Re: When to call it?
It's easy for me to shake my head at this and say "it would never happen here" but I know it has, however we largely don't have the same weather systems in the UK and apart from the steppes in Russia I doubt anywhere in Europe does so weather accidents are rare, building or rigging accident are far more common here.
What we do seem to have a better grip on is a national/international standard for the construction and inspection of these structures. I think it was Christian from Germany that questioned the size and seemingly spindly construction of the roof structures and I have to agree the big systems I've seen in the US seem to be very simple structures for their size and possible loading from wind and rain.
In the UK large events tend to use some form of the "Orbit" stage it is a kind of dome structure which is internally braced and uses the main platform as an integrated part of the structure to assist in ballast and providing a strong footing. These things were probably developed more to keep the rain off the performers as much as anything else but because of the strict laws here they have ended up very strong and reasonably windproof, most have some sort of sacrificial panel that'll blow out or can be quickly released if the windspeed goes too high to minimise the windage.
In the photo I'll lay odds that every structure ( inc the crane)has a windspeed indicator and some sort of alarm attached not just for max speed but also for a rising trend in the windspeed which is what the decision to lower the structure or evacuate it is usually based on, ie if your max allowed speed is 60 Knots then if the average speed goes above 40 and continues to rise plans should be set in motion to secure the structures, the actual figures will be discussed on site etc by the stage co and the local enforcing officer and will take into account local geography and average weather for the area and will be part of the event licencing application .
I really hope that some sort of national standard comes out of this tradegy because in IMO if the big guys suffer from this kind of thing what chance have you of regulating the "backyard specials" G
