Ever seen a construction zone barricade like the image I've attached below? With supports made from angle iron? I was on a busy highway with wide shoulders where someone had turned it sideways for the weekend, and it blended in with the background buildings, trees, and other stuff. This made the angle iron bottom pieces stick out on the shoulder where I was riding, and I hit them square-on with my bike. No tire damages, but got two simultaneous flat tires. The tires survived (26 inch street tires on a road-converted MTB), but the tubes ruptured so badly they could not be patched. Lucky I had two spare tubes with me and was able to get rolling again.
http://images.clipartof.com/small/25085-Clipart-Illustration-Of-A-White-And-Orange-Striped-Road-Block-Type-III-Barricade-Board-With-A-Blank-Sign-In-A-Construction-Zone.jpg