The Federal Emergency Management Agency (FEMA) is trying to get the word out that highway bridges are never safe during tornados.
There is a widespread belief that overpasses offer some safety. Overpasses look like a protective space, but they are the farthest thing from it.
People think they can crawl in a space at the very top of the embankment, underneath the road above. There is very little room there and often no ledge at all, leaving people in an unsteady position at the top.
In fact, it isn't obvious at first sight, but overpasses have no ledges and no hand holds. There are no girders or beams, just smooth concrete.
Once in this precarious position, people are actually in the worst possible situation: They are trapped in an elevated space where winds will be stronger than on the ground. Overpasses become wind funnels, channeling violent, shifting winds exactly to the location of the so-called shelter.
Instead of being sheltered, they are actually bombarded by winds carrying debris so vicious that it can reduce a large tree to toothpicks.
Compounding the problem is that people stop their cars on the road, blocking traffic and endangering every other driver. In the worst recorded tornados, cars under a bridge completely blocked the road, leaving hundreds of drivers with no way to escape.
So what should drivers do?
Don't drive in violent weather.
Find any stable building and stay there. Even in the most violent tornados, people who stay inside are always safest, according to FEMA.
If you are on the road, and can observe the direction of a tornado, you can drive at right angles to it. This advice has been removed from the National Weather Service guidelines, but it is better than sheltering in an overpass.
If your life is in extreme and immediate danger, and only as a last resort, get out of the car and lay flat in a ditch. The winds will be weakest on the ground. Cover your head. Don't stay in the car.