Teen drivers' awareness of vehicle instrumentation in naturalistic research.

INTRODUCTION: Naturalistic driving methods require the installation of instruments and cameras in vehicles to record driving behavior. A critical, yet unexamined issue in naturalistic driving research is the extent to which the vehicle instruments and cameras used for naturalistic methods change human behavior. We sought to describe the degree to which teenage participants' self-reported awareness of vehicle instrumentation changes over time, and whether that awareness was associated with driving behaviors. METHOD: Forty-two newly-licensed teenage drivers participated in an 18-month naturalistic driving study. Data on driving behaviors including crash/near-crashes and elevated gravitational force (g-force) events rates were collected over the study period. At the end of the study, participants were asked to rate the extent to which they were aware of instruments in the vehicle at four time points. They were also asked to describe their own and their passengers' perceptions of the instrumentation in the vehicle during an in-depth interview. The number of critical event button presses was used as a secondary measure of camera awareness. The association between self-reported awareness of the instrumentation and objectively measured driving behaviors was tested using correlations and linear mixed models. RESULTS: Most participants' reported that their awareness of vehicle instrumentation declined across the duration of the 18-month study. Their awareness increased in response to their passengers' concerns about the cameras or if they were involved in a crash. The number of the critical event button presses was initially high and declined rapidly. There was no correlation between driver's awareness of instrumentation and their crash and near-crash rate or elevated g-force events rate. CONCLUSION: Awareness was not associated with crash and near-crash rates or elevated g-force event rates, consistent with having no effect on this measure of driving performance. PRACTICAL APPLICATIONS: Naturalistic driving studies are likely to yield valid measurements of driving behavior.

Naturalistic assessment of the learner license period.

The purpose of this study was to describe the characteristics and progression of practice driving during the learner license period in a sample of teenagers. During the first and last 10h of practice driving, we examined (1) the amount, variety and complexity of conditions of practice; (2) the nature of parental instruction; and (3) errors that teens made while driving. Data were collected from 90 teens and 131 parents living in Virginia, USA, using in-vehicle cameras, audio recorders, GPS and trip recorders. Based on data collected from the instrumented vehicles, teens practiced for 46.6h on average, slightly higher than the GDL requirement for their jurisdiction, though half did not complete the required 45h of practice and only 17% completed the required 15h of night time driving. Exposure to diverse roadways increased over the practice driving period, which averaged 10.6 months. Most driving instruction occurred in reaction to specific driving situations, such as navigating and identifying hazards, and could be characterized as co-driving. Higher order instruction, which relates to the tactics or strategies for safe driving, was less frequent, but remained stable through the practice driving period. Instruction of all forms was more likely following an elevated gravitational force (g-force) event. Errors decreased over time, suggesting improvements in manual and judgment skills, but engagement in potentially distracting secondary tasks increased (when an adult was in the vehicle). A small percentage of trips occurred with no passenger in the front seat, and the g-force rate during these trips was almost 5 times higher than trips with an adult front-seat passenger. Taken collectively, these findings indicate (1) most teens got at least the required amount of supervised practice, but some did not; (2) instruction was mainly reactive and included some higher order instruction; (3) teens driving skills improved despite increased exposure to complex driving conditions, but secondary tasks also increased. Opportunities remained for improving the quality and variability in supervision and enhancing the development of skills during the lengthy period of practice.

The relative odds of involvement in seven crash configurations by driver age and sex.

INTRODUCTION: Much is known about sex and age differences in collision types, but most studies have examined the effect of declining physical and mental capabilities on older drivers' performance. Fewer studies have focused on the relationship between younger driver's sex and crash type, and these studies have largely ignored the multidimensionality of crashes, have not consistently examined sex differences, and are based on outdated data. This study addressed these issues by examining differences in the likelihood of involvement in seven crash configurations between adolescent and adult male and female drivers. METHOD: Fatal crash data from the Fatality Analysis Reporting System and nonfatal crash data from the General Estimation System for years 2005-2009 were used. Crash configurations were identified using point of initial impact, manner of collision, and vehicle action (i.e., striking or struck). Logistic regression estimated relative odds ratios among four driver groups: male and female drivers aged 15-19 years, and male and female drivers aged 45-64 years. RESULTS: Crash likelihood varied dramatically by driver age and sex across crash configuration. Adolescent male drivers were most likely to be in single-vehicle and fatal head-on crashes; adolescent drivers had a higher likelihood of front-to-rear crashes; adults had the highest likelihood of rear-end crashes; and female drivers had higher likelihoods of left- and right-side crashes. CONCLUSIONS: These findings may result from differences in driving experience, driving styles, or cognitive spatial abilities. Future research is needed to identify contributors to different crash configurations so that they can be directly addressed through tailored interventions and programs.

Driving exposure by driver age in Michigan.

BACKGROUND: This study compared driving exposure between two high-crash-risk groups (16-17 and 18-24-year-olds), with a low-crash-risk group (35-64-year-olds). In addition, patterns of association between driving exposure measures and demographic and driving behavior variables were examined. METHODS: Respondent's total miles, minutes, and trips driven were calculated within a 48-hour period, using state-wide survey data collected in 2004 and 2005. RESULTS: The youngest drivers drove fewer miles and minutes, but a comparable number of trips as the two older groups. Employment and high vehicle access were associated with greater driving exposure for 16-17-year-olds and 18-24-year-olds. Employment, high household income, large household size, and low vehicle access were associated with greater driving exposure for 35-64-year-olds. More driving was done alone than with passengers present and during the day than at night across all ages. There was a positive association between two driving exposure measures (miles and minutes driven) and demographic and driving behavior variables, which did not extend to trips driven. DISCUSSION: Driving exposure is directly related to stage of life. The entire sample of 16-17-year-old respondents were in high school, which directly influenced their driving times, destinations, and purpose. Those aged 18-24years displayed driving behavior patterns that were closer to the older drivers, while retaining some differences. The oldest drivers were likely to be shouldering the greatest household responsibilities, and their greater driving exposure may reflect this reality. IMPACT ON INDUSTRY: These findings provide new information about driving exposure for two high-risk and one low-risk group of drivers. They also raise concern over potential workplace safety issues related to teens' higher driving exposure, and concomitant crash risk, related to being employed. Future research should examine this issue more carefully so that evidence based recommendations can be made to enhance the safety of teens who are employed, especially those who are employed as drivers.

Teen driving exposure in Michigan: demographic and behavioral characteristics.

Motor vehicle crashes are the leading cause of death and a leading cause of non-fatal injury for teenagers in the United States. Understanding teen crashes requires a good measure of crash risk. The measure of exposure that is used in the calculation of risk estimates determines what information the resulting rates and rate ratios provide and the conclusions that can be drawn about teen driver crash risk. The purpose of this study is to provide an initial description of three measures of individual-level exposure to driving for 16-17-year-olds in the state of Michigan, using data from the state-wide Michigan Travel Counts survey conducted in 2004 and 2005. The total miles, minutes, and trips driven within the 48-h survey period were calculated for each respondent using self-reported measures and geo-spatial mapping. Young drivers who worked and those with greater access to a vehicle drove significantly more than their peers who did not work and those who had less access to a vehicle. Those from urban residences spent more time driving than those from rural residences. All 16-17-year-olds drove substantially more during the day than at night, and on their own than with passengers. There was little difference in overall driving exposure and driving behavior between young men and young women. This study provides an initial description of driving exposure and behavior for a population for which there is very little specific information about amounts and patterns of individual driving exposure. The relationship between individual driving exposure and risk of motor vehicle crash, injury or fatality requires further investigation.