[NEMDF]

(Hindsight being 20-20...) Maybe they should have closed the road to traffic while they were doing the tightening of the cables. Seems like, with it only having been installed on Saturday, they didn’t have experience with adjusting the cable system. JMHO

[Robert A Cook PE]

That “stress test” is post-tensioning work on the cables running inside tubes in the concrete, pulling the ends together to create compression across the bridge. Needs to be done correctly and evenly and properly as the concrete sets after pouring.

But, this was done using Obama’s democrat money in a democrat congressional district in a democrat city for a liberal (democrat) university in a liberal city using (likely) illegal alien construction crews. I trust NO ONE in that entire group to follow the law, much less follow engineering and Code requirements.

[proxy_user]

This is rather off-topic, but back when I was in info tech, we had to run a ‘disaster recovery test’ every year on each system. They caused far more disasters than they prevented!

However, in computers, you could just delete your mistakes and move on.

[mewzilla]

FNC has presser on bridge collape (sic).

[Delta 21]

Lefty loosie, Righty tighty!!

[Red Badger]

it was unclear what builders were using as temporary supports.

Nothing.....................

[lightman]

About five years ago there was a horrific accident on one of the Interstates near Harrisburg, Pennsylvania, when a girder that was being placed for a bridge spanning the roadway fell from the crane into traffic, with a fatality.

Ever since then PennDOT has insisted on full road closures whenever girders are being placed.

[TTFlyer]

Place the blame squarely on where it belongs:

Semi-auto Concrete Nail Guns and the NRA!

"Hey Hey NRA - How Many Bridges Are You Gonna Collapse Today?"

[jaydubya2]

"it was unclear what builders were using as temporary supports"

Air?

[ctdonath2]

A favorite old quote:

Fail-safe systems fail by failing to fail safely.

Whatever happened here, there should have been backup structure in place to secure the bridge when primary structure failed. A single point of failure should _never_ result in the whole thing crashing down.

[butlerweave]

Chinese Steel ,Russian Concrete with Mexican Labor

[Diana in Wisconsin]

“...it was unclear what builders were using as temporary supports.”

I guess they assumed the cars and people beneath would hold it up?

What a nightmare for all involved!

[Real Cynic No More]

“This was about collaboration.”

Better to have been about tried and proven knowledge and expertise than koombaya.

[catnipman]

“950-ton concrete span”

seems like it would have been much safer to use a much lighter, all steel span like essentially all other pedestrian bridges ...

https://www.outtherecolorado.com/favorite-pedestrian-bridges-in-colorado-part-2/

[Chewbarkah]

A post-mortem of what happened must look into the politics that drove the engineering. From initial appearances, failure began with decisions to require an artsy, landmark design, at huge expense and extra complexity, to market the college. Administrators wanted not to solve a need, but to look cool. There is obviously room in the middle of the highway for a center support and conventional bridge.

Testing and adjusting with the road open was idiotic and irresponsible, but almost assuredly driven by the politics of avoiding a public outcry over closing the road for 2 years. Contractors who get jobs are the ones who say “yes, we can do that...for the right price”. Trying to hold up a suspension bridge with one or two construction cranes was foolish beyond comprehension, but a consequence of reckless requirements. Why the main support mast was not built ahead to placing the spans is mysterious.

The non-engineers who insisted on these things will say they relied on others to make it all safe.

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[Real Cynic No More]

If the post-tensioning cables became looser subsequent to initial tensioning, that is an indicator that the concrete surrounding the tension mounting mechanism likely weakened or even crushed over time. Especially since the tensioning steel should actually have increased in stress after the bridge was placed in position last week. Additional tightening of the tensioning mechanism while the bridge was under its dead load might have stressed the concrete surrounding the tensioning mechanism to failure, resulting in the catastrophic collapse.

[Kozak]

I guess if failed the stress test....

[al_c]

Florida Sen. Marco Rubio, R-Fla., tweeted Thursday that the cables that suspended the bridge "had loosened & the engineering firm ordered that they be tightened. They were being tightened when it collapsed."

Huh? What cables? Is he talking about cables that were supposed to come from a tower and support the bridge, or other cables?

[DesertRhino]

Good lord people. Here’s a clue. When someone refers to bridge building as an emerging technology and says we are only beginning to understand it.....that would be sarcasm!
You see, humanity has a several thousand year track record of building bridges.

That’s the joke...get it?