Behavior of Vehicles during Tornado Winds

Abstract

The degree to which motor vehicles offer protection to occupants from tornado winds and associated debris was examined. The goal is to improve tornado safety recommendations for those in isolated mobile homes and in vehicles when a tornado approaches. Field surveys were made after tornadoes in northern Georgia (March 1994), Middlefield, OH (May 1995), Louisville, KY (May 1996), Arkansas (March 1997), and Texas (May 1997). A sample of 180 vehicles parked outdoors adjacent to a home and exposed to tornado winds were examined from these five events to determine the behavior of the vehicles in relation to estimated wind speed. Wind speeds on the vehicles were estimated by the adjacent building damage and the Fujita scale. About 35% of the vehicles were moved by the wind but there was no difference in percent of vehicles moved among F1 (73–112 mph), F2 (113–157 mph), and F3 (158–206 mph) wind speeds. There was a significant difference in the percentage of vehicles tipped by the winds between vehicles at sites with F1 or F2 damage (4% tipped) and sites with F3 damage (15% tipped). There was also a significant difference in the probability of potential vehicle occupants being seriously injured between vehicles at sites with F1 or F2 damage (16%) and sites with F3 damage (39%). Most vehicles parked outside houses with damage as high as F3 were not moved by the wind and were not tipped by the wind.