Human elements of system safety: Fatigue risk management - PowerPoint PPT Presentation

Human elements of system safety: Fatigue risk management

Introduction • Safety improvement project • Human elements of system safety: – Human factors integration – Fatigue risk management • Practically oriented • Share common issues • Successes • This visit not part of compliance program 2

Topics • Importance of managing fatigue-related risk – Fatigue, safety and productivity • Fatigue risk management in practice • Achieving compliance 3

Your needs and expectations? 4

The regulatory context • Human factors taken into account in – SMS development, SMS Human factors – SMS operation – SMS maintenance • Human factors principles/knowledge Human Factors integrated into operational and business systems National Regulations Schedule 1 Cl 17 5 5

Fatigue is one of many performance influencing factors Distraction D&A Expectation Fatigue interacts with and amplifies Fatigue other performance Workload influencing factors Time Systems Environ pressure Health and ment procedures Stress Experience pre- occupation 6

The regulatory framework • General duty General duty – RSW not fatigue (fatigue SMS ‘impaired’ impairment) • FRMP integrated into SMS Human factors • Regulations: Human Factors – Risk based approach Fatigue Monitoring & – Specified fatigue hazard & risk Risk review, hazards to be assessment  identification Reporting considered Safe hours of • ---- • ---- ( KPI’s, work (SFAIRP) – Monitoring of planned Hours of work) vs. actual hours – Occurrence reporting (breaches of scheduling Fatigue Risk practices) Management Program – Notification of change (work scheduling practices) 7 7

The regulatory framework RISSB Fatigue Risk Management Guidance •Information on research and technologies •Case studies 8 8

Importance of managing fatigue related risk Fatigue, safety and productivity

The context of rail operations • 24/7 operations • Sustained attention tasks • Busy one hour, monotonous the next • Systems depend on human performance Image credit: Abigroup 10

Fatigue • Largest identifiable and preventable cause of accidents in commercial transport modes • 15-20% of all accidents • More than drug/alcohol incidents • Often underestimated Akerstedt 2000 11 11

Incident cost – US rail data Human factors accident – average cost Human factors accident x 4 $1,800,000 (with likely fatigue) $1,600,000 $1,588,000 $1,400,000 average cost $1,200,000 $1,000,000 All causes accidents $800,000 $489000 $600,000 average cost $400,000 $200,000 $0 Low fatigue High fatigue Source: US Department of Transportation Federal Railroad Administration 2011 12

Fatigue and risk Fatigue MECHANISM

Sources of fatigue Work environment Task dimensions Social/psychological factors Rest environment Human physiology Blocks image credit: www.freeimages.co.u

Sources of fatigue – human physiology • Circadian (body clock) rhythm effects • Time awake • Sleep inertia • Sleep loss over days (chronic sleep loss) 15

Sources of fatigue – sleep physiology • Circadian(body clock) rhythm effects MODEL OF SLEEP (circadian) cyclical alerting process 16

Sources of fatigue – sleep physiology S • Circadian(body clock) rhythm effects • Time awake MODEL OF SLEEP S leep process = drive to sleep with time awake C (circadian) cyclical alerting process 17

Sources of fatigue – sleep physiology S • Circadian(body clock) I sleep inertia rhythm effects • Time awake • Sleep inertia (grogginess) MODEL OF SLEEP S leep process = drive to sleep with time awake C (circadian) cyclical alerting process I Sleep Inertia = transient grogginess 18

Sources of fatigue – sleep physiology N = 17 Z > 4.16 3.08 2.58 2.33 1.65 Source: Wright et al 2013 19

Sources of fatigue – sleep physiology Combined effect of circadian rhythm and extended N = 17 wakefulness Z > 4.16 3.08 2.58 2.33 1.65 20

Circadian effects on performance Source: Folkard and Tucker 2003

Circadian effects on incident risk: UK SPADs Passenger Freight Maintenance Source: RSSB 2010 Research Programme T699 Appendix F 22

Circadian effects on train driver sleep Arbitrary line at 5 hours for comparison purposes Source: Roach et al 2003

Effect of longer break = more sleep Arbitrary line at 5 hours for comparison purposes Source: Roach et al 2003

Sources of fatigue – physiology Chronic sleep loss effects Performance deterioration Self rated sleepiness Van Dongen et al 2003 (Figures from Hursh 2010)

Sources of fatigue – physiology Chronic sleep loss effects No sleep 4 hours time in bed No sleep 6 hours time Performance Lapses in bed 8 hours time in bed 14 days of restricted sleep 2 4 6 8 10 12 14 Source: Van Dongen et al 2003 Days of sleep loss

Sources of fatigue – physiology Sleep loss and performance 800 0 12 Hours Awake 600 0 400 0 200 0 0 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 800 0 36 Hours Awake 600 0 400 0 200 0 0 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 800 0 60 Hours Awake 600 0 400 0 200 0 0 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 800 0 84 Hours Awake 600 0 400 0 200 0 0 1 4 7 10 13 16 19 22 25 28 31 34 37 40 43 46 49 52 55 58 61 64 67 70 RESPONSE NUMBER Source: Van Dongen & Hursh 2010 27

Number of consecutive shifts and incident risk: UK SPADs Passenger Freight Maintenance Consecutive shifts Data source: RSSB 2010 Research Programme T699 Appendix F 28

Sources of fatigue – physiology Recovery from sleep loss 9 hrs 8 hrs 7 hrs 5 hrs 3 hrs Belenky et al 2003 recovery sleeps restricted to 7 days of restricted sleep 8 hours time in bed

Sources of fatigue – task effects • Time on task 30

Continuous hours worked and incidents - UK SPAD data Passenger Freight Data source: RSSB 2010 Research Programme T699 Appendix F 31

Sources of fatigue – social/psychological factors HEALTH Obesity Shiftwork sleep disorders Diseases SHIFTWORK MENTAL STATE Productivity Sleep loss Mood Unpredictable hours and Emotional control Irregular hours Stress Safety Limited control Depression Penalty rates SOCIAL WELL BEING Relationships Family harmony Financial security 32

Recap – sources of fatigue • Physiological factors What controls are in – Circadian place for these – Time awake hazards? – Sleep inertia 1. ……… – Sleep loss over days • Task and workload 2. ……. • Social/psychological 3. …… Others: – Work environment – Rest environment – Commuting – …

Fatigue and risk MECHANISM Errors TASK…..……….…… Fatigue …….. Violations

Attention • Decreased attention span • Lapses on attention rich tasks (eg monitoring, driving) • Tunnelling – narrowing of field of attention • Micro-sleeps • Sleep incapacitation 35

Video extract from documentary Dead Tired has been removed 36

Cognition (thinking) • Slower to interpret and integrate information • Short term recall, working memory • Reduced ability to learn • Decision making  Difficulty weighing up options  Persist with ineffective responses 37

Motivation and insight • Compensatory effort to maintain performance • Initiate tasks ok but then deteriorates • Divert attention to interesting tasks • Neglect tasks judged to be non essential • Less interested in outcomes • Less likely to pick up someone else’s errors • End goal seduction 38

Emotional control • Feeling low and irritable • Inability to suppress responses • Terse communications 39 Source: Walker 2009

Summary: fatigue effects on performance Decreased Increased error detection error and recovery probability 40

Summary: fatigue effects on performance Decreased Short cuts & likelihood of violations detecting more likely problems 41

Fatigue risk management in practice: Developing and reviewing the FRMP

Multiple layers of defence Optimise alertness & Optimise sleep Manage errors performance Error Work Fitness for Job/task Work Engineered detection Staffing scheduling task design controls environment and recovery Fatigue- Fatigue- related slip, lapse, related Z mistake, or incident Z violation Z Investigate incidents and initiate corrective action *Layers of defence and accident trajectory concepts based on Reason, J 1997. Managing the risks of organizational accidents, Ashgate, Aldershot 43

Scoping the fatigue management program Likely exposure Likely exposure Risks of tasks Risks of tasks to fatigue to fatigue Scope of Scope of fatigue risk fatigue risk management management program program High risk tasks, High risk tasks, Low risk tasks, Low risk tasks, high fatigue high fatigue low fatigue low fatigue exposure exposure exposure exposure = detailed = detailed = basic program = basic program program program 44