National Roadside Survey:

NHTSA Changed Methodology to Address Driver Concerns

GAO-18-328R: Published: Mar 12, 2018. Publicly Released: Mar 12, 2018.

Additional Materials:


Susan A. Fleming
(202) 512-2834


Office of Public Affairs
(202) 512-4800

What GAO Found

All of the researchers and other public safety stakeholders GAO spoke with highlighted the critical value of data from the National Roadside Survey (NRS), which is a nationwide survey conducted about every 10 years to estimate alcohol and drug use by drivers. These stakeholders noted that NRS data are unique, comprehensive, and reliable. Stakeholders also said that these data support initiatives, such as identifying policy or legal priorities and measuring progress toward goals, to identify and address impaired driving, and the data have been used to update drug-testing standards and law enforcement training. Stakeholders also expressed concerns about a current statutory prohibition on the National Highway Traffic Safety Administration's (NHTSA) use of federal funding for future surveys, stating that without additional NRS data there will be no reliable method to track trends in drugged driving, including which drugs are used by drivers and the drugs' prevalence.

In the most recent survey, sponsored by NHTSA in 2013-2014, researchers interviewed more than 11,000 drivers at 300 locations nationwide. Methods used at law enforcement checkpoints and NRS's data collection sites differ in key ways. For example, unlike mandatory law-enforcement checkpoints, participation in the NRS is voluntary, and NHTSA has reported that no participants have ever been arrested for being impaired. By contrast, participation in law enforcement checkpoints is not voluntary and drivers may be arrested if found to be impaired. In addition, information on a person's identity is not collected at a NRS site, while law enforcement officers may collect such information at a checkpoint.

GAO found that NRS's methodology followed Office of Management and Budget (OMB) standards and guidelines for survey principles related to the protection of privacy. Further, NHTSA's protocols are designed to ensure that drivers understand that participation in the survey is voluntary and anonymous, and, midway through the 2013-2014 survey, NHTSA changed several survey protocols to help drivers understand that they have the choice of whether to participate. For example, NHTSA

  • used researchers instead of police officers to direct traffic, 
  • added additional signs to indicate that the survey was voluntary, and
  • ended the use of passive alcohol sensors prior to obtaining driver consent.

Why GAO Did This Study

Since 1973, the NRS has estimated alcohol use by drivers on our nation's roadways, with drugged driving included in the most recent surveys in 2007 and 2013-2014. Participation in the survey is random, voluntary, and compensated. Nevertheless, in the most recent survey conducted in 2013-2014, some drivers expressed concern that the visible presence of uniformed officers at some survey sites made those sites appear to be mandatory law-enforcement checkpoints. In addition, collection of blood and saliva as part of the testing process raised privacy concerns. In response to these concerns, Senate Report 113-182 included a provision for GAO to review the survey's methodology and report to the Senate and House Appropriations Committees. This report examines: (1) the overall value of NRS's data, according to selected researchers and other public safety stakeholders; (2) key differences between methods used at NRS's data collection sites and law enforcement checkpoints; and (3) the extent to which NRS's methodology ensures voluntary participation and protects participants' privacy.

GAO interviewed selected researchers and public safety stakeholders (e.g., officials with the White House Office of National Drug Control Policy and the National Institute on Drug Abuse and members of the Society of Forensic Toxicologists, among others, who were chosen based on having a mission relevant to the issue of drug-impaired driving and on recommendations from NHTSA and other stakeholders) regarding the value of NRS data. GAO also compared NHTSA's methodology for the 2013-2014 NRS with the agency's guidance for law enforcement's sobriety checkpoints. Finally, GAO reviewed NRS's protocols for ensuring voluntary participation and assessed NRS's methodology for privacy protections against the OMB's standards for surveys.

For more information, contact Susan Fleming at 202-512-2834 or

Dec 13, 2018

Dec 12, 2018

Nov 14, 2018

Oct 24, 2018

Sep 26, 2018

Sep 5, 2018

Jul 18, 2018

Jul 16, 2018

Jun 27, 2018

Looking for more? Browse all our products here