Human factors refer to the scientific study of interactions between humans and other elements of a system, and the application of principles to optimize human well-being and performance. In railways, human factors consider all people-related issues that impact safety and effectiveness. The goal is to create a working environment that contributes to healthy, safe operations. Some key human factor considerations in railways include individual characteristics, team dynamics, and organizational policies that can influence behavior and safety. Understanding the causes of human failures through models like the Swiss cheese model can help design control measures to prevent accidents.

1. Human Factors in Railway &
Transportation
By- Shiv Mohan

2. Human Factors
“The study of ergonomics (or human factors) is a scientific discipline concerned with
the understanding of interactions among human and other elements and the profession
that applies theory, principles, data and methods to design in order to optimize human
well-being and overall system performance”
In the specific railway domain, we find the following definition for Human Factors:
“all the ‘people’ issues we need to consider to assure the lifelong safety and
effectiveness of a system or organisation”[RSSB, Understanding Human Factors]
Human factor: A scientific discipline that applies systematic methods and
knowledge about people to evaluate and improve the interaction between
individuals, technology and organisations. The aim is to create a working
environment (that to the largest extent possible) contributes to achieving healthy,
effective and safe operations
[MTO Safety, “Study on the assessment and the acceptance of risks related to human interactions within the European
railways” – Final report. http://www.era.europa.eu/The-Agency/Procurement/Pages/ERA_2011_SAF_OP_02.aspx ]
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3. Human Factors
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Human factors refer to
environmental,
organisational and job
factors, and human &
individual
characteristics which
influence behaviour at
work in a way which can
affect health & safety

4. Why is the study of Human Factors
important
1- To ensure well-being and optimise performance
2- To contribute to the efficiency of risk control measures
3- To Predict the likely effect on Railway Operation
4- To design more effective organisations
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5. Human Factors
 Individual factors- health and fitness for duty, drugs and alcohol, fatigue,
ergonomics, motivation, work load (high and low), stress, cognitive factors
(vigilance, memory, situational awareness), task experience, competencies
and human error
 Team factors - social norms and behaviours, peer pressure, communication,
team climate, diffusion of responsibility, morale, sharing of work
 Organisational factors - change management, safety culture, leadership,
supervision, policies and procedures, environmental aspects, equipment,
rosters and staffing, planning and resource management, emergency
management, physical facilities and equipment.
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6. Human Factors
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8. Causes of Human failures - 1
 JOB FACTORS
1. illogical design of equipment and instruments
2. Constant disturbances & interruptions
3. Missing or unclear instructions
4. Poorly maintained equipment
5. High workload
6. Noisy or unpleasant working conditions
 INDIVIDUAL FACTORS
1. Low skill and competence levels
2. Tired staff
3. Bored or disheartened staff
4. Individual medical problems
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9. Causes of Human failures - 2
 ORGANISATION & MANAGEMENT FACTORS
1. Poor work planning, leading to high work pressure
2. Lack of safety systems and barriers
3. Inadequate responses to previous incidents
4. Management based on one way communication
5. Deficient co-ordination and responsibilities
6. Poor management of health and safety
7. Poor health & safety culture
 Very Often, little attempt is made to understand why the human failures
occurred.
 However, finding out both the immediate and the underlying causes of an
accident is the key to preventing similar accidents through the design of
effective control measures.
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10. Swiss Cheese Model
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11. Accident Pyramid
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12. Human Failures
• 90% of workforce accidents have human error as cause . But generally human
error is taken as operator error though in majority of cases measure of
responsibility lies with system designers
• Human error has causes, some understood some not. But human errors can
be controlled both through proper system design and organization and
management factors.
• Human error was a factor in almost all the highly publicised accidents in the
recent history.
 Clapham, Ladbroke grove, Southall rail accidents
 Limitations of human behaviour
 Human characteristics that can lead to difficulties interacting with the
working environment:
 Attention
 Perception
 Memory
 Logical Reasoning
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13. Human Failures
 Limitations of Human Behaviour
 1- Attention
 For a fairly short period – 20 minutes.
 To small number of tasks at a time.
 2. Perception
 We are forced to interpret information while perceiving the world. i.e. we
sense rather than access it directly.
 3. Memory
 Limited capacity - remembering things and accessing this information in
case of need.
 4. Logical reasoning
 Humans are not very good at thinking logically. Because of above
limitations human failures take place
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14. Active & Latent Human Failures
 Active failures have an immediate consequence and are usually made by front-line people such
as drivers, control room staff or machine operators. In a situation where there is no room for
error these active failures have an immediate impact on health and safety.
 Latent failures are made by people whose tasks are removed in time & space from operational
activities. E.g. designers, decision makers and managers. Examples of latent failures are:
 Poor design of plant and equipment
 Ineffective training
 Inadequate supervision
 Ineffective communications; and
 Uncertainties in roles and responsibilities
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15. Human Failures
 Human failures can be
categorized into two
 ‘Error’ and ‘Violation’
 Error – an action or decision
which was not intended and
involved a deviation from an
accepted standard leading to
undesirable outcome.
 Violation – Deliberate
deviation from rule or
procedure
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16. The Nature of Human Error
 Accidents rarely have single cause, usually they result from a no. of hazards
combining in place and time due to

 Failures of Procedures
 Management Direction
 Equipment
 People
Either latent or occurring simultaneously
 The final differentiating factor between a serious incident and a “near miss”
is chance
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17. Example
• The fire killed 31 people and injured
100 people in
• Immediate cause- ignition of waste
material beneath an old escalator
• The incident was due to
- failures in overall management
- Design Failure
- Installation Failure
- Maintenance failure
- Communication Failure
- Failures in Training
- Failures of Emergency procedures
KINGS CROSS FIRE
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18. CLAMPHAM ACCIDENT
 35 people died and nearly 500 were
injured.
 Immediate cause- signal failure due
to a wiring fault. New wiring had been
installed, but the old wiring had been
left connected at one end, and loose
and uninsulated at the other.
 There was other contributing factors
- working practices were wrong
- Inadequate supervision
- worked a 7 day week for the previous
13 weeks
- Inadequate training with poor work
procedures
- Unrealistic requirement from General
management in terms of cost and
time scale
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The Clapham Junction rail crash was a
multiple train collision just south
of station in London that occurred on 12
December 1988.

19. Conclusion from Examples
 1- Develop the measure to prevent occurrence or limit the consequence
when they occur
 2- Human behaviour and Human error play a major role in railway accidents
 3- Human errors have often been described as misbehaviours or negligence
by operator but there are several contributing factor
 4- Human behaviour takes place in a physical, social , technical and
organizational context where many people play a part
 5- At each interface point, there is a need to define the human process and
the expected performance
 6- identify the possible sources of errors and mitigate them by design or
process.
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20. Human Errors - types
 Types of Human Error
 Perception Error – Information not consciously perceived, since mind preoccupied.
 E.g. View correct signal but misread aspect
 Signal with less sighting time or Signal in which information drowned in a large
number of stimuli
 E.g. Failure to locate the signal
 Decoding Error- Stimulus received and perceived but not interpreted correctly.
E.g. Driver reading wrong signal
 Misrepresentation error - People act according to their understanding based on
mental models.
 E.g. Approach release signal – driver knows it will clear.
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21.  Wrongly timed action
 When to brake – decision depends on speed. Will be different if driver has just
started from station, or train is travelling at less than line speed, train is subject
to speed restriction etc.
 In British Railways, heavy reliance is placed on driver’s knowledge of route in
order to ensure that he acts on caution signal at right time.
 Wrongly executed action
 Misjudged train behaviour, misjudged environmental conditions
 Includes all misjudgments of train handling, failure to take account of adhesion
conditions and gradient etc.
 Communication error
 Wrong information communicated
 Ambiguous or incomplete information
more of concern during degraded situation
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22. Human Errors - Factors
 Triggers to Human error
 Individual stressors – family problems, ill-health, tired, boredom, alcohol &
drugs, inadequate training & experience.
 Equipment stressors – illogical design of equipment and instruments, poorly
designed displays & controls, inaccurate & confusing instructions &
procedures, poorly maintained equipment (frequently failing).
 Work environment stressors – poor lighting, extreme heat and humidity,
restricted workspace, noise, vibration.
 Extreme task demands – high workload, tasks demanding high levels of
alertness, monotonous and repetitive job, situations with many distractions
and interruptions
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23. Human Errors - Factors
 Social, Organization & Management Stressors
- Insufficient staffing levels,
- Inflexible or over-demanding work schedules (due to poor work planning),
- poor management of health & safety, poor health & safety
culture,
- Lack of safety systems and barriers,
- Inadequate responses to previous incidents,
- One way communication by management,
- Deficient coordination and responsibilities
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24. Operator Process
- Making decisions
- Forming intentions to act
- Consequential action
 We must accept the possibility of error and the consequences of error.
System are designed to minimise these errors but
 Qualities required in Human Operator ( essential for minimum error rate)
 1- Skill , knowledge and understanding of the operating rules
 2- understanding of the plans and ability to respond to changes to plan
 3- ability to check and evaluate the information
 4- ability to perceive when intervention is necessary
 5- ability to behave consistently under stress when the situation is urgent
and possible consequences are severe
 6-
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25. Information
- Operators working with routine information and standard procedures show
automatic or skill based behaviour
- In Degraded and Emergency scenario, operators to apply predetermined
solutions, acting according to rules or follow a step by step process of
thinking and decision making to act safely
- Information processing behaviour can be shaped by the perception of risk or
danger, experience , learning, motivation and attitude
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26. Comprehension
 1- Information design in terms of display and meaning must be consistent,
unambiguous, easily detectable and easily understandable
 2- Human actions are always related to an individual prehistory and a social
environment. When drastic decisions have to be taken, preconditioning can be
imp cause of error.
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27. Human Process of Information
 1- Human errors are unavoidable
 2- Human information processing is determined by the ability to absorb and
evaluate information, the capability of short term memory and the capacity
of longer term memory
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Level of Human
behaviour
Stress due to
too low demands
Optimum level
of Stress
Stress due to
excessive demands
Based on Skills 2/1000 1/1000 2/1000
Based on rules 2/100 1/100 2/100
Based on
Knowledge
2/10 1/10 2/10

28. Adaptability
 1- As an operator , human has proved himself to be a highly flexible control
mechanism
 2- Human is capable of grasping very quickly the logical connections in large,
complex quantity of data and of filtering out meaningless data
 Stress-
 1- Human performs best under a sufficient high degree of stress. When stress
exceeds a specific level , it becomes distress and causes drastic drop in human
performance
 2- Distress impairs the power of judgement and determination and totally
cancel or misdirect attention
 3- Human only functions optimally with a controlled flow of information.
Monotony and overstimulation increases the error rate
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29. Human Errors - Control and reduction
 Error control and reduction
• Addressing the conditions and reducing the stressors which increase frequency of
error.
• Designing system keeping user in mind and limitations of human beings.
• Designing plants and equipment to prevent slips and lapses, increase the chance of
detecting and correcting them.
• Task design keeping human limitations in mind. Proper shift arrangement.
• Effective training arrangements, Job rotation & Job enrichment
• Ensure proper supervision for inexperienced staff, or for tasks where there is a need
for independent checking
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30. Human Errors - Control and reduction
• Creating procedures and instructions which are clear, concise, available, up-to-
date, accepted by users.
• Separate procedure for rare events requiring decisions and actions.
• Considering possibility of human error during risk assessments.
• Incident investigation to look for human causes so as to reduce risk of a repeat
incident
• Monitoring measures to reduce error for effectiveness.
• Errors can also be reduced by good quality management system and safety
management system
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31. Human failures - Violations
 Violations
 Deliberate deviation from rules, procedures, instructions and regulations.
 Routine- Breaking rule or procedure is normal way of working.
 Situational - Breaking rule due to pressure.
 Exceptional- Happens in abnormal situations
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32. Human failures - Routine Violations
 Reasons for Routine Violation
 The desire to cut corners to save time and energy
 The perception that the rules are too restrictive
 The belief that the rules no longer apply
 Lack of enforcement of the rule; and
 New workers starting a job where routine violations are the norm
 Reducing Routine Violations
 Routine monitoring
 Improve design that does not allow corner cutting
 Involve people in making rules. Do away with unnecessary rules.
 Increase awareness. Explain the reasons behind certain rules or procedures and
their relevance
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33. Human failures - Situational Violations
 Reasons for Situational Violation:
 Braking rules due to pressure
 under time pressure, insufficient staff for the workload, the right equipment not
being available, or even extreme weather conditions.
 Reduce Situational Violation:
 Improving the working environment
 Appropriate supervision
 Improving job design and planning
 Establishing a positive health and safety culture
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34. Human failures - Exceptional Violation
 Exceptional
 Rarely happen and only then, when something has gone wrong.
 While handling a new problem people break rule in false belief that the benefits
outweigh the risks.
 Steps to reduce:
 Provide training and organise drills for handling abnormal and emergency
situations
 Think during risk assessment
 Try to reduce the time pressure on staff to act quickly in novel situations
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35. MAN- MACHINE INTERFACE
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36. Man Machine Synergy - 1
 Human Strengths
1. Capable of grasping very quickly the logical connections in large, complex quantities of data &
filtering out meaningless data
2. Able to combine a wide variety of impressions to form opinions and draw conclusions
3. Able to spot mistakes easily when data is shown graphically
4. Possessing an almost inexhaustible flexibility in dealing with unforeseen events
5. Powers of rapid perception along with capacity to think analytically
6. Able to make quick decisions
7. Possessing self discipline and sense of responsibility
8. Able to adapt and improvise
9. Able to understand complex systems
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37. Man Machine Synergy - 2
 Strong Points of Automatic Systems
1. Work faster than man can think
2. Work consistently and predictably within the range of tasks allotted to them
3. Work quickly and efficiently with in their programmed range
4. Perform perfectly a large number of simple functions
5. Fault tolerant architecture can be provided
 Negative Consequences of Automatic Systems
1. Automatic systems reduce the human’s manual dexterity since they do this simple work in
most situations, reducing the ability of humans to take over functions when there is a
problem
2. Automatic systems perform much of their work independently, but do not free man of
responsibility for the performance of the overall system.
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38. Man Machine Synergy - 3
 Negative Consequences of Automatic Systems (contd.)
3. When the reliability of automatic systems is perceived as being very high
operators are less attentive, often without realising it.
4. Monitoring systems are often more prone to error than the systems they
are supposed to be monitoring, leading to many false alarms.
5. Systems can provide too much information, making it difficult to discover
real anomalies quickly.
6. The automatic system depends on the instructions it receives from man
and must ultimately remain under his control.
 The distribution of work between man and automatic systems should
combine the merits of both.
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39. Human Interaction
- Interaction plays major part in safety of
railway operation
- Ever increasing with higher traffic,
automation and increased outsourcing
- Role and interaction with system, device
or equipment
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40. Human Ergonomic
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41. Designing for People: Ergonomics
 Ergonomics is the application of scientific knowledge about humans to the design of
products, systems and environment.
 Objective of Ergonomics is to improve efficiency, safety and a sense of well being.
 Ergonomics should be properly integrated into the development life cycles of systems. It is
now accepted good practice to consider Human Factor & Ergonomics at each stage of
design, for every railway related system that includes human activities.

 For Ergonomic design of controls on a panel following aspects can be considered.
 Size (relative to force required), Weight (relative to user position)
 Resistance (to prevent accidental use), Feedback (to user’s senses)
 Coding by colour, coding by shape, coding by texture, coding by size
 Location, Compatibility (between displays & controls)
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42. Human Factors in Safety Management
System • Management Commitment
• Safety Policy
• Risk Management
• Job Design
• Competence Management
• Collection of Safety Data (Monitoring)
• Investigation of accidents/incidents
• SMS review based on emerged HF
• Information flow
• Internal and External Communication
• Change Management
• Organisation learning
• Continuous improvement
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43. Competence Management
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44. Conclusion
 1- The Development of high technology systems does not necessarily ensure overall system
reliability. Even in automated systems human beings are essential to ensure safe and
efficient operation. Your action is very important for safety
 2- Good human reliability is best achieved by ensuring that human being is properly
integrated to Process. Follow the process
 3- The availability of suitably qualified and competent staff is essential. Please ensure that
you are competent
 4- The Human error rate can be minimised by training, motivation , applying theories of
ergonomics and labour psychology. Please make sure you are trained and keep yourself
motivated
 5- Training and Experience is critical to achieve performance level. Ask if you require
additional training
 6- Provision of relevant information and guidance is important . Refer the Rules &
Procedures
 7- Effective Safety Communication is paramount for system safety and reliable operation
 8- Incident information and documentation are essential for the identification of risk and
encouragement of a high degree of safety responsibility amongst employees.
 9- Root cause analysis of failures and incidents must include human behaviour analysis to
improve safety

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