I'm traveling and haven't had time to dig up the whole report, but according to the Ottawa Citizen, "freak" weather alone was responsible for the stage roof collapse last year:
Provincial government engineers were unable to find any evidence of “structural issues” that might have contributed to the collapse, a Ministry of Labour spokesman confirmed Friday.
I'm glad to hear that the stage was apparently properly engineered and constructed!
The article also quoted Bluesfest director Mark Monahan:
“However tragic the event was,” he said, “it is somewhat of a relief to know that no-one was at fault and it was really an act of nature. It also allowed us to re-examine our preparations. We are now better prepared if something like that ever happened again.
"no-one" was at fault? Really? Every stage has a maximum wind load, and it should be part of the operational plan to clear the stage if damaging winds are likely. As Jesse of AccuWeather's Weathermatrix blog showed last year, a "bow echo" was clearly visible approaching the show site on radar:
Even a non meteorologist storm chaser like me can tell you what's likely out in front of a bow echo like that: very strong winds. And the power of the storm was evident in the sky, as I showed in my post from last year. The show director apparently "monitors" the weather backstage, and went on to say:
“It was pretty scary,” he said. “All we could do is react. I have been in these weather situations before and have never had the feeling I had when I saw that storm coming. I knew we couldn’t ride it out. “The stage just folded,” he added. “It was like slow-motion.”
A "reaction" it seems to me, would have been to clear the stage and get the audience away from the structure. I haven't seen any evidence that anyone did that on this show site. I'm glad that no one was killed in this event, but this to me seems still like an operational failure, just as was the case in the Indiana tragedy, as I wrote here. It's just a matter of luck that "no-one" was killed here, since strong thunderstorms are hardly "freak" events in the summer in this part of the country.
All the more reason that show techs should keep an eye on the sky; you can read my article on weather resources here.