Based on a rendered image from one of the stories about it before the collapse it looks like it was going to be a cable-stayed bridge but I don’t see any evidence of cables in that wreckage. I suppose those were planned for later and they overestimated the span’s ability to support itself without them,
edit: fuck, beaten
This shouldn’t even be a technically challenging bridge to build. It’s only spanning what looks like 6 lanes of traffic and is for foot traffic. The ground appears to be level. It doesn’t seem to be using any exotic materials.
I would listen to what the construction workers are saying. It could very well be the case that the thing was just slotted in there and the construction guys were saying “shouldn’t we, you know, like use some bolts or something? This thing is going to slip out…”
At least there won’t be any confounding factors llke “6 months ago a truck hit the bridge” or “there might have been some water eating away at a support”. The cause of the failure should be apparent.
Makes sense. But hints at a big fuckup somewhere. You design this sort of structure for various stages (transport, assembly, etc.), not just the final, in-use form. Especially if you know that you’ll have a not-finished-yet structure spanning a highway that’s in use for almost a year.
Chinese steel, Mexican workers, ISIS, …
Pedestrians (The bridge wouldn’t be there if everyone drove cars like god intended).
Don’t forget obesity. The pedestrians were obviously too fat, being Miami and all.
“Accelerated Bridge Construction”
“move fast and break things” might be okay for for fly-by-night Silicon Valley startups but is not a real principle of engineering.
The ghost of John Roebling is looking down in disapproval.
They’ll apply a post install patch to fix it.
No, if it’s the main FIU campus it’s several miles west.
Maybe we should look in to the whole “lowest bidder gets the contract” idea.
Old town Key West is an exception. The ‘burby part probably a death zone, like the rest of the damn state, but I knew better than to wander out that far.
Lowest bidder works fine as long as (1) you have experienced engineers reviewing the bids and (2) political clout is not a factor in the process. As I said upthread, the chance of (2), in Miami, approaches zero.
Followed by “Highly Accelerated Bridge Deconstruction”
Nope. I’d have to know a lot more about the structural design of the bridge and about the planned assembly to make any sensible comment.
Prefabricating bridges and lifting them on their abutments is pretty straightforward and not at all unusual. But you’ve got to think it through properly and stick to the script when doing it.
And once it’s up, do not do anything with it it was not designed for.
What strikes me is that, given that this is a pedestrian bridge made of concrete, I’d say that the dead load already makes up most of the maximum design load. So maybe that pylon and those cables should have been added right away. But right now this is pure speculation on my part.
The renderings show it, and what’s there is identical to the bridge shown during the move less the tower and (covered?) cables. Someone gave the go-ahead for leaving the bridge as it was w/o temporary dunnage and for traffic to proceed. A lawyer’s cattle call.
Weird how well it correlates with failure.
But hey, it’s better than no-bidder gets the contract.
In our area we have a 30-odd mile system of pedestrian/bike only roads (paseos) interconnected by many bridges, the system allowing users to traverse across much of our community without placing a single toe on a cross-walk or having to deal with a traffic light. Picturesque, fun, and relaxing. We use it a lot, but now I’m having second thoughts:
I’m pretty sure that just means they build the bridge off-site (even if just in a nearby lot), then move it into place. The benefits being that much of the work is done on the ground and traffic is not affected during construction. It doesn’t mean that they somehow rush to get it done, and cut a bunch of corners in the process.
I mean, obviously someone fucked up here. But that doesn’t mean that “Accelerated Bridge Construction” was the fuck up.
The $14.2 million bridge at Southwest Eighth Street and Southwest 109th Avenue is being built using Accelerated Bridge Construction methods, which have been advanced at FIU. The university said the modular construction method reduces potential risks to workers, commuters and pedestrians and minimizes traffic interruptions.
I (vaguely) remember a NASA astronaut saying something along the lines of how tense it was to sit at the top of a rocket built by a committee of lowest-bid contractors…
Maybe I’m too much of a layman here, but 950 tons for a 174 foot pedestrian bridge seems really overbuilt. Is it really necessary to use so much concrete? Is this just to make it safer against trucks running into it several times over the years?
