2007 National Roadside Survey of Alcohol and Drug Use by Drivers: Methodology

This report describes the methodology for the 2007 U.S. national field study to estimate the prevalence of alcohol-, drug-, and alcohol-and-drug-involved driving, primarily among nighttime weekend drivers, but also daytime Friday drivers. This study involved randomly stopping drivers at 300 locations across the continental United States; sites were selected through a stratified random sampling procedure. Data were collected during a 2-hour Friday daytime session at 60 locations, and during four 2-hour nighttime periods (10 p.m. to midnight and 1 a.m. to 3 a.m. on both Friday and Saturday nights) at 240 locations. Both self-report and biological measures were taken. An objective was to obtain at least 7,500 oral fluid samples for analysis. Biological measures included breath alcohol measurements on 9,413 respondents, oral fluid samples from 7,719 respondents, and blood samples from 3,276 respondents. Oral fluid and blood samples were subjected to laboratory screening and LC/MS-MS and GC/MS confirmation respectively for both alcohol and 20 categories of drugs. These data are being analyzed to develop the first national prevalence estimate of alcohol- and drug-involved driving. This first report describes the field methods used to conduct this study, including data collection procedures. Overall response rates are also presented. Two other reports will present the results of the data collection and analyses; one will focus on alcohol use prevalence estimates among drivers and compare them with previous National Roadside Surveys conducted in 1973, 1986, and 1996; the other report will provide drug use prevalence estimates among drivers.