Suspension Bridges of Disbelief

Suspension bridges are far and away the target of choice in America’s action blockbusters. In just the past three years, the Golden Gate Bridge has been destroyed by a Kaiju, Godzilla, a Skynet-initiated nuclear blast, and a tsunami. Americans don’t build real bridges anymore, or maintain the ones that we have, but we sure love to blow them up in movies.

There is logic here: A disaster scene involving a famous bridge serves both to root the film in the real world and to demonstrate the enormity and the immediacy of the threat. The unmaking of these huge structures shocks us because many bridges have gained an aura of permanence in our collective consciousness. Although we know when the Brooklyn Bridge was built and who built it, we feel like it has always been there and always will be. The destruction of our familiar human topography is even more disturbing than the deaths of the CGI victims, and I’m not just saying that as a misanthrope who loves bridges.

However, in all of the planning, storyboarding, rendering, and compositing of these special effects shots, nobody pauses to consider how suspension bridges actually behave. I can accept messianic alien orphan superheroes and skyscraper-sized battle robots, but I will not stand for inaccurate portrayals of structural mechanics. It’s fine to bend the laws of physics if the plot warrants it, but most suspension bridge mistakes are so needless and stupid that their only function seems to be irritating engineers.

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Argh, thar be a big wheel

If you’re marooned on a desert island, you want to have a Professor who can build useful items out of coconuts. [LostMachine] is one of those guys, and he’s currently building a land-loving pirate ship. The wacky vehicle will use the giant wheel above to propel the vessel while the captain sits comfortably in the lofty crow’s nest. A crack-pot concept? Not really, he plans to take this to Burning Man where it will be a fairly useful build compared to the folks who have really gone off the deep end.

The story here is the build quality. Take some time to watch his videos which we’ve embedded after the break. In the first, he details his method for creating a precisely level building surface on top of his uneven driveway. This is accomplished by welding supports in a circle that are level compared to the center point. He goes on to share his liquid-cooling system for cutting the pipe supports with a custom-built jig and an old windshield washer water system pump from an RV (second video). The final video shows the construction of the wheel which came in with 2000 welds and about 250-300 hours of construction time.

If you hadn’t guessed, [LostMachine] is a structural engineer. Unfortunately he was laid-off this spring which has put a damper in his building schedule. We hope that with a quality project like this in his portfolio a new job is just around the corner for him.

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