Relative crash risk and road safety during rainfall in Texas from 2006 to 2021

This study examines the relationship between precipitation and crashes on Texas roadways, spanning from 2006 to 2021. Employing a matched pair methodology, the research offers insights into the multifaceted impact of precipitation on crash likelihood, leveraging extensive crash data and gridded hourly precipitation records. The findings reveal that precipitation significantly increases crash risk, with an annual minimum rise of 32% and an average increase of 38%. Interestingly, rainy conditions are associated with reduced crash severity compared to dry weather. Although the relative risk is higher for all crash types during rainy conditions, the relative risk for no-injury crashes is 40% higher compared to fatal crashes (< 1% of all crashes). Spatial analysis highlights a correlation between population density and crash frequency. Moreover, the study investigates the interplay among roadway types, weather conditions, and driver behavior. Precipitation intensity was associated with a 36-52% increase in crash risk, with higher increases for more intense rainfall (over 25 mm/hr). The relative risk varied by age group. The highest risk was observed in young adults (18-30 years old) and the lowest in individuals older than 65. Generally, females exhibited a risk that was 7-13% lower than their male counterpart, depending on the age group. Temporal factors-including time of day, day of the week, and month of the year-significantly impact road safety during precipitation, with early morning hours posing the highest crash risk due to rush hour traffic and changing lighting conditions. This comprehensive study enhances our understanding of road safety dynamics, providing foundational insights to inform policy development for safer and more sustainable transportation systems. Addressing human factors, alongside advancements in vehicle safety technology and road design, holds promise for reducing crash severity and improving overall road safety outcomes.