That particular underpass— Gregson Street train trestle in Durham, NC— is notorious. There are several videos floating around YouTube about it. The trestle is about a hundred years old and looking good for its age, and despite what the videos seem to show, is only hit about once a month.
In fact, all of the vehicles are actually shown hitting a "crash beam" that is slightly lower than the trestle itself. Smacking into the trestle proper could cause a train derailment that would be even worse.
Point of interest, the signage says 11'8", but the actual measured clearance of the crash beam (not the trestle) is about 11'10˝" to give vehicles about 2˝" leeway. Everyone that hits the crash beam is underestimating their height by AT LEAST that much!
Engineering: Finding complex solutions to simple problems you didn't even know you had.