Many moons ago, I was driving behind a trolly bus, in stop-go traffic.
For whatever reason, I moved to the next lane, the car that was behind me moved up into my old position behind the bus.
Then I heard a crash of breaking glass.
At the top of each of the bus's pick-up arms there's a "wiper" consisting of a holder with a pulley wheel that pushes up onto the wire. This holder is a serious piece of metal, perhaps a foot long, diameter tapering from perhaps 2 inches to 5 where it holds the pulley wheel. The crash I heard was when the holder and the pulley wheel detached themselves from the arm, broken the safety chain that is meant to stop this happening, and gone through the windscreen of the following car, landed between driver and passenger. It would have been me if I hadn't switched lanes.
Don't ask me why I moved lanes, there was no driving advantage, but I've always listened to that inner voice. It's saved me on more than one occasion.
(Apologies for the picture, best I could find.)