The instinct to go towards man-made structures (culvert vs. tree) could have cost these people their lives. I'll wager they spent a more comfortable night under the tree with boughs to sit on then in the metal culvert with water coursing through the bottom.

That's why practicing with what God gives us in nature is so important, and so incredibly neglected by 99% of people.
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When the SHTF, no one comes out of it smelling pretty.