Well it does happen. Most of the time the driver just isn't paying attention because here in the U.S. all over passes are marked. The dispatchers for companies coming here to Fort Wayne never think about it, cause they use that crappy map quest; made for cars!!! Any trucker who likes to keep his job will check his Rand McNally road map atlas and check for himself. I have backed out several tractor trailers over the years here and on the road. Though sometimes, myself included, we run into trouble when some dumb fool repaves under the over pass without grading it down first. Lucky for me I was going slow enough to just catch the forward edge of the box and crumpled it a bit. Having hauled cars for awhile, the rule of thumb is, approach slow and if in doubt, get out and stick it. Good thing cause when in Chicago with a car carrier once, I stopped and put up the stick, too low to go. When the drivers behind me complained and cursed me out I said better a hold up of 5 min. than being stuck and wait to get pulled out and delaying for hours. Some people just don't get it, including some truckers sadly. Though I had to laugh at the two P/u's with hay; blind definitely leading the way.