I found this one in my wanderings.
There's a sign that says, "Do not cross bridge when covered by water."
Of course that begs the question, "Why did they build this so low in the first place?"
It's not exactly as if they didn't know that it would be subject to flooding. This is the combined Shenandoah Rivers [north and south forks], in Virginia, shortly before it melds with the Potomac at Harper's Ferry. Water here has been traveling for as much as 300 miles. I'm told there are several other similar bridges in the area.