Naturalistic assessment of novice teenage crash experience

Background

Crash risk is highest during the first months after licensure. Current knowledge about teenagers’ driving exposure and the factors increasing their crash risk is based on self-reported data and crash database analyses. While these research tools are useful, new developments in naturalistic technologies have allowed researchers to examine newly-licensed teenagers’ exposure and crash risk factors in greater detail. The Naturalistic Teenage Driving Study (NTDS) described in this paper is the first study to follow a group of newly-licensed teenagers continuously for 18 months after licensure. The goals of this paper are to compare the crash and near-crash experience of drivers in the NTDS to national trends, to describe the methods and lessons learned in the NTDS, and to provide initial data on driving exposure for these drivers.

Methods

A data acquisition system was installed in the vehicles of 42 newly-licensed teenage drivers 16 years of age during their first 18 months of independent driving. It consisted of cameras, sensors (accelerometers, GPS, yaw, front radar, lane position, and various sensors obtained via the vehicle network), and a computer with removable hard drive. Data on the driving of participating parents was also collected when they drove the instrumented vehicle.

Findings

The primary findings after 18 months included the following: (1) crash and near-crash rates among teenage participants were significantly higher during the first six months of the study than the final 12 months, mirroring the national trends; (2) crash and near-crash rates were significantly higher for teenage than adult (parent) participants, also reflecting national trends; (3) teenaged driving exposure averaged between 507 and 710 km (315–441 miles) per month over the study period, but varied substantially between participants with standard errors representing 8–14 percent of the mean; and (4) crash and near-crash types were very similar for male and female teenage drivers.

Discussion

The findings are the first comparing crash and near-crash rates among novice teenage drivers with those of adults using the same vehicle over the same period of time. The finding of highly elevated crash rates of novice teenagers during the first six months of licensure are consistent with and confirm the archival crash data showing high crash risk for novice teenagers. The NTDS convenience sample of teenage drivers was similar to the US teenage driver population in terms of exposure and crash experience. The dataset is expected be a valuable resource for future in-depth analyses of crash risk, exposure to risky driving conditions, and comparisons of teenage and adult driving performance in various driving situations.     

Time and distance to first accident and driving patterns of young drivers with pay-as-you-drive insurance

We conducted a study of approximately 16,000 drivers under the age of 30 that had purchased a pay-as-you-drive insurance policy, where their risk of being involved in a crash was analyzed from vehicle tracking data using a global positioning system. The comparison of novice vs. experienced young drivers shows that vehicle usage differs significantly between these groups and that the time to the first crash is shorter for those drivers with less experience. Driving at night and a higher proportion of speed limit violations reduces the time to the first crash for both novice and experienced young drivers, while urban driving reduces the distance traveled to the first crash for both groups. Gender differences are also observed in relation to the influence of driving patterns on the risk of accident. Nighttime driving reduces the time to the first accident in the case of women, but not for men. The risk of an accident increases with excessive speed, but the effect of speed is significantly higher for men than it is for women among the more experienced drivers.     

The characteristics of young pre-licensed drivers: Evidence from the New Zealand Drivers Study

Aim

The aim of this study was to identify demographic and behavioural factors associated with pre-licensed driving.

Method

A cohort comprising 3526 newly licensed drivers aged 15–24 years old from throughout New Zealand completed a questionnaire which sought information on pre-licensed driving behaviour and factors thought to be related to this.

Results

Almost half of the participants had driven on-road prior to passing their learner license theory test; 14% had driven more than 20 times; and 7.5% had driven more than 200 km. Multivariate logistic regression showed the results differed depending on the outcome examined. In general pre-licensed driving was significantly higher among males, among Māori, those living in a rural area, and those living in an area of high deprivation. Furthermore, those who drove pre-licensed were more likely to engage in other risky behaviours such as hazardous drinking and cannabis use, and have medium to high scores for sensation seeking and aggression/hostility.

Conclusion

The young people who were pre-licensed drivers displayed a range of demographic and behavioural characteristics that indicate they may be at higher crash risk than their peers who did not drive before licensing. Identifying those who drive before licensing and targeting road safety interventions towards this group may help reduce the high crash risk among novice drivers.     

Modeling the behavior of novice young drivers during the first year after licensure

Novice young drivers suffer from increased crash risk that translates into over-representation in road injuries. In order to effectively confront this problem, a better understanding of the driving behavior of novice young drivers and of its determinants is needed. This study analyzes the behavior of novice young drivers within a Graduated Driver Licensing (GDL) program. Data on driving behavior of 62 novice drivers and their parents, who voluntarily participated in this experiment, were collected using in-vehicle data recorders that calculate compound risk indices as measures of the risk taking behavior of drivers. Data were used to estimate a negative binomial model to identify major determinants that affect the driving behavior of young drivers during the first year after licensure. Estimation results suggest that the risk taking behavior of young drivers is influenced by gender, sensation seeking tendency, driving behavior of their parents, amount of supervised driving and level of parental monitoring.     

Validation of the Behaviour of Young Novice Drivers Scale (BYNDS) in a New Zealand young driver population

The Behaviour of Young Novice Drivers Scale, the BYNDS (Scott-Parker et al., 2010), is a reliable and valid self-report 44-item instrument which explores the frequency of a breadth of risky driving behaviours which appear to place young and novice drivers at an increased risk of road crash injury. As part of a larger collaborative research project, the Australian-developed BYNDS was piloted in a sample of 20 young New Zealand drivers n = 14 aged 16–18 years, 9 males; n = 6 aged 19–24 years, 2 males. The wording of 21 BYNDS items was modified to reflect the cultural context of the participating New Zealand drivers. The refined BYNDS was applied in a sample of 325 young drivers n = 116 aged 16–18 years, 65 males; n = 209 aged 19–24 years, 98 males, and the factor structure examined, including exploratory factor analysis for each gender. The 5-factor structure of the BYNDS was supported, with young drivers reporting considerable engagement in risky driving exposure, moderate engagement in transient violations and mood-related driving, and less fixed violations and driving misjudgements. Risky driving exposure was predictive of self-reported crash involvement for both males and females, suggesting targeted intervention regarding when, and the circumstances under which, the young driver is on the road.     

Graduated driver licensing program component calibrations and their association with fatal crash involvement

Graduated driver licensing (GDL) programs are specialized licensing systems for beginner drivers adopted in all U.S. states, Australia, Canada, and New Zealand. GDL programs reduce novice drivers’ exposure to high-risk driving situations while they gain driving experience. Several studies document the success of GDL programs overall in reducing young teen crash rates. However, little is known about which specific components of these programs (e.g., nighttime driving restrictions) and which calibrations of these components (e.g., 10 PM, 11 PM, 12 AM, or 1 AM), are associated with the largest crash reductions. The goal of this study was to identify the GDL component calibrations associated with the largest reductions in fatal crash involvements for 16–17-year-olds. Driver fatal crash involvements for all U.S. states from 1986 to 2007 were analyzed using Poisson regression models to estimate the association of various GDL component calibrations with 16- and 17-year-old driver fatal crash incidence, after adjusting for potential confounders. We found clear evidence that (a) a minimum learner permit holding period of 9–12 months and (b) a passenger restriction allowing only one teen passenger for 6 months or longer are the calibrations for the learner permit holding period and passenger restriction components associated with the largest reductions in 16–17-year-old driver fatal crash involvements. Additionally, the data suggest that (a) disallowing learner driving until age 16, (b) disallowing intermediate licensure until age 16½ to 17, and (c) a nighttime driving restriction starting at 10 PM or earlier are the calibrations for these components associated with the largest reductions in 16-year-old driver fatal crashes. There was no clear evidence to support particular calibrations for supervised driving hours or unrestricted license ages.     

Evaluation of electronic stability control effectiveness in Australasia

Electronic stability control (ESC) is an in-vehicle technology aimed at improving primary safety by assisting the driver in avoiding loss of control of the vehicle. The aim of this study was to use available crash data from Australia and New Zealand to evaluate the effectiveness of ESC in reducing crash risk and to establish whether benefits estimated from overseas studies have translated to the Australian and New Zealand environments. The sample analysed included 7699 crashed vehicles fitted with ESC which comprised of 90 different models. Poisson regression was used to test whether the differences in the observed and expected crash counts for ESC fitted vehicles were significant, with exposure being induced from counts of rear end impacts. It was found that ESC reduced the risk of single vehicle crashes in which the driver was injured by 68% for 4WDs compared with 27% for passenger cars. The effect of ESC on multiple vehicle crashes in Australia and New Zealand was not clear. The long-term benefits of fitting ESC to all vehicles in Australia were also investigated based on the estimated single vehicle crash reductions.     

An evaluation of the general effect of the New Zealand graduated driver licensing system on motorcycle traffic crash hospitalisations

In 1987, New Zealand introduced a comprehensive Graduated Driver Licensing System (GDLS) which was designed to allow new drivers to gain driving experience while being excluded from high risk situations. This study sought to evaluate the impact of the GDLS on motorcycle traffic crashes that resulted in serious injury. Injury crash data were obtained from the New Zealand Health Information Services national public hospital inpatient data files for the years 1978–1994, inclusive. Cases were disaggregated into three age groups, 15–19 years, 20–24 years, and 25 years or older, for which injury trends were obtained. In order to determine whether trends in motorcycle traffic crashes simply followed national trends in other injury events, two non-traffic comparison groups for the main target group (15–19 years) were included. Using time series analyses, the introduction of the GDLS was found to be closely followed by a significant reduction (22%) in motorcycle traffic crash hospitalizations for the 15–19 year age group. An examination of vehicle registration and driver licensure data suggests that the reduction in injury crashes may, largely, be attributable to an overall reduction in exposure to motorcycle riding.     

Licence restrictions as an under-used strategy in managing older driver safety

While many older drivers remain unimpaired or otherwise effectively compensate for functional deficits, a minority are currently faced with two main options: either continue to drive with arguably an unacceptable crash risk; or cease driving, perhaps at the instigation of licensing authorities. Licence restrictions represent a possible third option for some older drivers, by better managing crash risk while still allowing acceptable levels of mobility. The present study has explored licence restrictions as applied to Victorian older drivers over a ten-year period. It has identified the types of restrictions and their extent of use in recent years, plus indications of potential safety benefits that may result from restricted licencing practices. Less than 10% of the older driver cohort had a licence restriction and in around 95% of instances, the restriction related to the need to wear corrective lenses; these numbers precluded a conclusive evaluation of safety benefits. However, two important findings emerged. First, the imposition of a licence restriction was usually associated with a reduction in absolute crash rates. Second, three restrictions were identified that most readily form the basis of a graduated driving reduction program.     

Are SUVs dangerous vehicles?

This study was a population cohort study of all licensed passenger vehicles in New Zealand in the years 2005–2006. The objective of the study was to evaluate the effect on road safety of sports utility vehicles (SUVs) compared to other passenger vehicle types. Statistical models were fitted to the population of 2,996,000 vehicles of which 17,245 were involved in an injury crash. Controlling for distance driven, vehicle and owner characteristics, SUVs were found to be relatively safe vehicles in terms of injury crash involvement and in terms of the injury rate of their own occupants or other road users into which they crashed. Current research on SUV safety clearly shows them to be a road safety concern, but only once a collision occurs. The present study shows that SUVs in New Zealand have relatively few collisions compared to other passenger vehicle types, allowing for factors such as distance driven, some allowance for the type of driving exposure (via the owners’ addresses) and for owner age and gender. Overall, the vehicle type implicated most frequently in injury crashes and involving the highest rate of road injuries was sports cars, causing clearly the most harm per licensed vehicle. Instead of concerning themselves primarily with SUVs, the focus of road safety agencies should be on the relatively high crash risk of sports cars, which are clearly a road safety concern. Their high crash involvement rate and injury rate is likely to be largely due to the way they are driven rather than to inherent characteristics of the vehicles themselves.     

Overall injury risk to different drivers: combining exposure,frequency, and severity models

Traffic crash risk assessments should incorporate appropriate exposure data. However, existing US nationwide crash data sets, the NASS General Estimates System (GES) and the Fatality Analysis Reporting System (FARS), do not contain information on driver or vehicle exposure. In order to obtain appropriate exposure data, this work estimates vehicle miles driven (VMD) by different drivers using the Nationwide Personal Transportation Survey (NPTS). These results are combined with annual crash rates and injury severity information from the GES for a comprehensive assessment of overall risk to different drivers across vehicle classes.Data are distinguished by driver age, gender, vehicle type, crash type (rollover versus non-rollover), and injury severity. After correcting for drivers' crash exposure, results indicate that young drivers are far more crash prone than other drivers (per VMD) and that drivers of sports utility vehicles (SUVs) and pickups (PUs) are more likely to be involved in rollover crashes than those driving passenger cars. Although, the results suggest that drivers of SUVs are generally much less crash prone than drivers of passenger cars, the rollover propensity of SUVs and the severity of that crash type offset many of the incident benefits for SUV drivers.     

Young female drivers in New Zealand

While a considerable amount is known about young male drivers both in New Zealand and overseas, research attention concerning female drivers of any age including those under the age of 25 has been far less prevalent. The present paper explores the reasons behind the historically low research interest in this population of road users, and seeks to provide information on the current status of young female drivers^† in New Zealand, with regard to both travel patterns and crash involvement statistics. The findings of the present study suggest that the exposure to risk of this group has increased with greater licensing and kilometreage. Increased crash involvement was identified for this group, a finding accentuated by the fact that this has occurred concurrent with a decrease in crash involvement of young male drivers. Drink driving patterns of this group are discussed, in response to the finding that the crash involvement and number of drink-drive convictions of females 15–24 have increased over time. Implications for research and countermeasures are outlined.     

Rating the overall secondary safety of vehicles from real world crash data: the Australian and New Zealand Total Secondary Safety Index

Various systems for rating secondary safety of particular makes and models of vehicles have been developed internationally. These measures generally evaluate crashworthiness (the ability of the vehicle to protect its own occupants in the event of a crash) separately from aggressivity (the harm a vehicle is liable to impose on other road users into which it crashes). This paper describes an approach using Australian and New Zealand data that combines these two facets of secondary safety into one ‘Total Secondary Safety Index’ estimated from real world crash outcomes. The Index estimates the risk of death or serious injury to all key road users in crashes involving light passenger vehicles across the full range of crash types. This paper describes the rationale and method for producing this Index, together with some estimates for common Australian and New Zealand makes and models of light passenger vehicles.     

“I drove after drinking alcohol” and other risky driving behaviours reported by young novice drivers

Background: Volitional risky driving behaviours such as drink- and drug-driving (i.e. substance-impaired driving) and speeding contribute to the overrepresentation of young novice drivers in road crash fatalities, and crash risk is greatest during the first year of independent driving in particular. Aims: To explore the: (1) self-reported compliance of drivers with road rules regarding substance-impaired driving and other risky driving behaviours (e.g., speeding, driving while tired), one year after progression from a Learner to a Provisional (intermediate) licence; and (2) interrelationships between substance-impaired driving and other risky driving behaviours (e.g., crashes, offences, and Police avoidance). Methods: Drivers (n = 1076; 319 males) aged 18–20 years were surveyed regarding their sociodemographics (age, gender) and self-reported driving behaviours including crashes, offences, Police avoidance, and driving intentions. Results: A relatively small proportion of participants reported driving after taking drugs (6.3% of males, 1.3% of females) and drinking alcohol (18.5% of males, 11.8% of females). In comparison, a considerable proportion of participants reported at least occasionally exceeding speed limits (86.7% of novices), and risky behaviours like driving when tired (83.6% of novices). Substance-impaired driving was associated with avoiding Police, speeding, risky driving intentions, and self-reported crashes and offences. Forty-three percent of respondents who drove after taking drugs also reported alcohol-impaired driving. Discussion and Conclusions: Behaviours of concern include drink driving, speeding, novice driving errors such as misjudging the speed of oncoming vehicles, violations of graduated driver licensing passenger restrictions, driving tired, driving faster if in a bad mood, and active punishment avoidance. Given the interrelationships between the risky driving behaviours, a deeper understanding of influential factors is required to inform targeted and general countermeasure implementation and evaluation during this critical driving period. Notwithstanding this, a combination of enforcement, education, and engineering efforts appear necessary to improve the road safety of the young novice driver, and for the drink-driving young novice driver in particular.     

Trajectories of kinematic risky driving among novice teenagers

Objectives

Elevated gravitational force event rates are associated with the likelihood of a crash or near crash and provide an objective measure of risky driving. The purpose of this research is to examine the patterns over time of kinematic measures of risky driving among novice teenage drivers.

Methods

Driving data were collected from 42 newly licensed teenage drivers during the first 18 months of licensure. Data recording systems installed in participants’ vehicles provided information on driving performance and driver characteristics. Latent class and logistic regression models were used to analyze trajectories of elevated gravitational-force (g-force) event rates, called kinematic risky driving, with respect to risk groups and associated factors.

Results

Kinematic risky driving over the 18-month study period was best characterized as two classes, a higher-risk and a lower-risk class. The rate of kinematic risky driving during the first 6 months generally maintained over 18 months. Indeed, of those classified by latent class analysis as higher risk, 88.9%, 94.4% and 94.4% had average event rates above the median in the 1st, 2nd, and 3rd 6-month periods, respectively, indicating substantial tracking over time. Friends’ risky driving, friends’ risky behavior, self-reported risky driving, and perceptions about risky driving and driving privileges were associated with trip-level rates of kinematic risky driving. However, none of these factors was associated with trip-level rates after stratifying by overall risk in a latent class model, although friend's risky driving was marginally significant.

Conclusion

Kinematic risky driving tended to track over time within the lower and higher risky driving groups. Self-reported risky driving and having risky friends were predictors of kinematic risky driving rates, but these variables did not explain the heterogeneity within higher and lower classes of risky drivers.     

Novice drivers’ individual trajectories of driver behavior over the first three years of driving

Identifying the changes in driving behavior that underlie the decrease in crash risk over the first few months of driving is key to efforts to reduce injury and fatality risk in novice drivers. This study represented a secondary data analysis of 1148 drivers who participated in the UK Cohort II study. The Driver Behavior Questionnaire was completed at 6 months and 1, 2 and 3 years after licensure. Linear latent growth models indicated significant increases across development in all four dimensions of aberrant driving behavior under scrutiny: aggressive violations, ordinary violations, errors and slips. Unconditional and conditional latent growth class analyses showed that the observed heterogeneity in individual trajectories was explained by the presence of multiple homogeneous groups of drivers, each exhibiting specific trajectories of aberrant driver behavior. Initial levels of aberrant driver behavior were important in identifying sub-groups of drivers. All classes showed positive slopes; there was no evidence of a group of drivers whose aberrant behavior decreased over time that might explain the decrease in crash involvement observed over this period. Male gender and younger age predicted membership of trajectories with higher levels of aberrant behavior. These findings highlight the importance of early intervention for improving road safety. We discuss the implications of our findings for understanding the behavioral underpinnings of the decrease in crash involvement observed in the early months of driving.     

Evaluating the crash and citation rates of Utah drivers licensed with medical conditions, 1992-1996

BACKGROUND: Medical problems may affect the ability to drive motor vehicles, and programs that control the issuing of driver licenses to individuals with medical conditions exist in most states. The main activity of these programs is the imposition of restrictions upon the driving privileges of individuals with medical conditions that are deemed to pose some risk to public safety. However, little is known about the effectiveness of these licensing programs. OBJECTIVE: The objective of this study was to compare the rates of adverse driving events (crash, at-fault crash and citations) experienced by drivers licensed with medical conditions to those of age-, sex- and location-matched controls. Separate comparisons were made for drivers reporting medical conditions licensed with full driving privileges, and those with restricted driving privileges (e.g. speed, area and time of day). DESIGN: Retrospective case-control. METHODS: The study population was all drivers licensed in the state of Utah who reported a medical condition on their driver license application, over the 5-year period 1992-1996. Drivers enter the program by self-reporting their medical problems. Control drivers were chosen from the entire population of drivers licensed in Utah for the same period. Information on driver license status, participation in the medical conditions program, citations, involvement in crashes, and death certificate data was obtained from the relevant state agencies. Probabilistic linkage methodology was used to link the records in these disparate databases for eventual analysis. Rates of citation, crashes and at-fault crashes, expressed as events per 10000 license days, were calculated separately for program drivers and their corresponding control groups for each medical condition category and restriction status. These data were used to determine an estimate of relative risk (RR) and 95% confidence intervals. Results: As a group, medical conditions drivers had modestly elevated rates of adverse driving events compared with control drivers (RR 1.09-1.74). Rates in the largest medical category, 'cardiovascular conditions', were not higher than controls. Rates were higher than control for some conditions, such as 'alcohol' and 'learning and memory', for some adverse events (RR 2.2 -5.75). Drivers with more than one medical condition appeared comparable to the general group of medical conditions program drivers. CONCLUSIONS: Drivers in Utah medical conditions program had modestly elevated rates of adverse driving events compared to matched controls. Possible underreporting of medical conditions and accurate assessment of exposure rates are potential weaknesses in the program.     

Night driving curfews in New York and Louisiana: Results of a questionnaire survey

New York and Louisiana, two states having night driving curfews, were included in a questionnaire survey of high school students conducted in 1983. Most students in these states knew about their curfew law. In both states the majority of licensed drivers said they had violated the curfew, but the majority claimed to have violated the curfew no more than twice. Students do not believe that the police enforce curfew restrictions vigorously, but many parents require their children to obey the law. New York students were more knowledgeable than Louisiana students about the restrictions, and there was more evidence in New York than Louisiana of reduced driving resulting from the curfew. These findings are consistent with results of an earlier study that found curfews in both of these states reduced crashes but estimated crash reductions during curfew hours were greater in New York than in Louisiana.     

Measuring the impact of passenger restrictions on new teenage drivers

Passenger restrictions for new teenage drivers that became law in 1998 in California provide an opportunity to study the effectiveness of such laws in reducing the number of passengers as well as the influence of teenage passengers on novice drivers. Using fatal and injury crash data from California's Statewide Integrated Traffic Records System, this study found that teenage passengers are a causal factor in crashes of 16-year-old drivers and that in the three years following implementation of the new law, the average number of teenage passengers carried by 16-year-olds decreased by approximately 25%. Without considering the beneficial effect of a decrease in the crash rate, the decrease in the number of teenage passengers in actual crashes resulted in an estimated saving of eight lives and the prevention of 684 injuries over a three-year period.     

Hazard perception and driving experience among novice drivers

The crash risk of novice drivers decreases rapidly during the first few months of post-licensing driving, indicating that some important safety-relevant traffic skills are learnt during this period. The present study tested the hypothesis that the risk decrease is related to improved hazard perception skills. A video-based hazard perception/reaction test, measuring reaction times to 31 traffic scenes, was administered to three groups of drivers, having held a licence for 1, 5, and 9 months, respectively, and to a group of drivers who had held their licences for several years. Average reaction times tended to decrease with experience, but the decrease was not significant. There were some significant differences in the expected direction for individual test items, indicating a possible effect of experience. One half of the situations were presented together with a secondary task, in order to investigate effects of increased mental load on hazard perception. Male novice drivers had relatively longer reaction times with the secondary task, compared to both female novice drivers and male experienced drivers. It is concluded that hazard perception as tested here is probably only a minor factor in explaining the initial risk decrease among novice drivers.