I'm referring to a car coming off a dolly, which seems more probable to me than a tow bar disconnecting or breaking in two. In either case that would have to occur PLUS the safety chains fail.
The problem for me is knowing that no matter how much is done in the name of safety, more can still be done. The legal braking requirement, whatever it may be, seems like a good place to draw the line on what is acceptable as a minimum.
__________________
|