Fatigue and sleepiness as risk factors in road traffic

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Fatigue and sleepiness as risk factors in road
traffic

• Fridulv SagbergInstitute of Transport Economics,
  Oslo

Meeting on Fitness to drive, Brussels, April
28, 2005
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IMMORTAL workshop on driver fatigue Main topics

• The scope of the problem
• Daytime sleepiness general and clinical aspects
• Precursors and indicators
• Driver warning systems
• Managing occupational driver fatigue

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IMMORTAL Deliverable P4.2

• Edited by Fridulv Sagberg, TØI
• Contributors
• Paul Jackson Awake Ltd, London
• Hans-Peter Krüger Universität Würzburg
• Alain Muzet CNRS-CEPA, Strasbourg
• Adrian Williams St. Thomas Hospital, London

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Driver fatigue A serious problem

• Incidence of falling asleep while driving gt 10
  per year
• About 4-5 of falling-asleep incidents result in
  crashes (including personal injury or property
  damage)
• In addition An unknown number of crashes where
  the driver is fatigued but not actually falling
  asleep
• Young males are over-represented
• Long-distance truck drivers are at high risk

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Consequences of falling asleep at the
wheel(Norwegian study, n1061)
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Crashes related to driver fatigue

• Between 5 and 15 of all personal injury crashes
  are related to fatigue (estimates vary
  considerably)
• High average severity
• Rural roads, low traffic and/or night-time
• Most fatigue-related crashes occur during daytime
• Higher risk during the night, but less traffic
• Night-time crashes are more severe

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Daytime sleepiness Main influences

• Amount of sleep
• cumulative effect of less-than-normal sleep for
  several consecutive nights
• Time since sleep
• Circadian rhythm
• Sleep-related problems/disorders

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Sleep-related disorders

• Obstructive sleep apnoea/hypopnoea syndrome
  (OSAHS)
• High prevalence among middle-aged men (4-5 )
• Narcolepsy
• Prevalence 1 in 2000
• Effective treatment available
• Normal sleep problems
• Difficult to fall asleep
• Waking up to early
• Drivers who report sleep problems are
  overrepresented in crashes

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Drivers with sleep problems are over-represented
in crashes

• Relative risk estimates from IMMORTAL
  case-control study
• Frequent sleep-onset insomnia 1.87
• Frequent tiredness 1.36(frequent once per
  week or more)

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What sleepy drivers do

• Most drivers feel various symptoms of tiredness
  before falling asleep at the wheel
• Symptoms may possibly be misinterpreted or
  ignored
• Many drivers erroneously think they can stay
  awake by effort
• They often try inefficient countermeasures
• opening window, playing music, etc.
• Therefore Countermeasures relying only on driver
  actions will have limited effect

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Driver warning systems

• Based on recording driver behaviour
• physiological indicators, eyelid closure, driving
  performance
• Warn driver when early signs of sleepiness are
  detected
• Interfere with driving (take over control to stop
  the car) when serious sleepiness is detected
• Ongoing research in other EU projects, e.g. AWAKE
  (see www.awake-eu.org)

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Fatigue management in occupational settings

• Educational programmes for companies
• Include fatigue management in company policy
• Work organisation
• Adequate shiftwork schedules
• Trip planning

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Policy implications

• Base countermeasures on the fact that many
  drivers are not motivated to stop driving when
  fatigued
• Warn drivers
• Further research on in-car systems
• Increased use of profiled edgelines and
  centrelines(rumble strips)
• Implement fatigue management in Occupational
  Health and Safety legislation
• Stimulate research on optimal rest-work
  schedules, as a basis for improved
  Hours-of-Service Regulations
• Inform the general public about sleep disorders
  and other risk factors
• Prevent serious consequences
• Forgiving road system
• Car occupant protection systems