Key Bridge

[howardoark]

Elon Musk has opined that the remains of the Key Bridge could be salvaged and used to construct a new bridge in 3 to 6 months. If Leprechauns (I'm not saying this is a realistic scenario) could unbolt all of the steel in the old bridge and gently bring the structural shapes to shore and inspection showed no signs of distress in the bolt holes and tests of 5% of the salvaged beams showed they were factory new, could they be reused?

 

[bridgebuster]

I doubt it.

 

[lexpatrie]

Sure, just lift it and move an entire steel rolling facility to the shore and melt and re-roll them. Those pieces will be bent, of uncertain mechanical properties, with at least some fatigue cracks in them. Elon, despite his alleged business acumen, is not always fully conversant in the facts before he speaks.

Generally there's a history of bridges that are delisted or obsolete being sold/moved, but typically they go from vehicular traffic to pedestrian traffic after they are moved.

 

[Tomfh]

The steel will be recycled in one form or another but it’s hard to see how the bridge itself is anything other than a write off.

 

[hokie66]

The bridge will undoubtedly take a different form. Maybe a cable stayed main span, with a much longer span than the destroyed bridge.

 

[RontheRedneck]

When one of our customers have a set of wood roof trusses fall down, the engineers will not do repairs on them - They must be replaced. The reasoning I've heard is that there may be hidden damage within the wood members.

It's obviously a different material. But I wonder if the same thing would apply?

 

[hokie66]

Not exactly. Steel is a much more ductile material than wood, but using bits and pieces in a new structure is generally more trouble than it is worth. Make new steel out of old, then it can be 'reused'.

 

[SnTMan]

... using bits and pieces in a new structure is generally more trouble than it is worth

IOW, costs more, takes longer, or both...

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[hokie66]

Both.

 

[JoshPlumSE]

Elon Musk has opined that the remains of the Key Bridge could be salvaged and used to construct a new bridge in 3 to 6 months. If Leprechauns (I'm not saying this is a realistic scenario) could unbolt all of the steel in the old bridge and gently bring the structural shapes to shore and inspection showed no signs of distress in the bolt holes and tests of 5% of the salvaged beams showed they were factory new, could they be reused?

Elon Musk is thinking like a CEO.... "let's do the quickest and dirtiest solution to the problem first. When that's done and we're no longer bleeding red ink, we'll come up with a long term solution."

His is an economic thought process, not an engineering one. I'm confident that he's right, That we could re-use a bunch of the existing steel and re-erect it in a half ass way that would be sufficient to carry half or 1/4 of the vehicle traffic that used to be carried by the bridge. And, be tall enough to allow the port to re-open with some restrictions.

But, it would never be a long term solution. Therefore, it is not possible to do for any government project. Maybe a military project where you know it only has to last long enough to fulfill the "mission parameters".

That being said it would not be possible for any public project. There will be many meetings first to determine scope, budget, time frame, environmental impact, economic impact, diversity, equity, inclusion. Who's going to get kick backs, who's not going to get kick backs. Who's to blame for the previous bridge failure. We'll be lucky if they decide anything in 3 to six months.

 

[AZPete]

Run a ferry service in the interim. Part of the ferry fee would go to the new structure, whatever it may be. Users pay for privilege, so the user fee very much is appropriate to the degree it contributes toward replacement cost.

 

[Tomfh]

His is an economic thought process, not an engineering one.

It seems to be his engineering approach; A rapid development process, reusing what works.

 

[JoshPlumSE]

Honestly, Musk's though process is a better process for critical situations. If your patient is bleeding out on the table, you do whatever you can to keep the patient from dying right now.... Then you figure out how to say his (or her) life in the long term.

Honestly, if we really believe that "climate change" will certainly result in dire consequences in the near future for humanity and the world, then we need to start having a more rational "ECONOMIC" thought process towards solving (or mitigating) the problem in the quickest, dirtiest and most economically efficient way.

PS No one actually believes that "climate change" will result in dire consequences in near future. If they did, then the "green lobby" would be jumping up and down encouraging us to build more nuclear plants, not demanding that we shut them down for silly reasons (like the did with San Onofre in California).

 

[JStephen]

An idea may sound great on paper, but somebody has to actually do it.
There aren't very many contractors around that can do that type of bridge erection (or re-erection).
If the few head people at those companies all think it's a stupid idea, it's not going to get done, period.
I can see that being a nightmare on the analysis, inspection, and liability fronts as well.
"Disassembling" a bridge sounds simple enough, until it's underwater, the water is moving and not necessarily clear, it's hugs pieces sticking out at random directions, the crane is bobbing around, etc. etc.

On the ferry idea- building ferries and ferry landings takes time, and when you're done, you still have an enormous bottleneck. Most of these humongous bridges have been built specifically to get away from ferries.