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Human Factors in Road Infrastructure Design

• María Alonso
• Human Factors Department, CIDAUT
• Road Safety Engineering Seminar
• BUDAPEST (27-28th June 07)

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Human error

• Everyone commits mistakes

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Human error
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Human error

• 90-95 of all road accidents have HUMAN ERROR
  as a component (Treat, 1977)

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Human error

• Treat (1977, et al.) performed a 5 year study
  that examined the causes of 2258 automobile
  accidents. Human error was the sole factor in 57
  and a contributing factor in 92.6.
• Treat et al. further found that of accidents
  caused by human error, perceptual error was
  involved in 90 and response error in only 10.
  If these results generalize to the other studies,
  then perceptual error is an important factor in
  over 80 of all automobile accidents.

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Human error

• Do not blame the driver!
• Not unsafe driver but unsafe system
• gt investigate the traffic system

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Human Factors

• Performance limitations
• Human performance fails if conditions exceed its
  tolerance limits

Personality
Fatigue
Alcohol
Memory
Decision making
Drugs
Information processing
Emotion
Sensation and perception
Stress
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Human Factors

• Examples of degraded performance
• Diminished ability to concentrate
• Increase in judgement errors
• Increase in failed detection of critical events
• Needless risk-taking
• Human Factors may be defined as the technology
  concerned with the analysis and optimisation of
  the relationship between people and their
  activities, by the integration of human sciences
  and engineering in systematic applications, in
  consideration for cognitive aspects and
  socio-technical working contexts (Cacciabue,
  P.C., 2004)

Human Factors
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DVE system
Vehicle
Environment
Driver
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Road infrastructure

• Road infrastructure gt drivers - environment
  interface
• information as a guide for drivers activity and
  their interactions with other road users through
• road elements
• the environmental context (Saad, F., 2002)

Vehicle

• Environment
• Road
• Roadside
• Weather Traffic conditions

• Driver
• State
• Personality
• Task demand

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HCD

• Human Centred Design needed by
• both engineers (knowledge of the traffic system
  and previous actuations) and traffic
  psychologists (understanding of human performance
  and behaviour)
• User Centred Design (UCD) approach, ISO 13407

preferences
DRIVER
expectations
needs
capabilities
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SER

• Self Explaining Roads
• How could the infrastructure
• support drivers activity?
• Adoption of homogeneous and consistent design
  principles that take account of the different
  tasks to be performed by the various road users
  and the constraints on their execution.
• Positive guidance
• Road readability

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RANKERS experimental work

• RANKERS experiments

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RANKERS experimental work

• Experiment 1
• Road layout vs. driver performance
• Experiment 2
• Road signs vs. driver perception and
• situation awareness

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2
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Experiment 1

• Objective
• Road layout VS. Driver performance
• Analyse speed variation as a function of radius
  of curvature, taking into account other variables
  which also influence drivers choice of speed
  curve direction, roadside environment.
• How do drivers approach a curve? At which speeds?
• When do they start to react to it? Braking or
  releasing gas pedal?
• How do they behave along the curve? Curve
  negotiation

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Experiment 1

• Scenario
• AP-66 motorway (León - Campomanes)

PICTURES
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Experiment 1

• Experimental vehicle

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Experiment 1

• In-depth exploration, expert analysis
• Experts drive session for road inspection

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Experiment 1

• Field Studies experimental design
• - Variables -

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Experiment 1

• Field tests
• Video
• test example

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Experiment 2

• Objective
• Analyse road sign features (design, content,
  amount) in terms of their adaptation to road
  environment, traffic situation and driver needs.
• Can drivers perceive certain road signs?
• Can they interpret them?
• Is the number of signs appropriate? Are them
  visible?

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Experiment 2

• Scenario
• AP-15 motorway (Tudela - Irurtzun)

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Experiment 2

• First exploratory phase
• Experts drive session for road inspection
• Video recording

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Experiment 2

• In-depth exploration, expert analysis
• Analysis of encountered problems

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Experiment 2

• Users Tests
• Subjective analysis of significant aspects of
  traffic signs
• 20 subjects
• Gender Male Female
• Age gt 25 years
• Experience gt 10.000 km driven
• Tools
• Driving profile questionnaire
• Traffic signs questionnaire

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Experiment 2

• Traffic signs questionnaire

• General aspects
• Indication
• Shape
• Colour
• Reinforced message
• Highlighted features
• Obstacles
• Is this sign necessary?
• Could this sign cause distraction?
• Appropriate frequency

• Assessment of traffic features
• Location
• Size shape
• Colour vs. Environment
• Text
• Symbols and Icons
• Typography
• Amount of information
• Contrast
• Distribution of contents

• Global assessment 1-5

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Results

• Experiment 1
• Road layout vs. driver performance
• Experiment 2
• Road signs vs. driver perception situation
  awareness

Recommendations Best practices
RANKING OF RECOMMENDATIONS
RSI eBook
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What to avoid?
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What to encourage?
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Human Factors in Road Infrastructure Design

• Thanks for your attention!