Evaluation of the effects of North Carolina's 0.8% blood alcohol concentration laws

NHTSA - Behavioral Safety Researchhttps://doi.org/10.21949/15254181998PDFResearch PaperFoss, Robert D.Stewart, J. RichardReinfurt, Donald W.University of North Carolina (System). Highway Safety Research CenterUnited States. National Highway Traffic Safety AdministrationUnited States. National Highway Traffic Safety AdministrationNorth CarolinaBlood alcohol levelsDrunk drivingDrunk driversTraffic accidentsState lawsSurveysImpact studiesAccident ratesDOT-HS-808-893NTIS-PB2000107130DTNH22-91-D-07089Klein, TerryFinal reportThis report describes a study of the effects of the North Carolina 0.08% blood alcohol concentration (BAC) limit on alcohol-related crashes. On October 1, 1993 the per se illegal BAC limit for drivers was reduced from 0.10% to 0.08%. To determine what effect that reduction had on drinking drivers in North Carolina, both survey data and a variety of motor vehicle crash data were analyzed. Telephone interviews of 802 individuals 17 months after the law was enacted indicated substantial awareness of the new, lower limit among drinkers-especially frequent drinkers. Structural time-series modeling was used to examine alcohol involvement in all crashes in North Carolina between 1991 and 1995. In addition, fatal and serious injury crashes, nighttime crashes and nighttime fatal/serious injury crashes were also studied. There was no significant change for any of the measures examined. in the rate, or in the trend, coinciding with introduction of the lower BAC limit. In another analysis, the proportion of fatally injured drivers with BACs above 0.10% in North Carolina was compared with 11 other states that have high rates of alcohol measurement in fatal crashes for 1990 - 1995. This analysis also showed no significant effect of the 0.08% law. Finally, using Fatality Analysis Reporting System (FARS) data, North Carolina was compared with the 37 states that retained higher BAC limits from 1991 through 1996 on several measures: (1) driver BAC > 0.01%, (2) driver BAC > 0.10%, (3) police-reported alcohol involvement, (4) single vehicle nighttime crash, (5) single vehicle nighttime male driver crash, and (6) estimated alcohol involvement. In simple before-after comparisons, only police-reported alcohol involvement and estimated alcohol involvement decreased more after October 1, 1993 in North Carolina than in the other 37 states. Both these findings resulted from an artifact of the analytic approach rather than from the lower BAC limit in North Carolina. In conclusion, the lower BAC limit appears to have had no effect on drinking drivers in North Carolina. /Abstract from report summary page/129