Many of us lucky enough not to live in areas which are frequently susceptible to tornadoes can only look on as we see images on the television. The so-called “Tornado Alley” in the Midwest and to a lesser extent the South-East of the USA are regularly hit by tornadoes which can literally rip properties from the ground and throw them around like a rag doll. Thankfully, we have seen great strides in the design and development of tornado shelters which quite literally save lives during these terrible storms.
There are many different aspects which come into consideration when looking to design and install a Tornado shelter.
Terrain
In a perfect world all tornado shelters would be underground well clear of houses but unfortunately due to rocky soil conditions and high water tables this is not always possible. While many properties in the USA do have basements you will notice that they are not as widespread as many people might think. Therefore, we have seen the introduction of an array of different tornado shelters to take into account different terrains and different preferences. However, whatever the terrain, and wherever the location, a tornado shelter should always be anchored either to the property’s foundations or something of a similar strength. The shelter is all good and well but we are taking of extreme winds which can literally rip up everything before them which is not tied down!
Underground shelter
The average tornado shelter has a floor space of 8’ x 12’ (2.5 m x 3.5 m) although the actual designs can vary widely – the Federal Emergency Management Agency (FEMA) recommends 6 ft.² of floor space per person for a tornado shelter. In many cases the typical underground tornado shelter is like that which features in movies such as the Wizard of Oz. The shelter is made from reinforced steel or concrete and these prebuilt structures are often installed underneath garages or in yards. There may be occasions where underground shelters are not accessible as it may be dangerous to leave the house when the winds are upon you. This is where tornado alerts come into play allowing people to stock up and pack up before the winds actually hit.
Safe room design
As the development of tornado shelters continues, many properties built in areas susceptible to high winds and tornadoes are now being constructed with prebuilt “safe rooms”. In many ways the safe rooms are similar to a fortified bank safe and again they are constructed using reinforced material such as concrete, wood and steel. As with any tornado shelter the structure needs to be safely anchored to the foundations of the property as they are in effect self-contained rooms. In the normal course of life they can double up as closets, storage rooms, etc but when the tornadoes come it is time to enter the safe room, triple lock the door and sit out the storm.
Prebuilt shelters
Many people looking to protect themselves from tornadoes and high winds will acquire prebuilt shelters which they can install within the property. As you might expect, it is highly advisable that the prebuilt shelter should be installed on the first floor of any property and safely anchored to the foundations of the house. Obviously there is no point having a tornado shelter on the second floor as during extreme winds it is common to see parts of properties flying down the street leaving the ground floor exposed. The structures come in an array of different styles but they tend to be made of steel panels which are bolted together to give an extremely secure environment.
Testing tornado shelters
The National Wind Institute at Texas Tech University in Lubbock is responsible for the vast majority of testing in relation to tornado shelters and similar structures. It may seem rather bizarre, but the Institute is able to create winds of up to 250 mph which simulate a tornado vortex. They also have what they describe as a modified “potato gun” which fires two by fours weighing fifteen pounds at speeds up to 100 mph. These may seem extreme tests but when you bear in mind they do actually mimic the winds and the battering that tornado shelters will receive in a full blown storm, this puts everything into perspective.
Basic advice about a tornado shelter
While many people may automatically assume that their basement is a safe place to hide in the event of a tornado, this is not necessarily the case. Due to the fact that at least one wall of the basement will be exposed to the elements this could blast open during a tornado. Indeed it is a common occurrence that when houses are ripped apart and lifted off the ground by tornadoes, the ceilings of previously thought safe basements are also exposed and destroyed. This is why the prebuilt structures are perfect, they create a tight and very strong box area, can be placed at angles under the ground with differently positioned stairways and once firmly anchored to foundations or similar support they will be going nowhere.
FEMA advises that all tornado shelters should contain a flashlight, first-aid kit, emergency radio, batteries, basic tools, blankets, water and dry food. Modern day tornado shelters are also fitted with GPS tracker systems so that in the event of a tornado which blocks direct exit from the shelter, the structure can be pre-registered with the emergency services and the occupants tracked and rescued at some point.
