Published on February 28, 2008
Fatigue and Driving : Fatigue and Driving Laurence Hartley, Murdoch University Western Australia. Terminology: Terminology Europe Sleepy drivers America Drowsy drivers Australia Fatigued drivers All synonymous with loss of alertness at the wheel, microsleeps, poor vehicle control, single vehicle crashes Renewed interest in fatigue: Renewed interest in fatigue Increased economic activity Globalisation Longer journeys Just in time delivery Increased fuel costs mean more work Increased industry competition Size of the problem: Size of the problem Fatigue survey & crash statistics Surveys : Surveys U.S. NSF 1998 32% sleep < 6 h 66% adults with sleep problem 8% with a sleep disorder 38% with excessive day sleepiness 57% have driven drowsy 23% had fallen asleep at the wheel U.K. Maycock 1997 29% close to falling asleep at wheel Fatigue related crashes : Fatigue related crashes U.S. AAA 1985, 40% of 221 truck crashes AUS Haworth 1988, 20-30% casualties & 25-35% of fatal truck crashes U.S. Federal Motor Carrier Safety Administration estimates 15% fatals AUS Ryan 1995 estimates 16% trucks U.K. Horne 1995 estimates 16-20% of all AUS fatigue crashes analysed using proxy measures: AUS fatigue crashes analysed using proxy measures Fatigue state of driver usually unknown A crash is due to fatigue if: Driver or Police record it is fatigue AND - PROXY MEASURES Wrong side of road & not overtaking Run off road & no avoidance manoeuvre, single vehicle Alcohol & speed not involved All proxy fatigue crashes in AUS: All proxy fatigue crashes in AUS Alcohol & speed fatalities for 1996 AUS: Alcohol & speed fatalities for 1996 AUS Truck proxy fatigue crashes in AUS: Truck proxy fatigue crashes in AUS All proxy fatigue fatalities & injuries by age of driver AUS: All proxy fatigue fatalities & injuries by age of driver AUS All proxy fatigue fatalities & injuries by driver sex AUS: All proxy fatigue fatalities & injuries by driver sex AUS AUS drivers’ reports of falling asleep at the wheel: AUS drivers’ reports of falling asleep at the wheel Males = 20 %, females = 6 % < 25y = 7 %, 25-59y =13 %, >60y = 7 % Metro = 9 %, country = 17 % White collar = 9 %, blue collar = 17 % Drivers affected by fatigue: Drivers affected by fatigue People working shift work or long hours With medical problems causing fatigue Commercial and long haul drivers Country drivers, holiday drivers Young male drivers Effect of Sleep Deprivation on Brain Glucose Metabolism, Belenky,1998: Effect of Sleep Deprivation on Brain Glucose Metabolism, Belenky,1998 Causes of driver fatigue 1: Causes of driver fatigue 1 Sleep loss Sleep loss: Sleep loss U.S. NTSB examined 107 single HGV crashes where driver survived & records were available for 4 days - In 58% of crashes driver said ‘fatigued’ In 18% of crashes driver was asleep Sleep loss: Sleep loss In fatigue crashes drivers had: inverted sleep/driving cycle driven at night with a sleep debt 5.5 h sleep versus 8.8h in non fatigue fragmented sleep, as in shared driving Sleep lossNodding off whilst driving and hours slept in AUS: Sleep loss Nodding off whilst driving and hours slept in AUS Sleep lossNear misses and hours slept before this trip in AUS: Sleep loss Near misses and hours slept before this trip in AUS Sleep lossHours of sleep and dangerous events when driving in AUS: Sleep loss Hours of sleep and dangerous events when driving in AUS Drivers with less than 6 h sleep have 3 times more dangerous events Drivers with less than 6 h sleep nod off 2.5 times more often Drivers with less than 6 h sleep use twice as much alcohol or drugs Arnold & Hartley 1998 Sleep LossStutts, Wilkins & Vaughn 1999: Sleep Loss Stutts, Wilkins & Vaughn 1999 Survey of 1400 US drivers Night shift workers = 6 times risk of a fatigue crash Less than 6 h sleep = 3 times risk of a fatigue crash Less than 5 h sleep = 5 times risk of fatigue crash Causes of driver fatigue 2 : Causes of driver fatigue 2 Time of day - Driving when you normally sleep Time of Day Hamelin,1987: Time of Day Hamelin,1987 Crash risk is lowest between 0800-1900 with less than 11 hours driving work Twice the risk of a crash when driving between 2000 - 0700 Twice the risk of a crash with more than 11 hours driving work Four times risk of a crash when driving between 2000-0700 after 11 hours of driving work Slide25: Time of Day - truckers nodding off Prokop and Prokop, 1955 Slide26: Time of day - percent crashes Mackie and Miller, 1978 Slide27: Time of day Relative risk of a single vehicle crash, Kecklund and Akerstedt 1995 Slide28: Time of day - U.S. F.M.C.S.A Slide29: Time of day - U.S. F.M.C.S.A Slide30: Time of day- Hours of sleep Kogi, 1985 Causes of driver fatigue 3: Causes of driver fatigue 3 Hours of work Hours of workMackie & Miller 1978: Hours of work Mackie & Miller 1978 Steering & lane wandering worse after 8-9 h Performance worse after 4 days driving In 750 fatigue & single truck crashes twice number of crashes in second half of the trip In fatigue & single truck crashes odds of crash increased after 5 h Hours of work-relative crash riskFolkard, 1997: Hours of work-relative crash risk Folkard, 1997 Slide34: Hours of work -U.S. F.M.C.S.A. Slide35: Hours of work -U.S. F.M.C.S.A. Hours of Work Hartley, Arnold et al. 1995: Hours of Work Hartley, Arnold et al. 1995 50% of truck drivers exceed 14 hours of work in any 24 hours 10% of truck drivers exceed 18 hours work in any 24 hours 12% of drivers obtain less than 4 hrs sleep on any day Countermeasures to fatigue 1: Countermeasures to fatigue 1 Behavioural countermeasures Behavioural countermeasuresHorne & Reyer, 1996: Behavioural countermeasures Horne & Reyer, 1996 USELESS Window down & radio up exercise USEFUL 2-3 cups of coffee before a 15 min nap (longer naps need time to recover) Countermeasures to fatigue 2: Countermeasures to fatigue 2 Technological countermeasures Technological countermeasuresHardware to measure fatigue: Technological countermeasures Hardware to measure fatigue Perclos - in-vehicle video of 80% eyelid closure correlations of 0.8 with lapses on Dinges Vigilance Task; better than self reported drowsiness or anything else in-vehicle device now available But, it can only warn the driver What can the driver do on the road? Will drivers ignore it? Will driver’s supervisors rely on it? Technological CountermeasuresHardware - SAVE Brookhuis et al. 1998: Technological Countermeasures Hardware - SAVE Brookhuis et al. 1998 Technological countermeasuresSoftware to predict fatigue: Technological countermeasures Software to predict fatigue Score based on prior sleep, wakefulness & time of day-Akerstedt & Folkard, 1997 Score base on hours of work & time of day - Fletcher & Dawson, 1998 US Army Sleep Management System - activity meter records sleep & integrates with time of day to predict sleep need & performance-Belenky, 1998 US DoT Countermeasures Research Program: US DoT Countermeasures Research Program Trip planning, hours of service Sleep, napping, circadian, melatonin Drugs Bright light Fitness for duty measures Vigilance testing Vehicle based measures Math models of sleepiness Countermeasures to fatigue 2: Countermeasures to fatigue 2 Regulations governing work & rest RegulationsU.S.A.: Regulations U.S.A. 10 h driving, 8 h rest, 60 h duty in 7 days - no reference to a 24 h clock So driver can start work 6 h earlier each day Driver can be on duty for 16 h in 24 h Enforced by police & log books Regulations under review Proposed regulations stand little chance of being accepted RegulationsEurope: Regulations Europe 9-10 h driving daily 56 h driving per week 9-11 h rest, or 12 h in 2 periods 24-45 h continuous rest per week enforcement - police & tachographs RegulationsAustralia: Regulations Australia 14 h work per day 8 h non work 6 h continuous non-work 84 h work per week 1 day off work per week Enforcement-Duty of Care under Occupational Safety & Health Inspectors RegulationsAustralia: Regulations Australia employer who contravenes the duty of care by exposing employees to a hazard can be fined $100,000 where the hazard causes injury or death a fine of $200,000 is imposed employee who contravenes duty of care can be fined $10,000 or $20,000 workplace review by: complaint or random inspection which leads to an Improvement or Prohibition notice.