Worst one I have ever seen was a crane falling off a low loader, it landed on a cycle path, killed someone on their bike.
And I learnt my lesson years ago, doing someone a favor, I was driving a large pick up truck loaded with scaffolding (not loaded by me)
Came off the motorway and was in town, in traffic, driving slowly, went over a hump and heard to 'pings'.
The ratchet straps had come loose.....nothing fell off though.
I quickly parked up and sat there, white as a ghost and sweating, thinking, what would have happened if I had still been on the motorway?......