Predicting seat belt use in fatal motor vehicle crashes from observation surveys of belt use

There is a large difference between the rates of observed seat belt use by the general public and belt use by motor vehicle occupants who are fatally injured in crashes. Seat belt use rates of fatally injured occupants, as reported in the Fatality Analysis Reporting System (FARS), are much lower than the use rates found in observation surveys conducted by the states. A series of mathematical models describing the empirical relationship between FARS and observed rates were explored. The initial model was a 'straw man' and used two simplifying assumptions: (a) belt users and nonusers are equally likely to be involved in 'potentially fatal collisions', and (b) belts are 45% effective in preventing deaths. The model was examined by comparing each state's FARS use rate with the predicted rate. The model did not fit the state data points even when possible biases in the data were controlled. We next examined the assumptions in the model. Changing the seat belt effectiveness parameter provided a reasonable fit, but required an assumption that seat belts are 67% effective in preventing fatalities. The inclusion of a risk coefficient for non-belted occupants also provided a reasonable fit between the model and data. A variable risk model produced the best fit with the data. The major finding was that a model consistent with the data can be obtained by incorporating the assumption that nonusers of seat belts have a higher risk of involvement in potentially fatal collisions than do seat belt users. It was concluded that unbelted occupants are over-represented in fatal collisions for two reasons: (a) because of a greater chance of involvement in potentially fatal collisions in the first place, and (b) because they are not afforded the protection of seat belts when a collision does occur.     

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.     

Trends in fatal crashes involving female drivers, 1975-1998

Since the mid-1980s there has been concern about the growing number of female drivers in the US involved in fatal motor vehicle crashes, and similar trends have been noted in other parts of the world. The present study examined whether this trend has continued into the 1990s and the reasons for it. Fatal crash data were obtained from the Fatality Analysis Reporting System (FARS), mileage data from the National Personal Transportation Survey, and licensure data from the Federal Highway Administration. Many more women were licensed to drive in 1998 than in 1975, and on average they drove more miles. When changes in total annual mileage were taken into account, per-mile crash rates decreased similarly for men and women (about 40%). An examination of the characteristics of their fatal crashes revealed that male and female drivers have seen similar reductions in single-vehicle, nighttime, and alcohol-related crashes. However, men continue to be involved more often in these types of crashes.     

Risk factors for fatal crashes in rural Australia

This paper presents findings from the rural and remote road safety study, conducted in Queensland, Australia, from March 2004 till June 2007, and compares fatal crashes and non-fatal but serious crashes in respect of their environmental, vehicle and operator factors. During the study period there were 613 non-fatal crashes resulting in 684 hospitalised casualties and 119 fatal crashes resulting in 130 fatalities. Additional information from police sources was available on 103 fatal and 309 non-fatal serious crashes. Over three quarters of both fatal and hospitalised casualties were male and the median age in both groups was 34 years. Fatal crashes were more likely to involve speed, alcohol and violations of road rules and fatal crash victims were 2½ times more likely to be unrestrained inside the vehicle than non-fatal casualties, consistent with current international evidence. After controlling for human factors, vehicle and road conditions made a minimal contribution to the seriousness of the crash outcome. Targeted interventions to prevent fatalities on rural and remote roads should focus on reducing speed and drink driving and promoting seatbelt wearing.     

Marginal effect of increasing ageing drivers on injury crashes

The safety effects of the ageing driving population have been a topic of research interests in health and transportation economics in recent years due to the ageing of the baby boomers. This study adds to the current knowledge by examining the marginal effects of changing the driver mix on injury crashes using data from the Canadian Province of Alberta between 1990 and 2004. Results from a Poisson regression model reveal that increasing the number of young and ageing drivers will result in an increase in the number of injury crashes whereas increasing the number of middle-aged drivers will result in a reduction. These results are in contrast to those obtained in a previous study on the marginal effects of changing the driver mix on fatal crashes in the Australian State of Queensland and some possible explanations for the differing results are provided.     

The relationship of underage drinking laws to reductions in drinking drivers in fatal crashes in the United States

This study reports on an effort to evaluate and interrelate the existence and strength of two core laws and 14 expanded laws designed to (a) control the sales of alcohol, (b) prevent possession and consumption of alcohol, and (c) prevent alcohol impaired driving by youth aged 20 and younger. Our first analysis determined if the enactment of the possession and purchase laws (the two core minimum legal drinking age laws) was associated with a reduction in the ratio of drinking to nondrinking drivers aged 20 and younger who were involved in fatal crashes controlling for as many variables as possible. The ANOVA results suggest that in the presence of numerous covariates, the possession and purchase laws account for an 11.2% (p=0.041) reduction in the ratio measure. Our second analysis determined whether the existence and strength of any of the 16 underage drinking laws was associated with a reduction in the percentage of drivers aged 20 and younger involved in fatal crashes who were drinking. In the regression analyses, making it illegal to use a false identification to purchase alcohol was significant. From state to state, a unit difference (increase) in the strength of the False ID Use law was associated with a 7.3% smaller outcome measure (p=0.034).     

Predictors of injury among younger and older adults in fatal motor vehicle crashes

With 2003 Fatality Analysis Reporting System data, we examined relationships among predictors of motor vehicle injury/fatality outcomes for younger (35–54 years) and older (65 years and older) drivers. Using the Precede-Proceed Model of Health Promotion as an organizing framework, we classified variables into person, vehicle and environment domains and conducted a multinomial logistic regression.Significant risk factors for older driver injuries were impact crashes at 1–3 o’clock (OR = 1.65; CI: 1.05–2.59), 7–9 o’clock angles (OR = 2.59; CI = 1.45–4.63), and driving with one passenger (OR = 2.25; CI: 1.58–3.20). Previous other motor vehicle convictions were significantly associated with reduced risk of injury (OR = 0.55; CI = 0.34–0.90). The 7–9 o’clock angle (OR = 3.06; CI: 1.83–5.12), and driving in daylight hours were risk factors for fatality among older drivers.Many risk factors (e.g., female gender, non-seatbelt use, rollover crashes, and vehicle body type), and protective factors (e.g., number of lanes and non-airbag deployment) were relevant for younger and older drivers. Findings showed relevant factors for drivers from both age groups, with some pointing to older adults, and set the stage for further research to develop injury and fatality prevention programs.     

A pattern analysis of traffic crashes fatal to older drivers

A synthesis of the various crash circumstances in which older drivers die is lacking. This study is based on data from Sweden's national archive of fatal RTCs, and focuses on crashes in which the deceased driver was aged 65+ (2002-2004; n = 152). Crash patterns were identified by means of cluster analysis using a sub-set of 12 variables describing both driver and crash event characteristics. Crashes where the driver had died of natural causes prior to crash made up 19.7% of the cases (30 crashes) and were mainly single crashes. Four additional clusters were also identified. Two involved making left turns at intersections, one over-represented among men, occurring typically at weekends, in low-speed areas (30.6%), and the second one, over-represented among women, consisting of crashes in dry road conditions, and on intermediate-speed roads (21.5%). A third cluster included head-on and single-vehicle crashes occurring in dry road conditions but on high-speed roads (29.8%). The last cluster consisted of crashes occurring during the winter and on high-speed roads (18.2%). Older drivers die in traffic in various circumstances, sometimes prior to crashing. Some circumstances cannot be easily alleviated but others could, e.g., through modifications of the road traffic environment and car active safety measures that can help compensate for age-related shortcomings.     

Graduated driver license nighttime compliance in U.S. teen drivers involved in fatal motor vehicle crashes

Background

Examination of teen driver compliance with graduated driver licensing (GDL) laws could be instrumental in identifying factors associated with persistently high motor vehicle mortality rates.

Methods

Fatality analysis reporting system (FARS) data from the years 2006 to 2009 were used in this nation-wide cross-sectional study of drivers covered by a state nighttime GDL law (n = 3492). A new definition of weekend, based on the school night in relation to the teenage social landscape, redefined Friday night as a weekend night and Sunday night as a weekday/school night and compared it to previous weekend definitions. Multiple logistic regression was used to examine independent effects of demographic, behavioral, environmental, contextual, and other factors on compliance with nighttime GDL laws. All analyses were performed in Stata version 11.

Results

Given coverage under nighttime GDL laws, drivers aged 15–17 years were non-compliant in 14.9% of the fatal MVCs in which they were involved, and nearly one-fifth (18.8%) of all fatalities aged 15–17 years were associated with non-compliance. Mortality risk was 10% higher using a revised social (school night) versus traditional (Sat–Sun) weekend definitions. In multivariable analysis, drivers non-compliant with nighttime GDL laws were more likely to be drinking (OR = 4.97, 3.85–6.40), unbelted (OR = 1.58, 1.25–1.99), driving on the weekend (OR = 1.82, 1.47–2.24), and killed (OR = 1.31, 1.04–1.65).

Conclusion

GDL non-compliance contributes to teen motor vehicle mortality. Legislative and enforcement efforts targeting non-school night driving, seatbelt nonuse and alcohol have potential to further reduce teen driving mortality.     

Factors affecting the severity of work related traffic crashes in drivers receiving a worker's compensation claim

Aim

To examine factors that contribute to the severity of work related crashes in New South Wales, Australia.

Methods

Workers’ Compensation data was linked to police crash records for the period 1998-2002. Multivariate analysis was carried out to assess the relationship between relevant risk factors and the severity of injury (permanent disability or death) in drivers who had received a claim for a work related crash.

Results

Age, gender, occupation, duty status, vehicle type, licence status, fatigue, speeding and location of the crash were independently associated with the severity of the crash. Drivers aged 65 years and older were nearly twice (OR: 1.824, 95% CI: 1.106-3.007) as likely to be permanently injured or die as a result of a work related crash compared to the younger age group (15-24 years old). The risk to older drivers was even higher in crashes occurring while on duty. Drivers involved in traffic crashes while commuting were more likely to be severely injured (OR: 1.28, CI: 1.15-1.42) than those on duty. Compared to car drivers, taxi drivers were more than twice (OR: 2.38, CI: 1.726-3.296) as likely to be severely injured.

Conclusions

The findings contribute to bridging the gap in knowledge in the area of work related crashes and highlight the higher risk of permanent disability and death in older drivers, taxi drivers and commuters.     

Differences in state drug testing and reporting by driver type in U.S. fatal traffic crashes

IntroductionDriving under the influence of drugs, including marijuana, has become more prevalent in recent years despite local, state, and federal efforts to prevent such increases. The Fatality Analysis Reporting System (FARS) is the primary source of drugged driving data for fatal crashes in the United States but lacks the completeness required to calculate unbiased estimates of drug use among drivers involved in fatal crashes.MethodsThis article uses the 2013 FARS dataset to present differences in state drug testing rates by driver type, driver fault type, and state-level factors; discusses limitations related to analysis and interpretation of drugged driving data; and offers suggestions for improvements that may enable appropriate use of FARS drug testing data in the future.ResultsResults showed that state drug testing rates were highest among drivers who died at the scene of the crash (median = 70.8%) and drivers who died and were at fault in the crash (median = 64.4%). The lowest testing rates were seen among surviving drivers who were not transported to a hospital (median = 14.0%) and surviving drivers who were not at fault in the crash (median = 10.0%). Drug testing rates differed by state blood alcohol content (BAC) testing rate across all driver types and driver fault types, and in general, states that tested a higher percentage of drivers for BAC had higher drug testing rates.DiscussionTesting rates might be increased through standardization and mandatory testing policies. FARS data users should continue to be cautious about the limitations of using currently available data to quantify drugged driving. More efforts are needed to improve drug testing and reporting practices, and more research is warranted to establish drug concentration levels at which driving skills become impaired.     

The relationship of alcohol safety laws to drinking drivers in fatal crashes

This paper presents an analysis of the relationships between the passage of key alcohol safety laws and the number of drinking drivers in fatal crashes. The study evaluated three major alcohol safety laws--administrative license revocation laws, 0.10 illegal per se, and 0.08 illegal per se laws--on the proportion of drinking drivers in fatal crashes. Drivers aged 21 and older in fatal crashes at two BAC levels--0.01-0.09 and 0.10 or greater--were considered separately. Drivers under age 21 were not included because they are affected by the Minimum Legal Drinking Age (MLDA) law. This study used data on drinking drivers in fatal crashes from the Fatality Analysis Reporting System (FARS) covering 16 years (1982-1997) for all 50 states and the District of Columbia. Also included in the study were such variables as per capita alcohol consumption and annual vehicle miles traveled (VMT), which could affect the number of alcohol-related crashes. The results indicate that each of the three laws had a significant relationship to the downward trend in alcohol-related fatal crashes in the United States over that period. This paper points out that this long-term trend is not the product of a single law. Instead, it is the result of the growing impact of several laws over time plus the affect of some factors not included in the model tested (such as the increasing use of sobriety checkpoints and the media's attention to the drinking-and-driving problem).     

Drugs related to motor vehicle crashes in northern European countries: a study of fatally injured drivers

The aim of this study was to find which drugs and drug combinations were most common in drivers who died, in particular, in single vehicle crashes where the responsibility for the crash would be referred to the driver killed. The study included all available blood samples from drivers, who died within 24 h of the accident, in the years 2001 and 2002 in the five Nordic countries (total population about 24 million inhabitants). The samples were analysed for more than 200 different drugs in addition to alcohol, using a similar analytical programme and cut-off limits in all countries. In three countries (Finland, Norway and Sweden) blood samples were available for more than 70% of the drivers, allowing representative prevalence data to be collected. 60% of the drivers in single vehicle crashes had alcohol and/or drug in their blood samples, compared with 30% of drivers killed in collisions with other vehicles. In single vehicle accidents, 66% of the drivers under 30 years of age had alcohol and/or drugs in their blood (alcohol only – 40%; drugs only – 12%; alcohol and drugs – 14%). The drugs found were mostly illicit drugs and psychoactive medicinal drugs with warning labels (in 57% and 58% respectively of the drivers under 30 with drugs present). Similar findings were obtained for drivers 30–49 years of age (63% with alcohol and/or drugs). In drivers aged 50 years and above, killed in single vehicle crashes (48% with alcohol and/or drugs) illicit drugs were found in only one case, and psychoactive medicinal drugs were detected less frequently than in younger age groups. In 75% of single vehicle crashes, the driver was under 50 years. Thus, the majority of accidents where the drivers must be considered responsible, occurred with drivers who had recently used alcohol, or drugs, alone or in combination. The drugs involved were often illicit and/or psychoactive drugs with warning labels. Therefore a large proportion of single vehicle accidents appear to be preventable, if more effective measures against driving after intake of alcohol and drugs can be implemented.     

Factors associated with civilian drivers involved in crashes with emergency vehicles

Motor vehicle crashes involving civilian and emergency vehicles (EVs) have been a known problem that contributes to fatal and nonfatal injuries; however, characteristics associated with civilian drivers have not been examined adequately. This study used data from The National Highway Traffic Safety Administration's Fatality Analysis Reporting System and the National Automotive Sampling System General Estimates System to identify driver, roadway, environmental, and crash factors, and consequences for civilian drivers involved in fatal and nonfatal crashes with in-use and in-transport EVs. In general, drivers involved in emergency–civilian crashes (ECCs) were more often driving: straight through intersections (vs. same direction) of four-points or more (vs. not at intersection); where traffic signals were present (vs. no traffic control device); and at night (vs. midday). For nonfatal ECCs, drivers were more often driving: distracted (vs. not distracted); with vision obstructed by external objects (vs. no obstruction); on dark but lighted roads (vs. daylight); and in opposite directions (vs. same directions) of the EVs. Consequences included increased risk of injury (vs. no injury) and receiving traffic violations (vs. no violation). Fatal ECCs were associated with driving on urban roads (vs. rural), although these types of crashes were less likely to occur on dark roads (vs. daylight). The findings of this study suggest drivers may have difficulties in visually detecting EVs in different environments.     

Personality subtypes of young moped drivers, their relationship to risk-taking behavior and involvement in road crashes in an Austrian sample

Objective

This study aimed to identify subtypes of young moped drivers and analyze how these subtypes are involved in risk preferences and road crashes.

Design

A group of Austrian teenage moped drivers (213, 28% girls) completed an online questionnaire about moped usage, injuries, driving style, inattention, impulsivity, and personality according to the Five-Factor Model of Personality and Cloninger's model of personality.

Results

A cluster analysis yielded four types of moped drivers. One type was characterized by a high level of neuroticism, the second type was characterized by a risky personality and a risky driving style, the third type had a more cautious driving style, and the fourth type was characterized by a risky personality and high levels on inattention and impulsivity.

Conclusions

Our conclusions suggest that young moped drivers should not be perceived as a homogenous group, according to measures of injury prevention and intervention.     

Analgesics and road traffic crashes in senior drivers: An epidemiological review and explorative meta-analysis on opioids

Aim

To assess the epidemiological evidence associating the use of analgesics with the occurrence of road traffic crashes in senior drivers including a meta-analysis with specific focus on opioids.

Methods

Systematic literature review of articles published between 1991 and 2012 retrieved from major databases using relevant key words. Eligible articles were fully reviewed and the main characteristics and results summarized. The methodological quality was assessed using the Newcastle-Ottawa Scale. Heterogeneity tests and forest and funnel plots were used as part of the meta-analysis on opioids.

Results

From the potentially eligible articles, nine were selected (4 case–control, 1 case-crossover, and 4 cohort studies) of which four were of medium and five of high quality; seven investigated opioids and four non-steroidal anti-inflammatory drugs. Crash involvement (n = 7) rather than responsibility (n = 2) was investigated. Age and sex were the most common covariates adjusted for. Both opioids and non-steroidal anti-inflammatory drugs showed mixed results including differences across estimates between and within studies. A marginal positive effect was observed in the pooled analyses on opioids (n = 6, OR 1.20; 95% CI 1.08–1.32).

Conclusions

The evidence is unconvincing in terms of number of studies, control of major confounders, and consistency of the results. The effect seen for opioids can be attributed to the lack of adjustment of key confounders such as concomitant illness or the consumption of alcohol or other psychoactive medications. There is a need for more efficient designs like larger population-based retrospective cohorts and nested case–control or case-crossover studies based on registers of high quality allowing adjustment for these factors and for the selection of unequivocal outcomes (e.g. drivers’ responsibility) to produce more persuasive empirical evidence.     

The role of ambient light level in fatal crashes: inferences from daylight saving time transitions

The purpose of this study was to estimate the size of the influence of ambient light level on fatal pedestrian and vehicle crashes in three scenarios. The scenarios were: fatal pedestrian crashes at intersections, fatal pedestrian crashes on dark rural roads, and fatal single-vehicle run-off-road crashes on dark, curved roads. Each scenario's sensitivity to light level was evaluated by comparing the number of fatal crashes across changes to and from daylight saving time, within daily time periods in which an abrupt change in light level occurs relative to official clock time. The analyses included 11 years of fatal crashes in the United States, between 1987 and 1997. Scenarios involving pedestrians were most sensitive to light level, in some cases showing up to seven times more risk at night over daytime. In contrast, single-vehicle run-off-road crashes showed little difference between light and dark time periods, suggesting factors other than light level play the dominant role in these crashes. These results are discussed in the context of the possible safety improvements offered by new developments in adaptive vehicle headlighting.     

The mixed effects of precipitation on traffic crashes

PURPOSE: This paper investigates the relationship between precipitation and traffic crashes in the US during the period 1975-2000. Traffic crashes represent the leading cause of death and injury for young adults in the US, and the ninth leading cause of death for the overall population. Prior studies have found that precipitation raises the risk of traffic crashes significantly. METHODS: A negative binomial regression approach is employed. Two different units of analysis are examined: state-months and state-days. The sample includes all 48 contiguous states. RESULTS: A surprising negative and significant relationship between monthly precipitation and monthly fatal crashes is found. However, in the daily level analysis, a strong positive relationship is estimated, as in prior studies. The source of the contrasting results appears to be a substantial negative lagged effect of precipitation across days within a state-month. In other words, if it rained a lot yesterday, then on average, today there are fewer crashes. Additional analysis shows that the risk imposed by precipitation increases dramatically as the time since last precipitation increases. For example, 1cm of precipitation increases the fatal crash rate for a state-day by about 3% if exactly 2 days have passed since the last precipitation and by about 9% if more than 20 days have passed. This basic pattern holds for non-fatal crashes as well. CONCLUSIONS: The lagged effects of precipitation across days may be explained by the clearing of oil that accumulates on roads during dry periods or by the conditioning of people to drive more safely in wet conditions. Either way, policy interventions that prepare drivers more adequately for the risks of precipitation following dry periods are likely to be beneficial.