Human factors in investigations undertaken by the
Rail Accident Investigation Branch (RAIB)
Presentation to the International Railway Safety
Conference
October 2012
Simon French
Deputy Chief Inspector, RAIB
John Cope
Principal Inspector, RAIB
What is the RAIB?
 The RAIB is the
independent railway
accident investigation
organisation for
investigating accidents and
incidents occurring in the
UK
 The RAIB’s sole purpose is
to improve safety of
railways.
 The RAIB does not
apportion blame or liability,
nor enforce law or carry out
prosecutions
 The Chief Inspector reports
to Secretary of State for
Transport on investigations
How does the RAIB investigate human factors?
 All accidents are subject
to detailed analysis of
the causal chain
 This will lead to the
exposure of human
factors issues in the
same way that ‘pure’
engineering or
operational issues are
identified
Example of causal analysis
Door opens
(after Kettering)
Contradictory indications
associated with illumination
of desk Pass Comm lamp
Customer Host does not
immediately pull Pass
Comm handle on receiving
passenger report
No passenger pulls Pass
Comm handle
Driver unaware of open
door
Delayed response following
passenger observation of
open door
No Level 3 driver alarm to
Driver for door open
Loss of illumination of door
interlock lamp is not
observed
Train not immediately
brought to stop
Case study – Derailment of a freight train
The accident
 At around 02:40 hrs on a
November morning two
locomotives hauling a
freight train derailed on a
set of points.
 The immediate cause of
the accident was that the
signaller had not manually
set the points for the safe
operation of the train. The
points had failed earlier in
the evening.
Case study (cont’d)
The report findings fell into many categories
Technical
 The initial failure of the signalling equipment was causal
Operational
 Signallers had limited opportunity to practise emergency skills
 There was a lack of guidance to managers on how to deal with such incidents
Managerial
 There had been limited safety learning from previous similar safety incidents
 The roster worked by the signaller was not subject to assessment using fatigue
assessment tools.
 The duty holder had no suitable framework of controls to manage fatigue in
safety-critical staff.
Human Factors
 The support tools available to the signaller to help him when equipment failed
were insufficient
 It is probable that the signaller’s actions were affected by fatigue, as a result of
the number of hours and the nature of the shifts that he had worked.
RAIB’s general experience
 RAIB’s experience is biased
towards higher risk events and
the analysis therefore provides
useful data on the impact of
human factors in the causation
of high risk events.
 Of the 222 accidents and
serious incidents investigated
by the RAIB since October
2005, the actions of train
drivers featured in 47 of them
and the actions of track
workers in 26.
 It should be recognised that
the potential consequences of
errors by these staff are much
greater, so they tend to be
more prominent in RAIB
investigations.
Types of activity where human actions are linked
to accident or incident causation
 The RAIB analysed the investigations it has
carried out in order to:
 identify the types of railway activity and human
error that feature in RAIB investigations;
 find typical examples of the factors that apply;
and
 categorise and describe the types of barriers
that feature in recommendations.
Train driving error (features in 47 investigations)
 Loss of alertness leading
to signals passed at
danger, collisions,
derailments or loss of
control
 Misjudgements
 Errors while undertaking
unfamiliar tasks
 Errors arising from
competence management
failings
 Inappropriate/slow
response to alarms
 Violations (e.g.
overspeeding)
Error while working on the track (26)
 Lack of appropriate
experience
 Misunderstanding of rules
 Competence shortcomings
 Cultural issues
 Violation of rules including
disregard of warnings and
briefings
 Workload and competence
issues
 Insufficient planning
 Planning errors
 Insufficient communication
and coordination
Error during shunting and train preparation (16)





Competence issues
Ergonomic issues
Violations
Errors and oversights
Characteristics of
individuals
Intentional or unintentional misuse of level
crossings (16)
 Violations or inappropriate
behaviour
 Misjudgement
 Environmental factors
 Disregard of warning lights
 Design and ergonomic issues
 Sighting of approaching trains
 Information deficiencies
 Audibility of train horns at
footpath crossing
 Conspicuity of lights at
Automatic Open Crossing (with
no barriers)
 Capabilities of users (eg
eyesight)
Staff error at level crossing (9)




Individual performance
Competence
Distraction
Lapses in attention
Signalling error (13)
 Competence mismanagement of points
and signaller authorised
movement of train when
route not correctly set
 Violation - unauthorised
system of work during
equipment failure
 Human capabilities - poor
communications
Missed defect – infrastructure (15)
 Work overload leading to
missed inspection of points
in degraded condition
 Competence
 Supervision and instruction
 Monitoring and review
Third parties (eg road vehicle incursion) (5)
 Various lapses on the part
of road vehicle drivers
leading to incursions
Error during operation of road rail vehicles (4)
 Competence - poor ontracking technique and
over-reliance on interlock
and insufficient allowance
made for affect of poor
adhesion on steep gradient
 Training - lack of
awareness of how to
respond to runaway
Error during dispatch from stations (4)
 Ergonomics
 Competence
 Individual errors
Key themes
 Seven broad areas:
 knowledge-based mistakes
leading to a task being
carried out incorrectly;
 distraction, loss of
concentration;
 cognitive lock-up;
 loss of situational
awareness;
 inaccurate mental models;
 omissions; and
 deliberate violations
Barriers (as reflected in RAIB recommendations) [1]




Removal of the hazard
Enhancement of design:
physical measures to reduce the
likelihood of staff or members of
the public making errors or to
minimise their consequences
Enhancement of design
assurance and approvals:
these recommendations are
typically designed to prevent
design deficiencies that have
led to human error from being
replicated in future trains and
infrastructure.
Steps to address safety
culture: such recommendations
are designed to address
attitudes and behaviours within
railway organisations
Barriers (as reflected in RAIB recommendations) [2]
 Management process;
typically these are changes to
management arrangements in
order to better manage a
particular risk:
 Enhancement of procedures
(operational, maintenance,
etc.): this can be done to
implement an improved
process or alternatively to
improve the clarity of existing
procedures.
 Training & competency:
since the safety of the railway
is critically dependent on the
professionalism of its staff
many recommendations
address the way that staff are
trained and assessed as
competent.
Final thoughts
 Human factors are a
significant feature in the
causation of many accidents
 Investigating the underlying
issues can be difficult
 It is often easier to
understand why humans
behave in the way they do
than it is to define a course of
action that will correct that
behaviour
 That does not prevent us
from trying to identify the role
that human factors play in
accidents and incidents
Further work
 In conclusion
 There is much to be learnt from a detailed analysis of
accidents and incidents
 The RAIB plans to extend and refine its analysis, and to
prepare a database of the human factors that have been
identified in investigations, and the associated mitigation
measures
• to inform future investigations
• as a source of data for investigators and researchers
• We intend to do this in consultation with RSSB and
others in the railway industry
Thank you