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.     

Fragility and crash over-representation among older drivers in Western Australia

This study assessed age-related and gender differences in the relative contribution of fragility and crash over-representation to serious injuries per crash-involved driver in Western Australia. Police-reported crashes for the period 1998-2003 were extracted from the Western Australian Road Injury Database. For each passenger vehicle driver age and gender group, serious injuries per crash-involved driver and driver involvements in crashes per 100 million vehicle-kilometre travelled (VKT) were calculated as the respective measure of fragility and crash over-representation. Results from the decomposition method of analysis showed that older drivers over the age of 70 sustained serious injury rates more than twice as high as those of the 30-59-year-old drivers. Fragility increased with age, contributing between 47% and 95% for drivers above 65 years, but crash over-representation was the dominant factor for male drivers above 80 years. In contrast, fragility contributed little to the excess injury risk of younger drivers under the age of 30. The importance of fragility as a contributing factor to the inflated serious injury risk per vehicle-kilometre travelled for older drivers suggested that road safety initiatives should be directed towards the protection of vehicle occupants as well as screening for their driving ability.     

Characteristics of traffic crashes in Maryland (1996-1998): differences among the youngest drivers

Motor vehicle crashes (MVCs) are the leading cause of death among teenagers in the US. The present study examines how crash rates and crash characteristics differed among drivers aged 16-21 in the state of Maryland from 1996 to 1998. The results show that, based on police reports. the youngest drivers have the highest rate of MVCs per licensed driver and per annual miles driven. Furthermore, crash characteristics suggest that inexperience rather than risky driving may account for the differing rates. Drivers closer to the age of 16 had their crashes under the safest conditions: during the day in clear weather while drinking less.     

Teenage drivers and motor vehicle deaths

In 1978, passenger vehicle drivers 16 and 17 years old were in crashes that resulted in 4198 deaths. Motor vehicles account for nearly half the deaths of 16–19 year olds in the U.S. Teenage drivers contribute substantially to motor vehicle related deaths, both their own and others. Teenage drivers have greatly elevated rates of fatal crash involvement per capita and especially, per licensed driver. More deaths per licensed driver are associated with the passenger vehicle crashes of 18 year olds than for any other age. Deaths per licensed driver are next highest for 16, 17 and 19 year olds. Various possible ways to reduce the deaths that result from teenagers driving are discussed.     

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.     

Some consequences of different older driver licensing procedures in Australia

Given both the expected growth in the number of older drivers and their over-involvement in fatal and serious injury crashes, there has been a world-wide call for improved licensing procedures to manage older driver safety. In particular, licensing authorities have been urged to move from mandatory assessment of all older drivers to assessment practices targeting only those at higher crash risk. The current study examined older driver fatal and serious injury crash involvement rates across all Australian States to determine a possible association with the different licensing procedures. In particular, older driver crash involvement rates in Victoria (where there is no age-based assessment program) have been compared with rates in other jurisdictions with assessment programs. Crash involvement rates have been calculated using two denominators: per population and per number of licensed drivers. Some data limitations notwithstanding, older drivers in jurisdictions with age-based mandatory assessment programs could not be shown to be safer than drivers in Victoria. Further, there is some indicative evidence that older drivers in Victoria may have a significantly safer record regarding overall involvement in serious casualty crashes.     

Female drinking and driving: recent trends in North Carolina

Data on driver licensing, DWI arrests, crashes, and fatalities in the State of North Carolina from the mid-70s to the mid-80s are analyzed to examine trends in drinking and driving by women. Findings presented are based on rates per licensed driver. Results suggest that more women are driving and are experiencing greater exposure to the hazards of drinking and driving. DWI arrest rates for women increased by 43% while rates for men decreased by 9%. Likewise, the proportion of legally intoxicated drivers among women is increasing. Women account for a growing proportion of alcohol-related (A/R) crashes and their involvement in single vehicle nighttime crashes is increasing. A dramatic decrease was observed in A/R fatalities in the male licensed driving population. This decrease was not paralleled by women. Authors conclude women will make up an increasing proportion of those arrested and convicted for DWI and will have more A/R crashes. Findings have implications for the design and implementation of education, deterrence, enforcement, and rehabilitation programs.     

Why have fatality rates among older drivers declined? The relative contributions of changes in survivability and crash involvement

ObjectivesThis study examined the trend in fatality rates per vehicle miles traveled (VMT) among older drivers relative to middle-aged drivers and quantified the contributions of changes in crash involvement and survivability to this trend.MethodsUsing U.S. national databases, changes in driver deaths per crash involvement (marker of death risk when involved in a crash) and crash involvements per VMT (marker of crash risk) from 1995–1998 to 2005–2008 among older drivers aged 70 and over relative to changes among middle-aged drivers aged 35–54 were computed. The contributions of these components to the relative changes in older drivers’ fatality rates per VMT were calculated using the decomposition methodology.ResultsFatality rates per VMT declined more among older drivers than among middle-aged drivers over the study period. Relative to middle-aged drivers, drivers aged 75 and older experienced large declines in crash risk and modest declines in death risk. Relative declines in crash risk accounted for 68–74% of the larger decline in fatalities per VMT among drivers aged 75 and older compared with middle-aged drivers. Drivers aged 70–74 experienced modest relative declines in crash risk and death risk. Declines in death risk among drivers aged 75 and older relative to middle-aged drivers were much larger in side-impact crashes; improvements in crash survivability accounted for nearly half of the relative decline in fatality rates in these crashes. Relative survivability did not change significantly in frontal impacts. Higher death risk was more important than higher crash risk in explaining older drivers’ elevated fatality rates per VMT relative to middle-aged drivers during 1995–1998, and the contribution of heightened death risk was even greater during 2005–2008.ConclusionsMany factors may have reduced crash involvements among drivers 75 and older, including changes in travel patterns, health, and roadway design. In side impacts, side airbags and reduced passenger vehicle incompatibility may have improved survivability for older drivers. Because excess fragility now makes an even larger contribution to older drivers’ elevated fatality rates, future countermeasures that improve survivability can likely provide large benefits.     

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.     

Evaluation of the effects of North Carolina's 0.08% BAC law.

This study was conducted to determine whether the lowered BAC limit for drivers in North Carolina resulted in fewer alcohol-related motor vehicle crashes. We used time-series analysis to examine several indicators of alcohol involvement in both injury and fatal crashes between 1991 and 1996. Data from NC crash files as well as the Fatality Analysis Reporting System (FARS) are used. We also examined several indicators used in previous research on lower BAC limits using a before-after design to compare North Carolina with 37 states that did not change their BAC limit for 24 months before and after the BAC limit was lowered. When controlling for the pre-existing downward trend in drinking driver crashes, along with other pertinent factors such as amount of travel and number of weekends per month, there was no evidence of either a significant shift or a change in the downward trend of alcohol-related crashes associated with the lowered BAC limit. In conclusion, although the lower BAC limit was actively enforced and a substantial proportion of drinkers were aware of the new BAC limit, the drinking-driving population in North Carolina, at the time the lower limit took effect in October 1993, was simply unresponsive to this change.     

Pregnant driver-associated motor vehicle crashes in North Carolina, 2001–2008

Background

Motor vehicle crashes are the leading cause of maternal injury-related mortality during pregnancy in the United States, yet pregnant women remain an understudied population in motor vehicle safety research.

Methods

We estimated the risk of being a pregnant driver in a crash among 878,546 pregnant women, 16–46 years, who reached the 20th week of pregnancy in North Carolina (NC) from 2001 to 2008. We also examined the circumstances surrounding the crash events. Pregnant drivers in crashes were identified by probabilistic linkage of live birth and fetal death records and state motor vehicle crash reports.

Results

During the 8-year study period, the estimated risk of being a driver in a crash was 12.6 per 1000 pregnant women. Pregnant women at highest risk of being drivers in serious crashes were 18–24 years old (4.5 per 1000; 95% confidence interval, CI,4.3, 4.7), non-Hispanic black (4.8 per 1000; 95% CI = 4.5, 5.1), had high school diplomas only (4.5 per 1000; 95% CI = 4.2, 4.7) or some college (4.1 per 1000; 95% CI = 3.9, 4.4), were unmarried (4.7 per 1000; 95% CI = 4.4, 4.9), or tobacco users (4.5 per 1000; 95% CI = 4.1, 5.0). A high proportion of crashes occurred between 20 and 27 weeks of pregnancy (45%) and a lower proportion of crashes involved unbelted pregnant drivers (1%) or airbag deployment (10%). Forty percent of crashes resulted in driver injuries.

Conclusions

NC has a relatively high pregnant driver crash risk among the four U.S. states that have linked vital records and crash reports to examine pregnancy-associated crashes. Crash risks were especially elevated among pregnant women who were young, non-Hispanic black, unmarried, or used tobacco. Additional research is needed to quantify pregnant women's driving frequency and patterns.     

Fragility versus excessive crash involvement as determinants of high death rates per vehicle-mile of travel among older drivers

Using multiple national data systems, the roles of fragility (susceptibility to injury) versus excessive crash involvement in the increased fatality risk of older drivers per vehicle-mile of travel (VMT) were estimated. For each age and gender group, deaths per driver involved in a crash (a marker of fragility) and drivers involved in crashes per VMT (a marker of excessive crash involvement) were computed. Compared with drivers ages 30-59, those younger than 20 and those 75 or older both had much higher driver death rates per VMT. The highest death rates per mile driven, 13-fold increases, were observed among drivers age 80 or older, who also had the highest death rates per crash. Fragility began to increase at ages 60-64 and increased steadily with advancing age, accounting for about 60-95% of the excess death rates per VMT in older drivers, depending on age group and gender. Among older drivers, marked excesses in crash involvement did not begin until age 75, but explained no more than about 30-45% of the elevated risk in this group of drivers; excessive crashes explained less of the risk among drivers ages 60-74. In contrast, crash over-involvement was the major factor contributing to the high risk of death among drivers younger than 20, accounting for more than 95% of their elevated death rates per VMT. Although both fragility and crash over-involvement contributed to the excess death rates among older drivers per VMT, fragility appeared to be of over-riding importance. These findings suggest that measures to improve the protection of older vehicle occupants in crashes should be vigorously pursued.     

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.     

Nighttime driving and fatal crash involvement of teenagers

Data from the 1977 National Personal Transportation Survey and from the Fatal Accident Reporting System were used to compute mileage-based fatal crash involvement rates of drivers, by age, sex, and time of day. Teenagers drive less than older drivers but do more of their driving at night. They have much higher numbers of drivers in fatal crashes based on miles driven than do older drivers; their nighttime rates are particularly high. Sixteen year olds, especially males, have by far the highest fatal crash rates per mile, both nighttime and daytime. More widespread adoption of driving curfew laws would very likely produce substantial reductions in fatalities involving 16 yr old drivers.     

The effects of age,gender, and crash types on drivers’ injury-related health care costs

There are many studies that evaluate the effects of age, gender, and crash types on crash related injury severity. However, few studies investigate the effects of those crash factors on the crash related health care costs for drivers that are transported to hospital. The purpose of this study is to examine the relationships between drivers’ age, gender, and the crash types, as well as other crash characteristics (e.g., not wearing a seatbelt, weather condition, and fatigued driving), on the crash related health care costs. The South Carolina Crash Outcome Data Evaluation System (SC CODES) from 2005 to 2007 was used to construct six separate hierarchical linear regression models based on drivers’ age and gender. The results suggest that older drivers have higher health care costs than younger drivers and male drivers tend to have higher health care costs than female drivers in the same age group. Overall, single vehicle crashes had the highest health care costs for all drivers. For males older than 64-years old sideswipe crashes are as costly as single vehicle crashes. In general, not wearing a seatbelt, airbag deployment, and speeding were found to be associated with higher health care costs. Distraction-related crashes are more likely to be associated with lower health care costs in most cases. Furthermore this study highlights the value of considering drivers in subgroups, as some factors have different effects on health care costs in different driver groups. Developing an understanding of longer term outcomes of crashes and their characteristics can lead to improvements in vehicle technology, educational materials, and interventions to reduce crash-related health care costs.     

Drinking and driving by young females

Recent research indicates that women are drinking and driving more often and that the proportion of female drivers involved in fatal crashes is increasing. U.S. Fatal Accident Reporting System data (Fell 1987) suggest that although overall alcohol involvement rates in fatal crashes have been declining for the past four years, the rates for females aged 21-24 have not, and their alcohol involvement rate in late-night single vehicle (SV) crashes, a surrogate measure of alcohol-related (A/R) crashes, is almost as high as that of male drivers. This paper examines the involvement of North Carolina (NC) female drivers who are less than 35 years of age for the period of 1976 through 1985 and reports on trends in driver licensing, arrests for drinking and driving, SV nighttime and A/R crashes, and measured blood alcohol levels in fatalities. It identifies an emerging driving-while-impaired (DWI) problem for younger women, particularly those 21 to 24 years of age. Significant trends pertaining to the involvement of women will have implications for the design and implementation of educational, deterrence, enforcement, and rehabilitation programs.     

Older drivers do not have a high crash risk--a replication of low mileage bias

The widespread claim that older drivers are overly involved in crashes has apparent support from crash data, especially when distance travelled is used as the exposure measure. However, independent of age, drivers travelling more kilometres will typically have lower crash rates per kilometre than those driving fewer kilometres. This paper uses Dutch travel survey data from a large sample of respondents to confirm previous research findings concerning the association between annual mileages driven and crash involvement. When the crash rates of drivers of different ages were compared after being matched for yearly driving distance, most drivers aged 75 years and above were indicatively safer than all other drivers. Only older drivers travelling less than 3000 km per year (just over 10% of all older drivers in the survey) gave any indication of elevated crash rates.     

Driver risk factors for sleep-related crashes

A population-based case-control study was carried out to examine driver risk factors for sleep-related motor vehicle crashes. Cases included 312 drivers involved in recent North Carolina crashes and identified on police reports as asleep at the time of the crash and 155 drivers identified as fatigued. Controls were 529 drivers also involved in recent crashes but not identified as asleep or fatigued, and 407 drivers not involved in recent crashes. All drivers were contacted for brief telephone interviews. Results showed that drivers in sleep-related crashes were more likely to work multiple jobs, night shifts, or other unusual work schedules. They averaged fewer hours sleep per night, reported poorer quality sleep, were less likely to feel they got enough sleep, were sleepier during the day, drove more often late at night, and had more prior instances of drowsy driving. Compared to drivers in non-sleep-related crashes, they had been driving for longer times, been awake more hours, slept fewer hours the night before, and were more likely to have used soporific medications. Knowledge of specific risk factors for sleep-related crashes is an important first step in reducing the thousands of deaths and injuries each year in the US attributed to drowsy driving.     

Age and gender patterns in motor vehicle crash injuries: importance of type of crash and occupant role

To evaluate the interaction of gender, age, type of crash, and occupant role in motor vehicle crash injuries leading to hospitalization, we analyzed 1997 Wisconsin hospital discharge data for patients with primary E-code diagnoses of motor vehicle injuries. The overall ratio of males to females (M/F ratio) hospitalized for motor vehicle crash injuries was 1.33 (95% confidence interval (CI): 1.26-1.41). The M/F ratio varied by type of crash and differed for passengers and drivers. For injuries sustained in collisions between vehicles, the M/F ratio was 0.96 (95% CI: 0.87-1.05); in loss of control accidents the M/F ratio was 1.95 (95% CI: 1.76-2.17). Within each type of crash, the M/F ratio for drivers was similar to that for the entire type; the M/F ratio for passengers was about half of the type total. Expressed as rates of hospitalization per 100,000 people in the general population, hospitalizations of drivers in collisions with another motor vehicle increased steeply in males, but not in females, beginning at about age 70. For drivers in loss of control crashes, male rates exceeded female rates in all age groups, with peaks in the groups 15-24 and 85-89. For passengers, injury rates from collisions with other motor vehicles were greater for females, especially in the elderly, and injury rates from loss of control crashes were similar for both genders, with peaks at 15-24 and 85-94. The higher fatality of men in loss of control motor vehicle crashes, compared to women, suggests an important area for further investigation.     

Quasi-induced exposure method: Evaluation of not-at-fault assumption

Crash rates are used to establish the relative safety of various variables of concern such as driver classes, vehicle types and roadway components. Appropriate exposure data for estimating crash rates is critical but crash databases do not contain information on driver or vehicle exposure. The quasi-induced exposure method, which uses not-at-fault driver/vehicle data as an exposure metric, is a technique used in order to overcome this problem. The basic assumption made here is that not-at-fault drivers represent the total population in question. This paper examines the validity of this assumption using the Kentucky crash database to define two samples of not-at-fault drivers. One sample included only not-at-fault drivers selected from the first two vehicles in a multi-vehicle crash (two or more vehicles involved) while the other included the not-at-fault drivers from multi-vehicle crashes with more than two vehicles involved and excluding the first two drivers. The assumption is that the randomness of the involvement of drivers in the second sample is more reasonable than the drivers in the first two vehicles involved in crashes. The results indicate that these two samples are similar; there is no statistical evidence demonstrating that both samples represent two different populations in the maneuvers and other variables/factors examined here; and they are representative simple random samples of the driver population with respect to the distribution of the driver age when there is no reasonable doubt about investigating officers’ judgments. Thus, estimating relative crash propensities for any given driver type by using the quasi-induced exposure approach will yield reasonable estimates of exposure.