Well, to really blow everyone's bubble, I'm reposting the photo below. This happened to us some 10 years ago on our previous trailer. We hit an expansion joint going over one of our wonderful Indiana bridges, and I suppose the massive bounce was just too much for the poor thing.
Anyway, in this situation, we had safety chains, break-away cable, and weight distribution bars. I think, no matter where that break-away cable was attached to the truck that day, it would have never helped! I know the safety chains were useless under this situation too. We do all we can to be as safe as we can, and then the unexpected happens.
Fortunately, total separation never happened. I was going only about 40 mph and came to a stop very quick. What you don't see in the photo, is the drop off embankment on the side of the road where earth meets bridge. We couldn't even pull over off the road, there was not enough room without rolling over a 30 foot cliff!
Yup, in this case, all the safety "stuff" in the world would not have helped if total separation would have happened!
This is now all in our past, but I look still look at the photos and shake my head every time! (Truly the "Man Upstairs" was watching over us that day!)