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Traffic Safety
  1. L S Robertson
  1. Retired injury epidemiologist, Yale University;

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    By Leonard Evans, Bloomfield Hills, MI: Science Serving Society, 2004, pp 445, US$99.50. ISBN 0-9754871-0-8

    Leonard Evans is a British trained physicist who retired after a career with General Motors and became the self-appointed president of an entity he calls Science Serving Society, the publisher of this book. In other words, the book is self-published. There is no indication of peer review of the book manuscript, which might have resulted in a more objective and scientifically sound work. He has published some of it in peer reviewed journals but there are gaping chasms in his coverage of the science of road injury reduction and unsound logic in some of his analysis and prescriptions for amelioration of injuries. Those desiring a comprehensive review of what we know to enhance road safety will not find it here.

    Evans sensibly discusses mobility and safety, risk homeostasis, errors in belt use in police records which bias belt effectiveness estimates, and irresponsible entertainment media. But there are odd lapses, particularly for a physicist, such as referral of high center of gravity (cg) as a factor in rollover without mentioning track width—that is, distance between the center of the tires (t). Higher cg only lowers vehicle stability if it is too narrow. The risk increases as t/(2 × cg) is lowered below 1.2, common for many pickup trucks and utility vehicles that have high rollover death rates.

    The dampened reduction in US death rates, discussed below, is partly due to increased rollover from unstable pickup trucks and utility vehicles, the sales of which have increased dramatically during the past two decades in the US.

    The main thesis of the book is that behavior causes motor vehicle crashes and this behavior must be changed in order to reduce motor vehicle crashes. Reducing incidence and severity of injury by changing vehicles and environments is largely dismissed as ineffective or not worth the costs. Most of the epidemiological research on road injuries and the effectiveness of countermeasures is ignored or mentioned with derision. Evans claims that evaluations of overall effect of vehicle regulations overstate the effect compared with specific studies of some of the crashworthiness and brake standards, but he ignores crash avoidance standards that have not been studied on a case-by-case basis.

    Most of his most contentious claims are based on mere eyeballing of trends in injury and death rates with no adjustment for important factors such as demographic shifts, population and vehicle density in geographic areas, and changing mix of vehicles, including non-motorized vehicles.

    In his emphasis on crash prevention, Evans does not acknowledge that the large majority of crashes in the US do not occur in geographic areas where the large majority of severe injuries occur. He recognizes that severe injuries occur mainly in areas of low traffic density but not that the large majority of crashes occur in high traffic density areas. If we target our efforts on preventing crashes without accounting for severity, prevention of injury will be reduced substantially. His major prescription for crash prevention is the widespread use of video cameras to record violations automatically and identify the license tag numbers of illegal speeders and those who ignore stop signs and red lights.

    Evans repeatedly emphasizes injuries imposed by air bags but says nothing about seat belt related injuries such as decapitations by belts and injuries to necks and spinal cords (the “seat belt syndrome”). He dismisses the benefit of a major change in the transportation of children from front to back seats in the US, which was a result of child injuries from air bag deployment.

    Evans examines the declines in fatal injury rates in the Australia, Canada, the UK, and the US with no adjustments for factors noted above, and claims that the US no longer has the lowest fatal injury rates because of overemphasis on air bags and other aspects of vehicle crashworthiness. Close examination of the timing of changes in trends in some of his graphs suggests that other factors were operative. Evans presents no budgets or other evidence of differential efforts to influence driver behavior in the countries he compares.

    In his claim that the US neglected driver behavior, Evans ignores increased US federal grants to the states for highway safety during the years of vehicle regulation. Much of US road safety policy is determined by state governments and is not influenced by vehicle regulation. One interesting comparison that Evans could have considered is comparison among US states.

    Scholars in US academic injury prevention centers and other academic safety departments will be surprised at Evan’s claim that the “US lacks academic safety institutions” and what exists is “nearly all in biomechanics and crashworthiness”.

    The mission for injury control researchers is not to argue whether behavior change versus vehicle and environmental change is superior nor to claim that a given country’s injury control efforts, based on gross rates, is superior to another’s. It is to find behavioral, vehicle, and environmental approaches that are demonstrated scientifically to reduce injury and are acceptable, or can be made acceptable within the culture of a given society. This book fails that test.

    Editor’s note

    For an alternative view, see Dinesh Mohan’s review of this book (