Structural Collapse - Stage Falls over at Indiana State Fair

[Broomstick]

The background:

The Indiana State Fair is an annual event going back over 150+ years, intended to promote agricultural in a state where agriculture is still one of the major industries. Lots of other things have also been tacked on, such as a midway, rides, and musical entertainment. For the latter, a stage is constructed every year on which to hold concerts, with all the elaborate lighting and sound equipment modern audiences have come to expect.

Last night, the Indianapolis area (where the fair is usually held) experienced a rapidly on-coming storm. A feature of such storms is something called the "gust front", where air ahead of the body of the storm can rapidly change direction and speed, sometimes visible as a cloud of dust and small debris kicked up by moving air. Last night, the gust front is estimated to have hit 60-70 mph or 96-112 kph. Yes, those are very strong winds. However, the region is known for strong winds, and indeed such gusts are records several times a year in an ordinary year throughout the state. In fact, this year my neighborhood recorded a wind gust of 160 kph associated with a storm. That wasn't associated with a tornado or hurricane, that was a "straight line gust" in a thunderstorm. Certainly, permanent structures in Indiana must be built to accommodate such a battering, one would think even temporary structures would be built to take the more common 100 kph wind speeds into account.

Here's what happened when the gust front hit the stage:

Events happen fast, so you may need to stop the video to see the details, but at 00:09 seconds you can see a rolling dust cloud just to the left of the stage. That's the gust front. 3 seconds later, at 00:12, the stage is down on the ground. 2 seconds later, at 00:14, you see the first of the fleeing crowd turn back, on the right of the view, to assist those trapped beneath the structure. You then see people pouring out of the seats towards the structure.

Here is a link to another video, which is fronted by a commercial (apologies for the inconvenience). It starts a little slow, but at 00:15 they switch to a video where you can see the crowd attempting to assist the trapped and injured, and self organizing to attempt to lift the steel structures with human muscle power, as well as some people in the foreground giving first aid and comfort to the injured.

As of this morning, there are 5 dead and 40+ injured from this accident.

Why is this here instead of in News and Politics? Well, because this has as much to do with the science of engineering and the morality of building engineering and crowds as anything else. I know there are people on this forum with more engineering and building knowledge than I have, and I know it is possible to build structures that can withstand the forces involved. Of course, temporary structures are more likely to be insufficient, but one can still hope that stage construction for such event will improve in the future.

So...

1) What could have been done to secure this structure to withstand 112 kph winds? The internet buzz was that there was a lack of guy wires, but that really boils down to speculation as it's unlikely you'd be able to see wires in the video available if they existed. Do they help enough to make a difference, or are more solid supports required?

2) If that is impractical, are there ways to build them so they collapse more slowly, allowing people more time to escape? Clearly, some were able to run out of the path of the collapse even with so little time available. I don't think you'll be able to make things perfect enough that no one could even be killed or hurt in such a scenario, but every additional second people have is more chance for them to survive.

3) Authorities were on the verge of shutting down the night's events and evacuating everyone - that's one reason no performers were actually on the stage at the time, and if they hadn't been at that point in the decision tree there may well have been more people in harm's way. I'm sure there will be ample speculation about whether they dragged their feet on that matter, but the fact is weather is still an imprecise science. "Should they have shut things down sooner?" is an entirely reasonable question to ask, but at least one of the people killed was a man working in the lighting rigs up in the roof of the structure - even if they evacuate the crowd, such staff tend to be the last to leave such a site and may have been caught in this even if the public was already gone.

4) At this point, I know that people certainly attempted to move the collapsed structure by muscle power, but I don't know if they were successful or not. How likely is it for a crowd, even one somewhat organized one with hundreds of people available, to shift such a structure, which was made largely of steel?

5) Finally, after all the scenes and discussions of mob violence this past week, I found it heartwarming to see a "mob" of people spontaneously do the right thing - rush in to help in any way they could.

[Cecelia5578]

but at least one of the people killed was a man working in the lighting rigs up in the roof of the structure

Okay, correct me if I'm wrong about something obvious, but at the first signs of heavy wind, he probably shouldn't have been up there in the first place. Was it really that essential what he was doing?

[Broomstick]

The problem with the gust front phenomena is that, basically, the gust front IS the first sign of high wind. Of course, there was some wind already occurring but apparently (going off witness reports - I wasn't there myself) nothing that hadn't been happening all day. Up in the rigging, under the roof, the technician wouldn't have been able to see the advancing dust cloud which, as noted, was moving at somewhere 100 kph so even if he had seen it he would have had very little time to react.

The weather was deteriorating, and the crowd had been informed that a storm was incoming - that is one reason you see empty seating in the stands, some people had already decided to leave well in advance of the expected rain. However, the official forecast had the storm 30 minutes away from that location. As I said, weather forecasting is not an exact science. The crowd had been informed that, in the event of a sudden change in weather they should go to either the "Pepsi coliseum" (a permanent structure) or the "swine barn" (presumably better constructed than the stage, as it did not collapse and is built to house large farm animals. One performer had finished and, absent an official cancellation or delay, the tech would be up in the rigging getting ready for the next set of performers.

As an update - the Indianapolis media are saying everyone trapped under the structure was freed within 20 minutes so, presumably, the attempts by the crowd to lift some of the structure did succeed, although later heavier equipment did arrive at the scene. There was substantial damage to the seating not only from the collapse, but from the crowd commandeering seats to use as makeshift stretchers.

[starslayer]

1) What could have been done to secure this structure to withstand 112 kph winds? The internet buzz was that there was a lack of guy wires, but that really boils down to speculation as it's unlikely you'd be able to see wires in the video available if they existed. Do they help enough to make a difference, or are more solid supports required?

Yes, guywires do help quite a bit. This is why you stake down the rain fly of a tent, or your shade tarp, etc. when you go camping, especially if you expect high wind. If the stakes are buried deep enough, and the wire strong enough, it's very unlikely for it to snap or for the stakes to get pulled out of the ground, which is what is needed to collapse the structure/blow your tent away.

2) If that is impractical, are there ways to build them so they collapse more slowly, allowing people more time to escape? Clearly, some were able to run out of the path of the collapse even with so little time available. I don't think you'll be able to make things perfect enough that no one could even be killed or hurt in such a scenario, but every additional second people have is more chance for them to survive.

Not really, unfortunately. Gravity's a bitch. Once a structure like that is going down, it will basically be in freefall.

4) At this point, I know that people certainly attempted to move the collapsed structure by muscle power, but I don't know if they were successful or not. How likely is it for a crowd, even one somewhat organized one with hundreds of people available, to shift such a structure, which was made largely of steel?

Given that everyone was successfully removed from underneath the structure before the heavy equipment got there, I'd say that the crowd was certainly successful at least in this instance. If you look at the stage, it's built to be as light as possible while still being strong enough to hold up the canvas roof and lighting rigs. This is one reason why guywires are needed if there's going to be wind, since the building is rather tall and not very strong on its own, yet still needs to withstand a large wind load. If it had been a bunch of large steel plates or beams, I'm not sure if the crowd would have been as successful, but with light steel trusses, it's certainly possible to get those moved out of the way with a bunch of people handy.

[HMS Sophia]

Just spoke to my father. He's a structural engineer.

What could have been done to secure this structure to withstand 112 kph winds?

Yes you can... but its not really a thing to do for a temporary structure. You would end up with something huge and immobile, whereas with a stage you want something easily transportable or collapsible.
The simple thing is, you design for a set of circumstances. Sometimes things exceed those set limits, and stuff falls over. It's unfortunate but it happens.

If that is impractical, are there ways to build them so they collapse more slowly, allowing people more time to escape?

Yes, you could. This apparently isn't something that comes up much, but you could do it.
If you're using screens (as seem to appear in this) you use links that break at low winds, so that you get less wind force on the structure once those break away, so that they don't act like sails.
Detachable or breakable links links is the way to go, so that some things break away sooner than others. Bits fall off, but eventually the entire structure will go... probably. If you're just left with a bunch of steel poles, they probably wont fall, because the wind force on them is much less than on something with hanging stuff.

He says he is thankful that he hasn't one fall over yet as well.

[madd0ct0r]

As has been previously said: guylines to strong anchor bolts. It's what you need, and what they probably had.

On my limited experience designing scaffolding, temporary structures are still subject to the same load analysis, but a lower factor of safety is allowed. In the case of wind, the design load might have included a factor based on the structure's design life. Basically, the biggest storm you might get in 10yrs will be a good chunk bigger then the biggest storm you might expect to get in a single year. This is a probabilistic thing – you could get that 10yr storm in any particular year or even two or three years in a row (it's just reasonably unlikely).
So it could be this gust front was outside the range of anticipated wind loads for the time period the stage was expected to be up. Given what you've said about common weather that seems unlikely but still possible.

There's a thousand and one things that could have gone wrong with the structure – soft ground (leaking toilet), fatigue crack in anchor ring, falling debris over stressing the guy wire, wire loosened after somebody backed a pick-up into by accident ect.
Or someone fucked up somewhere. It's possible.

Managing the failure mode: there's things you can do, but fundamentally it's a big set of trusses carrying a lot of heavy lights, sitting on high pillars. It's not exactly an intrinsically stable structure.

As for lifting it – normally I'd assume 20kg per person (safe working limit). This is a farming community in an emergency. Say 40kg per person on average. To lift one end of the girder you get the lever working in your favour:
assume everyone at same end, girder weight distributed equally along it's length and pivoting on the other end. Girder weight acting at L/2, crowd acting at L, gives you a multiple effect of two:

I wouldn't be surprised if 10 guys can lift the end of an 800kg girder to get the people out.
Make that 13 guys and you're past a tonne.

[Broomstick]

Keep in mind those folks must have been in emergency mode - a lot of them had run from the falling structure, the weather was, um, stimulating shall we say, and there were people trapped under the structure crying out and asking for help. It's a situation where people might have easily been exerting more than 40kg of lifting power, at least some of them might have, in a flight-or-flight response. Some of the videos on YouTube seem to have cadence-counting for the lifters - the "1, 2, 3, LIFT!" sort of chant that would also help coordinate the efforts. The folks trying to save lives wouldn't be concerned with "safe work limits", they'd be exerting the maximum force they could.

[Hawkwings]

It looks like at 7 seconds into that video, when the tarp roof tears free and starts billowing, is when the structure is really pulled down. While it was secured down, the wind would have gone over it and not exerted much lateral force on the structure. When it broke free though, it became a gigantic sail that caught the wind and pulled the top of the scaffolding over. Then gravity takes over. One way to help prevent this in the future may be to have the roof tarp on cables that will release if there is too much tension.

[HMS Sophia]

It looks like at 7 seconds into that video, when the tarp roof tears free and starts billowing, is when the structure is really pulled down. While it was secured down, the wind would have gone over it and not exerted much lateral force on the structure. When it broke free though, it became a gigantic sail that caught the wind and pulled the top of the scaffolding over. Then gravity takes over. One way to help prevent this in the future may be to have the roof tarp on cables that will release if there is too much tension.

That's what I said above. Links that split when a force over a certain amount is placed against them would have limited the sail effect, and could probably have stopped the collapse.

[CaptainChewbacca]

Am I crazy, or is there LIGHTNING discharging across the structure prior to collapse? Is that shorting electrical equipment, or was there enough dust in the air to create large static discharges?

According to the news I just watched, temporary structures are not required to be inspected for stability in this state. That'll probably change.

[HMS Sophia]

Am I crazy, or is there LIGHTNING discharging across the structure prior to collapse? Is that shorting electrical equipment, or was there enough dust in the air to create large static discharges?

I think it's part of the back screen light show. When the screen goes down you can see it bend with the screen. I could be wrong but that's what it looks like to me.

[KhorneFlakes]

Am I crazy, or is there LIGHTNING discharging across the structure prior to collapse? Is that shorting electrical equipment, or was there enough dust in the air to create large static discharges?

According to the news I just watched, temporary structures are not required to be inspected for stability in this state. That'll probably change.

That's one thing I noticed too? What the hell. I've seen wierd stuff, but really...lightning? Why is there lightning?

That's...confusing. I don't like the obvious implications, either.

[Darth Wong]

There are plenty of things that an engineer could have done to make that structure able to withstand gale-force winds. However, it's most likely that an engineer was not employed. In practice, people tend to place great faith in personal experience. A man who says "I been puttin' up dese here rigs for twenny years" is going to be listened to with much greater interest than a man who is fresh out of university. Rules of thumb tend to rule the day unless someone in management insists that a properly licensed professional sign off on it, and since this professional will cost money (and his recommendations will cost money too, as well as time), there are a lot of managers who would prefer not to go that way.

Of course, it's also possible that a fully licensed structural engineer actually did sign off on it, but honestly, these kinds of structures go up all the time, and I've seen the companies that put them up, and I don't get the impression that they bother.

People only ask "why didn't they take precautions" after a disaster happens. Before it happens, people are only interested in schedules and budgets.

[Broomstick]

The governor of Indiana announced today that he was behind the idea of getting such structures as these stages inspected - something apparently not required in this state.

Another tidbit I have is second-hand and not from the internet and thus unconfirmed: one of the people I work with from time to time is a civil engineer involved in building construction. He stated that he knows the company who put up that stage and that their expertise is in building stages of that sort for indoor stadiums. Needless to say, indoor stadiums do not have to contend with the same sort of weather concerns as outdoor venues do. If that's true that might be a significant factor in this. They could be a company that can say, as Darth Wong put it, we "been puttin' up dese here rigs for twenny year" and yet have little or no experience building structures required to take the sort of side-loads imposed by winds. While I have no reason to doubt this co-worker, it is second-hand and I haven't been able to confirm that, so take it with a pinch of salt. As far as I know it could be a company with experience in building outdoor stages that has just been lucky so far. And as Mike points out, experience isn't the only thing that's important.

Here is a relevant article from the Indianapolis Star newspaper, with added emphasis at a few points.

If you're wondering which Indiana agency regulates the massive stage rigging at the State Fairgrounds, the answer is apparently none of them.

If you're wondering how often the structures are inspected by the government, the answer is apparently never.

The Indiana Department of Homeland Security, which inspects buildings, elevators and amusement park rides, does not regulate outdoor stages and did not inspect the stage at the Indiana State Fair before heavy winds toppled the heavy structure onto a crowd Saturday night, said John Erickson, a Homeland Security Department spokesman.

Companies that erect outdoor concert stages are not required to obtain a state permit, submit engineering plans or undergo inspections, he said. The department also keeps no files on safety records or complaints.

"There is no permitting process," Erickson said Monday. "There is no regulation on it. We do not regulate putting up of scaffolding in a business or an entertainment setting or anything of that type."

Nor, apparently, does the Indiana State Fair, although the state does inspect the rides. State Fair spokesman Andy Klotz said Monday afternoon he was still trying to determine whether anyone looked at the stage rigging before the concert.

"I don't know who's responsible, if anyone," Klotz said. "I've had conflicting information on this today."

At the heart of the matter is how to classify a stage, rigging and roof, the elaborate structure that supports tons of lights, speakers and other heavy equipment high in the air.

Under Indiana Administrative Code, a structure -- temporary or permanent -- has to meet stringent code requirements, such as being able to withstand winds of up to 90 miles per hour. [145 kph] The winds at the fairgrounds blew less fiercely than that Saturday evening, about 60 to 70 mph, according to the National Weather Service.

But the Indiana Department of Homeland Security said temporary outdoor stages are not, strictly speaking, structures.

"You're talking about scaffolding and equipment," Erickson said, "not a structure."

More proof that anything with "Department of Homeland Security" attached is likely to be moronic - I think most of the general public would look at a stage like that and, if asked if it is a structure, likely would say "yes". Even if they aren't legally defined as "structures" there should still be some sort of oversight to help prevent such events as a stage collapse.

Saturday's accident was at least the fourth stage accident since the start of July, The Associated Press reports. Earlier this month, wind blew over a lighting rig at a music festival in Tulsa, Okla., and lightning toppled a stage under assembly near Quebec City. Last month, a summer gale toppled a stage at a music festival in Ottawa, Canada, where the band Cheap Trick was performing. Three people were hospitalized.

Indiana native Paul Harding, a fellow at the American Institute of Architects and partner in a Chicago architectural firm, called the lack of a building permit and inspections "a very serious problem."

"If something is not permitted, the whole system is short-circuited," he said. "You don't have the checks and balances you would normally get with a project."

He said his first reaction when he saw the photos of the stage before it fell was that it looked "unbelievably flimsy."

"And after looking at the photographs of (structural pieces) after the collapse," he said, "they seemed thinner and more delicate than you would expect for a structure like that."

The owner of the company that provided the rigging, Mid-America Sound Corp. of Greenfield, is launching its own probe. Company officials did not return several phone calls requesting comment.

The company has hired an outside agency, Borshoff, to respond to media questions. The agency said that Mid-America has provided equipment for thousands of artists in hundreds of venues without a safety problem.

Concert industry expert George Strakis wouldn't speculate on why a gust of wind was able to topple Mid-America's stage structure at Saturday night's concert at the Indiana State Fair.

But Strakis, an Indianapolis resident who has toured as Whitney Houston's sound engineer for 22 years, could recap the deadly accident's sequence of events.

"For whatever reason, the rigging buckled and weight shifted," he said. "It went down face forward."

Rigging for Grandstand concerts is a combination of metal framework that's left in place throughout the fair, plus equipment added on by individual tours. The framework sits on a permanent concrete slab that acts as the stage floor.

Mid-America owns the superstructure framework. Sugarland's tour, which visited the fair Saturday, brought its own speakers, lighting and a circular video screen as onstage production elements.

Strakis -- who is not affiliated with the fair, Mid-America Sound or Sugarland -- said tours of Sugarland's scope routinely attach 50,000 pounds of gear to overhead trusses.

"I believe everybody that puts up a stage is going to understand they are going to put up a stage that can withstand a 70 to 100 mph blow," Strakis said.

Strakis said all concert-production rigging is certified to aeronautical specifications, with the idea that aircraft in flight endure more stress than is encountered on the ground.

What I think that means is that the materials are aircraft-grade, which means a higher quality control and alloys that are designed to be both lightweight (relatively speaking) and able to withstand flexing as well as static loads, but I'm not sure. "Aircraft grade" truss materials aren't that hard to come by, for example, it mostly means they're made of a particular alloy such as one of the 7075 aluminum variations. While these materials are quite useful and wonderful they aren't magic - they still need to be properly assembled and braced.

"This will need a lot of calculation," he said, "to really understand what happened with this storm and the stage."

In Chicago, those calculations are required to be submitted to city officials before a temporary stage is even erected. All temporary structures used there -- including stages like the one at the fairgrounds -- also require a permit, said Bill McCaffrey, spokesman for the city's Department of Buildings.

In Chicago, the permitting process for stages is identical to that for all permanent buildings and structures, which requires the submission of architectural or structural engineering documentation. Those items are reviewed by professional staff to determine whether a permit can be granted, McCaffrey said.

Stages are then inspected by the department after they are erected, he said, "to make sure they were constructed according to the plan specifications."

Stage manufacturers typically provide high-wind action plans that lay out steps that must be taken in the event of bad weather or high winds. Typically, he said, outdoor stages are designed to withstand wind speeds of at least 30 to 35 mph.

Needless to say, designing for those windspeeds (48-56 kph) would be hopelessly inadequate in Indiana. That's why, even though the company that built the stage has experience doing that in many places there may be reason to question if they were up to doing it in a place where 100 kph winds are not particularly unusual, and local standards design for 145 kph.

When wind speeds top a manufacturer's recommended limits, the plans detail changes that should be taken for safety. For instance, McCaffrey said, stagehands may have to remove curtains or other objects that can be caught by the wind as speeds increase.

In Indianapolis, permits are required for stages used for special events, said Kate Johnson, spokeswoman for the Department of Code Enforcement. However, she said the city regulations do not cover the fairgrounds, which is state-owned, and the city has no jurisdiction over buildings on that property.

Regulations aside, the industry has best-practices standards for outdoor stage rigging.

In the apparent absence of regulations, that book might well occupy a prominent spot in the lawsuits that will, inevitably, arise from this.

Those standards are laid out in a 33-page document distributed by the trade association, PLASA, which bills itself as "the worldwide voice of entertainment technologies." The group advises frequent inspections, particularly for rigging such as that at the Indiana State Fair that is left intact between uses.

Users of the overhead structures are advised to keep on hand an "operation management plan" that includes specific guidelines for wind. And the group recommends bracing the rigging against the wind with mechanisms such as wire guys anchored to ground anchors, diagonal braces and ballast applied to the tower sections.

When the rigging is left intact between events, PLASA advises inspection of cross-bracing cable assemblies and anchorages between each use.

"It would benefit public safety if some of the standards that are out there would be adopted into law," said Bill Gorlin, a structural engineer and vice president of the entertainment division at McLaren Engineering Group, based in West Nyack, N.Y.

"Everyone wants these events to be safer."

Several state agencies are investigating the collapse and aftermath, including the Indiana State Police, Department of Homeland Security and Department of Labor.

But there was no information Monday from those investigations. In fact, as of Monday afternoon, no companies had filed incident reports with the Department of Labor over workplace deaths, even though two workers were killed in the accident, said Chetrice Mosley, a spokeswoman for the state department.

Under Indiana law, they are required to notify the state within eight hours.

Whoops. Can you say "dropping the ball"?

[Darth Wong]

Don't worry, the free market will correct the problem. No need for a nanny state solution. Right?

[Broomstick]

Oddly enough the Republican governor did call for some sort of required inspection in the future... but then he's what passes for a moderate Republican, which is why he knows better than to run for PotUS although there were rumors he might do so earlier in the year.

[Sea Skimmer]

Looks like the bad weather was in fact, highly predictable. I suggest following the link because they also have a chunk of radar map from the time of the event.

http://www.msnbc.msn.com/id/44166368/ns/weather/

Indiana fair tragedy was no 'fluke,' expert says
Weather Channel challenges governor's assertion with detailed look at events
ddressed the severe weather threat in greater
detail early on Saturday (August 13). This
product highlighted that damaging winds and
large hail would be the most significant
impacts with any thunderstorms moving
through central Indiana during the late
afternoon and evening. Other risks included
dangerous lightning and heavy rainfall.

Severe Weather Watch and Warning
At 4:45 p.m. ET Saturday, a line of strong
thunderstorms were already in progress over
northern and central Illinois. The line
continued to intensify as they marched into
Indiana and at 5:57 p.m. ET a severe
thunderstorm watch was issued for all of
central Indiana. Hail up to one inch in
diameter, wind gusts of up to 70 mph and
lightning were all highlighted within the watch.

As the line drew closer to Indianapolis, a
severe thunderstorm warning was issued for
Marion County, Ind., at 8:39 p.m. ET which
included the Indianapolis metro area. By
definition, a severe thunderstorm is one which
produces wind speeds of 58 mph or greater or
hail one inch in diameter or more.

At 8:49 p.m. ET, ten minutes after the bulletin
was issued, the stage rigging at the Indiana
State Fair dramatically collapsedonto concert-
goers after an outflow boundary or gust front
swept through the fairgrounds. That is a ten-
minute lead time for event officials to evacuate
concert-goers and usher them into a place of
safety and shelter. Does this seem like a fluke
to you ... a chance occurrence? If a known
hazard — wind gusts in excess of 60 mph — is
approaching, how is the destruction it causes
a fluke?

Senior meteorologist Stu Ostronotes that "this
wasn't an isolated pop-up thunderstorm that
suddenly sprouted and produced a 'pulse'
type of severe wind report. Although not a
derecho, what produced the wind at the
concert was a strong, long-lived line of
thunderstorms which had produced many
severe wind/hail reports a couple of counties
upstream. As noted elsewhere, there had been
a severe thunderstorm watch (in fact, it was in
effect well out ahead of where radar showed
the storms to be at the time it was issued) and
a severe thunderstorm warning issued.

And climatologically it's not like this was in an
unusual place or time [for severe weather to
strike]. It was in the evening, in the summer, in
Indiana. While the absolute peak of summer
severe wind occurrences on average is a little
earlier (late June into July) and a bit farther to
the east, the zone includes Indianapolis in
August."

But with all this said, it shouldn't have even
come down to a warning issued by the
National Weather Service. Brad Panovich, chief
meteorologist at WCNC-TV, Charlotte, N.C.,
notes in a recent blog entry of histhat



evacuations and the priority of seeking shelter
even before the issuance of a severe
thunderstorm warning should have already
been in place. We are talking about a recipe for
disaster — an approaching line of severe
thunderstorms containing high winds and
lightning bearing down on a large, metal but
seemingly fragile outdoor stage set with its
rigging standing high and hovering over the
crowd below.

Story: Indiana fair's storm plan is brief,
generic

He writes, "Problem here is you have people
in an outdoor event and around a temporary
structure which requires them to seek shelter
at a much lower threshold. Something that
should have been known by those organizing
the event. One of the fatalities was a stage
hand in a metal light structure running a spot
light, with lightning clearly visible in the
distance. Lightning alone was sufficient reason
to evacuate people and since lightning was
within 10 miles of the fair grounds patrons
should have been seeking shelter."

The science of meteorology is growing by
leaps and bounds especially with continuing
advances in satellite and radar technology.
When severe weather strikes, we are in awe of
the power and the visuals but we shouldn't be
in awe of the severe weather event itself. There
are definitive and well-known reasons why
hail reaches softball size or a tornado strikes
one neighborhood but misses the other or
why wind gusts reach 70 mph. This isn't
voodoo, this is meteorology. The science is
getting better and better each day in timing of
significant weather and its location down to
city landmarks and even street level.

Let's stop dismissing the science and making it
a scapegoat. The gust front was not random.
This was a severe weather event which was
well predicted but still led to the deaths of 5
people who were hoping to see a Sugarland
concert.

This is a teaching moment. There are lessons
to be learned — the main one being we should a
ll be weather aware especially when
outdoors; taking the necessary precautions in
advance of approaching severe weather.
Knowledge is power. When attending an
outdoor event, find out the weather forecast
for the day beforehand and monitor the sky.
Don't just leave the decision making to event
officials. Use your common sense and take
matters into your own hands. If you don't feel
safe, do something about it. Seek safety and
look after the well-being of your friends,
family and others around you.

[Broomstick]

And... another stage collapse, this time in Belgium at the Pukkelpop Festival. Three dead, 70+ injured.

It's the fourth stage collapse this summer.

Clearly, these incidents are not "flukes" or isolated, there is definitely something amiss. Partly, it's people being complacent about the weather - there was a storm rolling in at Pukkelpop, and videos show people remaining outside in wind, rain, and lightning which is bad enough. Video also shows it was another truss-built stage. In this case tents at the festival were also blown down.

[Darth Wong]

And... another stage collapse, this time in Belgium at the Pukkelpop Festival. Three dead, 70+ injured.

It's the fourth stage collapse this summer.

Clearly, these incidents are not "flukes" or isolated, there is definitely something amiss. Partly, it's people being complacent about the weather - there was a storm rolling in at Pukkelpop, and videos show people remaining outside in wind, rain, and lightning which is bad enough. Video also shows it was another truss-built stage. In this case tents at the festival were also blown down.

It's quite disturbing that these structures are not considered "structures" despite fulfilling the dictionary definition of the term, and are therefore not subject to stringent regulations even though they are intended for use by the public.

[Broomstick]

I remember a time when an "outdoor stage" was a pretty minimal affair - back in the late 60's/early 70's it was a stage open to the sky with a minimal sound system. Nothing overhead, no video equipment, etc. Even if such a stage collapsed it is far less likely to cause serious injury or death so lack of regulation doesn't carry the same potential cost when there was an accident.

Over time, concert stages (both indoor and outdoor) have evolved into audio-visual extravaganzas utilizing state of the art equipment in quantity and massive amount of power. The stability of the structures haven't kept up with the weight being hoisted aloft, especially when subjected to wind loads. Air in motion can be massively powerful - aside from the awesome power of hurricanes, typhoons, and tornadoes, people have used it for centuries to propel ships weighing many tons across oceans, and it's air that holds up airplanes. Just because you can't normally see it, and aren't normally aware of being immersed in it, doesn't mean it's not there and it's not powerful.

I don't accept the notion of "oh, well, it's a temporary structure, it can be secured". I know you can secure temporary structures/scaffolding against winds such as occurred at the Indiana State Fair because that is done routinely in Chicago, which is subjected to much the same weather conditions. Of course, doing that does cost more. Then again, Chicago has a lot fewer collapses, injuries, and deaths.

If they aren't subject to regulations regarding construction and bracing then it's time to write some.

[cosmicalstorm]

Holy shit, here is a video of the pukkelpop-collapse. That storm came out of fucking nowhere. I've spent two rainy seasons on Roskilde but that is insane.
http://www.liveleak.com/view?i=7a1_1313718844

[Darth Wong]

Holy shit, here is a video of the pukkelpop-collapse. That storm came out of fucking nowhere. I've spent two rainy seasons on Roskilde but that is insane.
http://www.liveleak.com/view?i=7a1_1313718844

Well, that's why we use satellites to track phenomena like this. Waiting until you can see it with the naked eye is a bad strategy. After all, there are some pretty obvious reasons why a high wind would be a fast-moving phenomenon.

[Sky Captain]

Storms like that don't materialize from nowhere. Even without looking into dopler radar and sattelite imagery there should be at least 10 minutes from dark clouds incoming to actual storm hitting the area. That's enough time to move people away from large unstable structures.
I have experieced similar unpredicted storm when sailing. Events went from nice warm day with few clouds to horizontal rain and wind over 20 m/s in 15 minutes, then 20 minutes later it was over. Still we had plenty of tme to remove sails and secure any loose items that could be blown overboard.
Things like that happen occasionally during hot summer days, it is nothing unusual.

[madd0ct0r]

Just saw this while job searching:

http://www.maxfordham.com/projects/u2-l ... rotection/

now that's a properly engineered stage set.