Thanks for the additional links, Craftlady.

Kimmy, that appears to me like exactly what happend. The chassis (or undercarriage) is an extremely heavy and solid part of the motorhome, made of all heavy heavy steel beams and this was a diesel pusher (diesel motor in the back) so the engine alone is quite heavy. It's really hard to say whether they were coming or going, but there's a good chance their tanks were full of water which again, is quite heavy. It looks like a little older model (mid to late 90's maybe) but I really can't tell what make it is, which would make a difference in how crushable it was. Needless to say, the higher end more expensive models are less likely to totally collapse like this than the lower end cheaper models. Also, with some manufacturers we know, the ONLY thing connecting the walls to the chassis are nails. Yes, nails - not even screws! They build the wall then nail it to the floor which is attached to the chassis. Needless to say, construction like this will totally collapse under a lot less stress. Terry is on his way to the factory right now to see how our walls are connected to the chassis. He says we're going to install a roll cage, similar to what the Nascar guys get in their cars.

Seriously though, this is such a freak thing that there is no way the manufacturers can predict and build for it. I say he HAD to have been going more than 25 - 30 miles per hour because at that speed, you're just not going to have the force to flip a ~30,000 - ~40,000 pound vehicle end to end!