摘要：Objectives. We compared rates of risky driving among novice adolescent and adult drivers over the first 18 months of adolescents' licensure. Methods. Data-recording systems installed in participants’ vehicles provided information on driving performance of 42 newly licensed adolescent drivers and their parents. We analyzed crashes and near crashes and elevated g-force event rates by Poisson regression with random effects. Results. During the study period, adolescents were involved in 279 crashes or near crashes (1 involving injury); parents had 34 such accidents. The incidence rate ratio (IRR) comparing adolescent and parent crash and near-crash rates was 3.91. Among adolescent drivers, elevated rates of g-force events correlated with crashes and near crashes ( r = 0.60; P < .001). The IRR comparing incident rates of risky driving among adolescents and parents was 5.08. Adolescents’ rates of crashes and near crashes declined with time (with a significant uptick in the last quarter), but elevated g-force event rates did not decline. Conclusions. Elevated g-force events among adolescents may have contributed to crash and near-crash rates that remained much higher than adult levels after 18 months of driving. Motor vehicle crashes are the leading cause of death and disability among adolescents, whose crash involvement is much higher than that of older, more experienced drivers.1 Crash risk is highest early in licensure, declining rapidly for approximately 6 months and then slowly for years before reaching stable, adult rates. 2 – 4 Crash risk among young drivers is particularly high under complex driving circumstances, such as late at night and with adolescent passengers. 4 A range of explanations for the high crash rates among novices have been proposed, including the complexity of learning to drive safely and adolescent propensity for risky behavior. 4 Learning basic vehicle management requires only a few hours of instruction and practice, 5 but judgment consistent with safe driving is thought to develop only with substantial driving experience. 6 Novices make mistakes on relatively simple problems when first learning a complex task (e.g., algebra, a musical instrument, golf), but over time they learn to process information quickly, become better judges of their abilities, make fewer errors, and resolve problems more efficiently. 7 Accordingly, novice drivers make more judgment-related driving errors than do experienced drivers. 8 Elevated g-force events are one of several important measures of risky driving, along with speeding, close following, distraction, and impairment. Elevated g-force events result from late braking, rapid starts, sharp turns, and yaw. These events are dangerous because they increase the potential for loss of vehicle control, reduce the time available to respond to hazards, 9 and render a vehicle less predictable for other road users, thereby reducing safety margins. They can also be uncomfortable for passengers. 10 Adolescents are thought to take more risks than adults in general 11 and while driving, 4 which provides frequent opportunities for adolescent risk taking typified by elevated g-force events (e.g., hard stops, rapid turns). High rates of elevated g-force events may reflect risk taking or skill and judgment deficiencies regarding how best to navigate turns and when to initiate stopping. If elevated g-force events are attributable to inexperience and associated deficiencies in vehicle management, judgment, and attention, then rates should decline with experience. If they do not decline with experience they are less likely to be attributable to lack of skill and judgment and more likely to reflect a risky driving style. Most previous studies on risky driving relied on driver self-reports, providing only estimates of the prevalence of crashes and risky driving. 12 Other studies used police reports on crashes and driving offenses, which can be incomplete and are prone to transcription errors. 13 Instruments installed in vehicles enable continuous assessment of the g-forces exerted by the vehicle as it maneuvers, crash involvement, and miles driven, allowing accurate calculation of rates and providing many analytic and interpretation advantages over simple frequencies or estimated exposure. 9 In-vehicle systems that monitor g-force events are commonly used by commercial trucking companies to reduce risky driving. 14 These systems have been adapted for use with novice adolescent drivers to provide feedback to the driver in the form of a blinking light when the vehicle exceeds an established g-force threshold. This information can also be stored electronically and shared with parents. Several studies have demonstrated that feedback about elevated g-force events can reduce these events. 15 – 17 Despite great interest in risky driving among adolescents, little objective information about its prevalence is available. Accordingly, it is of interest to compare the driving performance of novice adolescent drivers with that of adults. Parents, who drove the same vehicles over the same period and geographic area as their newly licensed adolescents, would be expected to exhibit stable, consistent, and relatively low-risk driving behavior. To our knowledge, ours was the first observational study conducted in the United States that compared novice and adult driving by continuously recording driving performance and mileage. We examined the relationship between per mile rates of novice adolescent and adult crashes and near crashes and risky driving during the first 18 months of licensure. We hypothesized that the rates of adolescent crashes and near crashes and risky driving would decrease with experience but that over the study period the averages would be higher among novice adolescent drivers than among parents.
