Most tornado injuries and casualties are not actually caused by the high wind speeds, but rather by flying debris that the storm picks up and hurls through the air at incredibly high speeds. As the touchdown of a funnel cloud can cause massive devastation and damage in only a few minutes, being able to quickly and safely access a shelter is of paramount importance to residents who live in the path of these severe storms.
In this week’s “TechKnow,” contributor and mechanical engineer Shini Somara explores new technology that could help determine what kind of shelters are built in the future.
Underground shelters versus aboveground shelters and safe rooms
The National Oceanic and Atmospheric Administration (NOAA) states that “being completely underground is the best place to be in a tornado.” Underground shelters fulfill NOAA’s two most important requirements to staying safe in a tornado: being as low to the ground and putting as many barriers between yourself and the outdoors as possible. For this reason, underground shelters and basements remain the number one option when seeking shelter in a severe storm or tornado.
Recently, some experts have been touting aboveground shelters, or safe rooms, as an equally safe (and in most cases, less expensive and more accessible) alternative to underground shelters. These shelters are built using the observed principles that small, interior rooms like bathrooms and closets are sometimes the only parts of a structure that remain standing after a tornado. Reinforced walls protect inhabitants from flying debris, and the shelters can be anchored into the foundation of the house.
One major benefit of in-home aboveground shelters or safe rooms is preventing residents from having to go outside (and risk being hit by debris) to seek refuge in an underground shelter. Other underground shelter risks include flooding and inhabitants becoming trapped underground by debris.
In the wake of the EF-5 tornado that hit Moore, Okla., in May of 2013, researchers found that all 16 aboveground shelters or safe rooms that were in the path of the storm survived, and in most cases were the only part of the structure to remain standing.
Schools as shelters
The devastating May 2013 tornado in Moore, Okla., destroyed or severely damaged three schools in its path, none of which featured tornado shelters or safe rooms. In fact, despite the state’s location in the middle of “Tornado Alley,” more than 60 percent of Oklahoma’s public schools have no shelter, and of the ones that do, less than half are built to withstand 250 mph winds.
The controversy over building shelters in Tornado Alley schools is not whether they are necessary, but rather debate over the cost of how stronger shelters should be built.
"Unless there is a basement (in which case a shelter is not necessary), it is probably impractical for to build a school that is safe in 300 mph gusts,” says Mike Smith, Senior Vice President and Chief Innovation Executive of AccuWeather Enterprise Solutions, using the old Fujita scale to estimate wind speeds. “I would build them up to F-3 (162 to 209 mph), which should be adequate since the mathematical odds of F-5 winds hitting a school are very low.”
Engineer and meteorologist Tim Marshall estimates that it will costs schools about $1 million each to install a safe shelter for students and faculty. Marshall also believes that shelters both above and below-ground will be equally effective at keeping students safe.
For now, cost and insurance concerns mean that most schools’ best option is to have primary and backup plans in place to get students and faculty to the safest possible area in the least amount of time. Non-profit funds are raising money to build some shelters, but it will likely take a bond issue or constitutional amendment to get the funds necessary to make sure every student is safe in the case of a dangerous tornado.
“Taxpayers have to make a hard decision about their children's safety,” says Marshall, who has visited Moore, Okla. three times in the past two decades to survey tornado damage. "It's pretty expensive for a school to have a $1 million shelter. It's up to the citizens to approve a referendum for this because it will increase taxes to fund this."
Read more: “Experts: ‘School Tornado Safe Rooms Costly but Worth Expense’” -AccuWeather
Watch "TechKnow," Sunday 7:30ET/4:30PT, to learn more about innovative tornado safety tech.