Alcohol-related relative risk of driver fatalities and driver involvement in fatal crashes in relation to driver age and gender: an update using 1996 data.

OBJECTIVE: To re-examine and refine estimates for alcohol-related relative risk of driver involvement in fatal crashes by age and gender as a function of blood alcohol concentration (BAC) using recent data. METHOD: Logistic regression was used to estimate age/gender specific relative risk of fatal crash involvement as a function of the BAC for drivers involved in a fatal crash and for drivers fatally injured in a crash, by combining crash data from the Fatality Analysis Reporting System with exposure data from the 1996 National Roadside Survey of Drivers. RESULTS: In general, the relative risk of involvement in a fatal vehicle crash increased steadily with increasing driver BAC in every age/gender group among both fatally injured and surviving drivers. Among 16-20 year old male drivers, a BAC increase of 0.02% was estimated to more than double the relative risk of fatal single-vehicle crash injury. At the midpoint of the 0.08% - 0.10% BAC range, the relative risk of a fatal single-vehicle crash injury varied between 11.4 (drivers 35 and older) and 51.9 (male drivers, 16-20). With only very few exceptions, older drivers had lower risk of being fatally injured in a single-vehicle crash than younger drivers, as did women compared with men in the same age range. When comparable, results largely confirmed existing prior estimates. CONCLUSIONS: This is the first study that systematically estimated relative risk for drink-drivers with BACs between 0.08% and 0.10% (these relative risk estimates apply to BAC range midpoints at 0.09%.) The results clearly show that drivers with a BAC under 0.10% pose highly elevated risk both to themselves and to other road users. 2000)

Tractor-trailer crashes in Indiana: a case-control study of the role of truck configuration.

Studies of the crash experience of tractors pulling multiple trailers have reached different conclusions concerning the relationship of truck configuration to crash risk. A previous case-control study found a significant increase in crash risk for double-trailer trucks in the state of Washington. The present case-control study was done of tractor-trailers crashing on Indiana interstates during November 1989-March 1991. Controls were obtained for 25% of the crash sites and were all tractor-trailers passing the crash sites during a traffic observation session one to four weeks following a crash on the same day of the week for 30 minutes at the same time of day. Logistic regression identified day of week, time of day, urban/rural area, and specific highway as significant predictors of controls' truck configuration. This model was applied to the cases to estimate the expected number of double-trailer cases. For all crashes combined, no increased crash risk was observed for doubles (Standardized Crash Ratio (SCR) = 83). Doubles were significantly underinvolved in multiple-vehicle crashes (SCR = 74), crashes on dry roads (SCR = 61), and crashes on wet (other than snow, ice, or slush) roads (SCR = 54). Doubles were significantly overinvolved in crashes on roads with snow, ice, or slush (SCR = 153). Because truck configuration was highly associated with driver age and work operation attributes among trucks in crashes, the absence of control data on these potential confounders precluded definitive assessment of the intrinsic risk of multiple versus single-trailer vehicles.

Daylight saving time and motor vehicle crashes: the reduction in pedestrian and vehicle occupant fatalities.

Fatal crashes were tabulated for 6-hour periods around sunrise and sunset, from 13 weeks before the fall change to standard time until 9 weeks after the spring change to daylight saving time. Fatal-crash occurrence was related to changes in daylight, whether these changes occurred abruptly with the fall and spring time changes or gradually with the changing seasons of the year. During daylight saving time, which shifts an hour of daylight to the busier evening traffic hours, there were fewer fatal crashes. An estimated 901 fewer fatal crashes (727 involving pedestrians, 174 involving vehicle occupants) might have occurred if daylight saving time had been retained year-round from 1987 through 1991.

The effect of daytime running lights on crashes between two vehicles in Saskatchewan: a study of a government fleet.

Keeping vehicle lights on to increase vehicle conspicuity during daytime hours has been found to reduce crashes in Scandinavia and the United States. Crashes of vehicles with and without daytime running lights owned by the Central Vehicle Agency of the Province of Saskatchewan were compared to a random selection of crashes drawn from provincial crash files involving vehicles without daytime running lights for the years 1982 through 1989. Daytime two-vehicle crashes involving vehicles approaching from the front or side were reduced by about 28% for the daytime running-light equipped vehicles. A 28% reduction in daytime running-light relevant daytime two-vehicle crashes corresponds to a 15% reduction in all daytime two-vehicle crashes.

The effect of city curfew ordinances on teenage motor vehicle fatalities.

Of 149 large cities surveyed, 72 were found to have nighttime curfew ordinances applying to teenagers of various ages. The typical city curfew identified starts at midnight, ends at 5 A.M., and affects all activity of teenagers ages 13-17 in a public place and unaccompanied by a parent. In comparisons of 47 cities with curfews covering 13- to 17-year-olds and 77 cities without curfews, curfews were associated with a 23% reduction in fatal injury for 13- to 17-year-olds for the 9 P.M.-5:59 A.M. time period. This is identical to the 23% reduction estimated for both fatal and nonfatal motor vehicle injuries for 13- to 17-year-olds in an earlier, more limited study of curfews in Detroit, Cleveland, and Columbus, Ohio.

Automobile driver fatalities in frontal impacts: air bags compared with manual belts.

OBJECTIVES: The effectiveness of air bags was estimated in this study by comparing driver fatalities in frontal crashes with driver fatalities in nonfrontal crashes, for cars with air bags and manual belts and cars with manual belts only. METHODS: Fatal Accident Reporting System data for drivers fatally injured during 1985 to 1991 in 1985 to 1991 model year cars that were equipped with air bags in or before model year 1991 were analyzed. RESULTS: Driver fatalities in frontal crashes in air bag cars were 28% lower than those in comparable cars with manual belts only. This percentage was used for estimating the overall fatality reduction in air bag cars. The reduction was greater in large cars (50%) than in midsize cars (19%) or in small cars (14%). Air bags reduced driver fatalities in frontal crashes involving ejection by about 9%. Fatalities in frontal crashes among drivers who were reportedly using manual belts at the time of the crash were reduced by about 15%. The comparable reduction among drivers who were reportedly not using manual belts was 31%. CONCLUSION: It was estimated that air bags reduced the total number of all driver fatalities by about 19%.

Alcohol-related relative risk of fatal driver injuries in relation to driver age and sex.

The relative risks of fatal crash involvement at various blood alcohol concentrations (BACs) were examined using data on fatal driver injuries from the Fatal Accident Reporting System in conjunction with driver exposure data from the second national road-side breath-testing survey. Based on driver fatalities in single-vehicle crashes, it was estimated that each 0.02 percentage increase in the BAC of a driver with non-zero BAC nearly doubles the risk of being in a fatal crash. Crash risk was found to increase with increasing BAC among all of the six age and sex groups studied. At BACs in the 0.05-0.09 percent range, the likelihood of a crash was at least nine times greater than at zero BAC for all age groups. Younger drivers with BACs in the 0.05-0.09 range had higher relative risks than older drivers, and females had higher relative risks than males. At very high BACs (at or above 0.15 percent), the risk of crashing was 300 to 600 times the risk at zero or near-zero BACs. These relative risk estimates are considerably higher than estimated in other studies, but other studies have based their estimates on all crashes rather than single-vehicle crashes only. In this study, relative risks were also lower when based on driver fatalities in all crashes. However, when plausible assumptions were made about the BAC distributions of other participants in multiple-vehicle crashes (whose actual BAC is often unknown), the relative risks based on the maximum BAC of the crash participants were nearly as high as those estimated in single-vehicle crashes.

City curfew ordinances and teenage motor vehicle injury.

Several U.S. cities have curfew ordinances that limit the late night activities of minor teenagers in public places including highways. Detroit, Cleveland, and Columbus, which have curfew ordinances, were compared to Cincinnati, which does not have such an ordinance. The curfew ordinances were associated with a 23% reduction in motor vehicle related injury for 13- to 17-year-olds as passengers, drivers, pedestrians, or bicyclists during the curfew hours. It was concluded that city curfew ordinances, like the statewide driving curfews studied in other states, can reduce motor vehicle injury to teenagers during the particularly hazardous late night hours.

Fatal crash involvement and laws against alcohol-impaired driving.

It is estimated that in 1985 about 1,560 fewer drivers were involved in fatal crashes because of three types of drinking-driving laws. The laws studied were per se laws that define driving under the influence using blood alcohol concentration (BAC) thresholds; laws that provide for administrative license suspension or revocation prior to conviction for driving under the influence (often referred to as "administrative per se" laws); and laws that mandate jail or community service for first convictions of driving under the influence. It is estimated that if all 48 of the contiguous states adopted laws similar to those studied here, and if these new laws had effects comparable to those reported here, another 2,600 fatal driver involvements could be prevented each year. During hours when typically at least half of all fatally injured drivers have a BAC over 0.10 percent, administrative suspension/revocation is estimated to reduce the involvement of drivers in fatal crashes by about 9 percent; during the same hours, first offense mandatory jail/community service laws are estimated to have reduced driver involvement by about 6 percent. The effect of per se laws was estimated to be a 6 percent reduction during hours when fatal crashes typically are less likely to involve alcohol. These results are based on analyses of drivers involved in fatal crashes in the 48 contiguous states of the United States during the years 1978 to 1985.

Motorcycle headlight-use laws and fatal motorcycle crashes in the US, 1975-83.

Fatal motorcycle crashes in the United States from 1975 to 1983 were analyzed. In the 14 states that had motorcycle headlight-use laws during the study period, about 600 daytime crashes of the type included in the study were prevented by these laws. This reduction corresponds to a 13 per cent reduction in fatal daytime crashes and to an average reduction of about five fatal crashes per year for each of the 14 states. About 30 states did not have motorcycle daytime headlight laws in effect during the study period. If all of these states had such laws, in an average year, approximately 140 additional fatal motorcycle crashes would have been prevented.

Variations in minimum licensing age and fatal motor vehicle crashes.

The effect of differences in the legal minimum licensing age on fatal motor vehicle crashes was studied in New Jersey (age 17), Massachusetts (age 16 1/2), and Connecticut (age 16). New Jersey's 17-year-old licensing law was associated with greatly reduced fatal crash involvement. It is estimated that 65 to 85 per cent reductions in 16 year-old-driver fatal crash involvement can be expected if the licensing age is increased from 16 to 17 without increasing fatal crash rates at older ages.

The economics of safety deregulation: lives and dollars lost due to repeal of motorcycle helmet laws.

Between 1976 and 1980, 28 state legislatures in the United States repealed or weakened their motorcycle helmet-use laws. This paper estimates the number of excess deaths attributable to this deregulatory activity, and the associated economic costs to society. Because of data limitations, no attempt was made to estimate the excess nonfatal injuries and associated costs. We applied a variant of log-linear contingency-table analysis to the monthly counts of motorcycle fatalities in the 48 contiguous states over the period 1975 through 1980. This analysis produced estimates of the total number of deaths, in each of 36 age-sex groups, that could be attributed to changes in the helmet laws. We then estimated the direct and indirect economic costs associated with fatalities in each age-sex group. Our findings indicate that 516 excess deaths occurred in 1980 in the 28 states that weakened or repealed their helmet laws. This represented 24 percent of the total motorcycle fatalities occurring in those states. Women and younger cyclists of both sexes comprised a disproportionate share of excess deaths. The economic costs to society that are associated with the excess fatalities resulting from the repeals of helmet laws total at least $180 million.

The repeal of helmet use laws and increased motorcyclist mortality in the United States, 1975-1978.

Monthly mortality figures for motorcyclists for each state in the United States were obtained for the period January 1975 through December 1978. Twenty-four states revealed or weakened their helmet use laws at various dates within this period. Two of these states subsequently reintroduced a strengthened law. This paper measures the effects of these law changes on motorcyclist mortality. The states that repealed or weakened their helmet laws were matched with one or more states from the same geographic region that either did not have helmet use laws or did not change such existing laws in this four-year period. The effect of weakening the law in each state was then estimated in three steps: 1) the mortality data from each state for the period prior to repeal were regressed on smoothed data from the matched states; 2) these equations were used to predict the numbers of motorcyclist deaths that would have been expected in each state in the period following the repeal or weakening of the law if the laws had not been changed; 3) these numbers of expected deaths were then compared with the actual numbers of deaths that occurred. Of the 26 law changes, it was found that 23 resulted in a greater number of actual deaths in the period following the repeal or weakening of the law than were predicted to occur if the law had not been changed. It is estimated that the repeals or weakening of motorcyclist helmet use laws were typically followed by almost 40 per cent increases in the numbers of fatally injured motorcyclists.

Driver education and fatal crash involvement of teenaged drivers.

Fatal crash involvement of teenagers per licensed driver and per population in 27 states was related to the proportions of teenagers who received high school driver education. Among 16--17 year olds, driver education was associated with a great increase in the number of licensed drivers, without a decrease in the fatal crash involvement per 10,000 licensed drivers- About 80 per cent of the 16--17 year olds who took high school driver education obtained licenses that they would not otherwise have obtained until age 18 or thereafter. The net effect is much higher death involvement rates per 10,000 population, on average, in states with greater proportions of 16-17 year olds receiving high school driver education. The data suggest that most teenagers would obtain licenses when they are 18--19 years old, irrespective of high school driver education, and indicate that differences among the states in fatal crash involvement rates per 10,000 licensed 18--19 year old drivers were not significantly related to either high school driver education or delayed licensure.