BLACKSBURG, Va. – Studying impaired drivers in a real-world setting can be difficult, which makes it harder to gain an understanding of driving under the influence.
Researchers at Virginia Tech have utilized a method of research that can help experts attain a wealth of knowledge on the subject, although it takes multiple years.
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The method was pioneered by the Virginia Tech Transportation Institute in the 1990’s. It uses cameras and sensors installed in the participant’s personal vehicles, which monitor their daily routines. This, as well as journal entries over the course of the study, allows researchers to study the participant both sober and under the influence.
“Because most studies have not followed a driver over time, that missing piece of how people adapt to driving under that influence is actually covered through this. Since the effect of cannabis and impairment is so individualized, this study shows use over time and provides an opportunity to look at that full individual window in depth.”
Kaitlyn Bedwell, study author and senior research associate at the Virginia Tech Transportation Institute
This most recent study was conducted on a larger scale between 2021 and 2023, and saw 14,700 trips made by drivers between the ages of 21 and 71. The findings were then published ina 2025 report.
Early study analysis found two main points:
- Time of day patterns: Cannabis-related trips spiked during typical lunch times and in the evening. Fridays were the most popular day of the week for imbibing.
- Behavioral changes: Some participants compensated for substance use by taking different routes, typically choosing to use more rural roads than sober trips.
Kaitlyn Bedwell, a study author and senior research associate at the Virginia Tech Transportation Institute, sees this long-term, unintrusive method as preferable to studies that involve driving simulators and other short-term studies.
“It allows for a precise assessment of driving performance in the real world, and that’s what’s going to capture the real complexity of driving, If you got this artificial simulation environment, it’s got limitations because the participant doesn’t face real consequence of crashing or the variability of other drivers.”
Kaitlyn Bedwell, study author and senior research associate at the Virginia Tech Transportation Institute
If you would like to see more on this study, you can read Virginia Tech’s write-up here.