Comment by ndespres | Hacker News Reader

Comment by ndespres | Hacker News Reader

> And in order to pull off the aesthetic, the bridge's designers had to make the diagonal supports beneath them a variety of different shapes and sizes. That complication may have led the designers to miss a crucial error, independent engineers who've examined the bridge's plans believe: One of the supports was not strong enough.

They aren't joking about the "variety of different shapes and sizes" for the diagonal supports. It's really incredibly ugly. In my view any "aesthetics" gained from the fake cables on the bridge are far outweighed by how goofy the whole thing looks when viewed from the side. It's really jarring, and I imagine that it would look rather cobbled together when walking over it.

I also was shocked by the reported "2000 pages of calculations" that 3 different structural engineers signed off on. I have a hard time imagining that none of these experts might have said at some point, "this is a bad bridge that should not be built!" even if mathematically it could have survived magnitude 10 earthquake. Which it clearly couldn't. I'm not an engineer but it ought to be outside the ethics of an engineer's role in approving a bridge design that appears to have redundancy (the cable stays AND the diagonal supports) when the cable stays are merely a foolish aesthetic choice. Doesn't seem much different than selling a car with an airbag icon on the steering wheel when no such airbag exists. It's a false claim to structural integrity.

One final thought- the PURPOSE for this bridge seems ill-conceived in the first place. Why is the campus divided by a highway to begin with?? But that's neither here nor there.

> Why is the campus divided by a highway to begin with?? But that's neither here nor there.

That's probably more circumstance than anything else. The area immediately north of the campus has a lot of residential housing, attractive to both students and employees, moreso because Miami's public transit is gawdawful; if you can walk to school/work, avoiding the traffic, that's a bonus.

Additionally, the campus wasn't always the behemoth it is now. The highway they speak of is SW 8th Street, or Tamiami Trail, if memory serves. It's a main road in the area The campus was always adjacent, but only semi-recently has it begun to truly crowd the road, likely a byproduct of all the insane construction going on in the school. FIU is far from the only school spending ridiculous money on infrastructure. The school was never really plopped down next to a major highway...they both just grew, and city planning has never been the area's strong point.

>It's a false claim to structural integrity.

That's not how engineering works at all. Structures are either safe for the conditions or not.

They don't have features that the public derives safety ratings for because that's impossible for the public to do under any kind of complex forces.

A cable from a bridge doesn't mean anything about it's safety or support. It's nothing like the airbag example.

> It's a false claim to structural integrity.

That's a weird claim to make. False claim to who? Joe on the street?

Joe may be as dumb as you assume, but if he sees a truss bridge with one set of struts he might well wonder how safe that is compared to all the other truss bridges he has seen. If he sees another truss bridge with only one set of struts, but with cable stays as well, he might well think that is a safer bridge than the first. He believed the bridge's implicit claim about cable stays, which was false.

Well, it was only yesterday that I learned that having a single set of struts is less stable. I always assumed they were two because they wanted to keep the middle of the bridge clear for the road.

This was my exact point: as a Joe on the street you just have to assume that the engineers got it right. A two set strutted bridge can still fail if the struts are two thin, or not of the right kind of steel/concrete. Do you really evaluate all buildings when you enter them, especially the modern weird and unstable looking ones? Have you ever avoided entering a building just because it has a crazy unstable looking design?

Maybe my image of this "Joe" upon whom you would look down was a little more knowledgeable than it should have been... Did you never play with an erector set as a kid?

My point is that if I know a bit about a subject, I don't fall into the trap of believing that I can point to "an obvious mistake" which was signed off by multiple professional people working in that area, especially in an area like civil engineering where you have criminal liability for "an obvious mistake".

Sure, I would never cross that bridge if I saw those fake stayed cables damaged after a storm, because again, I am in no position to judge the design of the bridge, but it is obviously damaged and I must assume that it is unsafe. Maybe a structural engineer would immediately spot that those stayed cables are fake and wouldn't worry about cross it. But if the bridge looks intact, I would just assume that the engineers knew what they were doing.

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