Deadly Rainfall: Flood Fatalities and Rain-related Fatal Crashes




Han, Zhongyu

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Floods cause numerous amounts of fatalities every year in the contiguous United States, especially in Texas. Vehicle-related flood fatalities account for high proportion in general flood fatalities. Rian is an important factor affecting fatal crashes. The purpose of this study was to identify the factors affecting flood fatalities, vehicle-related flood fatalities, and fatal crashes. Data were compiled from the storm data, which is maintained by the National Climatic Data Center (NCDC), and the Fatality Analysis Reporting System (FARS) database that maintained by the National Highway Traffic Safety Administration (NHTSA), respectively. Normalization had been conducted in several places when processing data with the data of population and vehicle miles traveled to comparing death rates or rain-related fatal crash rate between different states, different age groups, or different months. For the section of flood fatalities in the contiguous United States from 1959 to 2019, the analysis revealed Texas has significantly more flood fatalities than other states. Comparing to the other flood types, flash floods caused the most fatalities. Male victims overrepresented the female and most of flood fatalities were vehicle-related. For the section of vehicle-related flood fatalities in Texas from 1959 to 2019, similar data has been analyzed and similar results have been found. Besides, May was the month that had the most vehicle-related flood deaths and the occurrence place of most vehicle-related deaths were classified into the category of on the road. Eighty percent of vehicle-related flood fatalities occurred in the area of Flash Flood Alley in Texas. Referring to the rain-related fatal crashes in Texas from 1994 to 2019, relative risk analysis was performed to statistically quantify the impact of rainy conditions at the hourly and monthly time scales. Rain-related fatal crashes account for 6.8% of the total fatal crashes on average. However, the proportion show higher fluctuation at the annual, monthly, and hourly time scales and the age and gender of the driver, type of the road, and posted roadway speed limit are factors that can affect the proportions. After normalization by the total number of licensed drivers or vehicle mile travelled, all and rain-related crashes show statistically significant decreasing trends. The relative risk of a fatal crash during rainy conditions was always greater than 1.0 at hourly, monthly, and annual time scales. However, it shows significant variability at the monthly (1.07 to 2.78) and hourly scales (1.35 to 2.57). Young male drivers are most likely to be involved in a fatal crash but less to be killed in the crash.


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fatal crashes, flood fatalities, rain, vehicle



Civil and Environmental Engineering