I have been informed that it was probably a searchlight tower. Makes sense, from the construction.
Printable View
Don't blame you, Bloke I worked with nearly destroyed a McDonalds store ( no great loss imo ), when his flat top came off turning into Springvale road. Thing was, he did all the right things, sorta. Tug test, visual check of the jaws, etc. Trouble was, the trailer had gone in a touch too high. The pin closed the jaws, but it sat on top, which a good visual check would have shown, but he'd done it every day, as we all do. He said he heard and felt a solid banging over bumps. Well, I would like to think that would have been enough warning. I know that I learned a thing or two about complacency.
Nobody was injured, thankfully. The spring brakes did what they are supposed to do.