re: Francis Scott Key Bridge in Baltimore has collapsed - container ship wrecked into it

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I'm a ME not civil so maybe you CE's can comment on how long it would even take to engineer a replacement bridge. Are there pre-engineered solutions a CE just need to throw in a few parameters and spit out drawings for a PE to review and stamp? Or would a bridge like this be a from the ground up design? I'd imagine just getting the supply chain up and running on a project like this would be several months in and of itself and that process doesn't start until there is an actual design and drawings.

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No. There's not any pre-engineered solutions. I'm assuming they'll maintain the existing approach spans and only replace the 3-span truss that went down. They will first have to decide on the type of structure they want (truss, cable stay, suspension, etc.) and what span arrangement (the original was 700'-1200'-700').

Everything has to be designed from the top-down to the latest codes for the latest design loads. Geometrics have to be nailed down as well. Design-Bid-Build would probably take 1.5-2 years design and 3-4 years to build. Accelerated delivery methods (Design-Build, Construcion Manager/General Contractor) could cut that total down by 1-2 years.

Lead time on materials is real, and, yes, there's not a good idea on exactly what is needed until design is finished. Something to remember is you don't need all of it on hand at the same time. Materials and fabrication for top of bridge elements can be in process while youre building the foundations and piers/bents.

It's going to be 5+ years to get something built. The Loyola Interchange in New Orleans is something you can maybe use for context. That project has taken about 5 years from design to opening, but that's not including the front end time to get proposals and bids in to award the work.