NRS results show drunk driving at lowest rate ever, drugged driving up significantly
In February, the National Highway Traffic Safety Administration (NHTSA) released the fifth National Roadside Survey (NRS) since 1973. The NRS is designed to estimate the prevalence of drinking and driving in the United States and as of 2007, was expanded to estimate the prevalence of drug use and driving.
The latest survey was conducted during 2013 and 2014 at a representative sample of 300 locations across the country. More than 9,000 drivers participated in the voluntary and anonymous survey.
The survey found that the use of alcohol by drivers continues to decline. In 2013/2014, about 1.5% of weekend drivers had blood alcohol concentrations at or above the legal limit of .08 breath alcohol concentration (BrAC) and 8.3% of drivers had a measurable amount of alcohol in their systems. The proportion of drivers during weekend nighttime hours who are at or above the legal limit of .08 BrAC decreased by 80% between 1973 and 2013/2014. The proportion with any measurable amount of alcohol in their systems dropped by about 77%.
While the estimates of alcohol prevalence in 2013/2014 are down from 2007 for low (.005 to .049 BrAC), medium (.050 to .079 BrAC) and high (.08+ BrAC) levels, the change is statistically significant only at the medium BrAC levels.
Participating drivers were tested for a large number of potentially impairing drugs using both oral fluid (saliva) and blood samples. The proportion of nighttime weekend drivers with illegal drugs in their systems was 15.2% in 2013/2014 while the proportion with prescription or over-the-counter medications that could affect driving was 7.3%. The proportion of total drug-positive nighttime weekend drivers increased from 16.3% in 2007 to 20.0% in 2013/2014, a significant increase.
Marijuana showed the greatest increase from 2007 to 2013/2014 was (THC). The percentage of THC-0positive drivers increased from 8.6% in 2007 to 12.6% in 2013/2014, a proportional increase of 47%.