The impact of work practices on fatigue in long distance truck drivers

Twenty seven professional truck drivers completed a 12 hour, 900 km trip under each of three driving regimes—a relay (staged) trip, a working hours regulated one-way (single) trip, and a one-way (flexible) trip with no working hours constraints. The results indicated that none of the driving regimes prevented fatigue and that the pattern of fatigue experienced during the trips appeared to be related to pretrip fatigue levels.     

Hours of service violations among tractor-trailer drivers

Federal regulation limits interstate truck drivers to 10 hours of driving after an 8-hour off-duty period. The need for enforcing these limits is supported by research showing that long driving hours is a risk factor for tractor-trailer crashes. To estimate the percentage of hours of service violators among long-haul tractor-trailer drivers, truck drivers were interviewed at an inspection site in Spokane, Washington and later observed arriving at inspection sites in either Moorhead or Worthington, Minnesota (approximately 1,200 miles). The sample used for the calculation of violators consisted of truckers driving alone who reportedly did not plan to make an interim pickup or delivery stop prior to arrival in Minnesota. The percentages of drivers violating the hours of service rules by more than one hour at average trip speeds ranging from 35 mph to 65 mph are presented. Assuming that the drivers averaged 40 mph over the complete course of the trip segment, including stopped time, 90% were in violation by more than one hour. Assuming that they averaged 50 mph, 51% were in violation by more than one hour. These speed assumptions are based on findings in the current study that team drivers averaged 38 mph, fleet managers' reports of scheduling single drivers at trip speeds of 45 mph to 47 mph, and reports in the literature that loaded tractor-trailers average 41 mph over flat terrain. Although the true percentage cannot be determined without knowing actual trip speeds, the estimated range of violators at probable speeds of 40 mph and 50 mph points to a substantial problem.     

Effect of consecutive driving on accident risk: A comparison between passenger and freight train driving

This study combined driver-responsible accidents with on-board driving hours to examine the effect of consecutive driving on the accident risk of train operations. The data collected from the Taiwan Railway Administration for the period 1996–2006 was used to compute accident rates for varied accumulated driving hours for passenger and freight trains. The results showed that accident risk grew with increased consecutive driving hours for both passenger and freight trains, and doubled that of the first hour after four consecutive hours of driving. Additional accident risk was found for freight trains during the first hour due to required shunting in the marshalling yards where there are complex track layouts and semi-automatic traffic controls. Also, accident risk for train driving increased more quickly over consecutive driving hours than for automobile driving, and accumulated fatigue caused by high working pressure and monotony of the working environment are considered to be the part of the reason. To prevent human errors accidents, enhancing safety equipment, driver training programs, and establishing a sound auditing system are suggested and discussed.     

Fatal traffic accidents among trailer truck drivers and accident causes as viewed by other truck drivers

Causality factors, the responsibility of the driver and driver fatigue-related factors were studied in fatal two-vehicle accidents where a trailer truck driver was involved during the period of 1991-1997 (n = 337). In addition, 251 long-haul truck drivers were surveyed in order to study their views regarding contributing factors in accidents involving trucks and the development of possible countermeasure against driver fatigue. Trailer truck drivers were principally responsible for 16% of all the accidents. Younger driver age and driving during evening hours were significant predictors of being principally responsible. In addition, the probability of being principally responsible for the accident increased by a factor of over three if the driver had a chronic illness. Prolonged driving preceding the accident, accident history or traffic offence history did not have a significant effect. Only 2% of the drivers were estimated to have fallen asleep while driving just prior to the accident, and altogether 4% of the drivers had been tired prior to the accident. Of the drivers 13% had however, been driving over 10 h preceding the accident (which has been criminally punishably in Finland since 1995 under the EC regulation) but no individual factors had a significant effect in predicting prolonged driving. The surveyed views regarding causes of truck accidents correspond well with the accident analysis. Accidents were viewed as being most often caused by other road users and driver fatigue was viewed to be no more than the fifth (out of eight) common cause of accidents. The probability of viewing fatigue as a more common cause increased significantly if the driver had experienced fatigue-related problems while driving. However, nearly half of the surveyed truck drivers expressed a negative view towards developing a technological countermeasure against driver fatigue. The negative view was not related to personal experiences of fatigue-related problems while driving.     

Evaluating the 2003 revised hours-of-service regulations for truck drivers: The impact of time-on-task on critical incident risk

On January 4th, 2004, the Federal Motor Carrier Safety Administration implemented a revised set of regulations concerning the hours-of-service (HOS) of commercial motor vehicle (CMV) drivers. One central component of the revised HOS regulations was a one-hour increase in allowable driving time, from 10 to 11 h. The current study evaluated the impact of the additional driving-hour on critical incident risk. Data from a naturalistic truck driving study, which resulted in over 2 million driving miles of continuously collected data, were analyzed. Driving hour bins (hours 1 through 11) were created and the frequency of critical incidents for each hour, and trips (opportunities) per each hour, were identified. A relative frequency was then calculated (critical incidents divided by opportunities) for each hour and odds ratios were determined. Analyses found an elevated risk in the 1st driving-hour, but no consistent significant difference between hours 2 through 11. Analyses on time-of-day, where incident rates were calculated for each of the 24 h in the day, were also conducted. The results found a strong positive correlation to national traffic density data. As an impact on U.S. national transportation policy, the results of this study do not support the hypothesis that there is an increased risk resulting from CMV drivers driving in the 11th driving-hour as compared to the 10th driving-hour, or any hour.     

Risky driving and recorded driving offences: A 24-year follow-up study

Permanent individual differences in driver behavior and accident risk have long been under active debate. Cognitive and personality factors have correlated with risky driving indicators in cross-sectional studies, and prospective cohort studies are now increasingly revealing early antecedents of risky behavior and injury mortality in adult age, with connections to stable personality traits. However, long-term stability in driver behavior or accident involvement has not been documented in a general driver population.This study reports 24-year follow-up data from a study that compared the recorded offenses between 134 drivers stopped by the police because of sustained risky driving and 121 control drivers stopped at the same locations at the same time in 1987 (Rajalin, 1994. Accid. Anal. Prev., 26, 555–562). Data were compiled from national driver records and accident statistics for the same drivers again 24 years later, and their yearly mileage and speed behavior was requested in a mail survey. The results showed that the two groups of drivers sampled on one trip a quarter of a century ago still differ from each other. The offenders still have more entries in their driver record, also when adjusted for age and mileage (OR = 1.59, CI = 1.03–2.46), they still report in the survey that they drive faster and overtake other cars more often. The results show that individual differences in driver behavior persist for decades, perhaps for life. However, in this on-road sample, the effect seems to be moderated by occupation which also presumably explains the lower mortality among the offenders during this 24-year follow-up.     

Rough set approach for accident chains exploration

This paper presents a novel non-parametric methodology--rough set theory--for accident occurrence exploration. The rough set theory allows researchers to analyze accidents in multiple dimensions and to model accident occurrence as factor chains. Factor chains are composed of driver characteristics, trip characteristics, driver behavior and environment factors that imply typical accident occurrence. A real-world database (2003 Taiwan single auto-vehicle accidents) is used as an example to demonstrate the proposed approach. The results show that although most accident patterns are unique, some accident patterns are significant and worth noting. Student drivers who are young and less experienced exhibit a relatively high possibility of being involved in off-road accidents on roads with a speed limit between 51 and 79 km/h under normal driving circumstances. Notably, for bump-into-facility accidents, wet surface is a distinctive environmental factor.     

Influence of safety belt usage on perception of the risk of an accident

Does the use of a safety belt increase or decrease the perception of the risk of an accident? Young and older male drivers were asked to drive an urban route and rate their perceptions of the risk of an accident. On the first driving trip all subjects were unbelted, while on the second driving trip half of the subjects wore a safety belt while half did not. Results indicated that young male drivers decrease their perception of the risk of an accident as they become familiar with a driving route if they are NOT wearing a safety belt. Young male drivers asked to wear a safety belt sustained their perception of the risk of an accident as they became familiar with the test route. Older drivers' perception of the risk of an accident was not affected by familiarity or safety belt usage.     

Tiredness! a natural explanation to The Grand Rapid "DIP"

The present analysis deals with the presumed improved driving skill of car drivers with low blood alcohol concentrations (BACs) compared to the driving skill of sober drivers. Several roadside surveys indicate such a controversial possibility, which is illustrated graphically in "The Grand Rapid Study" (1964) as a relative accident risk curve for driving while intoxicated (DWI). A curve which shows a "DIP" below a baseline accident risk of one for sober drivers in the interval between BACs of 0.01 and 0.04 g/l. Since then, various attempts have been made to show this "DIP" in the otherwise "exponentially" raising curve to be an artificial distortion based on disproportionate demographic subgroups. It is, however, our thesis that the observations of "The Grand Rapid Study" and other roadside surveys are valid, because the presumed mono-causal traffic accident curve hides "tiredness" as an additional human risk factor. This makes the first part of the night-time relative accident risk curve for impaired drivers artificially augmented by "tired" drivers with insignificant amounts of alcohol in the blood and therefore incorrectly accused of accidents due to DWI. The accident risk curve for higher BACs raises similarly abrupt due to drivers impaired by a combined effect of alcohol and "tiredness". Moreover, to imply an accident risk of one for all sober drivers independent of the time of the day is debatable as an increased accident risk is present in the late night-time hours due to "tired" drivers. This increase in "tired" sober accident drivers suppresses the accident risk curve for DWI with BACs of 0.01-0.04 g/l below the fixed baseline of one for the background population.     

Young drivers' optimism bias for accident risk and driving skill: Accountability and insight experience manipulations

This study aimed to determine whether two brief, low cost interventions would reduce young drivers’ optimism bias for their driving skills and accident risk perceptions. This tendency for such drivers to perceive themselves as more skilful and less prone to driving accidents than their peers may lead to less engagement in precautionary driving behaviours and a greater engagement in more dangerous driving behaviour. 243 young drivers (aged 17–25 years) were randomly allocated to one of three groups: accountability, insight or control. All participants provided both overall and specific situation ratings of their driving skills and accident risk relative to a typical young driver. Prior to completing the questionnaire, those in the accountability condition were first advised that their driving skills and accident risk would be later assessed via a driving simulator. Those in the insight condition first underwent a difficult computer-based hazard perception task designed to provide participants with insight into their potential limitations when responding to hazards in difficult and unpredictable driving situations. Participants in the control condition completed only the questionnaire. Results showed that the accountability manipulation was effective in reducing optimism bias in terms of participants’ comparative ratings of their accident risk in specific situations, though only for less experienced drivers. In contrast, among more experienced males, participants in the insight condition showed greater optimism bias for overall accident risk than their counterparts in the accountability or control groups. There were no effects of the manipulations on drivers’ skills ratings. The differential effects of the two types of manipulations on optimism bias relating to one's accident risk in different subgroups of the young driver sample highlight the importance of targeting interventions for different levels of experience. Accountability interventions may be beneficial for less experienced young drivers but the results suggest exercising caution with the use of insight type interventions, particularly hazard perception style tasks, for more experienced young drivers typically still in the provisional stage of graduated licensing systems.     

Has the difference in accident patterns between male and female drivers changed between 1984 and 2000?

The motorcar accident pattern of culpable young (18-25 years old) and middle-aged (35-55 years old) male and female drivers was studied in Finland. The aim was to see whether the difference in accident patterns between males and females has remained constant or whether it has changed over a 16-year period. Two different sets of traffic accident data were used. The first set of data covered all motorcar accidents for which damages were paid between 1987 and 2000, a total of 140802 accidents. The second set of data covered all fatal motor vehicle accidents in Finland during the time period between 1984 and 2000, a total of 2401 accidents. The results are analysed and discussed in the framework of a four-level hierarchical model of driving behaviour [Keskinen, E., 1996. Why do young drivers have more accidents? In: Junge, F., Fahrerinnen (Eds.), Young Drivers (in German and in English). Berichte der Bundesanstalt für Strabetaenwesen, Mensch und Sicherheit, Heft M 52, Bergisch Gladbach, Germany; Hatakka, M., Keskinen, E., Gregersen, N.P., Glad, A., Hernetkoski, K., 2002. From control of the vehicle to personal self-control; broadening the perspectives to driver education. Transportation Res. Part F 5 (3), 201-215]. Female drivers had proportionally more accidents that were connected to vehicle manoeuvring and control of traffic situations, e.g. reversing and loss-of-control accidents in a sober state and when not speeding. Male drivers, and especially young male drivers, had proportionally more accidents connected to higher levels of driving behaviour like motives for driving and attitudes. Factors that characterised these accidents were speeding and alcohol consumption. Male drivers also had previous traffic offences more often than female drivers. The study concludes that the difference in accident patterns between male and female drivers has remained constant, i.e. the accident pattern of female drivers was as dissimilar to the accident pattern of male drivers in the year 2000 as in the middle of the 1980s.     

An analysis of driving and working hour on commercial motor vehicle driver safety using naturalistic data collection

Current hours-of-service (HOS) regulations prescribe limits to commercial motor vehicle (CMV) drivers’ operating hours. By using naturalistic-data-collection, researchers were able to assess activities performed in the 14-h workday and the relationship between safety-critical events (SCEs) and driving hours, work hours, and breaks. The data used in the analyses were collected in the Naturalistic Truck Driving Study and included 97 drivers and about 735,000 miles of continuous driving data. An assessment of the drivers’ workday determined that, on average, drivers spent 66% of their shift driving, 23% in non-driving work, and 11% resting. Analyses evaluating the relationship between driving hours (i.e., driving only) and SCE risk found a time-on-task effect across hours, with no significant difference in safety outcomes between 11th driving hour and driving hours 8, 9 or 10. Analyses on work hours (i.e., driving in addition to non-driving work) found that risk of being involved in an SCE generally increased as work hours increased. This suggests that time-on-task effects may not be related to driving hours alone, but implies an interaction between driving hours and work hours: if a driver begins the day with several hours of non-driving work, followed by driving that goes deep into the 14-h workday, SCE risk was found to increase. Breaks from driving were found to be beneficial in reducing SCEs (during 1-h window after a break) and were effective in counteracting the negative effects of time-on-task.     

An analysis of accident data for franchised public buses in Hong Kong

This paper analyses data on accidents involving franchised public buses operating in Hong Kong. The data were obtained from the Royal Hong Kong Police, the Hong Kong Government Transport Department, the two major franchised bus operators and international sources. The analysis includes an international comparison of accidents with emphasis on the situation in Hong Kong compared to urban areas in the United Kingdom. An attempt has been made to identify the characteristics of bus accidents; accident incidence has been related to time of day, day of the week, time of year, weather conditions, driver's age and experience, hours on duty and policy-reported cause. The results indicate that Hong Kong has a high accident rate compared to Japan, the U.K. and the U.S.A., with particularly high pedestrian involvement rates. Bus accidents peak at around 9:00 AM and 4:00 PM but the accident rate is high throughout the day. Monday and Saturday appear to have a higher than average accident rate. The variability of accident rate throughout the year does not seem to be significant and the accident rate does not appear to be influenced by weather conditions. Older, more experienced drivers generally have a safer driving record than their younger, less experienced colleagues. Accident occurrence is related to the time the driver has been on duty. The paper questions the reliability of police-reported accident causation data and suggests improvements in the design of the accident report form and in the training of police investigators. The relevance of the Hong Kong study for accident research in general is also discussed.     

Voluntary risk taking and skill deficits in young driver accidents in the UK

In absolute terms, young drivers have three to four times as many accidents per year as older drivers; and even allowing for their relative numbers in the population, their accident involvement is about 2.5 times higher than older drivers. A sample of 3437 accident reports was considered, including 1296 in detail, from midland police forces in the UK, involving drivers aged 17-25, and covering the years 1994-1996 inclusive. Four types of accident were identified as being of particular concern due to their high frequency: 'cross-flow'-turns; rear-end shunts; loss of control on bends; and accidents in darkness. (The term 'cross-flow' is used in relation to turns to denote an intersection accident where a driver is turning across the path of oncoming traffic, i.e., left turns in the US and continental Europe, but right turns in the UK and other countries where driving on the left side of the road is the norm.) An examination of driver risk taking behaviours as revealed in police interviews gave an insight into some of the motivational factors underlying young driver behaviour. Young driver accidents of all types are found to be frequently the result of 'risk taking' factors as opposed to 'skill deficit' factors. It had previously been thought that one of the main problems that young drivers have is in the area of specific skills needed in the driving task. However, it appears that a large percentage of their accidents are purely the result of two or three failures resulting from voluntary risk taking behaviour, rather than skill deficits per se. It is shown that specific groups of young drivers can even be considered as above average in driving skills, but simultaneously have a higher accident involvement due to their voluntary decisions to take risks.     

Investigation of the driving experience of a sample of Victorian learner drivers

This paper presents the results of an investigation of the driving experience of a small sample of learner drivers in Victoria, Australia. Participants (n = 110) kept a continuous logbook of their driving experience over the 2 years of the learner-driver period, including information about the distance and time of each driving trip, their level of confidence, and monthly data concerning the number of crashes, near misses, and unpleasant emotional interactions with their supervising driver. The analysis of these data suggests that learner drivers accrue relatively little driving experience and that they tend to obtain this experience in daytime, fair-weather driving. The implications of these results are discussed.     

Driver risk factors for sleep-related crashes

A population-based case-control study was carried out to examine driver risk factors for sleep-related motor vehicle crashes. Cases included 312 drivers involved in recent North Carolina crashes and identified on police reports as asleep at the time of the crash and 155 drivers identified as fatigued. Controls were 529 drivers also involved in recent crashes but not identified as asleep or fatigued, and 407 drivers not involved in recent crashes. All drivers were contacted for brief telephone interviews. Results showed that drivers in sleep-related crashes were more likely to work multiple jobs, night shifts, or other unusual work schedules. They averaged fewer hours sleep per night, reported poorer quality sleep, were less likely to feel they got enough sleep, were sleepier during the day, drove more often late at night, and had more prior instances of drowsy driving. Compared to drivers in non-sleep-related crashes, they had been driving for longer times, been awake more hours, slept fewer hours the night before, and were more likely to have used soporific medications. Knowledge of specific risk factors for sleep-related crashes is an important first step in reducing the thousands of deaths and injuries each year in the US attributed to drowsy driving.     

Modeling safe and unsafe driving behaviour

A sample of 743 Dutch drivers was queried about driving-related errors and violations, and about the frequency of their accident involvement over the past 3 years. In addition, the following risky behaviours and characteristics related to driving were measured through self-report: strategic decisions made about driving before starting a trip, attitudes related to committing violations, psychological precursors of unsafe driving (such as being tired or stressed when driving), and physical precursors of unsafe driving (suffering physical or psychological handicaps when driving). The results show that several scales have acceptable reliability coefficients, though several others are in need of improvement. Path analysis showed that an acceptable structural model could be developed to describe all empirical relationships. Considerable parts of the variance in the violations scores and the psychological precursors scores could be explained by the other model variables. In terms of predictive power, "unsafe" attitudes, physical precursors, and psychological precursors had the most impact, each explaining up to 9% of the variance in violations scores, errors scores, and/or psychological precursors scores. The way these results can be utilized in future accident prevention programs and in driver training programs are indicated, as are their implications for future research.     

Exploratory study of fatigue in light and short haul transport drivers in NSW, Australia

This exploratory study sought to identify relationships between work characteristics and fatigue experiences among light and short haul road transport drivers. Surveys were distributed to drivers of light goods vehicles (< or =12 t gross vehicle mass) undertaking short haul work (within a 100 km radius of base) in seven geographical regions of NSW, Australia. The participating drivers (n=321) reported a range of freight tasks. They typically worked a 50-h, 5-day week primarily as day shifts, and spent just over half of their work time driving. Despite the predominance of regular, day work, 38% of participants experienced fatigue at least once a week while driving for work and 45% had nodded off while driving during the preceding 12 months. Stepwise logistic regression analysis revealed that longer daily work hours, higher subjective work demands, as measured by the NASA TLX workload scale, and the percentage of freight movements undertaken from customers to depots each explained unique variance in the frequency of fatigue experiences. The results of the study suggest that fatigue is an issue for some light and short haul road transport drivers and identifies work characteristics that should be investigated further.     

Driver licenses as a measure of older drivers' exposure: a methodological note

The limitations of the number of driver licenses as an estimate of driving exposure were demonstrated by comparing Finnish and Swedish driver licensing practices, licensing rates and accident rates of older drivers. In Sweden, there is no screening for older license holders, and most of them keep their licenses for life. In Finland, there is a heavy and costly medico-legal control system for older license holders, leading to both screening and self-screening. Consequently, in the two countries, the numbers of driver licenses do not reflect the numbers of active older drivers in the same manner. This difference affects the comparative accident statistics: with respect to population, Finland and Sweden have similar age trends in accidents risk, but with respect to the number of driver licenses, the Finnish older drivers seem to have a higher risk of accident than the Swedish ones. It is concluded that if group comparisons of accident risk are presented using the number of driver licenses as an estimate of exposure, the licensing legislation and practice should affect all the groups in an identical manner for the comparison to be valid.     

Women drivers' behaviour, socio-demographic characteristics and accidents.

The purpose of this study was to examine factors which affect driving behaviour and accident rates in women in Australia. Two groups of women (aged 18-23 and 45-50 years) participating in the Australian Longitudinal Study on Women's Health, completed a mailed questionnaire on driver behaviour and road accidents. Self reported accident rates in the last 3 years were 1.87 per 100,000 km for the young drivers (n = 1199) and 0.59 per 100,000 km for the mid-age drivers (n = 1564); most accidents involved damage only, not injury. Mean scores for lapses obtained using the Driver Behaviour Questionnaire, were similar in the two age groups and similar to those found in other studies. In contrast, scores for errors and violations for the young women were higher than for the mid-age group and previous reports using the same instruments. Riskier driving behaviour among young women was associated with stress and habitual alcohol consumption. In the mid-age group, poorer driver behaviour scores were related to higher levels of education, feeling rushed, higher habitual alcohol consumption and lower life satisfaction scores. Accident rates in both groups were significantly related to lapses. Women born in non-English speaking countries had significantly higher risk of accidents compared to Australian-born women: relative risk = 3.40, 95% confidence interval (1.93, 5.98) for the young drivers; relative risk = 1.77, 95% confidence interval (1.11, 2.83) for mid-age drivers. These findings support the need for road safety campaigns targeted at young women to reduce dangerous driving practices, such as speeding, 'tail gating' and overtaking on the inside. There is also a need for further research to understand how lifestyle characteristics are associated with higher risk of accidents and to explore factors which might account for the higher risk for women drivers who were born overseas.