It’s no secret that Hollywood doesn’t mind taking liberties with historical facts, physics, and whatever else they need to in order to create a fun, exciting film or sequence. In fact, it’s far more rare to get something that is accurate than not, but that’s the price we pay for wanting to be entertained and not educated. If I want the latter, I’ll watch a documentary.
Still, there are some things that are so glaringly wrong that it can’t help but be written about. That’s where Alex Weinberg, a New York structural engineer, comes in. He wrote a very fun piece over at Hack A Day that goes through some of the most iconic suspension bridge disaster sequences in film history and analyzes how well they’re portrayed. And interestingly enough, he found that Final Destination 5‘s death-filled sequence was actually rather solid!
Weinberg incredulously exclaims, “The most realistic bridge collapse sequence somehow comes from a film franchise in which people regularly get cut in half by errant kites.”
He explains in detail that even though it wasn’t bad, there were still some issues that should be noted:
The origin of the structural failure in this situation is pretty absurd because the asphalt driving surface on a traffic bridge is non-structural. The road itself rests on a steel structure, which would probably not be seriously compromised by some sawing and jackhammering on the asphalt. Further, it’s hard to invent a scenario in which any of this could cause a failure at the top of a vertical suspender. But who knows, maybe there had been some plot-friendly corrosion in the steel. Regardless of the initial cause of failure, the collapse progresses in a halfway believable manner: The road deck falls, but the main catenary cables and the bridge towers remain. With no road to support, the vertical cables swing dumbly over the void.
On a pedantic note (as all best notes are), the collapse shown in the film does not accurately reflect the change in shape that the real parabolic cables would take. Without the dead weight of the main span, the main cables would sag noticeably less between the towers because they would only be carrying their own weight. Since the cables themselves cannot appreciably change in length, they would droop much more at the outer spans where the load is still applied. In the movie, the intact portions of the road deck should be sagging much lower. This is a rare fictional collapse scenario for which we have a real world comparison, the 1940 Tacoma Narrows Bridge collapse.
Below is the clip from Final Destination 5 as well as a diagram that Weinberg created to show how suspension bridges work.