Family reports of medically impaired drivers in Missouri: Cognitive concerns and licensing outcomes

This study investigated reasons why older adults (n = 689) were reported to the Driver License Bureau, Missouri Department of Revenue, by family members as potentially unfit to drive with an emphasis on cognitive concerns and associated licensing outcomes. A total of 448 drivers were reported to have some cognitive issue; common symptoms included confusion, memory loss, and becoming lost while driving. Diagnostic labels (Alzheimer’s disease (AD), cognitive impairment/dementia, brain injury/insult) were listed for 365 cases. A physician evaluation is required for license review. Of those with a diagnostic label, half (51%, n = 187) failed to submit this evaluation and almost all were de-licensed immediately. Of those evaluated by a physician, diagnostic agreement between family members and physicians was high for specific conditions (100% for AD, 97% for acute brain injury), and less so for cognitive impairment/dementia (75%). This latter finding suggests that physicians and family members may understand cognitive symptoms differently. Whether cognitively impaired or not, few family reported drivers in this sample (∼2%) retained a valid license. Family members may be in the best position to recognize when medical-functional deficits impact on driving safety, and physicians and driver licensing authorities would do well to take their observations into account with respect to older driver fitness.     

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.     

Driving behaviors and accident risk under lifetime license revocation

This study explored the driving behaviors and crash risk of 768 drivers who were under administrative lifetime driver's license revocation (ALLR). It was found that most of the ALLR offenders (83.2%) were still driving and only a few (16.8%) of them gave up driving completely. Of the offenders still driving, 67.6% experienced encountering a police roadside check, but were not detained or ticketed by the police. Within this group, 50.6% continued driving while encountering a police check, 18.0% of them made an immediate U-turn and 9.5% of them parked and exited their car. As to crash risk, 15.2% of the ALLR offenders had at least one crash experience after the ALLR had been imposed. The results of the logistic regression models showed that the offenders’ crash risk while under the ALLR was significantly correlated with their personal characteristics (personal income), penalty status (incarceration, civil compensation and the time elapsed since license revocation), annual distance driven, and needs for driving (working, commuting and driving kids). Low-income offenders were more inclined to have a crash while driving under the ALLR. Offenders penalized by being incarcerated or by paying a high civil compensation drove more carefully and were less of a crash risk under the ALLR. The results also showed there were no differences in crash risk under the ALLR between hit-and-run offences and drunk driving offences or for offenders with a professional license or an ordinary license. Generally, ALLR offenders drove somewhat more carefully and were less of a crash risk (4.3 crashes per million km driven) than legal licensed drivers (23.1 crashes per million km driven). Moreover, they seemed to drive more carefully than drivers who were under short-term license suspension/revocation which previous studies have found.     

Trends in older driver crash involvement rates and survivability in the United States: An update

Objective

Previous research has shown that fatal crash involvement rates per licensed driver aged 70 and older declined significantly more per year in the United States than rates for middle-aged drivers aged 35–54 during 1997–2008, and per vehicle mile traveled from 1995–1996 to 2001–2002. Analyses of police-reported crash data during 1997–2005 indicated that the greater declines for older drivers were due to decreases in crash involvement and in the risk of dying in the crashes that occurred. The current study examined if trends in crash rates, crash involvements, and survivability persisted into more recent years.

Methods

Trends for drivers 70 and older were compared with trends for drivers aged 35–54 for U.S. national fatal passenger vehicle crash involvements per 100,000 licensed drivers during 1997–2012 and for U.S. national fatal passenger vehicle crash involvements per vehicle miles traveled in 1995–1996, 2001–2002, and 2008. Using police-reported crash data during 1997–2008 from 20 U.S. states, trends in involvement rates in non-fatal crashes of various severities per 100,000 licensed drivers and changes in the odds of death and the odds of death or serious injury in a crash were compared between older and middle-aged drivers.

Results

During 2007–2012, declines in national fatal crash involvement rates per licensed driver were similar for drivers 70 and older and middle-aged drivers (18 percent each). However, when considering the entire study period, fatal crash involvement rates continued to reflect a substantially larger decline for drivers 70 and older than for middle-aged drivers (42 vs. 30 percent per licensed driver during 1997–2012, 39 vs. 26 percent per vehicle mile traveled from 1995–2006 to 2008). When analyses of police-reported crash data were extended through 2008, non-fatal injury crash involvement rates per licensed driver declined more for older than for middle-aged drivers (39 vs. 30 percent), and unlike in prior research, average annual declines were significantly larger for drivers 80 and older. Property damage-only crash involvement rates similarly declined significantly more for older than for middle-aged drivers (15 vs. 3 percent). Drivers 70 and older in 1997 were 3.5 times more likely than middle-aged drivers to die in a crash, and this ratio declined to 3.2 by 2008.

Conclusions

Although declines in fatal crash involvement rates in recent years have not differed between older and middle-aged drivers, this did not undo earlier gains for older drivers. The recent slowing in the relative magnitude of the decline for older drivers may be related to the differential effect of the U.S. recession on fatal crash involvements of drivers in these age groups. The decreased likelihood of being involved in a crash of any severity and increased survivability when a crash occurred held when examining data through 2008, and for drivers 80 and older, significant declines in crash involvement relative to middle-aged drivers extended to non-fatal injury crashes.     

Elderly drivers’ everyday behavior as a predictor of crash involvement—Questionnaire responses by drivers’ family members

When or whether elderly drivers stop driving is concerning not only to the drivers themselves but also to their family members. Therefore, it is important for family members to take the initiative if they wish to obtain information on the likelihood of the drivers’ involvement in crashes. On the basis of the older drivers’ Everyday Behavior Questionnaire (EBQ) developed in this paper, we attempt to predict drivers’ involvement in crashes using the responses given by their family members. The results revealed that this 14-item questionnaire has a sufficient level of internal consistency as well as a significant correlation (r = 0.29) with the experience of involvement in crashes in the last three years (p < 0.01). Although the EBQ is a proxy-reported questionnaire and does not include items directly related to driving behaviors, the correlation between the EBQ and crash involvement is stronger than that of the self-reported Driver Behavior Questionnaire reported in deWinter and Dodou (2010), who conducted a meta-analysis and estimated the overall correlation among samples of earlier studies. In addition, logistic regression analysis showed that the EBQ score and the exposure to driving risks, measured by the frequency of driving, are significant predictors of involvement in crashes.     

Declines in fatal crashes of older drivers: changes in crash risk and survivability

Objectives

Previous research has found that older driver fatal crash involvement rates per licensed driver declined substantially in the United States during 1997–2006 and declined much faster than the rate for middle-age drivers. The current study examined whether the larger-than-expected decline for older drivers extended to nonfatal crashes and whether the decline in fatal crash risk reflects lower likelihood of crashing or an improvement in survivability of the crashes that occur.

Methods

Trends in the rates of passenger vehicle crash involvements per 100,000 licensed drivers for drivers 70 and older (older drivers) were compared with trends for drivers ages 35–54 (middle-age drivers). Fatal crash information was obtained from the Fatality Analysis Reporting System for years 1997–2008, and nonfatal crash information was obtained from 13 states with good reporting information for years 1997–2005. Analysis of covariance models compared trends in annual crash rates for older drivers relative to rates for middle-age drivers. Differences in crash survivability were measured in terms of the odds of fatality given a crash each year, and the historical trends for older versus middle-age drivers were compared.

Results

Fatal crash involvement rates declined for older and middle-age drivers during 1997–2008 (1997–2005 for the 13 state subsample), but the decline for drivers 70 and older far exceeded the decline for drivers ages 35–54 (37 versus 23 percent, nationally; 22 versus 1 percent, 13 states). Nonfatal injury crash involvement rates showed similarly larger-than-expected declines for older drivers in the 13 state subsample, but the differences were smaller and not statistically significant (27 percent reduction for older drivers versus 16 percent for middle-age drivers). Property-damage-only crash involvement rates declined for older drivers (10 percent) but increased for middle-age drivers (1 percent). In 1997, older drivers were 3.5 times more likely than middle-age drivers to die in police-reported crashes (6.2 versus 1.8 deaths per 1000 crashes), but this difference was reduced during the 9-year study period to 2.9 times, as the rate of older drivers dying in a crash declined (5.5 deaths per 1000 crashes in 2005) and the death risk remained relatively stable for middle-age drivers.

Conclusions

Contrary to expectations based on increased licensure and travel by older drivers, their fatal crash risk has declined during the past decade and has declined at a faster rate than for middle-age drivers. The decreased risk for older drivers appears to extend not only to nonfatal injury crashes but also to property-damage-only crashes, at least as reported to police in the 13 states included in the nonfatal injury analysis. Although insurance collision data suggest that overall crash risk of older drivers may not be changing relative to middle-age drivers, the current analysis indicates that the reduced fatality risk of older drivers reflects both less likelihood of being involved in a police-reported crash and greater likelihood that they will survive when they do crash.     

Evaluation of Iowa's graduated driver's licensing program

The effectiveness of Iowa's graduated driver's licensing (GDL) program was evaluated for a 4-year period before and after implementation in 1999. Since some changes had occurred in the crash reporting format, changes in crash rates for younger drivers were compared to those for 35-44-year-old drivers (middle-age group of drivers) who were used as a control group. After implementation of GDL, the 14-, 16- and 17-year-old age groups experienced a greater decrease in crash rate than the middle-age control group while 15-year-old experienced a smaller decrease. This suggests that the crash rate for 15-year-old drivers may actually have increased when downward trends were adjusted for. Iowa's GDL program allows holders of the instruction permit to travel unaccompanied to and from school and school-endorsed activities after obtaining a minor school license. Fifteen-year-old with minor school licenses account for up to 26.7% of 15-year-old license holders yet represent up to 74.8% of 15-year-old drivers involved in crashes (depending on the year) from 1998 to 2004. As a result, 15-year-old drivers with minor school licenses are involved in 7.2-8.9 times more crashes, are 7.7 times more likely to have one or more sanctions, and are 4.8 times more likely to receive one or more moving convictions than their peers with a regular instruction permit. This help may explain why 15-year-old drivers did not seem to benefit from implementation of the GDL program in Iowa.     

Older drivers, medical condition, medical impairment and crash risk

New evidence has appeared to support the fact that the over-involvement of older drivers in traffic accidents disappears when the low mileage bias is taken into account. As a group, older drivers are as safe as or safer than other age groups, and only low mileage older drivers have a high crash rate. Furthermore, the role of the medical condition of older drivers in traffic accidents, as well as the fitness to drive evaluation, are objects of controversy. We examined all this with a cohort of 4316 drivers attending Medical Driving Test Centres for a mandatory fitness to drive evaluation. Our data shows that older drivers (> or =75) have a lower crash rate. Medical conditions that impair fitness to drive, as a tendency, increased with advanced age and with lower mileage group. The multivariate analysis of variance showed that there is an effect (p<0.0001) of age-range and mileage on the annual crash rate per million kilometres driven, while a medical restriction ("fit to drive with restriction") has no effect (p>0.05). Our data suggests that health status is not associated with increased crash risk for the low mileage group, although further studies are needed.     

'Low mileage bias' and related policy implications--a cautionary note

This research examined a relationship asserted in recent literature in the field of traffic safety and injury prevention—that a significant indicator for elevated crash risk among older drivers, and potential trigger for individualized assessment at license renewal, is a low (<3000 km) annual driving distance. Sampling problems in earlier reports, in particular a reliance on self-report measures of both exposure and crash involvement, are highlighted. A pattern of misestimation for those who self-report an extremely low or extremely high number of miles driven is documented, that casts serious doubt upon the effect reported earlier. The present findings underscore the need for objective exposure measures for future analyses of this nature, and impact discussions about the feasibility of this suggested strategy to aid detection of at-risk older drivers by licensing officials.     

Acceptability and validity of older driver screening with the DrivingHealth Inventory

Research has indicated that technology can be effectively used to identify high-risk older drivers. However, adaptation of such technology has been limited. Researchers debate whether older drivers represent a safety problem as well as whether they should be screened for driving fitness. The present study examined how drivers feel regarding technological screening and mandatory state testing. The validity and acceptability of a new technological screening battery for identifying high-risk drivers, the DrivingHealth Inventory (DHI), was also evaluated. In a sample of 258 Alabama drivers aged 18-87, older drivers performed significantly worse than younger drivers on sensory, cognitive, and physical subtests of the DHI, and older drivers with a crash history performed worse than older drivers without crashes. Regardless of age, 90% of participants supported states requiring screening for older drivers' license renewal. The majority of the participants (72%) supported use of technological screening batteries such as the DHI as a driver screening tool. Considering the acceptability and potential efficacy of the DHI, it may be a useful tool in evaluating driving fitness among older adults.     

Characteristics of belted and unbelted drivers

Drivers who had been observed wearing or not wearing shoulder belts were compared using vehicle registration data, driver records, and telephone interviews. The observations were made on the New York Thruway during a special seat belt publicity and enforcement program, which achieved a 75% overall belt use. The results showed that those drivers who still did not wear a shoulder belt despite New York law and the special Thruway program were more likely to be male, to be driving older vehicles, to have more prior traffic convictions, to have more prior injury crash involvements, and to say they are more likely to take risks than others. Although drivers reported that assessing points against the drivers license for belt law violations could increase belt use, citations for belt use law violations were very rare, and enforcement would probably have to increase before any new penalty could be effective.     

Using the U.S. National Household Travel Survey to estimate the impact of passenger characteristics on young drivers’ relative risk of fatal crash involvement

Motor vehicle crashes are the main cause of morbidity and mortality in teenagers and young adults in the United States. Driving exposure and passenger presence, which can both vary by driver and passenger characteristics, are known to influence crash risk. Some studies have accounted for driving exposure in calculating young driver fatal crash risk in the presence of passengers, but none have estimated crash risk by driver sex and passenger age and sex. One possible reason for this gap is that data collection on driving exposure often precludes appropriate analyses. The purpose of this study was to examine, per 10 million vehicle trips (VT) and vehicle-miles traveled (VMT), the relative risk of fatal crash involvement in 15-20-year-old male and female drivers as a function of their passenger's age and sex, using solo driving as the referent. The Fatality Analysis Reporting System provided fatal motor vehicle crash data from 1999 to 2003 and the 2001 National Household Travel Survey (NHTS) provided VT and VMT. The NHTS collects driving exposure for both household and non-household members (e.g., friends, colleagues), but demographic characteristics only on household members. Missing age and sex of non-household passengers were imputed with hot deck using information from household passengers’ trips with non-household drivers, thereby enabling the calculation of crash rate and relative risk estimates based upon driver and passenger characteristics. Using this approach, the highest risk was found for young male drivers with 16-20-year-old passengers (relative risk [RR] per 10 million VT = 7.99; 95% confidence interval [CI], 7.34-8.69; RR per 10 million VMT = 9.94; 95% CI, 9.13-10.81). Relative risk was also high for 21-34-year-old passengers, again particularly when both drivers and passengers were male. These effects warrant further investigation and underscore the importance of considering driving exposure by passenger characteristics in understanding crash risk. Additionally, as all imputation techniques are imperfect, a more accurate estimation of U.S. fatal crash risk per distance driven would require national surveys to collect data on non-household passenger characteristics.     

Effect of Florida's graduated licensing program on the crash rate of teenage drivers

On 1 July 1996, Florida instituted a graduated licensing program for drivers younger than age 18. For the first 3 months, holders of learner's licenses are not allowed to drive at all between 19:00 and 06:00 h; thereafter, they may drive until 22:00 h. Learner's licenses must be held for 6 months prior to eligibility for the intermediate license. Sixteen-year-old intermediate license holders are not permitted to drive unsupervised from 23:00 to 06:00 h, 17 year-olds from 01:00 to 06:00 h. All drivers younger than 18 have strict limits on the number of traffic violations they can accumulate and, effective 1 January 1997, all drivers younger than 21 are subject to a zero tolerance law for drinking and driving. Florida crash data for 1995-1997 were obtained and compared with similar data from Alabama, a state that borders Florida but does not have graduated licensing. For 15, 16, and 17 year-olds combined, there was a 9% reduction in the fatal and injury crash involvement rate in Florida during 1997, the first full year of graduated licensing, compared with 1995. On a percentage basis, crashes declined most among 15 year-olds, followed by 16 year-olds and then 17 year-olds. Reductions were not seen among Alabama teenagers nor among 18 year-olds in Florida.     

Identifying crash involvement among older drivers: agreement between self-report and state records

Older drivers have a high crash rate per vehicle mile of travel. Coupled with the growth of the number of older drivers on the road, this has generated interest in the identification of factors which place older drivers at increased risk. However, much of the existing research on medical and functional risk factors for crash involvement has generally been inconsistent. Methodological differences between studies have been hypothesized as being partly responsible for such inconsistencies. The source of information used to identify crash-involved drivers has been identified as one such difference. This paper reports on the agreement between self-report and state record for identifying crash involved-older drivers. We also sought to determine whether the prevalence of visual and cognitive impairment differs across crash-involved drivers identified by either or both sources. Finally, we assessed whether risk factors for crash involvement differed when crash-involved drivers were identified by either self-report or state records. Results indicated that there was a moderate level of agreement between self-reported and state-recorded crash involvement (kappa=0.45). However, we did find significant differences between crash-involved drivers identified via state records and/or self-report with respect to demographic (age, race), driving (annual mileage, days per week driven), and vision impairment (acuity, contrast sensitivity, peripheral visual field sensitivity, useful field of view). We also found that the possibility for biased measures of association is real. Useful field of view impairment was associated with both self-reported and state-recorded crash involvement; however, the magnitude of the associations was disparate. Moreover, glaucoma was identified as a significant risk factor when considering state-recorded crashes but not self-reported crashes. While validation of these findings is required, research designed to identify risk factors for crash involvement among older drivers should carefully consider the issue of case definition, particularly if self-report is used to identify crash-involved older drivers.     

Crash involvement of drivers with multiple crashes

A goal for any licensing agency is the ability to identify high-risk drivers. Kentucky data show that a significant number of drivers are repeatedly involved in crashes. The objective of this study is the development of a crash prediction model that can be used to estimate the likelihood of a driver being at fault for a near future crash occurrence. Multiple logistic regression techniques were employed using the available data for the Kentucky licensed drivers. This study considers as crash predictors the driver's total number of previous crashes, citations accumulated, the time gap between the latest two crashes, crash type, and demographic factors. The driver's total number of previous crashes was further disaggregated into the drivers' total number of previous at-fault and not-at-fault crashes. The model can be used to correctly classify at-fault drivers up to 74.56% with an overall efficiency of 63.34%. The total number of previous at-fault crash involvements, and having previous driver license suspensions and traffic school referrals are strongly associated with a driver being responsible for a subsequent crash. In addition, a driver's likelihood to be at fault in a crash is higher for very young or very old, males, drivers with both speeding and non-speeding citations, and drivers that had a recent crash involvement. Thus, the model presented here enables agencies to more actively monitor the likelihood of a driver to be at fault in a crash.     

Physician input and licensing of at-risk drivers: A review of all-inclusive medical evaluation forms in the US and Canada

This article details a systematic review of medical evaluation forms in support of licensing decisions for medically at-risk drivers. Comparisons were made between all-inclusive forms utilized by 52 State and Provincial Departments of Motor Vehicles (DMVs) in the US and Canada. Comparisons focused on length, format, content, instructional quality, medical coverage, ease of use, and other qualitative characteristics. Median page length was 2 (range 1–10), and mean word count was 1083 (494–3884). Common response options included open-ended (98%), forced choice (87%), and check box (81%). While the majority of forms (77%) required driver consent, only 24% requested information from the driver. Less than half (46%) included text on confidentiality protection. While all forms requested general medical information, just over half included specific sections for vision (54%) and cognitive/neurological conditions (56%). Most forms (81%) required that a judgment be made concerning driver safety, and half prompted for possible license restrictions. Criterion-based quality ratings were assigned on a five-point Likert scale by group consensus. One third of forms were rated as marginal or poor in comprehensiveness and utility, and just two garnered an excellent overall rating. Findings are discussed relative to current research on driver fitness and elements of a proposed model form. Best practice recommendations include a page length limitation, emphasis on in-person evaluation (i.e., as opposed to a records-only review), prompts to collect crash and other driving history information, clear instructions and stepwise format, content prompts across relevant medical categories, documentation of functional status and impairment levels, options for driving with restrictions in lieu of de-licensing, and emphasis on relative (vs. absolute) clinical judgments of overall driver safety.     

Young driver crash rates by licensing age,driving experience,and license phase

Background

Few studies have concurrently assessed the influence of age and experience on young driver crashes, in particular in the post-Graduated Driver Licensing (GDL) era. Further, little attention is given to the transition from intermediate to full licensure. We examined the independent and joint contributions of licensing age, driving experience, and GDL license phase on crash rates among the population of young New Jersey (NJ) drivers.

Methods

From a unique linked database containing licensing and crash data, we selected all drivers who obtained their NJ intermediate license at 17–20 years old from 2006–2009 (n = 410,230). We determined the exact age at which each driver obtained an intermediate and full license and created distinct, fixed cohorts of drivers based on their age at intermediate licensure. For each cohort, we calculated and graphed observed monthly crash rates over the first 24 months of licensure. Further, we examined crash rates by age at licensure, driving experience (i.e., time since licensure), and license phase.

Results

First-month crash rates were higher among the youngest drivers (licensed at 17y0m). Drivers who were licensed later experienced a reduced “steepness” in the slope of their crash rates in the critical initial months of driving, but there did not appear to be any incremental benefit of later licensure once drivers had six months of driving experience. Further, at each age, those with more driving experience had lower crash rates; however, the benefit of increased experience was greatest for the substantial proportion of teens licensed immediately after becoming eligible (at 17y0m). Finally, independent of age and experience, teen drivers’ crash risk increased substantially at the point of transition to a full license, while drivers of a similar age who remained in the intermediate phase continued to experience a decline in crash rates.

Conclusion

Age and driving experience interact to influence crash rates. Further, independent of these two factors, there is an abrupt increase in crash risk at the point of transition from intermediate to full licensure. Future studies should investigate whether this increase is accounted for by a change in driving exposure, driving behaviors, and/or other factors.     

Risk and type of crash among young drivers by rurality of residence: Findings from the DRIVE Study

Background

Most previous literature on urban/rural differences in road crashes has a primary focus on severe injuries or deaths, which may be largely explained by variations of medical resources. Little has been reported on police-reported crashes by geographical location, or crash type and severity, especially among young drivers.

Methods

DRIVE is a prospective cohort study of 20,822 drivers aged 17-24 in NSW, Australia. Information on risk factors was collected via online questionnaire and subsequently linked to police-reported crashes. Poisson regression was used to analyse risk of various crash types by three levels of rurality of residence: urban, regional (country towns and surrounds) and rural.

Results

Compared to urban drivers, risk of crash decreased with increasing rurality (regional adjusted RR: 0.7, 95% CI 0.6-0.9; rural adjusted RR: 0.5, 95% CI 0.3-0.7). Among those who crashed, risk of injurious crash did not differ by geographic location; however, regional and rural drivers had significantly higher risk of a single versus multiple vehicle crash (regional adjusted RR 1.8, 95% CI 1.3-2.5; rural adjusted RR: 2.0, 95% CI 1.1-3.6), which was explained by speeding involvement and road alignment at the time or site of crash.

Conclusions

Although young urban drivers have a higher crash risk overall, rural and regional residents have increased risk of a single vehicle crash. Interventions to reduce single vehicle crashes should aim to address key issues affecting such crashes, including speeding and specific aspects of road geometry.     

Belt use by high-risk drivers before and after New York's seat belt use law

Belt use among drivers traveling on limited access highways was observed before and after New York's mandatory seat belt use law. The results showed that high-speed drivers had lower belt use rates before the law and increased their belt use less in response to the law. Belt use rates before the law were 25%, 29%, and 28% for the high-, medium-, and low-speed groups as compared with 51%, 64%, and 57%, respectively, after the law. High-speed drivers also had inferior previous driving records, confirming their higher risk of motor vehicle crash involvement.     

Modelling crash propensity of carshare members

Carshare systems are considered a promising solution for sustainable development of cities. To promote carsharing it is imperative to make them cost effective, which includes reduction in costs associated to crashes and insurance. To achieve this goal, it is important to characterize carshare users involved in crashes and understand factors that can explain at-fault and not-at fault drivers. This study utilizes data from GoGet carshare users in Sydney, Australia. Based on this study it was found that carshare users who utilize cars less frequently, own one or more cars, have less number of accidents in the past ten years, have chosen a higher insurance excess and have had a license for a longer period of time are less likely to be involved in a crash. However, if a crash occurs, carshare users not needing a car on the weekend, driving less than 1000 km in the last year, rarely using a car and having an Australian license increases the likelihood to be at-fault. Since the dataset contained information about all members as well as not-at-fault drivers, it provided a unique opportunity to explore some aspects of quasi-induced exposure. The results indicate systematic differences in the distribution between the not-at-fault drivers and the carshare members based on the kilometres driven last year, main mode of travel, car ownership status and how often the car is needed. Finally, based on this study it is recommended that creating an incentive structure based on training and experience (based on kilometres driven), possibly tagged to the insurance excess could improve safety, and reduce costs associated to crashes for carshare systems.