Indiana State Fair Stage Collapse

If you've ever stood under a large line array, looking up nervously at the seemingly too-thin cables holding them up, and knowing how much they weigh, that stage collapse last weekend really sent a chill up your spine.

My thoughts immediately went to how that could even happen. Yeh, it was a high wind, but surely these structures are overdesigned for even worst-case scenarios, aren't they? OSHA regulations? Engineering standards? Licensed technicians? What's going on?

So I went a-googling for comments by knowledgable people, but there isn't much out there yet. The state fair commission has hired a local engineering firm to study the incident, but we won't hear about that for months. But...I'm thinking that anyone who rigs stages for a living could take one look at those videos and tell you what went wrong.

Turns out there have been a few similar collapses recently. This, in fact, was the third such collapse in three weeks! This source lists at least 5 recent instances.

Here's some of the best information I've found so far: a blog catering to the stage lighting industry, and an article from an Indianapolis TV station noting the lack of horizontal bracing. Here's a 2008 article about wind loads on temporary structures calling for safety standards that apparently have not been made mandatory.

In the coming weeks I'm sure we'll be hearing more from the industry about this, especially given that one of the 5 dead was one of the lighting riggers who was up in the scaffolding when it collapsed. If I were so employed, I'd be asking a lot of tough questions right now.

That was a horrible event. We had a very similar accident in Ottawa a couple weeks prior.

I noticed in video from both accidents, that the tenting around the structures was pretty substantial. I wonder if that could turn the stage into a giant para-sail. My thoughts on the Ottawa accident were that had the sides and back blown out, there was really not that much to catch the wind.

The Indiana accident was so similar. There seemed to be a large wedge shape section on top, oriented 90 deg. to the stage. I'm sure the authorities are studying the environmental conditions very closely. Both accidents involved severe weather.

These should have been avoidable accidents and I'm sure that we will see changes as a result.

Wow, that 2011 picture REALLY looks unstable!  I'm surprised they were even able to get it to stand at all.

EEEK!!!!

That was something to behold...in the second photo...NO horizontal bracing?!?!?

Someone was either looking to save a few dollars on installation costs...or just plain lazy.

Rectangles are inherently weak shapes. Triangles are the strongest. Look at the roof joists in your attic, the scaffolding at any construction project, the trusses holding up bridges. Even model railroaders know this from building scale model railroad trestles. It's a very old construction technique.

Unfortunately, diagonal members also obscure the view of the stage. As I started looking through photos of stages, I realized that horizontal and diagonal bracing is actually quite rare. Every outdoor stage photo I've examined looks dubious for surviving a hurricane or earthquake.

The primary concern for stages, from an engineering standpoint, is the ability to suspend weight vertically: lights, speakers and roof. A simple cube works fine for this. The primary artistic concern is visual transparency. The cube shape works fine for this, too, and indoor stages are largely invisible to audiences.

It's only outdoor venues that have to be braced against wind loads. Outside, you don't have the space limitations of an indoor installation so you can use guy wires for horizontal rigidity.

Guy wires don't sound as dependable or look as reliable, but they certainly can be. I've seen some enormous radio antennas held in place by wires. But these were anchored in poured concrete footings that no amount of wind would ever budge.

I'm starting to think the Indiana State Fair tragedy may come down to the number and placement of guy wires, and most significantly, how they were anchored.

Mike, your observation about growing up with Erector Sets is right on. I spent so many hours with mine that my fingertips would be raw from tightening nuts by hand. And it quickly taught me what kinds of structures could stand on their own and hold weight, and which ones could be easily destroyed by the cat or my little brother.

 It is sad that some people lost their lives in order for people to begin to consider making important changes to the requirements for these structures. The Titanic was supposed to be unsinkable and look what it led to....better ships but at what cost?

 One of the last shows I attended(the blue man group) had large speaker arrays hanging from small cables and this made me very nervous to be close to those. The very last show was "Joseph" at Sight and Sound theatre. Its a permenant venue and everything there was rock solid.Top notch sound too.