Highway Overpass a Safe During a Tornado?

highway overpass during a tornadoOne myth that could potentially cost someone their life is the belief that a highway overpass provides safe shelter from tornadoes. This is a myth for reasons which may not be immediately obvious to some, and probably started when a video clip aired nationally that showed a family and a news crew running up and hiding beneath an overpass to shelter themselves from an oncoming tornado. This is not what you want to do and could prove fatal.

Millions of people all across the country saw the below video and figured this was the safest thing to do. Since then, many people have been killed by doing exactly what they saw on TV. It goes against common sense, because you’d think the concrete and the overall strength of the overpass would offer good protection. Not to mention, you can in most overpasses crawl way up into the rafters which may appear to offer even more protection. This isn’t the case.

Since the video to the left aired on television, the National Weather Service as well as meteorologists all across the country have been trying to educate people that this is not where you should seek shelter. The people who did survive that event were lucky as the tornado was relatively weak and didn’t land a direct hit on the overpass. An overpass is a very dangerous place to hide and there are several reasons for this. The first being, an overpass will channel fast moving debris that will pelt and batter anything that happens to be in the air flow.

Crawling way up into the rafters won’t protect you as the debris will ricochet and most undoubtedly hit you. If the wind alone doesn’t suck you out, a piece of debris will most likely knock you out. You cannot avoid the debris.

Second, as the tornado first approaches the winds will come from one direction, but as the tornado passes, the winds will make an almost 180° turn and start blowing from the opposite direction. The same principal applies to a hurricane as the eye crosses overhead. So, any person who puts a barrier between themselves and the oncoming winds under a highway overpass, such as a girder or support beam, will only be fully exposed once the tornado crosses the overpass. This crossover will happen much too quickly for the person to rearrange themselves into a safer position.

Third, although this hasn’t been proven scientifically (as of 01/17/2005), the wind from a tornado which passes through the highway overpass could possibly increase because as the wind is being squeezed through a narrower space. Think about blowing out candles on a birthday cake. You narrow your lips and blow to increase the speed of the breath coming out of your mouth. If you didn’t so this, the breath coming out of your mouth would move much slower because the opening of your mouth is larger. A good majority of the scientific community believes the same principal may be true of a tornado crossing an overpass, although no scientific data has been gathered as of this writing.

Fourth, the higher above ground level you are, the faster the wind speed. Most overpasses ramp up at an angle to meet the road above. As you climb higher above ground, the winds will only get faster. It has been proven that wind speeds closest to the ground are much slower than even just a few feet above ground.

So what should you do if there’s a tornado heading your way? The best thing to do is not put yourself in that situation. If you see a nasty looking funnel cloud ahead, pull over and wait. In all likelihood, if you proceed you’re going to run into some large hail that will undoubtedly damage your car. If you see a tornado in the distance, turn around and drive the other way. But if you’re out in the open and the tornado is fast approaching heading right for you, the first thing you want to do is get out of your car. That’s right! Run away from your vehicle and get as low to the ground as you possibly can. In a ditch, no matter how shallow, is best. The reason being, the winds closer to the ground are considerably slower! If you’re even just a few feet above ground level, the winds speeds will be ferocious. Even though a highway overpass is made of concrete, it is not a safe place to be during a tornado.

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