A massive construction crane has crashed into Mecca's Grand Mosque in stormy weather, killing at least 107 people and injuring 238, Saudi authorities said, less than a fortnight before the annual hajj pilgrimage.
Key points:
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[li]Spokesman said crane collapse was caused by strong winds and heavy rain[/li]
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It looks to me like the boom went over backwards, which would mean it wasn't over the mosque, but swung out the other way. Could be wind, but the reports I'm seeing show 25 mph wind, which wouldn't normally be blowing unladen cranes over. Could be operator error, could have dropped a load, who know.
At face value it seems like it was simply that the design wind loads were exceeded. I can't imagine that they design these for the full 100 year storm.
Maine Professional and Structural Engineer
American Concrete Industries
The crane was left with the boom almost vertical. If the operator had left the boom about 20 degrees lower, it would still be standing.
Does anyone know the rating of the crane. From the looks of the undercarriage in one photo it looks like a big one.
Bill
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"Why not the best?"
Jimmy Carter
The crane shown here may be 10 times the size of the one at Mecca, not sure about that.
But the point being, that if a storm blows up, you can't just drop the boom in a hurry on some of these big cranes.
Note that using that smaller crane as ballast is an innovative technique to speed that process up.
If you knew a hurricane was blowing through in a day or so, it'd be different.
I did see another youtube video with a title that said rain was largely to blame. Which is possible, ie, soil falure underneath.
I did a little more research on the crane at Mecca. The crane in the video is a 1600, rated at 600 tonnes.
The crane at Mecca was an 11350 rated at 1350 tonnes, over twice the capacity of the crane in the video.
Bill
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"Why not the best?"
Jimmy Carter
Found this in a Wikipedia article about the incident:
"The report said "the main reason for the accident is the strong winds while the crane was in a wrong position"
and
"Liebherr Group experts who participated in the investigation of the collapse found no structural flaws in the crane. Their report stated that the crane's 190 meter long boom was not sufficiently secured by its operators so as to withstand the high winds present on the day of the collapse, and that use of that crane in those 80–105 kph winds was well outside the manufacturer's recommended operating parameters."
I'm not exactly sure what that means or what they should have done differently.
The boom was almot vertical. If the operator had left the boom a few degrees lower and possibly secured the hook to the chassia the accident would not have happened.
Bill
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"Why not the best?"
Jimmy Carter
