This myth began in the early 1990s after a TV crew sought shelter under an overpass and survived. The video was shown repeatedly all over the nation. By 1999, climbing under overpasses was so common that the extra cars became a traffic hazard, sometimes closing the highway. In a group of 17 people huddling under an Interstate 35 overpass in central Oklahoma in May 1999, all but one was blown out of the overpass by a tornado. One was killed.
Overpasses act as wind tunnels.
Climbing up the slope puts a person higher than when the person was at road level. Most newer overpasses don't even have a slope, but have a perpendicular concrete wall. The best thing to do if you are in a car when a tornado approaches is to get out of it and into a sturdy building. If you can't get to a building, get out of the car and lie down in a ditch, Krause said. Not easy to do, he admits.