The National Roadside Study (NRS) seeks to create national estimates of alcohol and other drug prevalence among drivers in the United States. The study will collect breath and oral fluid specimens from 8,000 drivers at approximately 300 roadside locations across the country. The study will also gather specimens from a convenience sample of other road users (e.g., pedestrians, bicyclists, electric scooter riders, and those with assistive aids) who are readily available at NRS data collection locations.

“We are looking to collect specimens from a nationwide representative sample of drivers to determine the prevalence of drug and alcohol-positive driving,” says project Co-Principal Investigator Jenna Darrah. “And it is important to note that positive does not equal impairment. We are noting the percentage of drivers and other road users who have these drugs and alcohol in their system actively. We cannot determine impairment from this. We're just looking at prevalence of positivity.

“The intent of this current study is to compare to the several previous iterations of national roadside studies that were conducted (1973, 1986, 1996, 2007, 2013-2014)” Darrah continued. “And we're also expanding into a new domain this for the current iteration, where we're collecting a convenience sample of other road users, where previous studies have only focused on drivers.”

What else is different about the current study when compared with previous iterations of the NRS?

“We want to keep it somewhat similar to these previous iterations with respect to being able to compare trends over time,” Darrah says, though there are new drug-related issues we may see the ramifications of such as the rise of fentanyl prevalence and the increased legalization of cannabis. “The testing of other road users is also important. If you are a drug or alcohol positive pedestrian on a sidewalk, and you stumble directly next to a lane of travel, you become a hazard to drivers and other road users on the roadway. Similarly, if you're riding a scooter under the influence of something, you could, again, be a hazard to another other road user as well as drivers on the roadway. It is important to capture that prevalence, because we need to consider both sides of the coin. Drivers who may be under the influence are a hazard to other road users, and other road users can also be a hazard to drivers.”

Dunlap has been involved in other pertinent prevalence studies. “Dunlap conducted The Long Beach/Fort Lauderdale Relative Risk Study, Darrah says. “We also led the creation of a step-by-step How-To Guide for conducting a State roadside survey of alcohol and other drugs. These projects prepared us and put us on this path to be able to execute the National Roadside Study successfully, and working with the Pacific Institute for Research and Evaluation (PIRE), who has lead iterations of the NRS previously, will be incredibly helpful.

There are many steps to setting up a roadside study.

“We are selecting 60 areas throughout the US,” Darrah says. “Let's say the Wake County, NC area is one of the 60. Within this area, we will collect at 5 locations. In Wake County, one location could be a street in downtown Raleigh, with a second location in Apex, and a third in Cary, etc. We pick locations where cars can easily pull off of the road, such as large parking lots. Again, we are aiming to collect data across 60 sites, with 5 locations at each site, so 300 sampling locations in total. We will need to go out and find viable locations, like parking lots, in each area that we select. We will need to get the necessary approvals from the management company who owns the parking lot or local law enforcement if it's an unused lot. And we need to make sure that each location allows individuals to pull their vehicles in and out safely, as well as having a sufficient flow of traffic on the roadway being sampled.

“And then location setup and staff training begins.”

The National Roadside Study is an important project for Dunlap to take part in.

“I'm excited to see the data and how it compares to the trends from 10 years ago,” Darrah says. “And I am grateful to be heavily involved in the project from the beginning, and to use my special toolkit of experiences to develop the research protocols and select the study locations.”