Impaired Vulnerable Road Users 2026
Hosted by Ms. Jenna Darrah
Ms. Jenna Darrah, Director of Field Research at Dunlap & Associates, Inc. holds an MS degree in Human Factors Psychology from North Carolina State University. Her research interests mostly fall in the field of impaired driving. She is currently co-Principal Investigator for the National Roadside Survey, Dunlap's largest ongoing project, assessing prevalence of alcohol- and drug-positive driving across the nation's roadways. She was heavily involved in a project assessing drug prevalence of severely and fatally injured road users presenting to trauma centers. The findings from this effort are guiding another ongoing project looking at the feasibility of developing a sentinel surveillance system for drug use among road users. Her involvement in other projects at Dunlap covers a broad array of topic areas, and she leads the efforts to prepare and execute the field data collection portion of projects.
The influence of unsafe human behaviors on nighttime pedestrian crash injury severity at intersections
Mr. Sheikh Muhammad Usman
Due to minimal protection, pedestrians are especially vulnerable to crashes at intersections. In the U.S., pedestrian fatalities at intersections have been rising, with approximately 75% occurring at nighttime. This study identifies factors associated with nighttime pedestrian crash injury severity at intersections. It analyzes police-reported pedestrian crashes in North Carolina from 2016–2022, comprehensively coded using the Pedestrian and Bicyclist Crash Analysis Tool, which offers detailed descriptors and crash types for robust analysis. The study employs both statistical and Artificial Intelligence (AI) methods. Ordered Logit Model is estimated to quantify the impact of the correlates of pedestrian crash injury severity, while AI algorithms—XG Boost, Light GBM, and CatBoost— are used to predict pedestrian crash injury severity and support effective urban planning. Findings reveal significant associations between pedestrian injury severity and several behavioral, infrastructural, and regulatory factors at intersections, including pedestrian and driver alcohol impairment, pedestrian dash/dart-out behavior, drivers failing to yield, inadequate lighting, and high-speed limits. The findings can potentially lead to the development of AI-driven intersection safety systems aimed at detecting and mitigating unsafe pedestrian-vehicle interactions by leveraging real-time sensor data.
Drug Testing of Other Road Users: Toxicology Testing and Data Gaps
Dr. Ryan Smith
In 2022, NHTSA published a report entitled “Drug Testing and Traffic Safety: What You Need to Know.” This report highlighted the numerous opportunities and challenges with drug testing data in the Fatality Analysis Reporting System (FARS). While this report focused on drivers, impairment among other road users is a critical transportation safety problem. This presentation will highlight drug testing rates among various road users, as well as person, environmental, and crash characteristics that impact the likelihood of a drug test being administered. Differences across states will be highlighted to show the national patchwork of drug testing data. Lessons learned and opportunities to enhance testing for other road users will be discussed.
Alcohol and Drug Prevalence Among Seriously or Fatally Injured Other Road Users
Ms. Amy Berning and Dr. Dennis Thomas
In 2022, NHTSA released Alcohol and Drug Prevalence Among Seriously or Fatally Injured Road Users. This groundbreaking study obtained thousands of blood test results from patients across several Level 1 trauma centers. All types of road users were included in the study, including pedestrians, bicyclists, as well as drivers. The blood samples were tested for positivity of 70 drugs, including alcohol and over-the-counter, prescription, and illegal drugs. Although it is unknown whether individual patients were impaired by any drug substances, the included drugs are all known to cause impairment in driving-related behaviors. This presentation will explore the study’s methodology, and why it was chosen to address this topic. It will also discuss results for alcohol and drug use across types of road user types. It will include several new analyses, conducted since the report’s release. It will note where there can be difficulties in data collection and analyses for this topic, for example with classifying vehicles such as scooters.
Research Discussion
Ms. Jenna Darrah, Mr. Sheikh Muhammad Usman, Dr. Ryan Smith, Ms. Amy Berning, and Dr. Dennis Thomas