Commercial Motor Vehicles Driver Fatigue, Long-Term Health, and Highway Safety: Research Needs

Alistair MacLeanCommercial Motor Vehicles Driver Fatigue, Long-Term Health, and Highway Safety: Research NeedsThe Royal Society of Canada is pleased to announce the publication of a new Expert Panel report from its sister academy, the National Academies in the United States. The full report can be accessed online.

Dr. Alistair MacLean has kindly provided a Canadian perspective on this report and its relevance to Canada and Canadians. Dr. MacLean is a Professor of Psychology at Queen’s University. From 1986 to 2000 he also held an appointment as Staff Scientist at The Toronto Hospital (Western Division). In addition to clinical work with sleep disordered patients, Dr. MacLean has carried out research in a number of different aspects of sleep. His recent research has focused on sleepiness and performance, in particular driving performance. He is a Fellow of the Canadian Psychological Association and a past President of the Canadian Sleep Society.

Commercial Motor Vehicles Driver Fatigue, Long-Term Health, and Highway Safety: Research Needs - A Canadian Perspective

The World Health Organisation (WHO) has predicted that, in the absence of effective action, road traffic injuries will become the fifth leading cause of death in the world and the United Nations General Assembly has proclaimed 2011 to 2020 a Decade of Action for road safety. This report from The National Academies of Sciences, Engineering and Medicine is timely, not only for the shared general concern about the pain and emotional trauma resulting from vehicular crashes, but also because of its specific relevance to Canadian concerns.

Commercial vehicle drivers make a considerable contribution to the economy. The combined trade relationship among Canada, the USA and Mexico amounts to $1.4 trillion annually, making trucking a major contribution to commerce. Similarly, mobility of people is facilitated by the bus networks. The economic consequences of crashes are estimated at between one and three percent of Gross National Product. In 2008, Canada was ranked 10th in terms of the number of fatalities per billion vehicle kilometers traveled compared to twelve other member countries of the Organization for Economic Cooperation and Development. In a 2015 WHO report, in comparison to the same countries, Canada is ranked 12th. In response to concerns about the safety of commercial drivers, Transport Canada along with the US Federal Motor Vehicle Carrier Safety Association and other associations and agencies developed the North American Fatigue Management Program. This is an internet-based program that provides information and countermeasures aimed at mitigating the effects of driver fatigue. Similarly, in response to concerns about the effect of medical problems on safe driving, in 2014 the Canadian Thoracic Society and the Canadian Sleep Society published a position paper on Obstructive sleep apnea and driving.

In recent years, mounting scientific evidence has led to an increased understanding of the relationships between sleep, circadian rhythmicity, brain functioning and performance. Sufficient sleep and optimal positioning of performance within the circadian cycle are critical for the prevention of fatigue which is a demonstrated risk to safety. Prolonged time on task, inadequate breaks, reduced sleep time, and limited time off duty reduce alertness and vigilance, slow reaction time and cognitive processing speed, and degrade working memory, situational awareness, and impulse control. The result is an increase in errors of omission (failure to respond in timely manner) and of commission (premature or incorrect responding) both of which compromise safe driving. Many people preferentially reduce sleep time to favour work time, commute time, and leisure time. Inadequate sleep can also result from lack of treatment of conditions including insomnia and sleep apnea. In addition to its effects on performance, chronic reduction in sleep time – especially to 6 or fewer hours a day – is associated with long-term health problems including obesity, hypertension, diabetes, and cardiovascular disease.

There is a substantial body of evidence, most relating to passenger vehicles, linking changes in driving behaviour to increased levels of fatigue. The data sources include: surveys, simulator studies, and naturalistic observation. Some of the most consistent changes that take place when drivers are fatigued include increased variability in lane positon and speed, an increase in the number of off-road events, and slowed reaction time. The magnitude of these effects is comparable to that produced by alcohol intoxication. Driving while sleepy is a common phenomenon reported by about 60 percent of drivers, as is falling asleep at the wheel which is reported by about 18 percent. Among the characteristics of crashes due to fatigue is that they are more likely to occur at night or in mid-afternoon (both points of increased sleepiness in the circadian cycle), they involve a single vehicle running off the roadway or rear-end or head-on collisions, and are more severe than non-sleep-related crashes. Estimates of the number of crashes due to sleepiness or fatigue vary widely. It is generally agreed that official statistics substantially underestimate the true figures and there is a broad consensus that the proportion of crashes due to sleepiness or fatigue is about 20 percent. Official statistics rely heavily on police reports and the determination that a crash is due to fatigue or sleepiness is more difficult than identifying, for example, alcohol as a causal factor. Drivers use many countermeasures to sleepiness: most are ineffective whatever the users believe. Caffeine, naps and short breaks can prove temporarily effective but there is no substitute for sleep.

In spite of the extensive literature on car crashes, the evidence relating to commercial vehicles is sparse. There are good reasons to believe that commercial vehicle drivers face different stresses from those affecting the drivers of passenger cars including irregular schedules and particular economic pressures related to commercial driving. This may result in lifestyles that put commercial vehicle drivers at more risk for insufficient sleep and health problems. Obstructive sleep apnea is known to be common in commercial vehicle drivers, is a major contributor to fatigue, and increases the risk of crashes. The Panel responsible for this report was convened “to assess the state of knowledge about the relationship of such factors as hours or driving, hours on duty, and periods of rest to the fatigue experience by truck and bus drivers while driving and the implications for the safe operation of their vehicles. The panel will also assess the relationship of these factors to drivers’ health over the longer term. It will identify improvements in data and research methods that can lead to better understanding in both areas.”

The Panel’s report contains substantive reviews of the vehicular, working and regulatory environments, data sources, research methods and principles, consequence of fatigue, health and wellness, and countermeasures to fatigue. With respect to fatigue, hours of service and highway safety they point out that the question of greatest importance is what factors mediate the causal path from fatigue to performance shortfalls to crashes and how crashes might be prevented. While acknowledging that hours of service are an important factor, they suggest that it is critical to view the issue more broadly in light of the rapidly evolving changes affecting drivers including: the increased use of technology for fatigue detection; improvements in the design of trucks and buses; improvements in the driving environment; possible improvements in drivers’ personal health habits; and improvements in scheduling policies. This demands ongoing research to extend our understanding of commercial vehicle safety. With respect to health and wellness, obstructive sleep apnea is already known to increase crash risk. However, a substantial body of evidence supports the conclusion that people with insufficient sleep are more likely to have chronic conditions including cardiovascular disease, diabetes, depression, or obesity. The relationship is, of course, bidirectional as health problems may also affect fatigue. In either case the risk of a crash is increased. Further research is needed to establish the relationship between these factors and crash risk and to determine the effectiveness of both specific countermeasures and fatigue management and health and wellness management programmes in increasing health and fatigue, and reducing crash risk.

The Panel makes a total of thirteen specific recommendations for future research on fatigue and highway safety and on commercial motor vehicle drivers’ health and wellness. The major themes of the recommendations with respect to fatigue include: the need for more extensive research and regular data collection; the importance of making data available, with the inclusion of appropriate privacy safeguards, to researchers including from existing and future data bases and from electronic on-board recorders which should be mandated; and encouraging the development and testing of new technologies. With respect to health and wellness, the recommendations include the need: for an ongoing survey of drivers’ health status and related factors; to provide information and encourage best practices in the medical review of commercial vehicle drivers; for research on obstructive sleep apnea and commercial vehicle drivers; and for research on driver fatigue management and training.