Baltimore's Francis Scott Key Bridge collapse & rebuilding thread

[Notonfoodstamps]

https://www.keybridgerebuild.com/images/equity_environment/FSK_CE_07.17.2024_w_Attachments.pdf

NEPA has been released.

Bridge length will be 2.4 miles. Road grade will be 4 degrees. Minimum bridge air-draft will be 230’. Minimum main span width will be 1200’.

[mhays]

I'm actually surprised. I thought they'd go for the quickest replacement rather than an actual improvement.

That said, I don't see any mention of a bike lane. That seems odd and unfortunate.

[Notonfoodstamps]

Originally Posted by mhays

I'm actually surprised. I thought they'd go for the quickest replacement rather than an actual improvement.

That said, I don't see any mention of a bike lane. That seems odd and unfortunate.

The replacement is almost guaranteed to be a cable-stayed. Knocks out two birds with one stone as they are the quickest method for spanning a navigable waterway of this size. The ports growth for the next century banked on MDTA doing this right.

Regarding a bike lane, the Key Bridge connects industrial areas and forms part of the 695 Beltway so there are no residential within a 1-2 miles of it. Having pedestrian access didn't make particular sense in this scenario.

[Notonfoodstamps]

https://navcen.uscg.gov/sites/default/fi...-24_FrancisScottKey_PatapscoRiver_MD.pdf

Initial design drafts for the replacement bridge

Cable Stayed
Main Span - 1400’
Air Draft - 230’ 9”

Span width is subject to change depending on further input for maritime community.

[wanderer34]

I was hoping for a classic suspension bridge, not the modern cable stayed ones. Something like the Golden Gate and the Brooklyn Bridges are perfect examples, but Baltimore needs a bridge, anyways, so no biggie!

[Cirrus]

Everyone's been expecting cable-stayed since pretty much day 1.

I do think old style suspension bridges are prettier, but nobody much builds them anymore because cable-stayed is 1) cheaper to build, 2) structurally stronger, and 3) safer.

[Busy Bee]

That's pretty much exactly what I was going to say.

[Steely Dan]

Originally Posted by Cirrus

I do think old style suspension bridges are prettier, but nobody much builds them anymore because cable-stayed is 1) cheaper to build, 2) structurally stronger, and 3) safer.

All generally true, with the lone caveat that for EXTREMELY long spans, suspension is still the go-to for bridge engineers.

But for the Francis Scott key bridge replacement, yeah, it's gonna be cable-stayed all the way for the reasons you mentioned.

[Notonfoodstamps]

Originally Posted by wanderer34

I was hoping for a classic suspension bridge, not the modern cable stayed ones. Something like the Golden Gate and the Brooklyn Bridges are perfect examples, but Baltimore needs a bridge, anyways, so no biggie!

Technically the Brooklyn Bridge is a hybrid suspension/cable stayed

As is, this would be the 3rd longest Cable Stayed in North America.

[Steely Dan]

Originally Posted by Notonfoodstamps

As is, this would be the 3rd longest Cable Stayed in North America.

At 1,400', I think it would be 10th in NA by main span.


Longest cable-stayed bridge spans in North America:

1. Gordie Howe Bridge, Detroit - 2,800' - U/C (span completed)
2. Atlantic Bridge, Panama - 1,740'
3. Baluarte Bridge, Mexico - 1,710'
4. Harbor Bridge, Corpus Christi - 1,661'- U/C (span @ 95%)
5. Audubon Bridge, Louisiana - 1,583'
6. Ravenel Bridge, Charleston, SC - 1,546'
7. Port Mann Bridge, Vancouver - 1,540'
8. Alex Fraser Bridge, Vancouver - 1,526'
9. Stan Musial Bridge, St. Louis - 1,500'
*. FSKB replacement, Baltimore - 1,400' - proposed
10. Centennial Bridge, Panama - 1,380'




I was hoping this one would be closer to 2,000' to take the #2 spot in NA, but it's looking like it might not be that exceptional of a span after all.

We'll see exactly where it ends up, I guess.

Wouldn't have to push the span too much further to take #2 in the US, at least. Hell, even #2 in all of NA isn't really that far away.

[Notonfoodstamps]

Originally Posted by Steely Dan

At 1,400', I think it would be 10th in NA by main span.


Longest cable-stayed bridge spans in North America:

1. Gordie Howe Bridge, Detroit - 2,800' - U/C (span completed)
2. Atlantic Bridge, Panama - 1,740'
3. Baluarte Bridge, Mexico - 1,710'
4. Harbor Bridge, Corpus Christi - 1,661'- U/C (span @ 95%)
5. Audubon Bridge, Louisiana - 1,583'
6. Ravenel Bridge, Charleston, SC - 1,546'
7. Port Mann Bridge, Vancouver - 1,540'
8. Alex Fraser Bridge, Vancouver - 1,526'
9. Stan Musial Bridge, St. Louis - 1,500'
*. FSKB replacement, Baltimore - 1,400' - proposed
10. Centennial Bridge, Panama - 1,380'




I was hoping this one would be closer to 2,000' to take the #2 spot in NA, but it's looking like it might not be that exceptional of a span after all.

We'll see exactly where it ends up, I guess.

Wouldn't have to push the span too much further to take #2 in the US, at least. Hell, even #2 in all of NA isn't really that far away.

I meant 3rd longest in the US. WeBuild pitched a 2300’ main span but it was pro-bono.

MTA is having open forums with the maritime community right now to address any concerns about main span width for current and or future vessels.

[Steely Dan]

Originally Posted by Notonfoodstamps

I meant 3rd longest in the US.

At 1,400', it would be the 6th longest cable-stayed main span in the US.

[TowerDude]

I think the bigger deal with the new bridge will be the increased height over the water which will allow for larger container ships to serve the Port of Baltimore.

[Notonfoodstamps]

Originally Posted by TowerDude

I think the bigger deal with the new bridge will be the increased height over the water which will allow for larger container ships to serve the Port of Baltimore.

Yeah, the only container ships that can’t fit are the giga +20k TEU ones bound from Asia. Baltimores routinely gets the 12-14k TEU Neo-Panamax ships.

The cruise industry on the other hand is probably licking its chops right now. There’s ~20 million people within an hour of two of Baltimore, so homeporting the newest Royal Caribbean or Carnival ship(s) is going to be massively profitable.

Originally Posted by Steely Dan

At 1,400', it would be the 6th longest cable-stayed main span in the US.

Thanks for the correction. MD just announced that it’s replacing the Bay Bridges a few days ago and the OG bridges have 1600’ spans. I’d assume the replacement spans will probably be cable-stayed and have a larger main span.

There’s going to be a lot going on infrastructure wise in the Baltimore area.

[Notonfoodstamps]

Official designs of the bridge will be unveiled today at 11:30am

https://wjla.com/amp/news/local/governor-moore-unveils-new-design-of-key-bridge

[Notonfoodstamps]

H - type tower design. No exact span dimensions, yet.

For scale context the BGE power poles are 650m apart. So the main span was increased from the initial 1400’ Coast Guard/MTA request.

Tweaks to the design might still happen as it’s a design/building project.

[Busy Bee]

Should be lovely. I think most expected it to look pretty much like this.

[Steely Dan]

The main span definitely looks greater than 1,400'!!

The two existing utility towers in the background here are 2200' feet apart, so maybe 1,600+ feet for the new span?


Source: https://www.thebaltimorebanner.com/econo...esign-towers-JQKH7YS3YJEGRKWFBIHDFBNXWY/

[Notonfoodstamps]

Originally Posted by Steely Dan

The main span definitely looks greater than 1,400'!!

The two existing utility towers in the background here are 2200' feet apart, so maybe 1,600+ feet for the new span?


Source: https://www.thebaltimorebanner.com/econo...esign-towers-JQKH7YS3YJEGRKWFBIHDFBNXWY/

Definitely looking like a ~1800’ span. The channel width is 800’ and it’s pretty much a universally accepted rule to have span length + 2x navigation width.

Less than 100’ splits #2-4 in the western hemisphere so it will be interesting on the final specs.

[Steely Dan]

No hard figures yet, but I did find this article that at least had some numbers in it.

The span will have two pylons with cables jutting out from the top, forming webs of support, towering more than 600 feet above the Patapsco River. That makes the structure significantly taller than the original steel truss bridge’s highest point of 358 feet and higher, even, than initially anticipated.

The Maryland Transportation Authority proposed in a document last summer pylons about 500 to 550 feet tall and a main span — that is, the gap between the two primary support piers — about 1,400 feet long.

To ensure the bridge is adequately protected, however, the new plan is for the main span to be at least 1,600 feet wide.

Source: https://www.thebaltimorebanner.com/econo...esign-towers-JQKH7YS3YJEGRKWFBIHDFBNXWY/



So the towers will be at least 600' tall and the span will be at least 1,600' long.

#2 cable-stayed bridge in NA is very much within easy reach here, if they want it.