Results of the 2013–2014 National Roadside Study of Alcohol and Drug Use by Drivers [Traffic Safety Facts]

Berning, Amy; Compton, Richard; Wochinger, Kathryn; National Highway Traffic Safety Administration · 2017 · OpenAlex-citations

DOI: 10.21949/1525810

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Summary

This report presents the findings of the 2013–2014 National Roadside Survey (NRS) of Alcohol and Drug Use by Drivers, conducted by the National Highway Traffic Safety Administration (NHTSA). The study aims to estimate the national prevalence of alcohol and drug use among drivers, continuing a series of surveys initiated in 1973. While previous surveys focused primarily on alcohol, the 2007 and 2013–2014 iterations expanded to include testing for potentially impairing drugs, including illegal substances and legal medications, allowing for the first national-scale examination of drug use trends. The methodology involved a stratified random sample of drivers across 60 sites in the contiguous United States, representing various regions and population densities. Data collection occurred during weekday daytime hours and weekend nighttime hours. Participants provided breath samples for alcohol concentration (BrAC), as well as oral fluid and blood samples for drug testing. Of the 11,100 eligible drivers, 85.2% provided breath samples, 71% provided oral fluid samples, and 42.2% provided blood samples. National prevalence rates were calculated using a complex weighting scheme based on crash volume and selection probability. The results indicate a significant long-term decline in alcohol use. The percentage of weekend nighttime drivers with any detectable alcohol (BrAC > .005) dropped from 35.9% in 1973 to 8.3% in 2013–2014. Specifically, drivers with illegal BrAC levels (≥ .08) decreased from 7.5% to 1.5%, an 80% reduction. Alcohol use was significantly higher during weekend nights (8.3% positive) compared to weekday days (1.1% positive). In contrast, drug prevalence did not show a significant difference between daytime and nighttime overall, though illegal drug use increased from day to night, while medicinal drug use decreased. Comparing 2013–2014 data to 2007 using consistent cutoffs, the prevalence of illegal drug use among weekend nighttime drivers rose from 12.4% to 15.1%. Notably, THC prevalence increased by 48%, from 8.6% in 2007 to 12.6% in 2013–2014. The study concludes that while alcohol-impaired driving has decreased substantially, drug use among drivers, particularly marijuana, is rising. The authors highlight significant challenges in determining impairment from drug presence, noting that unlike alcohol, there is no established correlation between drug concentrations and driving performance due to factors like individual metabolism, tolerance, and detection windows. The report suggests that changes in state marijuana policies may contribute to increased use, warranting continued monitoring.

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• illicit drugs

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• Empirical Findings: observational prevalence
• Methodological Resource: dataset resource