Francis Scott Key Bridge (I-695) complete collapse after large ship hits it

[Bobby5280]

$5 billion!? Why??? Are they proposing to build the roadway 500' above the Patapsco River and pack 10 lanes into it? Or maybe every law firm within 500 miles of the construction site is going to get a fat check.

[Plutonic Panda]

Yeah, that's really bizarre. The article says it will be at least 5 billion so possibly more. That doesn't make sense.

[Rothman]

Cuomo Bridge was $4B.  Seems about right taking into account the insane inflation in the construction industry since.

[kphoger]

I'm skeptical about the reliability of the source, considering the article refers to them only as "two people engaged in the discussions".

[GaryV]

Gordie Howe Bridge is at $6.4B Cdn. So $5B is not an unreasonable guess. Depends on who is really guessing, I guess.

[Beltway]

Cuomo Bridge was $4B.  Seems about right taking into account the insane inflation in the construction industry since.

Tappan Zee Bridge has 10 lanes with full shoulders right and left.

MDTA proposal has 4 lanes.

Politico is saying the bridge cost could exceed $5 billion:
https://www.politico.com/news/2025/09/11/baltimore-bridge-rebuild-expected-to-cost-over-5-billion-00558793

Who came up with this? I don't see any engineering source quoted.

How did MDTA come up with the $1.7 to $1.9 billion estimate? Was there any well-scoped preliminary design cost estimate?

I worked in road design and working up detailed engineering cost estimates was one of my duties.

I am regularly adding things like this Politico article to my website article.

Gordie Howe Bridge is at $6.4B Cdn. So $5B is not an unreasonable guess. Depends on who is really guessing, I guess.

Gordie Howe includes several miles of approach freeway and a freeway interchange with I-75 and dual customs plazas on both sides of the border.

[Beltway]

Risks during construction of cable-stayed bridge

Synthesis of the ship strike vulnerability during long-span segmental bridge construction, especially relevant to the Key Bridge context. Something else that the highway agencies have had no transparency about. Yet another reason to avoid building deep water main piers close to a shipping channel.

During construction, long-span segmental bridges are uniquely vulnerable to ship strikes due to their staged cantilever erection method. As segments are added outward from each pier, the growing cantilever arms remain unsupported at their tips until closure, creating a precarious balance. At this phase, the structure lacks redundancy -- each arm is anchored only at its base, and any impact near the pier can destabilize the entire span. This fragility is compounded by the absence of permanent protective structures like dolphins or fender systems, which are typically installed only after the main piers are complete. In high-traffic shipping lanes, this leaves the bridge exposed to vessel strikes at its most delicate stage.

Even a minor collision -- such as a glancing blow from a barge -- can misalign segments, disrupt post-tensioning sequences, or trigger progressive collapse. The dynamic loads introduced by a ship strike are amplified by the cantilever geometry, especially if the impact occurs before epoxy shear keys have cured or before stabilizing cables are fully post-tensioned. Construction equipment itself, cranes, barges, and temporary platforms, adds to the risk, as their failure or displacement during a strike can cause cascading damage.

This is a vulnerable period to high winds as well, even a category 1 hurricane (the lowest) would put it at high risk of serious damage or destruction.

There would be at least a 12 month period where large partially completed and minimally support structures exist. A collapse of one main pier and structures could again block the shipping channel for weeks, and require an additional $500 million or more to rebuild that.

This phase of vulnerability is often hidden from public view, creating a visibility bias in how infrastructure resilience is perceived. Renderings and progress photos may suggest strength and completion, but until closure and full tensioning, the bridge is a choreography of unsupported mass -- one that can be undone by a single miscalculated impact. In the case of the Key Bridge, this underscores the need for strategic reframing: not just of collapse analysis, but of the entire construction-phase risk logic that precedes it.

[Rothman]

Risks during construction of cable-stayed bridge

Synthesis of the ship strike vulnerability during long-span segmental bridge construction, especially relevant to the Key Bridge context. Something else that the highway agencies have had no transparency about. Yet another reason to avoid building deep water main piers close to a shipping channel.

During construction, long-span segmental bridges are uniquely vulnerable to ship strikes due to their staged cantilever erection method. As segments are added outward from each pier, the growing cantilever arms remain unsupported at their tips until closure, creating a precarious balance. At this phase, the structure lacks redundancy -- each arm is anchored only at its base, and any impact near the pier can destabilize the entire span. This fragility is compounded by the absence of permanent protective structures like dolphins or fender systems, which are typically installed only after the main piers are complete. In high-traffic shipping lanes, this leaves the bridge exposed to vessel strikes at its most delicate stage.

Even a minor collision -- such as a glancing blow from a barge -- can misalign segments, disrupt post-tensioning sequences, or trigger progressive collapse. The dynamic loads introduced by a ship strike are amplified by the cantilever geometry, especially if the impact occurs before epoxy shear keys have cured or before stabilizing cables are fully post-tensioned. Construction equipment itself, cranes, barges, and temporary platforms, adds to the risk, as their failure or displacement during a strike can cause cascading damage.

This is a vulnerable period to high winds as well, even a category 1 hurricane (the lowest) would put it at high risk of serious damage or destruction.

There would be at least a 12 month period where large partially completed and minimally support structures exist. A collapse of one main pier and structures could again block the shipping channel for weeks, and require an additional $500 million or more to rebuild that.

This phase of vulnerability is often hidden from public view, creating a visibility bias in how infrastructure resilience is perceived. Renderings and progress photos may suggest strength and completion, but until closure and full tensioning, the bridge is a choreography of unsupported mass -- one that can be undone by a single miscalculated impact. In the case of the Key Bridge, this underscores the need for strategic reframing: not just of collapse analysis, but of the entire construction-phase risk logic that precedes it.

Florida managed it just fine.

"Hmmmmm," [Prostetnic Vogon Jeltz] said, "Synthesis of the ship strike vulnerability during long-span segmental bridge construction..."  He considered this for a moment, and then closed the book with a grim smile...

[Beltway]

Florida managed it just fine.

Despite their reputation, the Sunshine Skyway and Dames Point Bridge were just listed by the NTSB among 68 U.S. bridges requiring a vulnerability assessment for ship strike collapse risk. Why? They were built before the 1991 AASHTO vulnerability guidelines. They have no current vessel impact risk calculation using modern standards. The NTSB emphasized that inclusion on the list doesn't mean imminent collapse -- but it does mean unknown risk.

These assessments were triggered by the Francis Scott Key Bridge collapse, which exposed how outdated design assumptions and lack of protective structures can lead to catastrophic failure. Florida's bridge wasn't "managed just fine" -- they were built before modern vulnerability assessments were required, and still lacks a comprehensive risk mitigation plan. Florida didn't "manage it" -- it got lucky, and now its flagship cable-stayed bridge is under federal scrutiny.

Cable-stayed bridges are another horse of a different color, and Maryland has no experience with them.

[Rothman]

Florida managed it just fine.

Despite their reputation, the Sunshine Skyway and Dames Point Bridge were just listed by the NTSB among 68 U.S. bridges requiring a vulnerability assessment for ship strike collapse risk. Why? They were built before the 1991 AASHTO vulnerability guidelines. They have no current vessel impact risk calculation using modern standards. The NTSB emphasized that inclusion on the list doesn't mean imminent collapse -- but it does mean unknown risk.

These assessments were triggered by the Francis Scott Key Bridge collapse, which exposed how outdated design assumptions and lack of protective structures can lead to catastrophic failure. Florida's bridge wasn't "managed just fine" -- they were built before modern vulnerability assessments were required, and still lacks a comprehensive risk mitigation plan. Florida didn't "manage it" -- it got lucky, and now its flagship cable-stayed bridge is under federal scrutiny.

Cable-stayed bridges are another horse of a different color, and Maryland has no experience with them.

Nice shift of the goalposts...

I don't see the NTSB's report on this matter as an emergency.

[Max Rockatansky]

Time to break the popcorn out again?   

[Beltway]

Nice shift of the goalposts...

No -- the public needs to see those issues addressed in the preliminary design phase.

The Corpus Christi Harbor Bridge project was a fiasco in several different areas, and this should be a warning on cable-stayed bridge projects.

[Rothman]

Nice shift of the goalposts...

No -- the public needs to see those issues addressed in the preliminary design phase.

Nice non sequitur

[Beltway]

No -- the public needs to see those issues addressed in the preliminary design phase.

Nice non sequitur

Uh huh.

My main desire over the last few days is to address the $5 billion estimate in the Politico article. How was it derived, it is accurate, etc.

[GaryV]

Why? They were built before the 1991 AASHTO vulnerability guidelines. They have no current vessel impact risk calculation using modern standards. The NTSB emphasized that inclusion on the list doesn't mean imminent collapse -- but it does mean unknown risk.

So because we don't know if they're vulnerable or not, that means they definitely are vulnerable. Gotcha.

[Max Rockatansky]

Me personally I'm finding cable stay designs to have become kind of bland.  Trouble is that they are probably the cheapest option out there and something needs to go up with relatively expediency.  It isn't as though the Key Bridge was a looker in terms of design aesthetics. 

But damn, there is sure a lot of logic flexing to steer this back around to "I think a tunnel is needed."  The strategy by Beltway seems to be deploying is weaponizing "safety' and hope nobody will question it.

If I recall correctly the Long Beach International Gateway Bridge ultimately cost around $2 billion by the time it was completed.  In theory the Key Bridge replacement would be a similar length and $5 billion seems kind of high at first blush for an estimate. 

[Bobby5280]

Multiple solutions are available to protect bridge piers. Fender systems can be installed at the base of the piers. "Dolphins" can be positioned near the piers. Or the piers can be surrounded with artificial islands loaded with "rip rap" (big rocks or concrete blocks). The Verrazano Bridge has that around its piers. I would expect a replacement to the Francis Scott Key Bridge to have one or more of those solutions installed. I don't think the old bridge had any of those safety measures.

With these new construction estimates being so ridiculously high it makes me wonder how much the proposed Great River Bridge cost has risen.

[NE2]

No -- the public needs to see those issues addressed in the preliminary design phase.

Nice non sequitur

Uh huh.

My main desire over the last few days is to address the $5 billion estimate in the Politico article. How was it derived, it is accurate, etc.

Nice goat.

[hotdogPi]

Anyone notice how there were no arguments between August 28 and September 12?

[Max Rockatansky]

Anyone notice how there were no arguments between August 28 and September 12?

This thread got a nice two-page lobotomy (deservedly so).  I was curious to see when it would start to unravel again.  I wouldn't say it has yet, I just get the feeling it is on the precipice.   

But yeah, I'll bite on the cost estimates with the replacement span being projected as questionably high.  Hence why I made a comparison to a similar cable stayed span built in my neck of the woods.

[kphoger]

The strategy by Beltway seems to be deploying is weaponizing "safety' and hope nobody will question it.

Yes, I did address that weaponization.  People deserve to know the truth, but don't worry, that's why I'm chronicling it.

[Max Rockatansky]

The strategy by Beltway seems to be deploying is weaponizing "safety' and hope nobody will question it.

Yes, I did address that weaponization.  People deserve to know the truth, but don't worry, that's why I'm chronicling it.

Ah yes, the diligent observational note taking must continue. 

[vdeane]

Cuomo Bridge was $4B.  Seems about right taking into account the insane inflation in the construction industry since.

Tappan Zee Bridge has 10 lanes with full shoulders right and left.

MDTA proposal has 4 lanes.

It was also built a decade ago.  Since then, we've had more than a bit of inflation and construction has been hit especially hard.  I remember railroad grade crossings used to cost around $300,000 for new lights/gates back then.  These days, the same upgrades cost close to a million dollars.

Gordie Howe Bridge is at $6.4B Cdn. So $5B is not an unreasonable guess. Depends on who is really guessing, I guess.

Gordie Howe includes several miles of approach freeway and a freeway interchange with I-75 and dual customs plazas on both sides of the border.

"Several miles" is a massive overstatement, especially since the extension of ON 401 was finished a decade ago as a separate project.

[Beltway]

If I recall correctly the Long Beach International Gateway Bridge ultimately cost around $2 billion by the time it was completed.  In theory the Key Bridge replacement would be a similar length and $5 billion seems kind of high at first blush for an estimate. 

Construction start   January 8, 2013
Construction end   October 2, 2020

Post Covid heavy construction costs have gone thru the roof, with all the supply chain issues. 100% inflation is not out of the question.

Besides that is a smaller bridge with a 1,000 foot main span, which was long enough to completely cross the waters.

Also, 91 months is a lot longer than the 36 months that MDTA is hoping for.

Multiple solutions are available to protect bridge piers. Fender systems can be installed at the base of the piers. "Dolphins" can be positioned near the piers. Or the piers can be surrounded with artificial islands loaded with "rip rap" (big rocks or concrete blocks). The Verrazano Bridge has that around its piers. I would expect a replacement to the Francis Scott Key Bridge to have one or more of those solutions installed. I don't think the old bridge had any of those safety measures.

Bridge protection schemes like those at the Sunshine Skyway have never faced a Dali-scale test. And they're not designed for the more probable threat: a medium-mass vessel at high speed.

A Panamax bulk carrier, at 50,000-60,000 DWT and 25-foot draft, is common in U.S. ports and perfectly capable of traveling at or above 14-15 knots in fairway conditions. After Dali, designers need to take into account that some ships will be handled with gross negligence.

The physics are unforgiving. Velocity multiplies impact energy exponentially.

Cuomo Bridge was $4B.  Seems about right taking into account the insane inflation in the construction industry since.

Tappan Zee Bridge has 10 lanes with full shoulders right and left.
MDTA proposal has 4 lanes.

It was also built a decade ago.  Since then, we've had more than a bit of inflation and construction has been hit especially hard.  I remember railroad grade crossings used to cost around $300,000 for new lights/gates back then.  These days, the same upgrades cost close to a million dollars.

True indeed!

Gordie Howe Bridge is at $6.4B Cdn. So $5B is not an unreasonable guess. Depends on who is really guessing, I guess.

Gordie Howe includes several miles of approach freeway and a freeway interchange with I-75 and dual customs plazas on both sides of the border.

"Several miles" is a massive overstatement, especially since the extension of ON 401 was finished a decade ago as a separate project.

Total new construction length between I-75 and ON-401 is 3.8 miles. Say 1.1 mile west of the bridge and 1.0 mile east of the bridge.

Why? They were built before the 1991 AASHTO vulnerability guidelines. They have no current vessel impact risk calculation using modern standards. The NTSB emphasized that inclusion on the list doesn't mean imminent collapse -- but it does mean unknown risk.

So because we don't know if they're vulnerable or not, that means they definitely are vulnerable. Gotcha.

It means what it says -- they were listed by the NTSB among 68 U.S. bridges requiring a vulnerability assessment for ship strike collapse risk.  I think you could say that means they are vulnerable.

[Rothman]

Why? They were built before the 1991 AASHTO vulnerability guidelines. They have no current vessel impact risk calculation using modern standards. The NTSB emphasized that inclusion on the list doesn't mean imminent collapse -- but it does mean unknown risk.

So because we don't know if they're vulnerable or not, that means they definitely are vulnerable. Gotcha.

It means what it says -- they were listed by the NTSB among 68 U.S. bridges requiring a vulnerability assessment for ship strike collapse risk.  I think you could say that means they are vulnerable.

No, you can't.  Not until an assessment concludes such.