Fatal traffic crashes involving drinking drivers: what have we learned?

Abstract

Alcohol involvement in fatal crashes (any driver with a blood alcohol concentration [BAC] = .01g/dL or greater) in 2007 was more than three times higher at night (6 p.m.-6 a.m.) than during the day (6 a.m.-6 p.m.) (62% versus 19%). Alcohol involvement was 35% during weekdays compared to 54% on weekends. Nearly one in four drivers (23%) of personal vehicles (e.g., passenger cars or light trucks) and more than one in four motorcyclists (27%) in fatal crashes were intoxicated (i.e., had a BAC equal to or greater than the .08 g/dL illegal limit in the United States). In contrast, only 1% of the commercial drivers of heavy trucks had BACs equal to .08 g/dL or higher. More than a quarter (26%) of the drivers with high BACs (>or=.15 g/dL) did not have valid licenses. The 21- to 24-age group had the highest proportion (35%) of drivers with BACs>or=.08 g/dL, followed by the 25- to 34-age group (29%). The oldest and the youngest drivers had the lowest percentages of BACs>or= .08 g/dL: those aged 75 or older were at 4%, and those aged 16 to 20 were at 17%. Utah had the lowest rate of intoxicated drivers in fatal crashes at one in every eight drivers (12%), followed by Kentucky, Indiana, Iowa, New Hampshire, and Kansas, all at 17%. Montana (31%), South Carolina (31%), and North Dakota (39%) all had more than 3 in 10 drivers in fatal crashes who were intoxicated in 2007. The United States enjoyed a remarkable downward trend in alcohol-related crashes between 1982 and 1995, which has since leveled off. That trend coincided with a period during which per capita national alcohol consumption declined, the number of young drivers decreased, and the proportion of female drivers increased. Those factors alone, however, did not appear to account for the overall reduction. This provides further evidence that impaired-driving laws and safety program activity may have been responsible for at least some of the decline. However, there was a general worldwide decline in alcohol-related crashes during the same period, and other socioeconomic factors may have played a role. Proven effective strategies that could reduce impaired driving further in the United States include more frequent highly publicized enforcement efforts, such as sobriety checkpoints; lowering the illegal BAC limit for driving to .05g/dL; and mandating alcohol ignition interlocks for all convicted impaired drivers.

Figure 1

Motorcycle fatalities, FARS 1995–2007 [Source: NHTSA, 2009a]

Figure 2

Driver BACs in motorcycle and passenger car fatal crashes, FARS, 1995–2007 [Source: NHTSA, 2009a]

Figure 3

Drivers involved in fatal crashes by BAC level, FARS 2007 (N=55,681) [Source: NHTSA, 2009a]

Figure 4

Drivers involved in fatal crashes by license status, FARS 2007 (N=55,681) [Source: NHTSA, 2009a]

Figure 5

Proportion of drivers involved in fatal crashes in 2007 with BACs .08+ [Source: NHTSA, 2009a]

Figure 6

Drinking and nondrinking driver fatal crash rates by driver age and the odds of drinking to nondrinking driver rates, 1990–1994 [adapted from Tippetts and Voas, 2002]

Figure 7

Fatalities in crashes involving drunk drivers (BAC≥.08 g/dL), 2007 (N=13,036) [Source: NHTSA, 2009a]

Figure 8

Ratio of drinking drivers to nondrinking drivers in fatal crashes, 1982 to 2007 (−51%) [Source: NHTSA, 2009a]

Figure 9

Percentage of reduction in fatally injured drinking drivers and pedestrians and per capita alcohol consumption in the United States, from the 1982 baseline year to 2003 [Source: NHTSA, 2009a, and Lakins, LaVallee, Williams, et al., 2008]

Figure 10

Relative crash risk by BAC from Blomberg et al. (2005) and Borkenstein (1974)

Figure 11

Passenger vehicle driver relative risk of fatal crash involvement by BAC (RR @ .00 g/dL BAC = 1) [adapted from Zador, Krawchuk, and Voas, 2000]