Moore, Oklahoma pretty much wiped off the map

[chitoryu12]

No mystery here, emergency prep is fucking expensive. Especially if you're talking about designing buildings from the ground up to withstand crises (earthquake, firestorm, flood, hurricane, tornado) they may never encounter. Anyone who wants to spend on this sort of safety gets ridiculed for wasting tons of money, especially while the economy's still crap, and then when something happens the same people who wouldn't or couldn't shell out demand to know how this could happen and find a scapegoat.

Happened in Florida, in New Orleans, in New York. Same old story, getting older fast.

Florida is all over the map when it comes to hurricane prep. My house was built in the late 70s, first one in the first neighborhood in the area. It's pretty much all cinderblock, and you'd need a truck to breach it. The main vulnerability (other than windows, which you just board up) is that the Florida room (for those uninitiated, a sort of den with large windows to give a good view of the outside while staying inside) is actually built slightly lower than ground level. So when the rains hit, it floods. We have a sump pump specifically to keep the backyard drained, but it can easily get clogged with weeds. Thankfully it's only flooded once in the history of the house, back in the 2004 spree of hurricanes. We prevented it later by hanging a gigantic tarp from the roof that stretched over the yard to catch the water. It was a cartoon solution, but it worked.

The biggest danger here is the tree cover. Florida has a ton of trees, and big ones. A lot of the older neighborhoods kept most of the forest when they started developing, back before the McMansion craze, so my own front yard has three huge trees with thick trunks. There's another one in the backyard, though it's bending into the NEIGHBOR'S yard. Either way, they can do serious damage if they fall. I'm talking "Our house has been bisected" or "Your car is no longer a car" damage.

[Sky Captain]

Having a school or any public building in a tornado prone area without shelter sounds like something you would expect from third world country with nonexistent building standards.
Given overall cost of a new building having a burried or partially burried room with thick reinforced concrete walls and heavy steel door would increase overall cost by few percent at most.

[phongn]

Instead of going on about anecdotes, can you tell me the overpressure of an EF5? That would let me figure out the actual protective cost in about ten minutes.

It doesn't exactly align with air overpressure from a nuclear blast; the sheer force of an EF5 can literally dig out and destroy a house's foundation (and anything above it) - and the EF scale is also somewhat subjective. It's a description of damage produced, not strictly wind force.

The NRC's Regulatory Guide 1.76: Design-Basis Tornado and Tornado Missiles for Nuclear Power Plants indicates a 230mph tornado should produce an underpressure of 1.2 psi at a rate of 0.5 psi/sec. The older AEC RG 1.76 had design bases up to a 360mph with a 3 psi underpressure at 2 psi/sec.

Having a school or any public building in a tornado prone area without shelter sounds like something you would expect from third world country with nonexistent building standards. Given overall cost of a new building having a burried or partially burried room with thick reinforced concrete walls and heavy steel door would increase overall cost by few percent at most.

Oklahoma is a poorer state that also likes low taxes, it has hard soil making it expensive to dig and reinforced facilities that can withstand an EF5 are expensive

[Meest]

The NRC's Regulatory Guide 1.76: Design-Basis Tornado and Tornado Missiles for Nuclear Power Plants indicates a 230mph tornado should produce an underpressure of 1.2 psi at a rate of 0.5 psi/sec. The older AEC RG 1.76 had design bases up to a 360mph with a 3 psi underpressure at 2 psi/sec.

That's what confused me about reports of the elementary kids moved to the hallway and told to hug the wall, would think tons of debris would be flying through. The hallway is the inner most area of the school? Sort of like it's advised not to stay under a bridge or overpass you can literally get sucked out.

[Simon_Jester]

A generic school typically has a series of classrooms (with windows) hanging off of one or more hallways, so yes, the hallway is going to be the innermost covered space. Especially in an elementary school, which tends to be smaller than middle or high schools and probably only has one hallway worth of classrooms.

Tornado drill for such a school might well not be realistically designed to survive an EF4 or EF5 tornado, it might be aimed at the more frequent but less destructive tornados that are more likely to destroy the roof but leave enough of the building standing that being 'covered' in the central hallway from any flying debris generated by the classrooms is enough.

[Broomstick]

Basically, if you want to survive an EF4 or EF5 tornado you want to be either underground in a genuine shelter with a roof or in a genuine "safe room" properly anchored to the ground (although no above ground shelter is considered adequate in an EF5, because the potential exists for it to be ripped out of the ground and turned into a projectile or to be smashed by a falling house or other major debris) . Simply dashing to the basement is no guarantee - those tornados can lift an entire building off its foundation and vacuum out the basement. For an EF5 an Anderson shelter, which is only 2/3 buried in the ground, would not be considered adequate. That sort of tornado could easily uncover it and suck it out of the ground. Don't get me wrong, it's better than being bare-assed to the wind, but there's a reason that Midwesterners of former eras went to the trouble of digging a pit with hand tools that was wholly underground. And, as shown in Moore, even if you have a basement there can still be hazards - just to clarify, reports are now that the school had a basement and it flooded, killing people sheltering there. Part of the problem is that tornadoes of that magnitude come from storms with torrential rains that can cause flooding, and power failures that shut down the pumps that keep basements dry.

Which is not say it's certain death if you're just in an ordinary basement, people have survived these with inadequate shelter, but you need a hefty dose of luck and you can get very badly hurt. I seen some pictures of some pretty bizarre impalements resulting from tornadoes.

The whole building code thing is funny. When most of the Midwest was built the codes only considered the lower level tornadoes, which are much more common than the big monsters, when they considered them at all. Private residences weren't required to have them at all. Growing up in the Midwest, you're taught from an early age the basics: what a tornado looks/sounds like, how to know when one is coming, if caught in the open get out of your vehicle and get to a low spot, if in a building get away from glass, windows, and get as deep into the interior of the structure as possible if there isn't a dedicated shelter or basement. Yet so many places were built in the 1950's-1980's without consideration of these phenomena.

Starting in the late 1970's/80's codes started to change. Mobile home parks, for example, are now required to have actual storm shelters adequate for all residents which is why fatalities have dropped for those places even through trailers still get destroyed. Big box stores typically build their public toilets to double as storm shelters. There's more and more awareness that private homes need shelters, with new construction sometimes incorporating it and more and more retrofit options being available.

However, it's cost-prohibitive to retrofit everything in a short time frame. As horrific as the damage can be, it is also very localized. There are places in tornado alley that, as far as our records go back, have never suffered even a small tornado. Of course, that can change with the next thunderstorm

[Zaune]

Oklahoma is a poorer state that also likes low taxes, it has hard soil making it expensive to dig and reinforced facilities that can withstand an EF5 are expensive

How much would it have cost to dig out a bunch of slit trenches, minimum wage for an afternoon x two dozen local farmhands with nothing better to do? Even that much might have saved some lives in the event of a near-miss.

[Simon_Jester]

Slit trenches outside the building would be worse than useless, because they would require little children to run out of the hallway and basement (which are relatively safe) into the open air in the midst of howling storm winds. "In the event of a near miss," the children's shelter positions would in all likelihood have been good enough.

Slit trenches inside the building would be of little use too- you need something with overhead cover and reinforced construction, anchored so firmly to the ground that the tornado can't rip it up bodily. If you have that strong a shelter, you have no need of the trenches- but building a mini-bunker like that to house a few hundred children is NOT easy.

[Flagg]

And OK Senaturd Tom Colburn is saying he wants offsets for disaster relief. What a bastard.

[energiewende]

Having a school or any public building in a tornado prone area without shelter sounds like something you would expect from third world country with nonexistent building standards.
Given overall cost of a new building having a burried or partially burried room with thick reinforced concrete walls and heavy steel door would increase overall cost by few percent at most.

There's a point at which these things are just bad luck. There are potentially millions of buildings that could be hit by hurricanes but reinforcing them all is only likely to save a handful of lives per year. The money would be better spent on other forms of relief.

[Simon_Jester]

And OK Senaturd Tom Colburn is saying he wants offsets for disaster relief. What a bastard.

This is the same guy who wanted to limit relief funding after Hurricane Sandy, right?

[Flagg]

And OK Senaturd Tom Colburn is saying he wants offsets for disaster relief. What a bastard.

This is the same guy who wanted to limit relief funding after Hurricane Sandy, right?

Yeap. So not a hypocrite, just a soulless cunt.

[Simon_Jester]

Saw a fun newspaper comment:

"The offsets should come out of Oklahoma state highway funds. The federal government shouldn't be willing to pay twice for what Oklahoma won't pay for once."

[RogueIce]

Having a school or any public building in a tornado prone area without shelter sounds like something you would expect from third world country with nonexistent building standards.
Given overall cost of a new building having a burried or partially burried room with thick reinforced concrete walls and heavy steel door would increase overall cost by few percent at most.

Seven of the children drowned though this article doesn't say where they were. This school was also built in 1966 so may well have predated newer building codes. Who knows if they ever had the money to retrofit.

And from the latest reports I've seen it looks like they've upgraded it to an EF5. As others have said in this thread, surviving (or not surviving) an EF5 is a matter of luck, especially with a direct hit as apparently happened to this school.

[Broomstick]

The news tonight stated that Oklahoma has been using a lottery system to pick homes to upgrade with storm shelters. 500 homes a year are retrofitted. Last year, 16,000 people applied to the program.

Average cost for an interior storm shelter i.e. "safe room" is $6,000-10,000 per shelter. It's cheapest to add it to new construction, retrofitting is more expensive.

Current building codes require safe rooms for school, but retrofitting older schools, like Plaza Towers, is proceeding slowly due to lack of funds. It costs approximately $1.4 million per school to build such shelters.

Do remember an EF5 is a rare event (even though Moore has gotten 2 in the past 14 years). I'd call it a Black Swan but they are foreseeable in that we know hundreds of tornadoes will strike the US every year, but there's no way to know exactly when or where.

An EF5 tornado is analogous to a 9.0 earthquake - there are limits to what our technology can do to mitigate the danger.

[Broomstick]

OK, I officially lost it watching the news tonight:

Little girl, something like 6 or 8, clinging to her mother and sobbing piteously about wanting to get the blood out of her hair, the blood that came from her friend who was lying on top of her in the debris pile, injured from the tornado and building collapse.

Little kids shouldn't have to go through that.

Yeah, yeah, she'll probably be OK in the long run, but.... {{{shudder}}}}... I'd be freaking out, too, if that happened to me.

[PhilosopherOfSorts]

Having a school or any public building in a tornado prone area without shelter sounds like something you would expect from third world country with nonexistent building standards.
Given overall cost of a new building having a burried or partially burried room with thick reinforced concrete walls and heavy steel door would increase overall cost by few percent at most.

As has been said, tornadoes of this magnitude are rare. That school may have stood up just fine to an F3, but an F5 is basically Mother Nature saying "I hate everything along this path, and want it all gone."

[Broomstick]

Given overall cost of a new building having a burried or partially burried room with thick reinforced concrete walls and heavy steel door would increase overall cost by few percent at most.

A few points:

1) A partially buried room is inadequate for an EF5. For that the shelter needs to be entirely underground. And even that might not be enough, see point #3.
2) 7 deaths occurred in a basement located shelter that flooded. It wasn't the tornado that killed them, it was water. Sometimes you get whammed with multiple instances of bad luck.
3) There was at least one instance of a fully underground, proper tornado shelter having its door entirely ripped off during this storm, leaving those inside to attempt to cram themselves into the far corner while trying to shield themselves from debris propelled into the shelter at better than 300 kph. Fortunately, no major injuries but the guy they interviewed who had been in the shelter looked like he'd been in a fight of some sort, they all got battered to one degree or another.

Bottom line, there are limits to how safe you can be in this situation.

[Sea Skimmer]

It is nonsenical that a shelter must be underground to survive an EF5. Seriously, we can make stuff above ground to withstand an atomic blast with 500-700mph blast wind, and the wind is only coming after the supersonic shockwave hits. I'm sure though that above a certain point its just always going to be cheaper to go underground, or mound over with shotcreted and wired earth.

[Napoleon the Clown]

The thing you need to remember about an EF5 is that it has sustained windspeeds in the hundred plus mile per hour range and it will be battering you with shit constantly. Getting slapped by a gust of wind is all well and good, but when you can have wind that's faster than your car going for several minutes straight shit gets crazy. You can easily find videos of houses being lifted off the ground before completely coming apart. Think of it as being like getting hit by something going at a decent clip versus something else going slower but continuously instead of instantaneously. About the only thing that can stand up to an EF5 is going to be a skyscraper or a nuclear plant's containment dome. And the skyscraper is going to potentially take a really nasty beating. See my previous link about the one that got twisted by a direct hit.

[madd0ct0r]

Skimmer, I think the underground rule of thumb is to reduce the chance of something like a lorry being thrown into the side of it.
Depending on the soil around it, havine a protrusion in prolonged wind (much much longer duration then the single nuke blast) might cause some really nasty scour pit effects around the structure, basically scouring out the foundation until the entire thing goes down.

Being built into a gently sloping concrete hill would reduce that risk, but take a lot more area up. Going down is probably cheaper.

[Broomstick]

It is nonsenical that a shelter must be underground to survive an EF5. Seriously, we can make stuff above ground to withstand an atomic blast with 500-700mph blast wind, and the wind is only coming after the supersonic shockwave hits. I'm sure though that above a certain point its just always going to be cheaper to go underground, or mound over with shotcreted and wired earth.

OK... the problem is not just "will this object survive being lifted several hundred meters into the air and dropped" but will the people inside survive that treatment? The reason for putting it underground is to keep it from becoming airborne. Nor is it just the wind - in an EF5 you have entire buildings lifted into the air and striking other buildings.

Yes, we can construct bunkers such as you describe but they are cost prohibitive to put in every house and public building. Not to mention how much interior space they would have to take up just to have sufficient mass and anchorage to stay put.

Yes, there are above-ground safe rooms, but they aren't considered as safe as an underground shelter.

[Sky Captain]

Why would there any difference between bomb shelter and tornado shelter? A nuclear blast wind will do exactly the same thing as F5 tornado, demolish entire buildings, throw multi ton objects into the air and hurl tons of smaller pieces of junk. A bomb shelter also have to deal not only with overpressure, but also with heavy stuff falling on it or it will be inadequate. If it is partially above ground it has to be firmly anchored or blast wind will rip it off the foundation and throw into air just like a tornado would do.

[madd0ct0r]

Duration. A bomb blast is intense but short lived. A tornado lasts for an order of magnitude or more longer.

this gives it time to 'dig out' structures. I believe someone earlier in the thread mentioned an EF5 can strip asphalt...

This is a rough example of what a small water current can do.
The mass of the air is much less, but the speed is much much greater so the kinetic energy available for scouring could actually be higher. I've found plenty of images where tornados have stripped the topsoil off, but none specifically looking at wind driven scour pit effects. It might be they're negligible, or possibly just filled in again with debris as the twister passes.

[Sea Skimmer]

OK... the problem is not just "will this object survive being lifted several hundred meters into the air and dropped" but will the people inside survive that treatment? The reason for putting it underground is to keep it from becoming airborne. Nor is it just the wind - in an EF5 you have entire buildings lifted into the air and striking other buildings.

You think I am not aware of what a tornado can do? Sorry big difference between this will cost money, and claiming above ground is impossible as you did. I'm not talking about a bunker either.

Skimmer, I think the underground rule of thumb is to reduce the chance of something like a lorry being thrown into the side of it.

The structure I had in mind originally could and in tests did withstand another structure of the same type being internally exploded by nine thousand pounds of aircraft bombs and propelled into it at supersonic speed. At a range of about one meter.

Depending on the soil around it, havine a protrusion in prolonged wind (much much longer duration then the single nuke blast) might cause some really nasty scour pit effects around the structure, basically scouring out the foundation until the entire thing goes down.

Yeah you know I've finding very little evidence of deep scour, and yet I already found a reference to a 1999 above ground shelter that did withstand a EF5 directly without even being designed for it, and inspired new standards for such shelters to withstand such hits. Numerous means exist to stop scour anyway. Sure it has to withstand a few minutes, but its not like what say, hours of flooding could do.

Being built into a gently sloping concrete hill would reduce that risk, but take a lot more area up. Going down is probably cheaper.

Probably. But I do assure you that if if you built a hill out of concrete you will withstanding absolutely fucking anything including railroad cars being thrown at it. If money were no issue like that then the USAF found you could build a structure which could in principle survive partly falling into a nuclear crater.