RETURN HOME SAFELY

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RETURN HOME SAFELY HEAVY VEHICLE DRIVER
FATIGUE CHRIS JONES 19 JUNE, 2008
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Background

• Fatigue associated with approximately 30 of
  vehicle crashes
• Fatigue related crashes tend to be at the more
  serious end of the spectrum
• Costs
• Direct e.g. medical, damage to truck, cargo
• Indirect e.g. infrastructure, community
• Listed on National Transport Safety Bureau (USA)
  Most wanted safety improvements

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Contents

• The definition of fatigue
• Effects of fatigue
• Causes of fatigue
• Fatigue management

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Definition of fatigue

• Section 26 Model legislation
• (1) Fatigue includes for example
• Feeling sleepy and
• Feeling physically or mentally tired and
• Feeling exhausted or lacking energy and
• Behaving in a way that is consistent with (a)-(c)
• Note the subjective and objective elements of the
  definition

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Impaired by fatigue

• Section 27 Model law
• (1) A driver is impaired by fatigue if the driver
  is fatigued to the extent that he or she is
  incapable of driving safely
• (3) A court may consider a driver to be impaired
  by fatigue even if the driver has complied with
  any requirements under this act (ie hours) or
  under any other legislation

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Effects of fatigue

• Slower reaction time
• Variable reaction time
• Lapses
• Errors of commission
• Impairment of higher order cognitive functions
  (e.g. planning, decision making)
• Mood changes (e.g. irritability etc)
• Impairment of self assessment

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Effects of fatigue

• Accuracy of self assessment is moderate, at best
  (alcohol)
• Limits to introspection
• Habituation to situation (Especially in people
  with sleep apnoea)
• In many cases, when a nomination of being too
  fatigued is made, it is too late. (Report based
  on feedback, rather than introspection?)
• Not sufficient to just ask someone if they are
  too fatigued!

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Causes of fatigue

• 3 main factors
• Time awake
• Homeostatic sleep pressure
• Time asleep
• also affected by quality, consolidation, medical
  conditions
• Time of day
• circadian rhythms

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Factor 1 Time awake

• Homeostatic sleep pressure
• The drive to sleep that increases with time awake
• Functional equivalence studies have shown that
  after 17-19 hours of wakefulness, performance on
  certain tasks can be the same as a BAC of 0.05.
• After 9 hours (time on task) fatigue related risk
  starts to increase exponentially, such that after
  16 hours risk is tripled (Note these studies were
  undertaken measuring work time, rather than time
  awake).

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Factor 2 Time asleep

• Minimum sleep need is approximately 6
  hours per 24 hours
• 6 hours only allows maintenance of performance,
  typically at a lower level than fully rested
• Recovery typically occurs with a sleep
  opportunity of greater than 8 hours
• Single periods of sleep more effective than
  interrupted
• The gap between needed and obtained sleep is
  carried forward as a sleep debt
• The bank balance can never be positive!

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Factor 3 Time of day

• Circadian rhythmicity ca 24hr cycle
• Maximum waking influence during day
• Minimum waking influence during night
• Minor dip in early afternoon (2-4 pm)
• Best quality sleep obtained at night
• Adaptation can occur, but it appears that
  eventually it will return to the classic cycle

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Other factors

• Driver health
• Medical conditions, such as sleep apnoea
• General levels of fitness and health
• Type of task
• Certain types of task can have a temporary
  alerting effect
• Drugs
• Licit and illicit
• Food and hydration

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Managing fatigue risks

• Model Act requirement
• that parties in the Chain of Responsibility take
  all reasonable steps to ensure that a driver does
  not drive a HV while fatigued.
• Examples of reasonable steps are contained in s
  23 of the Model Act
• Duty relates to risk of an event occurring, not
  that it happened

Drivers, operators, receivers, consigners,
consignees, distribution centres, schedulers,
rosterers, loaders, unloaders management etc.
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Countermeasures

• Effective
• SLEEP!
• Napping
• Coffee (?)
• Not effective
• Winding window down
• Turning on radio

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Managing fatigue risks

• A single intervention is unlikely to eliminate
  fatigue risk
• Swiss cheese approach
• (J. Reason)

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Managing fatigue risks

• Examples of layers that could be added
• Scan how activities interact with fatigue factors
  (ie contracts that require too long wake / too
  short sleep opportunity)
• Survey what is happening (how many hours sleep
  are people getting)
• Conduct root cause analyses on accidents and near
  misses
• Policies in relation to napping (and provision of
  facilities)
• Staff training (note scheduler training
  requirements in Model Act)
• Ideally, fatigue management should be part of a
  holistic safety management system

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Managing fatigue risks

• An effective fatigue risk management system
• Addresses the causes of fatigue (time awake,
  sleep opportunity and sleep obtained, circadian
  rhythms)
• Is systematic (e.g. has reporting in place,
  adopts an appropriate methodology)
• Considers external interactions (e.g. incentives
  in commercial arrangements that may cause
  fatigue)
• Takes a shared responsibilities approach
• Works within a just culture framework

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Thank you