All ETDs from UAB

Advisory Committee Chair

David Schwebel

Document Type

Thesis

Date of Award

2023

Abstract

In the United States, motor vehicle crashes account for approximately 21.8% of unintentionaldeaths, and 17.2% of these crashes involved the death of a pedestrian in 2020. Two preventable factors that impact pedestrian fatalities are alcohol intoxication and smartphone distraction. Approximately 30% of fatal pedestrian crashes involve a pedestrian with a BAC of at least 0.08, and distraction is a commonly observed risk factor that was shown to impair crossing performance in virtual environments. The present research considers both distraction and intoxication as risk factors for pedestrian safety, examining both risk factors in isolation as well as their interactional effects on pedestrian safety. Thirty-nine adult participants were recruited. They completed two visits to cross a virtual street either after drinking alcohol to produce a BAC of 0.08 or after drinking a placebo, in randomized order. During each visit, they crossed the street both while texting and without distraction, also in randomized order. The number of unsafe crossings (crashes plus close calls within 1 sec of a crash) reflected pedestrian risk. There are five other pedestrian safety outcome measures including Time to Contact with Oncoming Vehicle (TTC), Start Gap, Distance to Oncoming Vehicle as Crossing Starts, Wait Time, and Missed Opportunities. Results showed that intoxicated participants were more likely to get hit. Distracted participants were more likely to wait longer and miss safe crossing opportunities, and get closer to oncoming vehicles, increasing their possibility of getting hit. Interactional effect of intoxication and distraction was significant for the number of unsafe crossings and TTC. Intoxicated pedestrians experienced more unsafe crossings than sober pedestrians only when they were not distracted; distraction only increased the number of unsafe crossings among sober pedestrians. As for their interactional effect on TTC, intoxicated pedestrians crossed closer to oncoming vehicles than those who were sober only among the undistracted. Distracted pedestrians universally had risky time to contact scores. This study informed intervention. Scientists and policymakers should establish a science-driven BAC threshold for safe pedestrian behavior that could be legislated and enforced. Alternatively, app-based interventions could incorporate features to both monitor BAC levels and reduce cellphone-induced distraction.

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