Bolzano, Italy. In the north of Italy a Self-Erecting Tower Crane came down striking three cars and injuring none.
In the pictures of the crane, it would appear that structurally speaking, there is no failure that is notable. Certainly damage is present, but it appears to have been caused by the accident rather than before the incident. Looking at the base we see that weights fell off, so we can't get a count. I've never heard of the wrong number of weights being put on. In this case, it would appear that the crane simply tipped, so that possibility can't be ignored. But it isn't likely. The ground looks good. There are matts there that could be a bit better but they do look like they took some time in trying to get the crane level as well.
Looking at the jib of the crane just behind the first car visible, you can see that the location of the trolley shows that it's likely that the crane was carrying a "bunk" of plywood. Was the moment limit set on this crane? Was the crane load tested to 100% and the limit verified? Does the crane have a scale on it for an accurate reference? Certainly a good operator should be able to guestimate this weight with some accuracy if you are going to be closing in on the limit of the crane. 1/2" Plywood = 1.42 lbs per square foot. 45.5 lbs per sheet, etc. You can have these references in a book, in your smart phone, maybe on a card in your hard hat... I know that I have some buried around the office somewhere that I would put in the hard hat given I were a bellman again.
Load test your cranes. It's really not that difficult, expensive, or time consuming. All of these factors compared to the cost of replacing the crane.. not even close to being on par. The beauty of a tower crane is that if you've load tested it, you can have some confidence that the limits will work and keep everyone safe.
consigli gru a torre in Bolzano