This is not a good result. And “Miraculously believed to be minor injuries” reported by police will need to be verified. But this is a good opportunity to talk about good crush.

Postings on Twitter have been numerous with exclamations of the “miraculous” result when a Nissan Altima was crushed in a severe rear-end impact by the Tractor-trailer yesterday, November 16, 2021, reportedly on Interstate 5 in Mount Vernon Washington.

Comments such as the one below were numerous, and rightfully so:

“Did you say MINOR INJURIES?!? OMG!! Someone was looking out for whoever was in that car, that is unbelievable. Wow, they are going to have one hell of a story for thanksgiving. Remarkable.”

However this gives us an opportunity to comment on “good” crush and the deceiving beliefs that often accompany incidents where major vehicle damage exists.

What if this collision involved a Sherman tank and, after impact, there was no visible crush to the tank? Would that be a good thing? Would it mean that the collision was likely of minor severity? What if the occupant of the tank died? Would we wonder why such a “miraculous” result occurred in such an obviously minor collision?

The point is that vehicle crush can be a good result. In a collision where vehicles possess kinetic energy it is important to dissipate (get rid of) that energy through vehicle crush rather than through occupant contact with the vehicle interior. In the example of the Sherman tank, because its structure is so stiff, it does not dissipate kinetic energy and therefore, during the collision it sustains a massive change-in-velocity over a very short time. This is not good. Because the occupant of the tank must now be involved in the “Second Collision” where the occupant’s body must impact the interior of the tank with a high difference in velocity between the two. So something so seemingly minor is, in fact, something very dangerous and the danger is not apparent because, in our minds, we correlate vehicle crush with collision severity.

No, I do not recommend that you should be involved in the collision shown above, and further demonstrated in the additional photo below.

Given the number of internet hoaxes that exist I take the approach that “I will believe it when I see it”, as I have never seen a collision like this in over 40 years of reconstructions where someone has survived.