Overview of the SRM-RPB – Version 7
Introduction
To manage safety effectively, it is vital that RSSB members are able to assess and understand the safety
risk associated with our railway. The Safety Risk Model (SRM) is a key source of information for the rail
industry in this area. It is a structured representation of the 120 hazardous events that could lead directly to
injury or fatality during the operation and maintenance of the GB mainline railway. The SRM considers the
system as a whole, rather than the details for a particular route or operator.
Where possible, the SRM is populated using relevant historical accident
data. Where little data exists, particularly for the low frequency but
potentially high consequence accidents, the model makes use of predictive
fault and event-tree modelling, structured expert judgement from technical
specialists, and statistical methods. In this way the SRM provides an
estimation of the underlying levels of risk on the railway that is not
obtainable from historical data alone.
The Department for Transport and the Office of Rail Regulation are using
the outputs of SRM as the primary means of measuring the performance of
the industry against the High Level Output Specification (HLOS) safety
metrics. The risk estimates in version 6 of the SRM (SRMv6) provided the
initial baseline against which safety performance through Control Period 4
(CP4, April 2009 to March 2014) will be compared. SRMv7 (March 2011)
provides the first comparison against the baseline HLOS safety metrics. To
enable this comparison to be meaningful, the update of the SRM to version
7 (SRMv7) has been split into two distinct stages. The first stage was to
incorporate all changes and error corrections into the model and produce a
revised version of the previous model – SRMv6.5. This interim version represents the risk as would have
been calculated for SRMv6 had the modelling changes implemented in SRMv7 been implemented at that
time. The second stage was then a data refresh of all of the individual models within the SRM with data up
to the 30 September 2010.
Overall Risk
SRMv7 indicates that the overall level of risk predicted for the railway is 140.9 [141.6] 1 FWI/year. It should
be noted that this excludes the direct risk from suicide and attempted suicide. However, all secondary risk
(eg the shock/trauma that can arise when drivers witness suicides) associated with these events have been
included. Table 1 shows a complete breakdown of this figure by accident category. This overall risk figure
represents a slight increase of 0.2% [0.3%] from the overall risk figure of 140.6 [141.1] FWI/year reported in
SRMv6.5 (updated SRMv6 figures).
Accident Category
FWI/year
Fatalities/
year
Major
injuries/
year
8.1
6.1
15.0
104.4
21.4
11.2
56.8
54.2
5.8
8.6
2.0
Trespass
48.6
45.7
27.0
20.0
10.4
28.6
0.4
Total
140.9
70.7
466.9
2096.6
10332.7
216.8
1575.6
NB: POS = Possession
Train Accidents (excl POS)
Movement Accidents (excl
POS and Trespass)
Non-movement Accidents
(excl POS and Trespass)
Inside possession (POS)
RIDDOR
Non-RIDDORReportable
reportable
minor
minor
injuries/yr
injuries/yr
Class 1
shock
trauma/yr
Class 2
shock
trauma/yr
9.2
1.3
3.0
346.0
1713.5
172.5
170.5
317.3
1534.7
7610.2
12.0
1397.0
50.8
91.5
989.4
2.4
4.7
Table 1: Total risk by accident category (excluding RIDDOR under-reporting)
1
For an explanation of the figures in square brackets please refer to the text on the RSSB RIDDOR Review on page 2.
Page 1
Overview of the SRM-RPB – Version 7
Risk to exposed groups
The overall figure of 140.9 FWI/year can be broken down by each exposed group as follows:
•
Passenger
52.0 FWI/year
•
Workforce
27.2 [27.9] FWI/year
•
Member of public
61.7 FWI/year
Absolute passenger risk has increased by 3% since SRMv6.5. However, over the same period, passenger
journeys have increased by 1% and passenger kilometres have increased by 5% (from 50.4 billion
passenger km in SRMv6.5 to 53.2 billion passenger km in SRMv6.5). It can be seen that if the passenger
risk is normalised by passenger kilometres, then risk has actually decreased, as the absolute risk increase
(3%) is less than the increase in the normaliser (5%).
Workforce risk is now 27.2 [27.9] FWI/year, representing an 8% [7%] reduction since SRMv6.5. This
reduction is largely considered to be a real change in the underlying risk. It is due to a number of risk
reductions across several hazardous events, but is mainly accounted for by decreases in the following
event types:
•
Workforce slip, trip or fall <2m.
•
Workforce struck by/contact with/ trapped in object not at station.
•
Workforce on-train incident (excluding sudden train movement & assaults).
•
Workforce physical assault.
Risk to the public has increased by 2% when compared with the SRMv6.5 figure. Given the tolerances
associated with the risk estimates, this is not considered to indicate a significant change in the underlying
risk.
RSSB RIDDOR Review
In 2010 RSSB was commissioned by Network Rail to undertake an independent review of compliance with
The Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 (RIDDOR) by Network
Rail staff and its contractors 2. This followed initial concerns by the ORR about the number of lost time
injuries reported when compared to the total number of major injuries being reported. The review
concluded that there were events within the Safety Management Information System (and hence in the
SRM data) that had been allocated the wrong injury classification, and that there were further minor injury
events that had not been reported at all. The injury classification changes have all been incorporated into
the version 6.5 and version 7 modelling and are accounted for in the risk estimates. However, the underreported events have not. An estimate of the likely extent of under-reporting has been made and a risk
contribution has been added to the final overall figures (indicated by numbers in square brackets [ ] after
risk figures).
HLOS Progress Metrics
The SRMv7 figures have been used to demonstrate progress against the HLOS safety metrics. These
have been calculated as follows:
•
SRMv7 passenger safety metric – 0.971 FWI per billion passenger kilometres.
•
SRMv7 workforce safety metric – 0.123 [0.126] FWI per million worker hours.
This represents a 1.8% decrease in the HLOS passenger safety metric and a 7.4% [6.5%] decrease in the
HLOS workforce safety metric. These should be compared against the target of at least a 3% reduction in
both of these safety metrics over CP4.
2
RSSB (2011) Independent Review of RIDDOR Reporting by Network Rail and its Contractors.
Page 2
Overview of the SRM-RPB – Version 7
Chart 2 illustrates the proportion of total risk for each exposed group, and highlights within each exposed
group the percentage of the risk from fatalities, major injuries, minor injuries, and shock/trauma. It can be
seen that risk to members of the public has the highest value at 44% of the total, followed by passengers
(37%) and then workforce (19%). For both passengers and workforce, major injuries contribute around
50% of the risk, while fatalities dominate the risk to the public (90.6%). Fatalities contribute 20.1% of the
risk to passengers, and 16.1% of the risk to the workforce.
Class 1 shock/ trauma
(0.002%)
Non-reportable minor injuries
(0.3%)
Total risk = 140.9 FWI/yr
Class 2 shock/ trauma (0.1%)
Reportable minor injuries
(0.6%)
Fatalities (20.1%)
Major injuries (8.4%)
Fatalities (90.6%)
Major injuries (55.1%)
Member of the
public
(44%)
Passenger
(37%)
Reportable minor injuries
(13.6%)
Workforce
(19%)
Non-reportable minor injuries
(10.1%)
Class 1 shock/ trauma (0.0%)
Class 2 shock/ trauma (1.2%)
Class 2 shock/ trauma (3.5%)
Fatalities (16.1%)
Class 1 shock/ trauma (3.9%)
Non-reportable minor injuries
(18.0%)
Major injuries (47.3%)
Reportable minor injuries
(11.1%)
Chart 2: Risk profile for the passengers, workforce and members of the public (% of total FWI/year)
Note: The direct risk from suicide and attempted suicide has been excluded, however all secondary risk associated with suicide has
been included.
Detailed risk profile
In version 7 of the SRM Risk Profile Bulletin (SRM-RPB), the 120 hazardous events have been grouped
into 22 categories. Chart 3 shows the risk profile for these categories, and also indicates the percentage
change in risk since version 6.5 (figures in brackets) for each category.
It can be seen that the greatest contribution to overall risk comes from trespass with 48.6 FWI/year. This
category is dominated by member of public fatalities and major injuries. The risk from trespass has
increased by 13% from version 6.5. The next highest contribution comes from slips, trips and falls with 30.6
FWI/year – the overall risk from this category has increased by 2% since version 6.5.
It can be seen that half of the categories have a level of risk of greater than 1.0 FWI/yr. Of those categories
which contribute significant amounts to the overall risk, only three exceed 10 FWI/yr (trespass; slips, trips
and falls; and assaults).
Page 3
Overview of the SRM-RPB – Version 7
0
5
10
15
20
25
30
35
40
45
50
Trespass
Slips, trips, and falls
30.6 (+2%)
Assault and abuse
11.5 (-5%)
8.8 (-18%)
Struck/crushed by train
On-board injuries
7.25 (-5%)
6.6 (-2%)
Platform edge incidents (boarding/alighting)
5.84 (-13%)
Contact with object
Platform edge incidents (not boarding/alighting)
Train accidents: collisions and derailments
Train accidents: collisions with road vehicles at level crossings
Manual handling/awkward movement
Falls from height
Suicide
Other
Road traffic accident
Train accidents: collisions with objects
Workforce electric shock
Machinery/tool operation
Fires and explosions (not involving trains)
Contact with person
Lean or fall from train in running
Train accidents: other
48.6 (+13%)
5.73 (+11%)
3.91 (+1%)
3.44 (-3%)
1.46 (-5%)
0.959 (-75%)
0.826 (-5%)
0.823 (+13%)
0.795 (+119%)
0.781 (+15%)
0.687 (-19%)
Passenger
Workforce
0.586 (-11%)
0.525 (+1%)
Public
0.462 (+35%)
0.424 (+6%)
0.255 (-16%)
Chart 3: Risk profile for the hazardous events categories
Note: The direct risk from suicide and attempted suicide has been excluded, however all secondary risk associated with suicide has
been included.
Further information
The risk breakdowns above, and others, may be found in version 7 of the SRM-RPB (June 2011). The
SRM-RPB contains risk profiles for each accident type, and for each person category, which show in detail
the hazardous events leading to the highest levels of risk.
An explanation of the modelling approach used is also included, along with a detailed description of the
changes that have occurred since version 6 (June 2009). The system boundaries are described in full, as
are the objectives of the SRM.
Following the update of the SRM to version 7, the SRM Risk Profile Tool (SRM-RPT) 3 will also be updated.
RSSB has produced Guidance on the Preparation and Use of Company Risk Assessment Profiles for
Transport Operators, which provides guidance to transport operators on how to prepare and maintain risk
assessments covering their operations. The principles in this document are designed to facilitate a
consistent and robust approach to risk assessment throughout the rail industry. The document also
suggests how to make the best use of the tools provided by the RSSB, such as the SRM-RPB and the
SRM-RPT.
Assistance
Copies of the SRM-RPB are available from www.safetyriskmodel.co.uk. If you would like assistance or
training in the use of SRMv7 and its outputs, please contact the risk team on 020 3142 5464 or
risk@rssb.co.uk.
3
Previously called the SRM Template Tool.
Page 4