Cranes and wind!

[PabloBrown]

Last night, I happened to notice that the crane in the building site next to where I live, was spinning around.  This in itself would not be weird if it weren't for the fact it was about 23:45, and there was no one in it.  Are cranes left to move freely in the wind, when not in use so as to prevent extra stresses on the upright?  Or is it just that someone made a mistake and a crane really shouldnt be allowed to move with the wind?

[sddsddean]

Tower cranes are always 'parked' with the slewing brake off for exactly the reasons you state. The jib will have the least wind resistence if it is able to 'weathervane' in the wind. If you look at the crane each night and morning, you will almost certainly find it has moved during the night as the wind shifts.

[darklar]

That would also explain why they always seem to be pointing the same way when 'parked'. I have always wondered why that was.

[sddsddean]

Exactly darklar.