 major injuries per year

180 class 1 minor injuries per year

1224 class 2 minor injuries per year

13.4 shock/trauma events per year
These total risk estimates are broken down by accident category and injury type in Table 12.
Class 1 minor
injuries/year
Class 2 minor
injuries/year
0.17
<0.1
0.72
3.2
2.4
3.3
<0.1
Movement accidents
(excl. trespass)
0.64
<0.1
4.0
15
61
<0.1
1.0
Non-movement accidents
(excl. trespass)
6.59
0.35
43
161
1160
<0.1
8.8
Trespass
0.21
0.19
0.20
0.21
<0.1
0.12
<0.1
Total
7.61
0.70
47.6
180
1224
3.58
9.80
FWI/
year
Class 2
shock/trauma/
year
Major injuries/
year
Train accidents
Accident category
Class 1
shock/trauma/
year
Fatalities/year
Table 12: Total risk by accident category
Table 13 shows the risk to each person category on YDS. The majority of the risk on YDS can
be attributed to the workforce (96%). The remaining 4% of risk is allocated to members of the
public and over-carried passengers. The risk to workforce is now 7.3 FWI/year in comparison
to the 7.2 FWI/year in SRM-YDS.
The absolute risk to members of the public and over-carried passengers is small and therefore
susceptible to large percentage changes in risk from year to year as it is based on relatively
few events, as can be seen in Table 13 and Table 14.
Version 8.1 - Issue 1.1 - December 2014
16
Total risk on the railway
Table 13: Total risk by person category
Major injuries/
year
Class 1 minor
injuries/year
Class 2 minor
injuries/year
Class 2
shock/trauma/
year
FWI/year
% change from
SRM-YDS to
SRMv8.1
Passenger
<0.1
-
<0.1
<0.1
0.27
-
<0.1
<0.1
-19.1%
Workforce
7.28
0.44
47
178
1220
3.3
8.8
7.2
+1.4%
MOP
0.33
0.26
0.57
1.4
3.9
0.25
1.0
0.29
+14.9%
Total
7.61
0.70
47.6
180
1224
3.58
9.80
7.47
+1.9%
Person
category
Class 1
shock/trauma/
year
Fatalities/year
SRM-YDS
FWI/year
SRMv8.1 YDS
Table 14 presents the risk broken down into person category and accident categories. The
table shows that overall risk due to train accidents (HETs) has increased by 6% but is still a
relatively small absolute risk at 0.2 FWI/year. Movement accidents (HEMs) have seen an
increase of 0.14 FWI/year which amounts to a 27.9% increase in risk (this is largely a
consequence of having a larger pool of data to analyse for SRMv8). Non-movement accidents
(HENs) have remained relatively constant. Overall, the total increase in risk from SRM-YDS
to SRMv8.1 is 1.9%.
Table 14: Total risk to each person category from each accident category
SRMv8.1 YDS
Accident
category
Total
FWI/year
SRM-YDS
Passenger
FWI/year
Workforce
FWI/year
MOP
FWI/year
Total
FWI/year
% change
from SRMYDS to
SRMv8.1
HET
0.17
-
0.13
<0.1
0.16
+6.0%
HEM
0.64
-
0.60
<0.1
0.50
+27.9%
HEN
6.80
<0.1
6.5
0.26
6.8
-0.1%
Total
7.61
<0.1
7.27
0.33
7.47
+1.9%
Figure 4 presents the total risk profile for the different workforce types on YDS sites10. Risk to
engineering staff is the highest of all workforce types at 36% of the total YDS risk. Across all
workforce types, major injuries are the highest contributors to workforce risk on YDS.
10
Workforce type groups are detailed in the glossary (section 13.2).
Version 8.1 - Issue 1.1 - December 2014
17
Version 8.1 - Issue 1.1 - December 2014
Class 2 minor injuries (12.4%)
Class 1 shock/trauma (0.7%)
Class 2
shock/trauma
(0.1%)
Fatalities (5.9%)
Major injuries
(60.1%)
Class 1 minor injuries (12.8%)
Class 2 minor injuries (21.1%)
Total workforce risk = 7.28 FWI/year
C
Class 1 minor injuries (12.2%)
Major injuries
(68.6%)
Cleaner/
admin
(14%)
Infrastructure
worker (21%)
Major injuries
(67.4%)
Fatalities (6.0%)
Class 1 shock/
trauma (0.2%)
Class 1 shock/
trauma (0.0%)
Class 2 minor
injuries (17.0%)
Class 1 minor
injuries (12.3%)
Fatalities (3.2%)
Class 2 shock/
trauma (0.2%)
Class 1 shock/
trauma (0.0%)
Class 2 minor
injuries (15.3%)
Class 1 minor injuries (11.3%)
Fatalities (8.1%)
Class 2 shock/trauma (0.1%)
Major injuries
(65.0%)
Driver/shunter
(30%)
Engineering
Staff (36%)
Class 1 shock/
trauma (0.0%)
Total risk on the railway
Figure 4: YDS risk profile for workforce (% of total workforce FWI/year)
18
Total risk on the railway
4.1.3
Estimation of YDS underreporting
There is some evidence for underreporting of incidents across the whole of the railway11. For
most areas of risk on the mainline railway this is not currently thought to be a significant issue
as:

Reporting into SMIS is mandatory.

RSSB operates a data quality programme for mainline data reporting.

Underreported events tend to be less severe and due to the way in which minor injuries
are weighted limits their effect on overall FWI risk.
However there are specific problems relating to the quality of YDS data. The reporting of
events that occur on YDS into SMIS is not mandatory, and some companies do not report any
incidents into SMIS at all. Consequentially there are gaps in the data for events on YDS sites.
To attempt to address this issue of underreported YDS events, the scale of underreporting
has been estimated based on reporting from all freight companies and train maintenance
companies, taking into account the size of each company.
Of the freight operators who have agreed to provide event data, there is evidence that up until
2008/09 reporting was not complete. However, incident reporting from April 2009 is considered
fairly complete and by looking at the level of reporting since then it is possible to estimate what
level of reporting would have occurred pre-April 2009 if there had been no underreporting. In
doing so, an increased freight-based rate of reporting was estimated, which in turn increased
the freight proportion of the overall risk figure. Using this same method, the gaps for other
freight reporting have been filled in and scaled accordingly.
Estimates can also be made for train maintenance companies. Discussions were held with
three of the four train maintenance companies regarding; the scale of their operations, their
injury rates and the types and locations of those injuries. One company has also provided
some injury data, which has been used to aid the estimates. Based on these discussions and
data an estimate was made of the number of injuries that would have been reported had the
companies been doing so.
An extrapolation from the data that is available can be made to estimate a figure for the risk
associated with the missing data. This gives an increase of around 24% in the overall level of
risk on YDS sites. If we assume a similar profile of injury types for this missing data we can
extrapolate the total risk by this proportion. This gives an overall risk on YDS sites:
Estimated total risk = 9.4 FWI/year
This provides an estimate of the overall risk on YDS sites (the equivalent figure calculated for
the YDS-SRM was 9.2 FWI/year). Note that there is more uncertainty in this estimate than the
base figure of 7.6 FWI/year based on the known dataset. The portion of the extrapolated figure
that relates to workforce is 9.0 FWI/year (based on the existing ratio of workforce risk to overall
risk).
11
Further information on data quality is given in Chapter 10 of the ASPR 2013-14
Version 8.1 - Issue 1.1 - December 2014
19
Total risk on the railway
4.2
Risk by ASPR hazard categorisation
The 131 HEs which make up the SRM have been grouped into the 22 accident groups used
in the ASPR [Ref. 6] in Table 26 (Appendix B). Combining the HEs in this manner allows
identification of the types of accidents that contribute the greatest proportion of risk.
4.2.1
Risk by annual FWI
Figure 5 presents the risk profile in FWI/year and indicates the percentage change in risk
between SRMv7.5 and SRMv8.1 for each of the 22 HE categories listed above. The greatest
overall risk contribution results from Slips, trips and falls with 39.0 FWI/year, an increase of
6% compared with SRMv7.5+YDS. The next-highest risk contribution results from Trespass
with 33.6 FWI/year, which is dominated by fatality risk.
The majority of risk from Slips, trips and falls occurs to passengers, contributing 27.2 FWI/year,
which represents 47% 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
9.6 FWI/year, followed by Platform edge incidents (both boarding/alighting and nonboarding/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 (10.2 FWI/year),
with the second-highest contribution coming from Contact with object (5.4 FWI/year). Together
these categories represent 47% of the risk to the workforce.
A large proportion of the risk to the public results from Trespass (33.5 FWI/year), followed by
Struck/crushed by train (not trespass) with 6.5 FWI/year. Together they represent 84% of the
risk to MOP.
For both Figure 5 and Figure 6 the large percentage change in road traffic accident risk is due
to significantly improved reporting of this type of event. The large percentage change in
trespass event is mainly due to the reclassification of suicide and trespass events as a result
of the SRMv8.1 update.
4.2.2
Risk by annual fatalities
Figure 6 shows the combined risk by event type in fatalities per year (excluding the contribution
from injuries, shock and trauma). Fatality risk is dominated by Trespass accidents, accounting
for more than half, with 31.3 fatalities per year down 25% on the SRMv7.5+YDS figure due to
the reclassification of a number of suicide/trespass events. The accident type contributing the
second-highest number of fatalities is Struck/crushed by train with 8.5 fatalities per year,
suggesting these events have remained relatively constant since SRMv7.5+YDS. Together,
these two categories account for 72% of all fatalities.
The highest contribution to passenger fatalities is Platform edge incidents (not
boarding/alighting), which accounts for 3.8 fatalities per year (representing 46% of passenger
fatality risk).
The most significant contributor to workforce fatalities is Struck/crushed by train, accounting
for 1.6 fatalities per year (39% of the workforce fatality risk total). The 31.3 fatalities per year
due to MOP Trespass represents 73% of public fatality risk.
4.2.3
Detailed risk profiles
More detailed risk profiles for each accident type and person category can be found in the
Annual Safety Performance Report 2013/14.
Version 8.1 - Issue 1.1 - December 2014
20
6.2 (+9%)
Platform edge incidents (not boarding/alighting)
Version 8.1 - Issue 1.1 - December 2014
0.40 (-27%)
0.39 (-10%)
0.31 (-9%)
Fires and explosions (not involving trains)
Lean or fall from train in running
Train accidents: other
0.42 (-9%)
0.53 (-19%)
Workforce electric shock
Contact with person
0.54 (-8%)
Train accidents: strikes with objects
1.1 (+10%)
Falls from height
1.1 (+7%)
1.2 (+16%)
Indirect risk due to suicide
Machinery/tool operation
1.2 (+4%)
1.3 (+62%)
Road traffic accident
Other
1.7 (-8%)
3.5 (-12%)
Manual handling/awkward movement
Train accidents: collisions and derailments
3.6 (+5%)
6.7 (-4%)
Contact with object
Train accidents: strikes with road vehicles at level…
6.9 (-4%)
On-board injuries
9.0 (+16%)
Platform edge incidents (boarding/alighting)
11.8 (+2%)
9.0 (+1%)
10
Struck/crushed by train
Assault and abuse
Trespass
Slips, trips, and falls
0
20
30
Public
Workforce
Passenger
33.6 (-25%)
39.0 (+6%)
40
Total risk on the railway
Figure 5: Risk profile in FWI/year (with % change from SRMv7.5+YDS)
21
Version 8.1 - Issue 1.1 - December 2014
0
0
0
Contact with person
Indirect risk due to suicide
0.03 (+10%)
0.06 (-1%)
Manual handling/awkward movement
On-board injuries
Machinery/tool operation
0.16 (-25%)
Platform edge incidents (boarding/alighting)
0.29 (-30%)
Fires and explosions (not involving trains)
0.17 (-47%)
0.32 (-21%)
Workforce electric shock
Contact with object
0.32 (-10%)
Lean or fall from train in running
0.21 (-5%)
0.32 (-3%)
Train accidents: strikes with objects
Train accidents: other
0.34 (-3%)
0.62 (+23%)
Falls from height
Other
0.66 (-67%)
0.87 (+293%)
4
4.3 (+7%)
3.2 (+6%)
2.4 (-13%)
1.4 (-27%)
2
Assault and abuse
Road traffic accident
Slips, trips, and falls
Train accidents: collisions and derailments
Train accidents: strikes with road vehicles at level…
Platform edge incidents (not boarding/alighting)
Struck/crushed by train
Trespass
0
6
8
Public
Passenger
Workforce
8.5 (+1%)
30
31.3 (-25%)
32
Total risk on the railway
Figure 6: Risk profile in fatalities/year (with % change from SRMv7.5+YDS
22
Key risk areas
5
Key risk areas
Effective safety planning requires a detailed understanding of risk areas – the activities or
circumstances where the safety risk profile for passengers, the workforce, and the public is
the greatest. This allows resources and effort to be concentrated where they will have the
greatest impact.
Though it is no longer produced, the SSP [Ref. 7] considered nine key risk areas (KRAs) that
have been selected from the original breakdown of the SRM into 15 risk areas. These nine
KRAs represent the top 98% of the overall SRM risk (and the percentage has remained the
same since SRMv7.5) and are thus considered to be the key to understanding the causes of
risk in the rail industry.
A complete breakdown of the SRMv8.1 figures into the 15 risk areas is shown in Table 15 and
diagrammatically in Figure 7 (the KRAs are indicated in both). These figures do not include
YDS risk.
Table 15: Grouped risk figures for SRMv8.1, not including YDS risk
Risk area
group
Engineering
Risk in
FWI/year
(% of
SRMv8.1)
4.48
(3.4%)
Infrastructure
2.47
% of
SRMv8.1
risk
(excluding
YDS)
(FWI/yr)
1.87%
Level crossing
0.20
Rolling stock
Risk areas (key risk
areas in bold)
SRMv8.1
risk
(excluding
YDS)
(FWI/yr)
SRM
v7.5
risk
(FWI/
yr)
Change
from
SRMv7.5
to
SRMv8.1
3.04
-19%
0.15%
0.23
-11%
1.81
1.37%
2.09
-13%
Environment
0.23
(0.2%)
Adjacent property/land
0.04
0.03%
0.03
+14%
Weather
0.19
0.14%
0.18
+5%
Passengers
28.0
(21%)
In stations
24.7
18.7%
23.1
+7%
On trains
3.32
2.52%
3.02
+10%
Crime
46.3
35.1%
57.3
-19%
General
2.02
1.53%
1.44
+14%
7.26
5.51%
6.80
+7%
3.63
2.75%
3.58
+1%
0.12
0.09%
0.06
+108%
Signaller
0.68
0.52%
0.78
-13%
Station staff
17.8
13.5%
16.6
+7%
Track worker
14.0
10.6%
13.6
+3%
Train crew
7.43
5.63%
7.38
+1%
Public
behaviour
Workforce
Total
59.3
(44.9%)
40.0
(30%)
Pedestrian
user
Level
Road
crossings
vehicle
user
Shunter
132.0
Version 8.1 - Issue 1.1 - December 2014
132.0
139.2
23
Key risk areas
Figure 7: Breakdown of SRMv8.1 (excluding YDS risk) by risk area
Level crossing
0.2%
Infrastructure
1.9%
Total Risk = 131.95 FWI/year
Rolling stock*
1.4%
Adjacent property/land
0.03%
Weather
0.14%
Train crew*
5.6%
Track worker*
10.6%
Workforce
30.3%
Station staff*
13.5%
In stations*
18.7%
Passengers
21.2%
Engineering
3.4%
Environment
0.2%
On trains*
2.5%
Signaller
0.5%
Shunter
0.1%
Level crossing*
RV user +
Pedestrian user
8.2%
RV user
2.8%
Pedestrian user
5.5%
General
1.5%
Public behaviour
44.9%
Crime*
35.1%
*Indicates that the risk area was one of the nine KRAs reported in the SSP 2009-2014.
The 15 risk areas relate to the sources of risk. For example the Infrastructure worker risk area
relates to the risk that arises from infrastructure workers carrying out their activities and their
behaviour in doing so, rather than the risk to infrastructure workers in their role. This means
that the risk areas relate to the causes of the SRM precursors.
In some cases, where a precursor has more than one cause, it has been necessary to assign
proportions of the precursor risk between two or more risk areas. Appendix C gives full details
of how the figures in Table 15 have been derived – it lists all of the precursors making up each
of the risk areas and gives the proportions that have been applied for any precursor split
between two or more risk areas.
The 15 risk areas can be further grouped into five higher level risk area groups – namely
engineering, environment, passenger behaviour, public behaviour and workforce behaviour.
These groupings can also be seen in Table 15.
Table 15 provides information to the industry regarding the significant causes of HEs.
Precursors, by definition, are the main contributors to the HEs that ultimately lead to harm.
Targeting the precursors through effective management actions will lead to a reduction in risk
for all associated HEs.
Version 8.1 - Issue 1.1 - December 2014
24
Key risk areas
5.1
Other risk groupings
It is also useful to group the HE and precursor into high level groups that relate to specific
causes or areas of risk on the railway. Significant risk groupings include track faults, rolling
stock, signals passed at danger (SPADS) and level crossings. Table 16 provides a summary
of the top level figures for a variety of groupings concerning these four broad categories. It
should be noted that these groupings are not mutually exclusive and the same precursor risk
contribution may be counted in more than one group.
Table 16: Selected SRMv8.1 risk groupings
Group description
Track faults - grouped for both passenger and
non-passenger trains (outside possession)
Passenger
train risk
(FWI/year)
Nonpassenger
train risk
(FWI/year)
Total Risk
(FWI/year)
-
-
1.75
Track faults (including incidents inside
possession)
1.67
0.11
1.77
Rolling stock faults
3.32
0.50
3.82
SPADs resulting in collision
0.36
0.24
0.60
SPADs resulting in derailment or level
crossing collision
0.06
0.03
0.09
Other SPADs and runaways
0.01
0.27
0.28
-
-
11.21
3.19
0.42
3.61
Footpath crossings
-
-
3.30
Non-footpath level crossings
-
-
7.60
All level crossings
Road vehicles at level crossings
To accompany this chapter a detailed breakdown of risk by key risk areas is provided in
Table C1, C2 and C3 which are available via the via the RSSB Rail Risk Portal
www.safetyriskmodel.co.uk
Version 8.1 - Issue 1.1 - December 2014
25
SRM risk vs observed risk
SRM risk vs observed risk
6
The level of safety risk estimated by the SRM is often higher than the observed rate of harm.
This is because the SRM accounts for rare events and the small contributions from many
different types of rare events add up to make an annual average modelled risk that is usually
higher than that which is observed. This holds despite the volatility in observed FWI and the
multi-year risk smoothing used in the SRM to reduce this volatility.
This is particularly the case for passenger risk as shown in Figure 8. This chart is an attempt
to show how the total observed passenger risk has changed over the last nine years and over
CP4.
The blue line represents an annual moving average of all observed FWI normalised by
passenger train km. This is calculated using all of the FWI data reported in the ASPR excluding
passenger assaults. Risk from passenger assaults has been estimated using BTP data
because such events are not well reported in SMIS. This includes all reported injuries in train
accidents as well as movement and non-movement related accidents.
The green line shows a risk metric that attempts to mimic the modelling of the SRM. This is
done by selecting different periods to average the different injury types over. The chart shows
fatalities averaged over ten years, major injuries over 2.5 years, class 1 and class 2 minor
injuries over four years. This is mostly based on data except, unlike the blue line, the FWI
contributions for HETs and passenger assaults are determined from the SRM modelling. This
is a significant simplification of the SRM and should be seen as a rough approximation.
Figure 8 shows the change in different measures of risk over the past nine years and illustrates
the volatility of taking a one-year average of observed risk compared to the relatively less
volatile SRM risk.
Some key observations are:

SRM risk estimation is nearly always higher than that of observed risk.

The occurrence of a major accident may temporarily push the rate of observed risk
higher than the SRM risk estimation (Grayrigg) or closer to the SRM risk estimation
(Ufton Nervet).

There has been a long term trend of decreasing risk, which is becoming less
pronounced and may now have started to plateau.

Because of the difficulty, without hindsight, of differentiating between genuine
trends/turning points and short-term statistical variation, and with the requirement for
a data sample large enough to produce robust risk estimates yet relevant to current
operations, the SRM estimates will lag during periods when the risk profile is changing.
The extent to which they lag is dependent on the time period used in the modelling and
this will vary from HE to HE.
Version 8.1 - Issue 1.1 - December 2014
26
Version 8.1 - Issue 1.1 - December 2014
Grayrigg
SRMv6.7
SRMv8.1
2004
2005
2007
SRM approximation
2006
2009
2010
Observed FWI (moving 12-month average)
2008
2011
SRM results
2012
2013
10 1 4 7 10 1 4 7 10 1 4 7 10 1 4 7 10 1 4 7 10 1 4 7 10 1 4 7 10 1 4 7 10 1 4 7
Ufton Nervet
SRM risk vs observed risk
Figure 8: Passenger observed FWI vs SRM FWI approximation
27
Normalised passenger risk
Uncertainty in the SRM risk estimates
7
Uncertainty in the SRM risk estimates
7.1
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. For cases where there is a lot of data available, there is a high
level of confidence in the estimations, however, where there is little 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 gives some background to the work that has been undertaken in this area, outline
the methodology that is currently being developed and presents some results based on the
version 8.1 update.
7.2
Uncertainty methodology
In 2003, RSSB commissioned research 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 occurrence of a hazardous event and the consequences associated with it can be
regarded as random. This means that there is inherent uncertainty in the SRM estimates, and
year to year it could be expected that different event counts and consequences would be
observed for a given hazardous event even if the ‘underlying risk’ did not change. The aim of
the uncertainty methodology is to quantify this uncertainty and determine relevant confidence
intervals within which we would expect the true value of the SRM estimates to lie given a
specified level of confidence.
The main part of the methodology consists of quantifying the uncertainty in the frequency and
in the average consequence estimates for each precursor. This involves constructing
distributions (either from data or expert judgement, or a mixture of the two) for each of these
factors. 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. Subsequently, these
can be sampled to give distributions of the risk at HE level, HEM/HEN level or at the overall
SRM system risk level which can be used to determine confidence intervals.
Version 8.1 - Issue 1.1 - December 2014
28
Uncertainty in the SRM risk estimates
7.3
SRM uncertainty results
The uncertainty methodology currently in development has been applied to the version 8.1
HEM/HEN risk estimates. YDS risk has been included, while HET risk has been excluded from
this analysis. Excluding the HET contribution gives an overall SRM combined HEM/HEN risk
of 131.6 FWI per year. Comparison between the uncertainty model and the SRM risk
estimates are given in Table 17 (values in this table exclude all HET risk).
Table 17: Comparison of SRM and uncertainty model risk estimates
SRM risk group
SRM estimate (FWI/yr)
Overall
Uncertainty model
distribution mean (FWI/yr)
131.6
132.9
HET
Not shown
Not calculated
HEM
49.6
50.0
HEN
82.0
82.8
Passengers
55.6
55.8
Workforce
32.2
32.5
MOPs
43.8
44.5
It should be noted that the uncertainty and confidence intervals in this section are based on
statistical uncertainty and do not take into account other potential sources of error such as
modelling assumptions (many models implicitly assume that the risk has been relatively stable
for the past few years) and data quality, particularly the underreporting of events.
Figure 9: Risk distribution for the total SRMv8.1 HEM/HEN risk
SRM
125.8
-7.1
Mean
Probability density
LL
121
132.9
UL
140.6
7.7
95%
123
125
127
129
131
133
135
Risk (FWI/year)
137
139
141
143
145
Figure 9 shows the 95% confidence interval12 around the overall HEM/HEN risk of 131.6
FWI/year. The boxes above the chart show some properties of the distribution of the risk that
12
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 SRMv8.1 data period, collect the data and calculate a 95%
Version 8.1 - Issue 1.1 - December 2014
29
Uncertainty in the SRM risk estimates
has been constructed. The central white box gives the mean (average) value of the distribution
and it can be seen that this corresponds well with the overall SRM HEM/HEN risk estimate of
131.6 FWI/year13 (see Table 2). The other two white boxes either side show the extent of the
95% confidence interval, with a lower limit (LL) of 125.8 FWI/year and an upper limit (UL) of
140.6 FWI/year. The blue boxes show the absolute risk difference between the LL/UL and the
distribution mean. In this case it can be seen that the UL is 7.7 FWI/year above the mean risk,
while the LL is 7.1 FWI/year below the mean risk. Note that all charts are drawn to the same
scale on the x axis to allow comparisons between them.
Figure 10 shows the 95% confidence interval for HEM risk and HEN risk considered
separately, while Figure 11 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.
Figure 10: Risk distribution for the SRMv8.1 risk for HEM and HEN separately
HEM
44.1
-6.0
Mean
Probability density
LL
38
50.0
UL
56.8
6.8
95%
40
42
44
46
48
50
52
Risk (FWI/year)
54
56
58
60
62
HEN
79.5
-3.3
Mean
Probability density
LL
70
82.8
UL
86.2
3.4
95%
72
74
76
78
80
82
84
Risk (FWI/year)
86
88
90
92
94
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.
13 This is to be expected from the way the HEM/HEN uncertainty model has been constructed. There is a slight
overestimate due to the use of lognormal distributions to model the uncertainty in low event counts.
Version 8.1 - Issue 1.1 - December 2014
30
Uncertainty in the SRM risk estimates
Figure 11: Risk distribution for the SRMv8.1 risk by person type
53.6
Passenger
Mean
55.8
-2.1
Probability density
LL
44
20
46
48
31.4
50
52
54
56
58
Risk (FWI/year)
33
60
Workforce
Mean
32.5
-1.1
2.1
62
UL
64
66
33.6
68
1.1
95%
22
24
38.1
26
28
30
32
34
Risk (FWI/year)
36
Member of Public
Mean
44.5
-6.4
Probability density
LL
57.9
95%
Probability density
LL
UL
38
UL
40
42
51.9
44
7.4
95%
35
37
39
41
43
45
47
Risk (FWI/year)
Version 8.1 - Issue 1.1 - December 2014
49
51
53
55
57
31
Uncertainty in the SRM risk estimates
Note that proportionally, there is more uncertainty in the estimate of HEM risk. This is
because HEM risk tends to be dominated by a relatively small number of fatalities, 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.
7.4
Uncertainty analysis next steps
The work presented in this chapter is on-going and the results should be treated as preliminary
findings, however they do illustrate 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 of this work 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. This can help inform decisions.
For example, when interpreting benefit-cost ratios to determine whether a measure is needed
to ensure safety so far as is reasonably practicable, the judgement as to whether the cost is
grossly disproportionate to the benefit is informed by an understanding of the level of
uncertainty in the estimates of both.
Version 8.1 - Issue 1.1 - December 2014
32
Individual fatality risk
8
Individual fatality risk
8.1
Introduction
Individual fatality risk is defined as the probability of a fatality to which a category of individual
is exposed. Fatality risk is distinct from FWI risk, because it excludes the component of risk
relating to injuries and shock/trauma.
The industry document Taking Safe Decisions [Ref. 2] clarifies that collective risk (rather than
individual fatality risk) is used in the formulation of arguments about whether a particular
measure is needed to ensure risk is acceptable. However, individual risk can help a company
understand its risk profile and prioritise safety management effort.
Note that the comparisons made in the following sections are between the figures reported in
the SRM-RPB version 7 (based on SRMv7), the YDS report (based on the SRM-YDS) and
the latest figures for SRMv8.1. Changes between versions shown here are due to both
modelling changes and the updating of data to 30 September 2013.
8.2
Fatality risk
The predicted individual fatality risk from SRMv8.1 was analysed for each of the person
categories listed below:

Passengers

Workforce, including:


Train drivers (eg passenger train (PT) drivers, freight train drivers,
driver/shunters)

Other train crew

Infrastructure workers

Other workforce (eg train dispatch and ticket line staff)

YDS based staff members (engineering staff and YDS cleaner/admin)
Members of the public
Fatalities on the railway are dominated by suicide and trespass, together amounting to 56.5%
of the total fatality risk. Excluding these types of event, Figure 12 shows the fatality risk for
each person category.
In the following sections, the individual fatality risk to each person category is discussed and
compared with its equivalent value in SRMv7+YDS.
To accompany this chapter a detailed breakdown of individual fatality risk by person group
and hazardous event is provided in Table D1 which is available from the RSSB Rail Risk
Portal www.safetyriskmodel.co.uk.
Version 8.1 - Issue 1.1 - December 2014
33
Individual fatality risk
Annual fatalities
Figure 12: Fatality risk for each person category per year (SRMv8.1)
14
11.61 Fatalities
per year
12
8.30 Fatalities
10
per year
8
4.22 Fatalities
per year
6
4
2
0
Passenger
8.3
Workforce
Public
Passengers
Of the population of train passengers, regular commuters have the greatest exposure to risk
from the railway environment. The individual fatality risk to a commuter is therefore assumed
to be indicative of the worst-case for the whole population of train passengers14.
Figure 13: Causal breakdown of passenger fatality risk
Platform edge incidents (not
boarding/alighting)
Train accidents: collisions and
derailments
45.8%
20.6%
Slips, trips, and falls
11.5%
Assault and abuse
7.3%
Struck/crushed by train
6.4%
All other risk categories
8.4%
0
1
2
Annual fatalities
3
4
It is assumed that, on average, each commuter makes 450 journeys per year (two journeys
per day, five days per week for 45 weeks per year). SRMv8.1 predicts a probability of fatality
of 1 in 403,976 per year for the average passenger (Table 18), which is a reduction of 33.6%
compared with the corresponding risk in SRMv7+YDS. This large reduction in individual
fatality risk is due in part to the increase in passenger journeys and partially due to a reduction
in observed and modelled fatality risk resulting from assaults and passenger train derailments.
As assault risk was not recalculated using the SRMv7 data cut-off the reduction in observed
fatalities is not directly comparable.
14
Whilst it is logical to do this, analysis has shown that per journey, regular commuters have a lower level of risk
than other travellers. This worst case should be seen as a best guess approximation.
Version 8.1 - Issue 1.1 - December 2014
34
Individual fatality risk
The most significant contributions to passenger individual fatality risk are broken down in
Figure 13.
Table 18: Total passenger individual fatality risk
SRMv8.1
SRMv7+YDS
% change
v7+YDS to v8.1
Fatality risk per year
8.30
10.44
-20.49%
Annual passenger journeys
1,508,403,942
1,259,400,000
Population size
(assuming each person
undertakes 450 journeys per
year)
3,352,009
2,798,667
2.48E-06
3.73E-06
1 in 403,976
1 in 268,169
Individual fatality risk
(probability of a fatality per year
per passenger)
8.4
19.77%
-33.62%
Workforce
The total workforce fatality risk calculated in SRMv8.1 was distributed into specific workforce
types in order to estimate their individual fatality risk.15 Individual and absolute fatality risks are
summarised in Figure 14 and Figure 15.
Population numbers for each of these workforce types; estimated from Network Rail (NR)
timesheet data (infrastructure workers and OTP drivers), and RSSB surveys of NR and each
TOC/FOC (all other workforce groups), are presented in Table 19 along with their individual
fatality risk.
Comparison of Table 18 with Table 19 shows that individual fatality risk to the workforce is an
order of magnitude greater than for passengers. This is in line with the workforce’s increased
exposure to the railway environment and the hazardous nature of the work carried out in the
rail industry.
Note that for SRMv7 ‘OTP driver’ risk was grouped with the ‘Other workforce’ risk. This has
been separated out here as the OTP driver risk is observed to be significantly higher than risk
for the ‘Other workforce’ group. Therefore there are no comparisons between SRMv7 and
SRMv8.1 for these workforce groups.
A summary of expected annual fatalities by workforce group is given in Table 27 in Appendix
C.
15
During this process a number of assumptions were made, which are detailed in Appendix D.1.
Version 8.1 - Issue 1.1 - December 2014
35
Version 8.1 - Issue 1.1 - December 2014
YDS
cleaner/admin
Other train crew
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
YDS
cleaner/admin
Other train
crew
YDS
engineering
staff
Passenger
train driver
Other
workforce
Freight train
driver
Infrastructure
worker
OTP driver
Driver
(shunter)
3
2.7
2.4
2.1
1.8
1.5
1.2
0.9
0.6
0.3
0
YDS engineering
staff
Passenger train
driver
Other workforce
Freight train
driver
Infrastructure
worker
OTP driver
Driver (shunter)
Individual fatality risk per 10,000 years
Expected annual fatalities
Individual fatality risk
Figure 14: Expected annual fatalities by workforce role
Expected annual
fatalities
Figure 15: Individual fatality risk by workforce role
Individual fatality
risk per 10,000
years
36
Individual fatality risk
Table 19: Workforce individual fatality risk breakdown
Person Type
Expected
annual
fatalities
Population
v8
Infrastructure
workers
2.399
30,500
OTP drivers
0.129
Individual fatality risk (probability of a
fatality per year)
SRMv7 or
SRMv8
% change
YDS-SRM
7.86E-05
9.22E-05
1 in 12,716
1 in 10,847
-15%
8.48E-05
1,525
-
-
1 in 11,799
Passenger train
drivers
0.473
Freight train
drivers
0.136
Other PT crew
members
0.204
Other workforce
0.594
13,145
3.60E-05
4.22E-05
1 in 27,805
1 in 23,670
5.74E-05
5.43E-05
1 in 17,432
1 in 18,410
1.54E-05
2.34E-05
1 in 65,117
1 in 42,818
2,378
6%
13,284
16,019
-15%
-34%
3.71E-05
-
-
1 in 26,960
Driver/shunter
0.120
YDS engineering
staff
0.146
YDS
cleaner/admin
0.022
8.5
8.96E-05
1.30E-04
1 in 11,161
1 in 7,721
2.29E-05
2.43E-05
1 in 43,652
1 in 41,226
1.04E-05
1.01E-05
1 in 95,757
1 in 99,455
1,338
-31%
6,379
2,123
-6%
4%
Members of the public
In hazardous industries where all operations occur within a discrete, clearly-defined,
geographical location, the numbers of exposed members of the public, and therefore individual
fatality risk to the public, can be determined. For the GB railway, however, it is only possible
to discuss fatality risk to the public population as a whole. The individual fatality risk to
members of the public (excluding suicides and trespass) is equivalent to 11.6 fatalities per
year. The most significant contributions to MOP individual fatality risk are broken down in
Figure 16.
Version 8.1 - Issue 1.1 - December 2014
37
Individual fatality risk
Figure 16: Causal breakdown of MOP fatality risk
Struck/crushed by train
54.7%
Train accidents: strikes with
road vehicles at level crossings
25.5%
Platform edge incidents (not
boarding/alighting)
4.3%
Slips, trips, and falls
3.9%
Falls from height
3.3%
All other risk categories
8.4%
0
2
4
Annual fatalities
6
8
The dominant fatality risk to members of the public (non-trespasser) occurs at level crossings,
including all events in the struck/crushed by train category. Individual fatality risk to members
of the public (non-trespasser) at levels crossings is equivalent to 9.3 fatalities per year, or
80.2% of the non-trespass total fatality risk.
Individual fatality risk estimates for regular crossing users have not been given as it has not
been possible to calculate reliable values given the uncertainty in usage data and the large
variations in crossing types.
Version 8.1 - Issue 1.1 - December 2014
38
The F-N curve
9
Multiple fatality risk: the F-N Curve
While there are no specific criteria associated with the acceptability of the frequency of train
accidents that could potentially lead to multiple fatalities, it is important to understand the
vulnerability of the railway to such accidents. Guidance on taking multiple fatality events into
account in the decision making process is given in Taking Safe Decisions.
9.1
F-N results
Using the event tree structures within SRMv8.1, for all the train accident hazardous events
with the potential to lead to multiple fatalities, an overall F-N curve (frequency versus number
of fatalities) for train accidents has been produced. This curve is shown in Figure 17.
The curve shows that as the number of potential fatalities associated with an event increases,
the frequency of occurrence of the event reduces rapidly. Key points on the curve and
information on how the rest has changed between SRM versions are given in Table 20 and
Table 21.
Table 20: Frequency of train-related incidents leading to multiple fatalities
Incidents (events/year) affecting passengers, staff and MOP
SRMv2
(Jul-99)
SRMv3
(Mar-01)
SRMv4
(Dec-03)
SRMv5
(Dec-05)
SRMv6
(Sep-08)
SRMv7
(Sep-10)
SRMv8.1
(Sep-13)
>=5 fatalities
0.700
0.416
0.265
0.189
0.186
0.173
0.144
>=10 fatalities
0.320
0.180
0.127
0.110
0.065
0.055
0.047
>=25 fatalities
[not
included]
[not
included]
[not
included]
0.021
0.020
0.016
0.011
Table 21: Return periods of train-related incidents leading to multiple fatalities
Years between incidents affecting passengers, staff and MOP
SRMv2
(Jul-99)
SRMv3
(Mar-01)
SRMv4
(Dec-03)
>=5 fatalities
1.4
2.4
3.8
5.3
5.4
5.8
6.9
>=10 fatalities
3.1
5.6
7.9
9.1
15.3
18.3
21.2
>=25 fatalities
[not
included]
[not
included]
[not
included]
48
50
62
87.0
Version 8.1 - Issue 1.1 - December 2014
SRMv5
(Dec-05)
SRMv6
(Sep-08)
SRMv7
(Sep-10)
SRMv8.1
(Sep-13)
39
Version 8.1 - Issue 1.1 - December 2014
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
1.00E-02
1.00E-01
1.00E+00
2
20
Number of passenger, staff and member of public fatalities
200
The F-N curve
Figure 17: The F-N Curve – all person and train accident types.
40
Cumulative frequency (events/year)
The F-N curve
The continued increase in expected time between train-related incidents that lead to multiple
fatalities can be seen from SRMv2 to SRMv8.1 (Figure 18). The more recent reductions are
due to a generally improving safety performance trend, as reflected in the SRMv8.1 train
accident model results. The reasons for these reductions include many steps that the industry
has taken to reduce the likelihood of accidents occurring (eg the introduction of TPWS) and to
reduce the consequences if accidents do happen (eg the overall improvement in train vehicle
crash-worthiness due to the removal of Mark 1 slam-door rolling stock). There is also likely to
be some effect from enhancements to the train accident models over successive SRM
versions.
Figure 18: Estimated frequency of train accident-related fatality events
0.8
0.7
v2, Jul-99
Frequency (events/year)
>=5 fatalities
>=10 fatalities
0.6
0.5
v3, Mar-01
0.4
0.3
v4, Dec-03
0.2
v5, Dec-05 v6, Sep-08
v7, Sep-10
v8, Sep-13
0.1
0.0
1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014
Figure 19 shows the F-N curve for the three main categories of train accident: collisions,
derailments and level crossing accidents. This chart shows that multi-fatality derailment events
generally occur more frequently for all severity levels and level crossing events least
frequently. Note that these three categories do not cover the entirety of the train accident HEs
in the SRM.
Figure 20 shows the contribution of key hazardous events to the F-N curve. It is apparent that
the majority of events with fewer than 100 fatalities are HET-12 (passenger train derailments)
events, whilst the majority of events with 100 or more fatalities (which are estimated to occur
very infrequently at a rate of less than 1 per 7500 years) result from HET-13 (non-passenger
train derailments) events as a result of train accidents involving trains carrying hazardous
materials.
Version 8.1 - Issue 1.1 - December 2014
41
Version 8.1 - Issue 1.1 - December 2014
1.00E-09
1.00E-08
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
1.00E-02
1.00E-01
1.00E+00
2
Collisions
Derailments
20
Level crossing RV strikes
Number of passenger, staff and member of public fatalities
200
The F-N curve
Figure 19: F-N curve – plotted separately for three categories of train accidents
42
Cumulative frequency (events/year)
The F-N curve
Figure 20: Contribution of key hazardous events to the F-N curve
100%
Percentage contribution to F-N Curve
90%
80%
HET-01
70%
HET-02
60%
HET-10
50%
HET-12
40%
HET-13
30%
HET-17
20%
10%
0%
2
5
10
30
100
300
Fatalities per event
9.2
F-N modelling approach
Only the train accident models have been considered in the F-N curve calculation as these
are the main contributors to multiple fatality events. Previous F-N figures have included all
HEs, however the contribution for non-train accidents with two or more fatalities to these
figures is minimal.
SRMv3 F-N results were presented in two versions — with and without the effects of TPWS.
For comparison in this section the without TPWS figures have been used, as SRMv3 was
produced during the transition period before TPWS had been fully implemented.
As in previous SRM versions, the basic F-N analysis suggests that the frequency of accidents
leading to 25 fatalities has reduced. However, even though the event trees within the SRM
break down the HEs into a large number of different potential outcomes, each consequence
estimate still only represents a single average consequence for that outcome. In reality a
greater spread of consequences might actually be possible. This is the case, for example, with
public fatalities in models involving the spillage of hazardous goods, where the possibility for
very high consequence events exists, albeit with a very low frequency.
Consequently, while the average risk associated with such outcomes is accurately modelled
within the SRM, the full range of higher and lower consequence outcomes that make up this
average is not always explicitly modelled. The F-N analysis has been adjusted for high-fatality
public events. The adjusted results have been calculated by redistributing the high-fatality
portion of public fatality events whilst maintaining the overall level of risk. As a result of the
correction, the frequencies of higher fatality events are now considered to be more realistically
represented on the F-N curve in SRMv6, SRMv7 and SRMv8.1.
Version 8.1 - Issue 1.1 - December 2014
43
Risk at the PTI
Remodelling risk at the platform-train interface
10
The update process to SRMv8 has involved the remodelling of several hazardous events that
together cover hazards at the platform-train-interface (PTI). The new structure provides more
granular information to improve understanding of PTI risk and the assessment of PTI hazards.
The following five passenger hazardous events and one member of public (non-trespasser)
hazardous event have been remodelled. These are:

HEM-05 and HEM-43 (train door closes on passenger/MOP incidents), remodelled to
single out ‘trap and drag’ incidents and train movement.

HEM-09 and part of HEM-06 (boarding and alighting incidents), restructured and new
precursors defined to detail train motion at the time of the event.

HEM-06, HEM-08, and HEM-10 (fall from platform and/or struck by train incidents),
restructured and new precursors defined to detail train motion at the time of the event.
The following sections describe the changes in more detail and explain further some of the
motivating factors behind the remodelling.
10.1
Background and objectives
High-profile accidents, including at James St in 2011, have focused attention on accidents at
the PTI involving train dispatch. Consequently there has been considerable interest in
improving the management of the PTI with discussions being held at an Industry Safety
Meeting in February 2013 and the ORR/RSSB industry workshop in April 2013.
The rail industry has established a PTI Strategy Group which is developing a PTI Strategy
focused on optimising safety, capacity and performance issues. To support the work of this
group and industry efforts to manage the risk there is a need to better understand risk at the
PTI, which this remodelling aims to facilitate.
Changes to the PTI model permit more detailed, immediate insight into PTI hazards than has
been the case for past SRM versions.
10.2
The remodelling process
10.2.1
Scope of changes
The hazardous events considered in this remodelling are all hazardous events which relate
specifically to passenger and member of public PTI risk. These hazardous events are given
in Table 22.
Version 8.1 - Issue 1.1 - December 2014
44
Risk at the PTI
Table 22: Remodelled PTI HE descriptions
10.2.2
HE Code
Description
HEM-05
Train door closes on passenger
HEM-06
Passenger falls between stationary train and platform
HEM-08
Passenger fall from platform and struck by train
HEM-09
Passenger injury while boarding/alighting a train (platform side)
HEM-10
Passenger struck by/contact with moving train while on platform
HEM-43
Train door closes on MOP (non-trespasser)
Remodelling steps
The remodelling process can be seen as a compromise between creating a highly detailed
model and being able to reliably quantify it using the available accident and incident data. In
order to create the new PTI accident models the available accident dataset was analysed with
an emphasis on finding what useful information could be reliably extracted from incident
narratives. The conclusions of this investigation were then used to decide on a consistent and
quantifiable way to restructure the models that would benefit the PTI strategy.
The datasets have all been recoded to the new structure and the model was analysed in this
new format for SRM v8.
10.2.3
PTI structural changes
Table 23 summarises the new model structure for each affected hazardous event.
Version 8.1 - Issue 1.1 - December 2014
45
Risk at the PTI
Table 23: Remodelled PTIHEs. Summary of changes
HE code
Description
Summary of changes
HEM-05
Train door
closes on
passenger
Remodelled to isolate 'trap and drag’ incidents. Now
distinguishes between events where the train door has
closed on a passenger, and where the train has or has not
subsequently moved with the passenger remaining trapped.
HEM-06
Passenger fall
between train
and platform
Expanded to segregate three train movement scenarios
that are connected to a passenger fall between a train and
platform.
There are now three sub-hazardous events covering
passenger falls involving a stationary train, a moving train
and a stationary train which subsequently moves.
HEM-08
Passenger fall
from platform
and struck by
train
Remodelled so that events are grouped according to the
motion of the train (arriving at, departing from, or travelling
through the station) at the time of accident.
HEM-09
Passenger
injury while
boarding and
alighting
Existing boarding and alighting sub-hazardous events have
been duplicated to distinguish between events involving
stationary and moving trains.
Passenger
struck
by/contact with
moving train
while on
platform
This event has been more rigorously defined so it is
restricted to events where a passenger has made contact
with a moving train while on the platform and has remained
entirely on the platform. Events that no longer fit this
definition were moved to newly created sub-hazardous
events for the other PTI HEMs.
HEM-10
A new sub-hazardous event for passenger alighting not at
platform has been added.
Precursors restructured to separate events according to
train motion (arriving at, departing from, or travelling
through the station) at the time of accident.
HEM-43
10.3
Train door
closes on MOP
(non-trespasser)
This hazardous event is the MOP (non-trespasser)
equivalent of HEM-05. Similarly it has been remodelled to
isolate 'trap and drag’ incidents.
Impact on the risk profile
These changes led to some events being re-categorised (for example, moving from HEM-08
or HEM-10 to HEM-06). Table 24 summarizes the hazardous events affected along with the
overall change in the modelled risk for version 6.6 to version 6.7 (an equivalent comparison
between SRMv7 and SRMv8.1 cannot be provided as results were not computed using the
new PTI structure for SRMv7). This table shows that overall risk at the PTI has remained
relatively the same but it has shifted between HEs significantly as a result of the remodelling.
Version 8.1 - Issue 1.1 - December 2014
46
Risk at the PTI
Table 24: Summary of the changes in risk for PTI hazardous events
HE
HE description
HEM-05
Risk (FWI/year)
v6.6
v6.7
Train door closes on passenger
0.57
0.66
HEM-06
Passenger fall between stationary train
and platform
1.55
2.80
HEM-08
Passenger fall from platform and struck
by train
2.19
1.50
HEM-09
Passenger injury while
boarding/alighting a train (platform side)
3.35
3.14
HEM-10
Passenger struck by/contact with
moving train while on platform
1.32
0.68
HEM-43
Train door closes on MOP (nontrespasser)
0.0021
0.0044
8.99
8.79
Total
Version 8.1 - Issue 1.1 - December 2014
47
SRM governance and RPB updates
11
SRM governance and RPB updates
11.1
Data and Risk Strategy Group
The Safety Risk Model (SRM) and related tools such as the SRM Risk Profile Tool are now
under the remit of the DRSG. This group is a subgroup of the SSRG. Full details of the scope
and remit of DRSG can be found on the RSSB website16.
11.1.1
SRM Practitioners Working Group
Throughout control period 4, including the production of SRMv8, SRM-PWG was 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 provided
governance for changes to the SRM.
The SRM-PWG was formed under the authority of the industry’s Safety Policy Group (SPG) the predecessor to the current System Safety Review Group (SSRG). SRM-PWG’s remit was
to engage stakeholders in the development and control of future versions of the SRM and its
related outputs. These outputs include the SRM-RPB and SRM-RPT.
The modelling changes implemented as part of the update of the SRM to version 8 have been
endorsed by SRM-PWG. The re-revised version 6 figures (SRMv6.7) and the SRMv8 figures
were presented to the group in March 2014 and recommended for approval by SSRG, which
took on responsibility after SPG was disbanded and before DRSG was formed. Following this
meeting the results were then presented to SSRG and approved in March 2014.
11.2
Update history
Since version 1 in 2001, the SRM-RPB has been updated regularly so that the risk profile
remains as current as is reasonably practicable. Since version 2, the SRM-RPB has been
issued approximately every 18–24 months. The last SRM-RPB update was for version 7
which was issued August 2011. Since then there have been two shorter versions of the Risk
Profile Bulletin, Risk Profile Reports (RPRs) which were:

Version 7.5, detailing the SRM v7.5 partial update,

The Yards, Depots and Siding Risk Profile Report detailing the development and
calculation of the YDS-SRM
This RPB version 8.1 is the ninth Bulletin (eleventh including Risk Profile Reports) release
and covers SRMv6.7, SRM-YDS and SRMv8.1. The update history up to and including this
version is shown in Table 25 below.
16http://www.rssb.co.uk/groups-and-committees/rssb-board/safety/system-safety-risk-group/data-and-risk-
strategy-group
Version 8.1 - Issue 1.1 - December 2014
48
SRM governance and RPB updates
Table 25: SRM update history
Version
Issue date
Data cut-off
Major change (from previous version)
1
January 2001
July 1999
First version
2
July 2001
July 1999
Re-release of SRMv1
3
February 2003
March 2001
4
January 2005
December 2003
Full data update and model enhancements
Inclusion of TPWS
Full data update and model enhancements
Full data update and model enhancements
5
August 2006
December 2005
Removal of Mk1 slam-door rolling stock from models
Inclusion of OTP risk model
Interim partial data update
5.5
May 2008
October 2007
6
June 2009
September 2008
Full data update and model enhancements
CP4 HLOS benchmark version
6.5
January 2011
September 2008
Enhanced version 6
7
June 2011
September 2010
Full data update
YDS
November
2012
September 2011
Introduction and calculation of yards, depots and
sidings risk profile
6.6
March 2013
September 2008
Enhanced version 6.5 (required for HLOS
comparisons)
7.1
March 2013
September 2010
Enhanced version 7 (required for HLOS comparisons)
7.5
March 2013
June 2012
Interim partial data update
6.7
March 2014
September 2008
Change in FWI weightings
Enhanced version 6.6 (required for HLOS
comparisons).
Model enhancements to allow like for like comparisons
with v8.
Full data update and model enhancements.
8
March 2014
September 2013
Full incorporation of YDS–SRM into main SRM model.
Final CP4 HLOS benchmarking.
8.1
May 2014
September 2013
Version 8.1 - Issue 1.1 - December 2014
Update of suicide and trespass risk models due to
improved data accuracy resulting from improved data
sharing with BTP.
49
SRM governance and RPB updates
11.3
Updates to the SRM during CP4
Version 8 is the final full update of the SRM required for HLOS metric comparisons across
CP4 using SRMv6 figures as benchmarks. Figure 21 illustrates the timeline of SRM updates
during CP4.
Figure 21: Timeline of updates of the SRM and RPB that occurred in CP4
Version 6
Mar 2009
(risk figures)
Jun 2009
(RPB)
2009
Version 7
Mar 2011
(risk figures)
Jun 2011
(RPB)
2010
2011
Version 7.5
Dec 2012
(risk figures)
Mar 2013
(RPR)
2012
CP4
11.4
2013
Version 8
Mar 2014
(risk figures)
Aug 2014
(RPB)
2014
2015
CP5
Future updates during CP5
Moving into CP5 there is no longer the requirement to use the SRM to track industry
progress against HLOS targets. SRM-PWG has been disbanded with DRSG taking its place.
As a result of this, future plans for the development of the SRM are being discussed and a
strategy is currently being developed.
Version 8.1 - Issue 1.1 - December 2014
50
Contributors
12
Contributors
Details of the preparation and approval of the SRM and SRM-RPB are given below:
Prepared by:
Carol Bloxsome
Steven Burke
Stuart Carpenter
Marcus Dacre
Joanna Evans
Alex Gilchrist
Ben Gilmartin
Jonathan Gregory
Chris Harrison
Alex Healy
Jay Heavisides
Matthew Hunt
Rachael Johnson
Albert Law
Reuben McDonald
Paul Murray
Kevin Thompson
Reviewed by:
George Bearfield
Marcus Dacre
Chris Harrison
SRMv8 and SRMv6.7 scope and update changes were endorsed by the SRM Practitioners
Working Group on behalf of the SSRG.
Approved by:
George Bearfield
Release date:
August 2014
Correspondence may be sent to:
RSSB
Block 2, Angel Square
1 Torrens St
London
EC1V 1NY
UK
Or:
risk@rssb.co.uk
Version 8.1 - Issue 1.1 - December 2014
51
Acronyms and glossary
13
Acronyms and glossary
13.1
Acronyms
ABCL
Automatic barrier level crossing, locally-monitored
AHB
Automatic half-barrier (level crossing)
ALCRM
All Level Crossing Risk Model
AOCL+B
Automatic open level crossing, locally-monitored (with half barrier)
ASPR
Annual Safety Performance Report
BTP
British Transport Police
CP4/CP5
Control period 4/5
CSM RA
Common Safety Method on Risk Evaluation and Assessment
DfT
Department for Transport
DRSG
Data and Risk Strategy Group
FP
Footpath level crossing
FWI
Fatalities and weighted injuries
GB
Great Britain
HE
Hazardous event
HLOS
High-level output specification
HSE
Health and Safety Executive
KRA
Key risk area
LC
Level crossing
LUL
London Underground Ltd
MCB
Manually-controlled barrier level crossing
MCB+OD
Manually-controlled barrier level crossing with obstacle detector
MCG
Manually-controlled gate level crossing
MOP
Members of the public
NR
Network Rail
OC
Open level crossing
ORR
Office of Rail Regulation
POS
Inside possession
PTI
Platform-train interface
RGS
Railway Group Standards
RIDDOR
The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations
1995
RMF
Risk Management Forum
Version 8.1 - Issue 1.1 - December 2014
52
Acronyms and glossary
RSSB
Rail Safety and Standards Board
SMIS
Safety Management Information System
SPAD
Signal passed at danger
SPG
Safety Policy Group
SRM
Safety Risk Model
SRM-PWG
Safety Risk Model Practitioners Working Group
SRM-RPB
Safety Risk Model: Risk Profile Bulletin
SRM-RPT
Safety Risk Model: Risk Profile Tool
SSP
Strategic Safety Plan
SSRG
System Safety Risk Group
TABS
Track Access Billing System
TfL
Transport for London
TPWS
Train Protection and Warning System
UWC(+T)
User-worked level crossing (+telephone)
VPF
Value of preventing a fatality
YDS
Yards, depots and sidings
13.2
Glossary
The following list describes terms as they are used in the SRM.
acceptable level of risk
The CSM RA defines risk acceptance principle to mean: “the
rules used in order to arrive at the conclusion whether or not the
risk related to one or more specific hazards is acceptable”. It
also defines safety measures to mean: “a set of actions either
reducing the frequency of occurrence of a hazard or mitigating
its consequences in order to achieve and/or maintain an
acceptable level of risk”.
The risk acceptance principles are explained in detail in Taking
Safe Decisions [Ref. 2]
ACTRAFF
A database for recording actual traffic movement across the
network.
assault
SMIS records incidents in which ‘in circumstances related to
their work, a member of staff is assaulted, threatened or
abused, thereby affecting their safety or welfare’.
BTP records and categorises criminal assaults in accordance
with Home Office rules. For the majority of RSSB’s work, BTP
crime codes have been grouped into higher level categories to
facilitate analyses and comparisons with SMIS records.
Version 8.1 - Issue 1.1 - December 2014
53
Acronyms and glossary
awkward movement
An injury caused by an unusual body movement, eg twisting or
stretching, which is received in the course of carrying out
normal everyday activities. It excludes any injuries received
from lifting or carrying objects which are classified under
manual handling.
child
A person aged 15 years or below.
cleaner/admin staff
All those workers who are not engineering and maintenance
staff, and who are not involved in shunting/driving activities.
It is specifically directed at those engaged in cleaning and train
servicing activities that do not actually involve any physical
maintenance work, plus those supervisors and administration
staff who are occasionally on the shop floor or in the yard.
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 acceptable, the change in risk associated with the
measure is a collective risk estimate.
consequence
The amount of safety harm directly caused by a hazardous
event. This is quantified in terms of fatalities, injuries and
occurrences of shock and trauma.
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.
driver/shunter
Drivers of trains undertaking shunting manoeuvres (and
entering/exiting the site) on YDS sites, and the shunters that
assist in those manoeuvres on the ground.
engineering staff
All workers who are undertaking engineering and maintenance
work (including maintenance during train servicing) on trains
and train-related components on a YDS site. This also includes
fitters and machine operators, loading workers (freight) and
other workers on the site involved in operational rail activities
that do not fit into other categories.
Version 8.1 - Issue 1.1 - December 2014
54
Acronyms and glossary
escalation factor
Any failure which significantly increases, or ‘escalates’, the
consequence of a hazardous event. For instance, a train
derailment (the hazardous event) could escalate into a bridge
collapse onto the train, a fire or release of hazardous goods.
An escalation factor may be a system failure, sub-system
failure, component failure, human error, physical effect or
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 occurs within one year of the accident.
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.
HLOS
A key feature of the access charges review. Under Schedule 4
of the 2005 Railways Act, the Secretary of State for Transport
(for England and Wales) and Scottish Ministers (for Scotland)
are obliged to send to ORR a high level output specification
(HLOS) and a statement of funds available, to ensure the
railway industry has clear and timely information about the
strategic outputs that Governments want the railway to deliver
for the public funds they are prepared to make available. ORR
must then determine the outputs that Network Rail must
deliver to achieve the HLOS, the cost of delivering them in the
most efficient way, and the implications for the charges
payable by train operators to Network Rail for using the
railway network.
individual fatality 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.
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55
Acronyms and glossary
infrastructure worker
A member of the workforce whose responsibilities include
engineering or technical activities on or about the track. This
includes track maintenance, civil structure inspection,
signalling and telecommunications renewal/upgrade,
engineering supervision, acting as a controller of site safety,
hand signaller or lookout and machine operation.
level crossing
A junction between a road, footpath, bridleway etc and the
railway, where both are at ground-level.
mainline railway
Any location that is connected to the running lines but is not a
YDS site
major injury
Injuries to passengers, staff or MOP as defined in Schedule 1
of RIDDOR. 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.
1 FWI is equivalent to 10 major injuries.
minor injury
Class 1: Injuries to passengers, staff or MOP, which are
neither a fatality nor a major injury, and:

For passengers or MOPs, result in the injured person
being taken to hospital from the scene of the accident
(as defined as reportable in RIDDOR 1995 amended
April 2012).

For workforce, result in the injured person being
incapacitated for their normal duties for more than
three consecutive calendar days, not including the day
of the injury.
Class 2: All other physical injuries that are not Class 1, but
must still be reported in SMIS for compliance with GE/RT8047
[Ref. 9]
1 FWI is equivalent to 200 Class 1 minor injuries, or 1000
Class 2 minor injuries.
movement accident
(HEM)
An accident causing injury to people, involving trains (in
motion or stationary) but excluding injuries sustained in train
accidents, which occurs within the scope of the SRM.
non-movement
accident (HEN)
An accident causing injury to people, unconnected with the
movement of trains, which occurs within the scope of the
SRM.
operational incident
An irregularity affecting, or with the potential to affect, the safe
operation of trains or the safety and health of persons.
The term operational incident applies to a disparate set of
human actions involving an infringement of relevant rules,
regulations or instructions.
Version 8.1 - Issue 1.1 - December 2014
56
Acronyms and glossary
operational railway
All railway lines for which the infrastructure manager has been
granted a safety authorisation, and the railway undertaking
has been granted a safety certificate by the ORR (under
European Safety Directive 2004/49/EC [Ref. 5]). This provides
evidence that there is a suitable safety management system
(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. 10].
outcomes
The range of scenarios that could arise following the
occurrence of a hazardous event.
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 or
has been over carried to a YDS site after a train has been
taken out of service. This does not include passengers who
are trespassing or who commit suicide — they are included
in the SRM as MOP.
possession (POS)
The complete stoppage of all normal train movements on a
running line or siding for engineering purposes. This includes
protection as defined by the Rule Book (GE/RT8000) [Ref. 9].
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.
probability
The likelihood of an event occurring on demand.
public, members of
(MOP)
Persons other than passengers or workforce members. This
includes passengers who are trespassing (eg when crossing
tracks between platforms), or attempting to commit suicide.
Any authorised visitors to a YDS site, except those who work
for, or are under contract to, the company who manages the
site, are considered to be MOP.
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57
Acronyms and glossary
railway infrastructure
All structures within the boundaries of Network Rail’s
operational railway, including the permanent way, land within
the lineside fence and plant used for signalling or exclusively
for supplying electricity for railway operations. It does not
include stations or YDS that are owned by, or leased to, other
parties. It does, however, include the permanent way at
stations and plant within these locations.
residual risk
The level of risk remaining with the current risk control
measures in place and with their current degree of
effectiveness.
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.
(The Reporting of
Injuries, Diseases and
Dangerous
Occurrences
Regulations)
risk
Risk is the potential for a known hazard or incident to cause
loss or harm; it is a combination of the probability and the
consequence for that event.
Safety Management
Information System
(SMIS)
A national database used by railway undertakings and
infrastructure managers 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 131 individual models, each representing a type of
hazardous event.
shock/trauma
Class 1: Shock or trauma results from being involved in, or
witnessing, events that have serious potential of a fatal
outcome, eg train accidents such as collisions and
derailments, or personal accidents such as being struck by a
train.
Class 2: Shock or trauma results from other causes, such as
verbal abuse, near misses, or personal accidents of a typically
non-fatal outcome.
1 FWI is equivalent to 200 Class 1 S/T injuries, or 1000
Class 2 S/T injuries.
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58
Acronyms and glossary
signal passed at
danger (SPAD)
An incident when any part of a train has passed a stop signal
at danger without authority or where an in-cab signalled
movement authority has been exceeded without authority.
Full definitions are available from GO/RT3119 [Ref. 9].
Strategic Safety Plan
(SSP)
This is a joint statement by the companies responsible for
Britain’s mainline rail network setting out and agreed industry
approach to managing safety.
The 2009-2014 plan was developed by bringing together
commitments made by individual companies in their own
individual safety plans, thus creating a link with the duty holder
planning process.
In the plan, trajectories have been developed which describe
the industry’s ambitions in nine key risk areas and identify
actions that are being undertaken to achieve them [Ref. 7].
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.
The consequences of suicide events are split into direct risk
(injuries to the suicidal person) and indirect risk (injuries to
persons who observe the event or are injured in any
associated accident).
train
Any self-powered vehicle, or vehicles hauled by a selfpowered vehicle, with flanged wheels on guided rails.
train accident (HET)
Reportable train accidents as defined in RIDDOR. The main
criterion is that the accident must be on or affect the running
line. There are additional criteria for different types of
accident, and these may depend on whether the accident
involves a passenger train.
Train Protection and
Warning System
(TPWS)
A safety system that automatically applies the brakes on a train
which either passes a signal at danger, or exceeds a given
speed when approaching a signal at danger, a permissible
speed reduction or the buffer stops in a terminal platform.
trespass
An occurrence of a person entering a location where they are
never authorised to be. This is distinct from a person behaving
inappropriately at a place where they are allowed to be under
certain conditions (eg level crossing violations/errors).
workforce
Persons working for the industry on railway operations, either
as direct employees or under contract.
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59
Acronyms and glossary
YDS site
Any location that is connected to but away from the running
lines, where train maintenance, stabling, marshalling and/or
servicing (including refuelling) takes place.
Version 8.1 - Issue 1.1 - December 2014
60
References
14
References
[Ref. 1]
HLOS Safety Metrics – baseline and progress metrics following completion of the
update of the SRM to version 8. Report delivered to SRM-PWG 27th March 2013.
[Ref. 2]
RSSB (2014) Taking Safe Decisions — How Britain’s railways take decisions
that affect safety. http://www.rssb.co.uk/Library/risk-analysis-and-safetyreporting/2014-guidance-taking-safe-decisions.pdf
[Ref. 3]
Network Rail (2012) Strategic Business Plans 2014-2019.
http://www.networkrail.co.uk/publications/strategic-business-plan-for-cp5/
[Ref. 4]
RSSB (2012) Yards, Depots & Sidings Risk Profile Report, version 1.
www.safetyriskmodel.co.uk
[Ref. 5]
European Railway Safety Directive 2004/49/EC.
http://www.dft.gov.uk/pgr/rail/Safety/ersd
[Ref. 6]
RSSB (2014) Annual Safety Performance Report 2013/14.
[Ref. 7]
RSSB (2009) The Railway Strategic Safety Plan 2009–2014.
http://www.rssb.co.uk/safety/Pages/default.aspx
[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]
Information on railway group standards, guidance notes and similar is available
at: http://www.rgsonline.co.uk
[Ref. 10]
Ovenstone, I.M. (1973) A psychiatric approach to the diagnosis on suicide. British
Journal of Psychiatry, 123 (572), pp15–21.
Version 8.1 - Issue 1.1 - December 2014
61
Appendices
Appendix A. SRM outputs
The outputs from the Safety Risk Model are available via the RSSB Rail Risk Portal
www.safetyriskmodel.co.uk.
The following tables of results are available:

Table A1 which gives a breakdown of risk at the sub-hazardous event level.

Table B1 which provides the most detailed breakdown of risk to the precursor level.

Table A2 which gives reasons for the changes in risk from version 7 to version 8/8.1.

Table C1 which contains the full breakdown of the SRM at precursor level into the Key
Risk Areas as summarised in Table 15.

Tables C2 and C3 which contain the breakdown of the SRM by Key Risk Grouping as
summarised in Table 16.

Table D1 which details individual fatality risk by person group and hazardous event
summarised in Chapter 8.

Table E1 details the normalisation data used in the calculation of SRMv8.1, the
sources of that data and an explanation of changes from v7 normalisers.
Tables are provided as .xls files, other formats are available on request.
Version 8.1 - Issue 1.1 - December 2014
62
Appendices
Appendix B. ASPR hazardous event groupings
Table 26: Accident groups used within the ASPR
Accident
grouping
Description of the types of event
contained within grouping
Hazardous events
Assault and abuse
All types of assault, verbal abuse and
threat. Also includes unlawful killing.
HEN-64, HEN-65, HEN-66
Contact with object
Any injury involving contact with objects,
not covered by another category.
HEM-20, HEM-32, HEM-42,
HEM-45, HEN-21, HEN-23,
HEN-26, HEN-44, HEN-55,
HEN-56, HEN-59, HEN-76,
HEN-79, HEN-80
Contact with
person
Injuries due to bumping into, or being
bumped into by, other people. Excludes
assaults.
HEN-55, HEN-56
Falls from height
Generally speaking, falls of more than
2m. Excludes falls down stairs and
escalators.
HEN-15, HEN-25, HEN-45,
HEN-78
Fires and
explosions (not
involving trains)
Fires or explosions in stations, lineside
or other in scope locations.
HEN-01, HEN-02, HEN-03,
HEN-04, HEN-05, HEN-48,
HEN-49
Indirect risk due to
suicide
Second party injuries arising from
suicide, suspected suicide and
attempted suicide.
HEM-31, HEN-77
Lean or fall from
train in running
Injuries resulting from accidental falls
from trains, or from leaning from trains.
HEM-03, HEM-07, HEM-15,
HEM-17
Machinery/tool
operation
Injuries from power tools, being trapped
in machinery, or track maintenance
equipment. Does not include injuries due
to arcing. Does not include injuries due
to being struck by things thrown up by
tools or from carrying tools/equipment.
HEN-22, HEN-27, HEN-56
Manual
handling/awkward
movement
Strains and sprains due to lifting or
moving objects, or awkward movement.
Excludes injuries due to dropping items
being carried, which are classed under
contact with objects.
HEN-73, HEN-74, HEN-82,
HEN-83
On-board injuries
All injuries on trains, excluding train
accidents, assaults, and those occurring
during boarding or alighting, or whilst
leaning from trains.
HEM-38, HEM-39, HEM-48,
HEN-62, HEN-63
Platform edge
incidents (not
boarding/alighting)
Accidents that involve falls from the
platform (with or without trains being
present) or contact with trains or traction
supplies at the platform edge. Excludes
accidents that take place during boarding
or alighting.
HEM-05, HEM-06, HEM-09,
HEM-16, HEM-21, HEM-22,
HEM-23, HEM-43, HEN-84
Platform-train
interface
(boarding/alighting)
Accidents occurring whilst getting on or
off trains. Includes falls between train
and platform where it is not known if the
person is boarding or 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
Version 8.1 - Issue 1.1 - December 2014
63
Appendices
Accident
grouping
Description of the types of event
contained within grouping
Hazardous events
Road traffic
accident
All accidents directly resulting from road
traffic accidents, apart from road vehicle
incursions not at LC.
HEN-35
Slips, trips, and
falls
Generally speaking, falls of less than 2m
at any in scope location (except on
trains), and falls of any height down
stairs and escalators.
HEN-14, HEN-16, HEN-24,
HEN-25, HEN-46, HEN-68,
HEN-78, HEN-80
Struck/crushed by
train
All incidents involving pedestrians
struck/crushed by trains, excluding
trespass, platform edge and boarding
and alighting accidents.
HEM-11, HEM-14, HEM-19,
HEM-27, HEM-45
Train accidents:
collisions and
derailments
Collisions between trains, buffer stop
strikes and derailments (excluding those
caused by striking road vehicles at level
crossings).
HET-01, HET-02NP, HET-02P,
HET-03, HET-06, HET-09,
HET-12, HET-13, HET-26,
HET-27
Train accidents:
other
Train divisions, train fires, train
explosions, structural damage affecting
trains.
HET-17, HET-20, HET-21,
HET-22, HET-23, HET-24,
HET-25
Train accidents:
striking objects
Train striking an object, including road
vehicles not at level crossings and trains
hit by missiles. Excludes derailments.
HET-04
Train accidents:
striking road
vehicles at level
crossings
Includes derailments.
HET-10, HET-11
Trespass
First-party injuries resulting from people
engaging in behaviour involving access
of prohibited areas of the railway, where
that access was the result of deliberate
or risk-taking behaviour. Errors and
violations at level crossings are not
included in this category.
HEM-12, HEM-25, HEM-30,
HEM-44, HEM-46, HEN-36,
HEN-37, HEN-38, HEN-39,
HEN-40, HEN-41, HEN-42,
HEN-43, HEN-71, HEN-72,
HEN-81
Workforce electric
shock
Electric shock involving third rail, OLE, or
non-traction supply. Includes burns from
electrical short circuits. Does not include
injuries due to arcing, which are classed
under ‘other’.
HEN-27, HEN-30, HEN-31,
HEN-32
Any other event not covered by the
categories above.
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, HEN-79
Other
Note that the risk from some HEs has been split across two or more accident types based on
precursor level risk estimates.
Version 8.1 - Issue 1.1 - December 2014
64
Version 8.1 - Issue 1.1 - December 2014
0.006
-
0.008
0.002
6.3E-04
-
-
-
0.002
0.200
0.004
0.874
0.056
1.628
0.395
0.061
0.057
0.317
0.022
0.002
0.059
4.223
-
0.144
0.146
0.027
-
-
-
0.005
0.012
0.015
-
0.037
0.029
-
0.011
-
0.120
0.002
-
-
-
0.043
0.007
0.027
-
0.029
0.007
0.001
0.003
-
0.002
0.002
Total annual
fatalities
0.059
YDS cleaner/
admin
-
YDS
engineering
staff
0.185
Driver
(shunter)
0.009
Other
workforce
4.1E-04
0.594
0.020
-
-
-
0.135
0.022
0.211
5.1E-04
0.060
-
-
0.042
0.047
0.047
OTP driver
0.164
0.129
-
0.004
5.1E-04
0.083
0.009
-
-
-
-
-
0.032
-
-
0.001
Infrastructure
worker
2.399
0.240
-
-
-
1.295
0.010
0.511
5.1E-04
0.051
0.021
0.034
0.003
0.133
0.102
1.8E-04
0.204
-
0.001
0.011
0.047
0.025
0.002
0.025
0.002
0.007
-
0.072
-
-
0.002
0.008
Other train
crew
-
0.136
0.002
0.049
0.006
0.060
0.010
-
0.007
Fires and explosions (not
involving trains)
Machinery/tool operation
Slips, trips, and falls
Train accidents: striking road
vehicles at level crossings
Train accidents: collisions and
derailments
0.473 Total annual fatalities
0.025 Workforce electric shock
0.004 Train accidents: other
0.044
0.205
0.105 Struck/crushed by train
-
0.071 Road traffic accident
Platform edge incidents
(boarding/alighting)
0.011 Other
-
0.002 Lean or fall from train in running
-
0.004 Falls from height
8.6E-05 9.2E-04
9.8E-04
-
0.002
-
4.1E-04
5.7E-05 6.3E-04 Contact with object
8.6E-05 9.3E-04 Assault and abuse
FT driver
0.011
PT driver
4.4E-05 2.6E-05 6.6E-05
NB – the shading
in this table
indicates the
relative
magnitude of the
figures. The
more green the
box is the higher
the risk figure.
0.021
Appendices
Appendix C. Individual fatality risk summary
Table 27: Workforce group individual fatality risk by cause classification.
65
Appendices
Appendix D. Modelling approach
D.1.
Key assumptions
Table 28 describes the main assumptions used in the analysis for SRMv8. Assumptions for
individual models are available on request.
Table 28: Key modelling assumptions in the SRM
Assumptions
1.
Train accident (HET) event frequencies are calculated based on all recorded incidents,
irrespective of injury, whereas movement and non-movement (HEM and HEN) event
frequencies are only based on incidents that resulted in an injury to a person.
2.
An average day has been divided into:

Night:
0000–0600 hrs
Peak:
0700–1000 and 1600–1900 hrs
 Off-peak: 0600–0700, 1000–1600 and 1900–0000 hrs

25% of peak trains are assumed to be crush loaded.
3.
Average train distributions:

Night:
0.6 PTs
Peak:
5 PTs
 Off-peak: 2 PTs

4.
and
and
and
0.4 NPTs per hour
0.05 NPTs per hour
0.38 NPTs per hour
Consequences are based on a five car train with average passenger loadings per train:

Night-loaded train:
2 passengers per carriage:
Peak-loaded train:
50 passengers per carriage:
 Off-peak-loaded train: 10 passengers per carriage:
 Crush-loaded train:
90 passengers per carriage:

5.
10 passengers per train
250 passengers per train
50 passengers per train
450 passengers per train
Average passenger train loadings are calculated using assumptions 2 and 3, as well as an
assumed proportion of passenger loadings at each time of day:

11% of all PTs are night loaded
 63% of all PTs are off-peak loaded
 19.5% of all PTs are peak loaded
 6.5% of all PTs are crush loaded
6.
Average train crew:

Passenger trains:
Freight, ECS & parcels trains:
 OTMs/RRVs:
 Shunting manoeuvres:

1 driver and 1 guard
1 driver
2 operators
1 driver (shunter)
7.
The frequency of train accidents at stations and in tunnels is based upon their respective
proportions of overall length compared with total track kilometres. The length of each platform is
assumed to be 200m.
8.
It is assumed that there is complete and correct reporting of injury events.
Version 8.1 - Issue 1.1 - December 2014
66
Appendices
D.2.
Hazardous event definitions
Full descriptions of all HEs and precursors used in the SRM are available via the RSSB Rail
Risk Portal www.safetyriskmodel.co.uk.
D.3.
Normalisation data
The values used to normalise data in SRMv8.1 along with equivalent values from past
versions of the SRM are provided in Table E1 available via the RSSB Rail Risk Portal
www.safetyriskmodel.co.uk
D.4.
Significant modelling changes for SRMv8
D.4.1.
Inclusion of YDS-SRM risk
Risk previously modelled in the YDS-SRM has been fully incorporated into this version of the
SRM.
D.4.2.
Remodelling of risk at the PTI
The platform-train interface risk models and precursor structure have be remodelled in order
to better understand risk at the PTI. Full details are given in Chapter 10.
D.4.3.
Inclusion of MCB+OD and AOCL+B crossing types
Two new crossing types, MCBs with obstacle detection and AOCL with half barriers, have
been introduced. All level crossing models (HET-10, HET-11, HEM-11, HEM-27, HEN-44,
HEN-46 and HEN-75) have been extended to explicitly calculate the risk at these crossing
types.
D.4.4.
New approach to assault data analysis
For this version a change has been made to the assault modelling. Algorithms have been
written and automated to match BTP recorded assault data with SMIS recorded assault data
in order to provide a larger, richer dataset. In previous updates this was done manually and
so only a subset of the data was analysed then scaled up. This has resulted in more reliable
assault risk modelling.
Version 8.1 - Issue 1.1 - December 2014
67
Appendices
Appendix E. Railway lines in SRM scope
The SRM only includes railway lines which are managed and/or operated by Network Rail.
Table 29 contains examples of some commonly-queried lines (and sections of lines), along
with the reason for their inclusion or exclusion.
Table 29: Railway lines in and out of scope of the SRM
about the
track/at
PTI
The Cambrian line18
The entire line, including St
Pancras, is managed, operated and
maintained by NR.
Owned and managed by NR.
In
Stations
High Speed 117
Notes


In
In


In
In


In
In


In
In


Out
In
NR
Managed?
Line / Section
In/Out of Scope
NR
operated
signalling?
Criteria
Heathrow Express:
Paddington to Heathrow Central
NR-owned infrastructure.
Heathrow Express:
Heathrow Central to Terminals 4
and 5
Nexus — Tyne and Wear Metro:
Fellgate to South Hylton
Owned by BAA but maintained on
their behalf by NR.
Nexus — Tyne and Wear Metro:
All sections apart from Fellgate
to South Hylton
LUL Metropolitan Line:
Chiltern services between
Harrow-on-the-Hill and
Amersham
LUL District Line:
Gunnersbury to Richmond
Neither managed by NR, nor is the
signalling controlled by NR.


Out
Out
This section is owned and operated
by LUL and its subsidiaries /
operators.


Out
Out19


Out
In


Out
Out


Out
In


Out
Out


In
In
LUL District Line:
East Putney to Southfields
LUL Bakerloo Line:
Services north of Queens Park
Island Line on the Isle of Wight
East London Line
Owned and managed by NR.
This section was a joint operation
with Silverlink Metro, for which NR
is now responsible.
LUL owns the infrastructure. NR
owns the signals, but the signalling
is operated by LUL.
Track managed by NR, who also
operates the signalling.
The service is wholly operated and
managed under a franchise to
South West Trains.
TfL owns and maintains the track,
but NR operates the signalling.
17
The risk from High Speed 1 train operations is modelled in the same way as all other lines, ie as an average
railway, rather than explicit modelling of High Speed 1 characteristics. The contribution of Eurostar services to
HEM/HEN risk is included.
18 The risk from the Cambrian line is modelled in the same way as all other lines, ie, as an average railway rather
than modelling explicit ERTMS characteristics. This is under investigation for future versions of the SRM.
19 PTI and on-board injuries on these Chiltern services are in scope, injuries on or about the track are out of scope.
Version 8.1 - Issue 1.1 - December 2014
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