Not far from where I live is the Blue Ridge Parkway. There is a small windy road going from the Valley floor up to the Parkway. It is closed to 18-wheelers. There are big signs saying: "Closed to 18-wheelers," and "An 18-wheeler cannot make it to the top of the mountain" and "Warning, no big tractor trailers."
Well, one day, Mrs. Tidewater and I were driving up said windy road, and as we neared the top, the switchbacks got tighter and tighter. About 1/4 miles from the top there was an 18-wheeler jack-knifed and stuck in one of the last switchbacks. The switchback was just way too tight and several of the wheels on his truck and trailer were already off the ground because of the uneven ground and tight turn.
We were able to squeeze by in our car, but the driver (probably not a rocket surgeon) was outside his truck, looking at his stuck truck and scratching his head. No sure how he got out of that one.
I remember thinking, "Well, Bud, you drove past a half a dozens signs telling you not to go this way in an 18-wheeler."