My friends that were at the concert said that the aftermath was absolute chaos. People were trampled trying to get into a nearby building. My friends took off toward the gate to get out as soon as they could which would have been a serious mistake had it been a tornado. Thankfully they are all just shaken up. What a tragedy. 
I’ll say. It looks a huge beast charging the puny humans.
I’ve been searching through Flickr for photos of the stage setup on the previous days. I found pics of some boy band, and you can see the trusses very clearly in these shots. There are guy wires.
gaffa, I wonder if one of the guy wires failed. The whole thing looks like it shifted to one side before toppling over.
I’ve done both. I’ve been the guy in charge of putting up roof systems, and I’ve been the guy in charge of hanging the lights and sound from them, too. Sometimes I did all that on the same gig. I have over 30 years experience in technical theatre and stagecraft.
Put me down as a bother person who is surprised at the number of engineers and meteorologists we seem to have participating in this thread.
Let the investigation happen, then bitch about things after you read what they find out. Until then, none of us really knows jack shit about this situation and any opinions offered are worth what people are paying for them: nothing.
True enough. The airplane industry is heavily regulated with safety regulations out the yin yang - I don’t think the same is true about the outdoor concert industry (but I could be wrong).
Since the majority of plane crashes are due to pilot error, or have it as a large component of the accident, it actually isn’t an unreasonable place to start the investigation.
Likewise, for structural collapses there is often a problem with either the engineering or the assembly. That’s not always the case, but it crops up often enough that it’s not an unreasonable place to start looking. Simply shrugging and saying “it’s a temporary structure, sometimes they fall down” isn’t really good enough. There doesn’t have to be negligence involved. Sometimes you can build something to code, it falls down, and upon investigating the conclusion is that the rules weren’t stringent enough, or didn’t take something into account, and need to be revised to reduce the chances of a repeat.
Numerous people who were on site, officials who were involved, and people who have seen the state fair grounds have also pointed out that the stage was, apparently, the only thing that blew down in this case. If the winds were such a “fluke” or truly unusual in intensity that does seem odd. Now, it may be that height of the structure had something to do with that, or some other factor.
I don’t agree with some of the more strident conclusions, but people do like to speculate and I don’t have a problem with that.
I don’t understand the comments about armchair meteorologists, nor do I have reason to doubt the statements so far about windspeed offered up in the media. As I’ve said, wind gusts at that speed are a known risk throughout the region, I don’t agree with the governor’s implying they’re some sort of totally unforeseeable fluke. No, so far as I know, there wasn’t some sort of monitor up on the stage to clock windspeed but the estimates are consistent with the dust cloud you see rolling towards the stage just prior to the collapse in some of the video footage. I’m sure someone has a way of using such information to refine wind estimates.
In addition, a windspeed of approximately 70 mph was recorded on an actual monitor about 7 miles from the accident scene (located at 62nd & Georgetown Rd, Indianapolis), so it wasn’t just pulled out of someone’s hind regions. A wind gust of 77 mph was recorded at another station somewhat more distant. Again, the numbers reported for the gust are not simply made of whole cloth, they’re based on actual readings nearby, and in fact, being given as 60-70 mph, aren’t even assuming they were the strongest winds in the area at the time.
Saying “They’re temporary structures engineered to withstand likely worst-case conditions. When the worst-case conditions exceed those predicted, there may be trouble.” is just as much being an armchair meteorologist as saying the gust that occurred was nothing special, except that it ignores what is known about the area and has been noted by people who live there several times: a 60-70 mph sudden gust is NOT a “worst-case” in Indiana and it is not a fluke, it actually occurs multiple times in a normal year. Now, if it had been a *100 mph *gust (which, as I noted upthread, we DID have occur in my neighborhood this year) that statement might be more valid.
Of course, more specific information will come to light with a decent investigation, which may or may not confirm or deny the conclusions of various people in this thread.
How awful.
I’ve been looking through Flickr for photos of the stage setup from years past. One thing was apparent:
The sound system for this year is much larger than past years.
Previous years had a four hangs of eight cabinets. This year, it has two hangs of eight, two hangs of twelve. That put even more weight right at the front. I can’t tell from the pictures what model the speakers are, but units like that range from 150 to 300 lbs per. Even figuring only 200 lbs per cabinet, that is four tons of speakers hung right at the front edge of the stage.
I’ve been looking closely at the video that Mahaloth linked to. I captured it, and have been able to frame by frame it (it has a Creative Commons copyright) and the left speaker stack was swinging before the collapse. That is, two stacks of speakers, approximately one ton each, with their centers of gravity exactly centered under the middle of the front horizontal truss, was swinging back and forth.
Yeah, I’m not an expert. I’m not part of a blue ribbon commission. But I have hung speakers from trusses and swinging is bad.
To be clear, my main “bitch” here was that Governor Daniels was apparently making assertions about a lack of liability before there was any investigation. That was imprudent at best.
I’m mystified by people who claim extensive experience and then turn around and say we don’t know anything about this. Nonsense. We don’t know all the details of this particular case–that’s what investigation is for–but both engineering and meteorology do have substantial bodies of real knowledge applicable to a general understanding. There is a reason that such collapses are extremely rare.
I admit that one of my first posts above was technically in error in leaving out the “possibility” of a weather event of exceptional intensity and astonishing localization. But I’d put that alongside the deliberate-sabotage theory for :dubious: unlikelihood. I stand by the position that most reasonable and appropriate starting hypothesis, by far, is some class of negligence by the company that erected the thing. As far as I’m concerned, anything else would be an extraordinary claim requiring extraordinary evidence. I should hope that the practical outcome of the investigation will be to identify the specific nature of that negligence so that the point of oversight failure can be remedied.
OK, I zoomed in on the left speaker hang and stabilized the footage. It is a quick and dirty job, but there was a lot of camera motion to remove.
For what it’s worth, the lighting equipment on the truss is lighter but not negligible. Those dozens of lights you see along the roof are PAR cans, no more than ten pounds a piece, but there are several dozen, so probably 500 pounds. If I’m wrong (the photo is pretty grainy) then the lighting fixtures are ellipsoidals or possibly some kind of LED fixture, more like twenty pounds a piece. We know that there were spotlight operators in the truss, and I think 300 pounds for an operator, a spotlight, and safety equipment for both, so say a minimum of 600 pounds of spotlight equipment. Lighting cable has to be pretty beefy to carry enough power safely and there are a hell of a lot of instruments to power up there, so I’d estimate an additional 500 pounds of cable, minimum. I don’t see any moving fixtures, but I expect there are at least a couple, for at least another 200 pounds. I’d estimate one half-ton to one ton of lighting equipment, possibly more, even much more. However, the lighting equipment is spread out much more than the sound equipment and is not hanging but is secured closer and firmer to the structure itself. The lighting equipment probably did not catch as much of the wind force as the speaker stacks, nor did they swing much if at all.
You can see in that picture that the trusses themselves did not shear. The breaks are far too clean and are in the exact same spot of the foreground trusses. Rather, the trusses failed at the joins between individual pieces of truss. You can see such a join in the picture Gaffa posted of guy wires. My guess is that the bolts holding the truss together sheared. Still, that wouldn’t happen until you had some incredible forces, such as you’d see during a collapse.
The thing that surprises me is the huge tarps and curtains that are flapping all over the stage. It’s incredible how much force wind can create on such structures; I worked on an outdoor stage in the Dakotas where we routinely had damage and changed plans based on wind forces under thirty miles an hour. I think that the combination of speaker stacks that swung out from under the trusses and lateral force from the tarps (which are nothing more than sails in the end) provided enough force to tip the thing.
perhaps she saw/heard/felt the speakers moving that you see in gaffa’s post, and that is what got her to move.
a very good thing she listened to that feeling.
i’ve never been struck by lightening, i’ve had it strike close to me, and i would not be in an outdoor venue with all that metal, electrical lines, etc around me with a storm coming in. i am a bit surprized that the concert wasn’t canceled or postponed until the weather cleared.
Yeah, you can see the separation very clearly in the still image. I’m not sure what mechanism is used to connect the upright trusses. Remember, this equipment is intended to be assembled and disassembled as quickly as possible. On many tours, a stage of this size will be set up, used for a concert, torn down, packed in trucks and moved to another town hundreds of miles away within one twenty-four hour period. Nuts and bolts take too long, and you have the possibility of dropping and losing them. Trusses are usually held together with truss pins.
One failure mode occurs to me. As noted by others that structure is only suitable for static vertical loads. What SHOULD keep that structure vertical when there is a sideways load is the guy wires. Now, if the sideways load was too high or the guy wires defective/weak/attached improperly they could break, the structure gets non vertical and it all comes tumbling down.
All certainly possible. But there is a failure mode that could be easily missed. Those guy wires would have to be under the PROPER amount of tension for them to do any good. If they weren’t tight enough to START with, the structure could easily shift TOO far sideways before the wires came under significant tension to resist the side load/shift and therefore they would’t be doing any good. The problem with the tension is it could be way off and it would not be obvious to anybody that it was so. Then again, I aint no expert on guy wire tension so this could all be engineering baloney.
And, I disagree with the concept that discussing what MAY have caused an accident is meaningless until you find out what caused it. Sure, its nice to find out what caused it and fix that. But its also IMO worthwhile to consider ALL the POSSIBLE ways things can go bad and come up with realistic ways to minimize those as well.
Looking at the video again, the suggestion had been made that they should have lowered the roof. Each tower section has a hoist on the top. all of which are synchronized to lift the whole roof truss at the same time. But it was not going to be possible to quickly lower the roof because of Sugarland’s giant circular LED videowall that was nearly the height of the whole roof. It is assembled in sections, being hoisted bit by bit as each section is added (it is also possible the whole thing is assembled on the stage and it is tilted up, but that would take the stage out of commission for too long). So they couldn’t bring the roof down without disassembling the videowall and the speakers.
It could very well be pins. It doesn’t really matter, since the basic principle of putting a straight length of hardened steel through the hole to keep it together is the same; either way, it would be almost impossible for those bolts or pins to fail with normal lateral movements. My general point is that it doesn’t look like individual sections of truss failed, but rather that the bolts or pins probably failed as the structure collapsed, and the structure would have collapsed even if they hadn’t failed. I would suspect that the bolts or pins failed well after the point of no return in the collapse, and were not a cause of the collapse but rather a symptom of it, but that’s a little speculative.