Driver Expectations of a Partial Driving Automation System in Relation to Branding and Training

OBJECTIVE

The current study examined whether differences in the branding and description or mode of training materials influence drivers' understanding and expectations of a partial driving automation system.

BACKGROUND

How technology is described might influence consumers' understanding and expectations, even if all information is accurate.

METHOD

Ninety drivers received training about a real partial driving automation system with a fictitious name. Participants were randomly assigned to a branding condition (system named AutonoDrive, training emphasized capabilities; or system named DriveAssist, training emphasized limitations) and training mode (quick-start brochure; video; or in-person demonstration). No safety-critical information was withheld nor deliberately misleading information provided. After training, participants drove a vehicle equipped with the system. Associations of drivers' expectations with branding condition and training mode were assessed using between-subjects comparisons of questionnaire responses obtained pre- and post-drive.

RESULTS

Immediately after training, those who received information emphasizing the system's capabilities had greater expectations of the system's function and crash avoidance capability in a variety of driving scenarios, including many in which the system would not work, as well as greater willingness to utilize the system's workload reduction benefits to take more risks. Most but not all differences persisted after driving the vehicle. Expectations about collision avoidance differed by training mode pre-drive but not post-drive.

CONCLUSION

Training that emphasizes a partial driving automation system's capabilities and downplays its limitations can foster overconfidence.

APPLICATION

Accuracy of technical information does not guarantee understanding; training should provide a balanced view of a system's limitations as well as capabilities.

Passenger Presence and the Relative Risk of Teen Driver Death

PURPOSE

This study examines the relative risk of death among crash-involved teenage drivers in relation to the number and ages of passengers present.

METHODS

We performed cross-sectional analysis of police-reported crashes in the United States in years 2016-2019 to estimate rate ratios for death among drivers aged 16-17 years by passenger composition (no passengers, one teen, ≥two teens, teens and adults aged 20-34 years, adults aged 20-34 years only, ≥one adult aged 35-64 years). Models were adjusted for confounding and effect modification related to driver, crash, and environmental factors.

RESULTS

Crash-involved teen drivers carrying ≥2 teen passengers were twice as likely to die as teens driving alone. The driver was seven times as likely to die when carrying a mix of teen and young adult passengers compared with teens driving alone. Teen drivers' risk of death was lowest in the presence of an adult passenger aged 35-64 years. Carrying one teen passenger presents greater risk of death than driving alone for male teen drivers but not for females.

DISCUSSION

When teen drivers crash, they are more likely to die if they are carrying teen and/or young adult passengers than if they are driving alone or with a mature adult. The results support the current graduated licensing policies restricting young novice drivers from carrying teenage passengers. Results also help to clarify why previous studies have found that young passengers are associated with increased risk of fatal crashes, but not nonfatal crashes: it appears that passengers may have an effect on crash severity.

Fatal hit-and-run crashes: Factors associated with leaving the scene

INTRODUCTION

Hit-and-run crashes are a criminal offense that leave the victim without prompt medical care or the ability to receive financial compensation.

METHOD

The purpose of the current study was to quantify the factors associated with the probability that a driver leaves the scene of a fatal crash, using multiple imputation to incorporate information from drivers who were never apprehended and thus whose characteristics were unknown.

RESULTS

The results of this study show that in addition to driver, vehicle, and environmental factors having significant impacts on the likelihood of a driver fleeing the scene, economic and demographic factors are important as well. Practical Applications: This analysis allows for a more holistic understanding of hit-and-run crashes and informs potential countermeasures and future research.

Estimating Cannabis Involvement in Fatal Crashes in Washington State Before and After the Legalization of Recreational Cannabis Consumption Using Multiple Imputation of Missing Values

The government of Washington state legalized recreational cannabis consumption in December 2012. We used data on all drivers involved in fatal crashes in Washington in the years 2008-2019 (n = 8,282) to estimate prevalence in fatal crashes of drivers with ∆9-tetrahydrocannabinol (THC; the main psychoactive compound in cannabis) in their blood before and after legalization. However, nearly half of the drivers were not tested for drugs; we therefore used multiple imputation to estimate THC presence and concentration among them. We used logistic regression followed by marginal standardization to estimate the adjusted prevalence of THC-positive drivers after legalization relative to what would have been predicted without legalization. In the combined observed and imputed data, the proportion of drivers positive for THC was 9.3% before and 19.1% after legalization (adjusted prevalence ratio: 2.3, 95% confidence interval: 1.3, 4.1). The proportion of drivers with high THC concentrations increased substantially (adjusted prevalence ratio: 4.7, 95% confidence interval: 1.5, 15.1). Some of the increased prevalence of THC-positive drivers might have reflected cannabis use unassociated with driving; however, the increased prevalence of drivers with high THC concentrations suggests an increase in the prevalence of driving shortly after using cannabis. Other jurisdictions should compile quantitative data on drug test results of drivers to enable surveillance and evaluation.

The effect of extending graduated driver licensing to older novice drivers in Indiana

INTRODUCTION

Graduated driver licensing (GDL) systems have been shown to reduce rates of crashes, injuries, and deaths of young novice drivers. However, approximately one in three new drivers in the United States obtain their first driver's license at age 18 or older, and thus are exempt from most or all provisions of GDL in most states.

METHOD

In July 2015, the state of Indiana updated its GDL program, extending its restrictions on driving at night and on carrying passengers during the first 6 months of independent driving, previously only applicable to new drivers younger than 18, to all newly-licensed drivers younger than 21 years of age. The current study examined monthly rates of crashes per licensed driver under the affected conditions (driving at night and driving with passengers) among Indiana drivers first licensed at ages 18, 19, and 20 under the updated GDL system compared with drivers licensed at the same ages under the previous GDL system. We used Poisson regression to estimate the association between the GDL system and crash rates, while attempting to control for other factors that might have also influenced crash rates. We used linear regression to estimate the association between the GDL system and the proportion of all crashes that occurred under conditions restricted by the GDL program.

RESULTS

Results showed, contrary to expectations, that rates of crashes during restricted nighttime hours and with passengers were higher among drivers licensed under the updated GDL system. This mirrored a statewide increase in crash rates among drivers of all ages over the study period and likely reflected increased overall driving exposure. The proportions of all crashes that were at night or with passengers did not change. Practical Applications: More research is needed to understand how older novice drivers respond when GDL systems originally designed for younger novice drivers are applied to them.

Acute sleep deprivation and culpable motor vehicle crash involvement

Study Objectives

To quantify the relationship between acute sleep deprivation and culpable involvement in motor vehicle crashes.

Methods

Participants were 6845 drivers involved in a representative sample of crashes investigated by the US Department of Transportation in years 2005-2007. A modified case-control study design was used to compare self-reported hours of sleep in the 24 hr before crashing between drivers deemed culpable versus nonculpable. Analyses controlled for fatigue-related, driver-related, and environmental factors. Specific errors that led to crashes were also examined.

Results

Drivers who reported having slept for 6, 5, 4, and less than 4 hr in the 24 hr before crashing had 1.3 (95% confidence interval [CI] = 1.04 to 1.7), 1.9 (1.1 to 3.2), 2.9 (1.4 to 6.2), and 15.1 (4.2 to 54.4) times the odds, respectively, of having been culpable for their crashes, compared with drivers who reported 7-9 hr of sleep. Drivers who had slept less than 4 hr had 3.4 (95% CI = 2.1 to 5.6) times the increase in odds of culpable involvement in single-vehicle crashes compared with multiple-vehicle crashes. Recent change in sleep schedule, typically feeling drowsy upon waking, and driving for 3+ hr were also associated with culpability (all p ≤ 0.013). Assuming nonculpable drivers comprised a representative sample of all drivers present where crashes occurred, these odds ratios approximate incidence rate ratios for culpable crash involvement per unit of time driving.

Conclusions

Driving after having slept less than 7 hr in a 24 hr period is associated with elevated risk of culpable crash involvement. Risk is greatest for drivers who have slept less than 4 hr and is manifested disproportionately in single-vehicle crashes.

Comparison of older and younger novice driver crash rates: Informing the need for extended Graduated Driver Licensing restrictions

BACKGROUND

Few previous studies have directly compared crash rates of older and younger novice drivers. To inform discussion about whether Graduated Driver Licensing (GDL) policies that are applied in the US for younger novice drivers should be applied to older novice drivers, we conducted a longitudinal study to examine overall, nighttime, and multiple passenger crash rates over the initial four years of licensure differ for novice drivers licensed at different ages.

METHODS

Using data from the New Jersey Traffic Safety Outcomes (NJ-TSO) data warehouse, we selected all NJ drivers who obtained their initial intermediate driver's license from 2006 through 2014 and had at least one month of follow-up from the date of licensure to study end or death (n=1,034,835). Novice drivers were grouped based on age at licensure: age 17; 18-20; 21-24; and 25 or older. We estimated monthly rates for overall crashes (per 10,000 licensed drivers) as well as: late night crashes (11:01 p.m.-4:59 a.m.); early night crashes (9:00 p.m.-11:00 p.m.); and multiple passenger crashes (two or more passengers). Average monthly rates were calculated for specific relevant time periods and Poisson regression models were used to compare rates: (1) between novice driver groups with the same time since licensure; (2) over the first 48 months of licensure within each novice driver group; and (3) between same-aged 21-year-old drivers with varying lengths of licensure.

RESULTS

Although initial (three months post-licensure) overall crash rates of novice NJ drivers age 21 and older were higher than rates of same-aged experienced drivers, they were substantially lower than initial rates for 17- to 20-year-old novice drivers, who are licensed under GDL policies. Moreover, older novice drivers experience much less steep crash reductions over the first year of licensure than younger novice drivers. Nighttime crash rates among the 21- to 24-year old and aged 25 and older novice driver groups were stable over the first year of licensure. For novice drivers under age 21, early night crash rates declined rapidly over the course of licensure, while changes in late night crashes were much smaller. First-year multiple passenger crash rates were highest for drivers licensed at age 18-20, and novice driver groups experienced varying amounts of reduction in multiple passenger crashes over time.

CONCLUSIONS

Study findings support NJ's current GDL policies for 17- to 20-year-old novice drivers and the potential for added benefits from beginning the nighttime restriction at 9:00 p.m. Conversely, there was a lack of compelling evidence for additional policies for drivers licensed at age 21-24 and no evidence to indicate a need for additional GDL policies for NJ novices aged 25 years and older.

The relationship between age and driving attitudes and behaviors among older Americans

Background

Due to a decreasing birth rate and longer life expectancy, the proportion of Americans over the age of 65 is expected to rise in coming years. Drivers over 65 drive two billion miles yearly, a number that will increase. For that reason, it is imperative to understand their attitudes and perceptions. It is also important to understand whether drivers over 65 can be treated as one cohesive group, or if there are differences among them.

Methods

A web-enabled survey was conducted among Americans in the years 2011–2013. Responses from 1793 persons over 65 regarding attitudes towards driving behaviors, support for safety interventions, and engagement in unsafe behaviors were analyzed. Respondents were stratified by age: 65–69, 70–74, and 75 and older. Age groups were compared using logistic regression. Other potential explanatory factors were analyzed and controlled for.

Results

The three groups were similar on many outcomes. However, statistically significant differences were found between them with regard to perceptions on speeding and the support for speed cameras, among other outcomes. In nearly all cases, those 75 and older were the most “pro-safety.” However, when adjusted for demographic characteristics other than age, a larger proportion of respondents 75 and older reported engaging in red light running and drowsy driving in the last 30 days, and the difference was statistically significant.

Conclusion

Older drivers are strongly “pro-traffic safety.” However, the finding that those 65–69 are less so is concerning. This is especially true if it is the result of a cohort effect instead of an age effect. The increase in certain behaviors among those 75 and older is also concerning; drivers over this age are more prone to fatal injury when involved in a motor vehicle crashes. This poses a public health issue as the 75and older population expands.

Driver license renewal policies and fatal crash involvement rates of older drivers, United States, 1986-2011

Background

Older drivers experience elevated risk of motor vehicle crash involvement, injury, and death. Several states attempt to address these risks through driver license renewal policies; however, little is known about their effects.

Methods

Data from 46 U.S. states from years 1986–2011 were examined. Associations between driver licensing policies and population-based fatal crash involvement rates of drivers aged 55 years and older, in 5-year age groups, were estimated using population-averaged negative binomial regression. Estimates were adjusted for seasonality, time trends, other traffic safety laws, and economic factors. Ratios of relative risks (RRR), which compared changes in fatal crash involvement rates of older drivers associated with changes in licensing policies to corresponding changes in fatal crashes of drivers ages 40–54, were computed to account for other possible sources of confounding.

Results

Mandatory in-person renewal was associated with a 31% reduction in the fatal crash involvement rates of drivers ages 85 and older (RRR: 0.69, 95% Confidence Interval [CI]: 0.48–0.97). When in-person renewal was not required, requiring drivers to pass a vision test was associated with a similar reduction for drivers ages 85+ (RRR: 0.64, 95% CI: 0.49–0.85). When in-person renewal was required, however, requiring a vision test was not associated with any additional reduction, nor was requiring a knowledge test or an on-road driving test. Requiring more frequent license renewal and requiring healthcare providers to report concerns about patients’ driving ability to licensing authorities were not associated with statistically significant reductions in fatal crash involvement rates of older drivers. No policy examined was found to have a significant impact on fatal crash involvement of drivers younger than 85.

Conclusions

Requiring drivers to renew their license in person, or to pass a vision test if not renewing in person, was associated with significant reductions in population-based fatal crash involvement rates for drivers ages 85 and older. The study could not determine how these effects were achieved, for example by specifically removing unsafe older drivers from the driving population or by fostering premature driving cessation. Other policies examined were not found to reduce fatal crash involvement rates of older drivers.

Driver licensing and reasons for delaying licensure among young adults ages 18-20, United States, 2012

BACKGROUND

Motor vehicle crashes are the leading cause of death for teens and young adults in the United States. Graduated driver licensing (GDL) systems were designed to protect young novice drivers by limiting their exposure to specific risks while they gain experience driving. In the United States, most states' GDL systems only apply to new drivers younger than 18. Some experts suggest that GDL might encourage young people to wait until age 18 to obtain a license, to avoid GDL requirements, resulting in older teenagers having less driving experience and higher crash risk than they might have had without GDL. This study examined the prevalence and timing of licensure among young adults, and explored factors associated with delaying licensure among those not licensed before age 18.

METHODS

An online questionnaire was completed by 1,039 persons aged 18-20 years, recruited from a representative panel of United States households. Main outcome measures were acquisition of driver's license (a) within 12 months of the state minimum age for licensure, (b) before age 18. Associations of timing of licensure with demographic characteristics were assessed using multivariable logistic regression. Respondents not licensed before age 18 were asked to rate the importance of various possible reasons for delaying licensure.

RESULTS

54% of respondents were licensed before age 18. Blacks (37%; adjusted Prevalence Ratio 0.67, 95% Confidence Interval 0.48-0.93) and Hispanics (29%; adjusted Prevalence Ratio 0.60, 95% Confidence Interval 0.45-0.81) were less likely than non-Hispanic whites (67%) to be licensed before age 18. Lower household income was independently associated with delayed licensure (P < .001). The most common self-reported reasons for not becoming licensed sooner were not having a car, being able to get around without driving, and costs associated with driving.

CONCLUSIONS

There was little evidence that GDL is a major contributor to delayed licensure; however, a substantial minority of young people do not obtain a driver's license until age 18 or older and thus begin driving outside of the GDL system, which in most states only applies to new drivers younger than 18. More research is needed to investigate the safety of older novice drivers.

Characteristics of teens-with-teens fatal crashes in the United States, 2005-2010

BACKGROUND

More than 40% of fatal crashes of 16- and 17-year-old drivers occur when transporting teenagers. Characteristics of this predominant crash type and prevention possibilities are described, based on data from fatal crashes in the United States during 2005-2010.

RESULTS

Fifty-seven percent of 16- and 17-year old drivers in fatal crashes had at least one passenger. Most commonly, all passengers were ages 13-19 (42% of all drivers and 73% of those with passengers). Of fatal crashinvolved drivers with teenage passengers and no passengers of other ages, 56% had one passenger, 24% had two, and 20% had three or more. Most frequently, passengers were the same sex and within one year of the driver. Risk factors involving speeding, alcohol use, late-night driving, lack of a valid license, seat belt non-use, and crash responsibility were more prevalent with teenage passengers than when driving alone, and the prevalence of these factors increased with the number of teenage passengers. Many risk factors were most prevalent with passengers ages 20-29, although few crashes had this occupant configuration. Risk factors were least prevalent with a passenger 30 or older.

DISCUSSION

Fatal crashes of 16- and 17-year-old drivers with teen passengers are a common crash scenario, despite passenger restrictions in 42 states and the District of Columbia during some or all of the study period. The proportion of these fatal crashes decreased slightly from 46% in 1995 (pre-GDL) to 43% in 2010 and showed no signs of decreasing during the six-year study period (range 41% to 43%).

PRACTICAL APPLICATIONS

Existing passenger restrictions are relatively weak and could be strengthened. Fatal crashes involving teen passengers, especially multiple passengers, are more likely to involve alcohol, late-night driving, driver error, and invalid licensure, so stepped-up enforcement of existing laws involving these behaviors might reduce the prevalence of such crashes.

Impact speed and a pedestrian's risk of severe injury or death

This study estimates the risk of severe injury or death for pedestrians struck by vehicles using data from a study of crashes that occurred in the United States in years 1994-1998 and involved a pedestrian struck by a forward-moving car, light truck, van, or sport utility vehicle. The data were weighted to correct for oversampling of pedestrians who were severely injured or killed. Logistic regression was used to adjust for potential confounding related to pedestrian and vehicle characteristics. Risks were standardized to represent the average risk for a pedestrian struck by a car or light truck in the United States in years 2007-2009. Results show that the average risk of a struck pedestrian sustaining an injury of Abbreviated Injury Scale 4 or greater severity reaches 10% at an impact speed of 17.1miles per hour (mph), 25% at 24.9mph, 50% at 33.0mph, 75% at 40.8mph, and 90% at 48.1mph. The average risk of death reaches 10% at an impact speed of 24.1mph, 25% at 32.5mph, 50% at 40.6mph, 75% at 48.0mph, and 90% at 54.6mph. Risks varied by age. For example, the average risk of death for a 70-year-old pedestrian struck at any given speed was similar to the average risk of death for a 30-year-old pedestrian struck at a speed 11.8mph faster.

Teen driver risk in relation to age and number of passengers, United States, 2007-2010

OBJECTIVE

To provide updated estimates of the relationship between the number and ages of passengers present in a vehicle and the crash risk per mile driven of 16- and 17-year-old drivers.

METHODS

Data on crashes that occurred in years 2007-2010 and data on the number of miles driven in years 2008-2009 were examined. Rates of crash involvement and driver death per mile driven were estimated for 16- and 17-year-old drivers with no passengers; with 1, 2, and 3 or more passengers younger than age 21 (and no older passengers); and with at least 1 passenger aged 35 or older.

RESULTS

For 16- and 17-year-old drivers, having 1 passenger younger than age 21 (and no older passengers) was associated with 44 percent greater risk per mile driven of being killed in a crash, compared to having no passengers (relative risk [RR]: 1.44, 95% confidence interval [CI]: 1.01-2.04). Having 2 passengers younger than age 21 was associated with double the risk of being killed in a crash, compared to having no passengers (RR: 2.02, 95% CI: 1.36-2.99). Having 3 or more passengers younger than age 21 was associated with roughly quadruple the risk of being killed in a crash, compared to having no passengers (RR: 4.39, 95% CI: 1.45-13.31). The relative risk of being involved in any police-reported crash in the presence of young passengers followed a similar pattern; however, the differences in risks of being involved in any police-reported crash were smaller and were not statistically significant. Having at least 1 passenger aged 35 or older in the vehicle was associated with a 62 percent lower risk per mile driven of being killed in a crash (RR: 0.38, 95% CI: 0.24-0.60) and a 46 percent lower risk of being involved in any police-reported crash (RR: 0.54, 95% CI: 0.31-0.93) for 16- and 17-year-old drivers, compared to having no passengers.

CONCLUSIONS

These results show that although the overall number of teen driver fatalities has decreased substantially over the past several years, carrying young passengers is still a significant risk factor for young drivers. In contrast, carrying adult passengers is associated with significantly lower risk of crash involvement.

Graduated driver licensing research, 2010-present

This is the latest in a series of reviews of research on graduated driver licensing (GDL) published in the Journal of Safety Research, covering the period January 1, 2010-June 1, 2012 and works in progress. The intent is to keep researchers and policy makers current regarding the existing state of knowledge about GDL, and to identify information gaps and areas where clarification of research findings are needed. The recent research indicates that we continue to learn about ways to extend GDL benefits, but there remain important questions in need of further inquiry. In terms of impact on industry, the review provides guidance for the future GDL research agenda.

Evaluation of New Jersey's graduated driver licensing program

OBJECTIVE

The objective of this study was to evaluate New Jersey's unique combination of a higher licensing age and a strong GDL system applicable to all novice drivers.

METHODS

Population-based crash rates for drivers of ages potentially affected by GDL were compared, pre- and post-GDL implementation, with those of adults ages 25-59, using data on fatal crashes and on all police-reported crashes.

RESULTS

After GDL implementation, there were statistically significant reductions in the crash rates of 17-year-olds, based on all reported crashes (16%), injury crashes (14%), and fatal crashes (25%), relative to those of drivers ages 25-59. The crash rates of 18-year-olds decreased significantly on the basis of all reported crashes (10%) and injury crashes (10%), relative to those of drivers ages 25-59. The fatal crash involvement rate of 18-year-olds decreased by 4 percent, which was not statistically significant. There was also a statistically significant reduction in fatal crashes of 16-year-old drivers; however, this is unlikely to have been attributable to GDL. Significant reductions in nighttime crashes (of all severity levels) of drivers ages 17 and 18 were observed, as were significant yet smaller reductions in their daytime crash rates. Reductions in fatal crashes of 17- and 18-year-olds carrying more than one passenger were sizable (23 and 24%, respectively) but were not statistically significant.

CONCLUSIONS

New Jersey's licensing age of 17 eliminates most crashes at age 16. To the extent that the relative inexperience of 17-year-old drivers may negatively impact their crash rates, this effect appears to be largely blunted by New Jersey's strong GDL system. New Jersey's GDL system also reduces crashes at age 18, an age group untouched by other states' GDL systems. New Jersey's combination of licensing policies for young drivers is a model for the nation.

Risks older drivers pose to themselves and to other road users

PROBLEM

Studies have shown that older drivers have high death rates and lower rates of involvement in crashes that kill others; but most studies have not considered drivers' responsibility for their crashes, and many have considered only one particular measure of risk.

METHOD

This study examines risks that drivers of various ages pose to themselves and to others on per-driver, per-trip, and per-mile bases, taking responsibility for crashes into account, using United States fatal crash data from 1999 through 2003 and travel estimates from 2001.

RESULTS

Relative to other age groups, drivers aged 85 and older face the highest risk of their own death, whereas teens pose the greatest risk to passengers, occupants of other vehicles, and non-motorists.

DISCUSSION

The oldest drivers pose more risk to other road users than middle-aged drivers do; the degree of their excess risk depends strongly upon how risk is measured.

IMPACT ON INDUSTRY

These results demonstrate the importance of keeping clear the meaning and implications of various risk measures.