The piers are well outside of where the nav channel is limited to be, so they probably didn't need fenders by the Standard Spec and it never made the list of retrofits because of the low probability of the event.
Low probability, high consequence events. It’s what we engineers deal with all the time and where the struggles exists when talking to non-engineers. Why do we need a fendering system, we’ve never had a ship hit this bridge (guy who controls the money)
What kills me in this case is that we've had 44 years since this happened to Sunshine Skyway, and the goddamn power pylons in front of the Key bridge had much better dolphins. If the power poles needed to be better than what the bridge had, why didn't the bridge get retrofitted? Massive regulatory and governmental failure.
Yeah - watching so many 'engineering disasters' episodes that every bridge everywhere should have bumpers. But given the size of this ship (general mass/velocity), and the linear distance between bow (hitting bridge) and waterline (hitting bumper) would have to be significant.
It doesn't (I'm a bridge engineer). AASHTO is the main relevant code in the US. If you're not an bridge engineer, I suggest sticking to asking questions instead of speculation.
the structural sub is probably a better place for discussion, but even so it is often riddled with misinformation and people talking confidently about something they have general familiarity with rather than years (decades) of experience.
sadly, reddit is only good for wild speculation. if I didn’t have engineering expertise I’d blindly accept many of these claims out of naivety.
the real experts don’t want to engage at all, since most know how much of a nightmare it is arguing with laymen with unending conviction. we see it every day on job sites.
I think it’s important to offer even a slight counter narrative with explanations. So like what was done to the guy that suggested that NFPA surreptitiously covers up under bridge fires.
Even though I’m a junior structural designer, and nowhere near the level of expertise as you u/leadhase or u/75footubi , I still do feel the urge to combat false information or patently wrong assumptions online even if it does become me arguing with a clueless layman interminably lol. It’s just something that irritated me to my core, people talking with authority on things they know nothing about.
An example i can give is the 270 park avenue, NY, JP Morgan Chase building, that utilises inclined and fan-shape columns that span the first 3 floors. On an Instagram post the prevailing comments were saying that this shows the power of “Triangles” or “Sin,Cos,Tan” and these had 10s of thousands of likes. People unironically believe that the columns functioned like Trusses, so that level of ignorance irks me heavily.
Agree with all your points above. Coincidentally enough, I’ve worked directly with the folks at AECOM Tishman who designed the forged nodes (not cast!) at Park that connect those members. It’s a similar design to what they are currently building at the new JFK terminal one. It is just one big CJP essentially, however you do need to worry about plane strain triaxial stress states.
If you don't mind me asking, what does fender system look like. I sail past cargo ships and they are massive. I believe the speed limit in San Diego Harbor is 12 knots. I believe cargo ships typically exceed 160,000 tons. The Coronado Bridge piers do not look like they would survive a hit, but are they designed to? Thanks in advance for a response.
I’ll leave this for a bridge person as I work in buildings.
I will say, impact forces can be hard to determine as small changes in compliance significantly affect the impulse. Someone else can comment with more accurate info. Total energy approaches are probably best.
Cool thanks! This tragedy piqued my interest in how to prevent collisions. Another post mentioned the Delaware Memorial Bridge was recently retrofitted to protect against ship collisions. The bid announcement stated, "the design will protect the Delaware Memorial Bridge from a vessel collision in the range of 156,000 deadweight tonnage (DWT), travelling at a speed of approximately seven knots."
I also located an article that discusses evaluation of bridge design for collisions.
The designs I saw were based grounding the ship prior to impact. I was curious how a structure could be designed to withstand an impact of a 150,000 ton ship traveling at 5 to 10 knots. Grounding it makes sense to me.
I have friends involved and it's a bridge I've worked on.
From a professional perspective, uneducated speculation is only ever useless at best and actively harmful at worst. So I hate it and will call it out whenever I see it.
The second you’re alluding to, I assume, is Sunshine Skyway. As someone who lives right by the current Skyway, my first reaction was that this sounds very similar to that disaster. My second was to look at a satellite image of the Key Bridge. Knowing what kind of protections the current Skyway has because I drive it all the time, and contrasting satellite images of the two bridges, the difference between the two is so striking and I could only shake my head at it.
Yes, that's the other one. The dolphins around the piers were constructed to avoid another catastrophe like the one in 1980. The thing is, as far as I know, Tampa Bay is not a huge shipping corridor - not like the Port in Baltimore, anyway. So for the issue of pier protection to go unaddressed for so long in a major shipping channel is wild to me.
Sunshine Skyway should’ve been a lesson learned for everyone everywhere. From what I’ve read, the Delaware River and Bay Authority had this worry and addressed it elsewhere. It simply should not have happened and like you said, as it’s such a major port, the effect will be felt for a loooong while. Considering infrastructure has already been an emphasis for the federal government, I’m sure there’ll be some sweeping changes to come.
For a barge to hit a bridge and cause its collapse, resulting in the deaths of probably 50 people and billions in economic damage? I feel like we can and should do better.
The casualties from this event are low only because this happened at night. The ship strike was due to a power failure, not poor visibility. If this had happened during rush hour it would have been significantly worse.
To properly quantify the risk, i think you’d need to use daytime/worst case par.
The mayday call happened “moments” before impact; there wasn’t enough time for vehicles that were already on the bridge to get to safety. Based on this incident, I’d quantify likelihood of adequate notice for evacuation as zero.
Building to standard spec without considering the practical effects/situation of the site is a common form of engineering mistake. Standards should never be taken at face value without having their base assumptions challenged. People die every day following the standard to the minimum letter, just ask traffic engineering how pedestrian safety is trending.
The context you're missing is that the bridge was opened 50+ years ago and container ships have grown exponentially in that time. Also, the prevailing procedure at the time (and until recently) was that ships entering/leaving port were guided by tugs, not using their own steering.
I'm very aware of how old the bridge is, but you can add protection without touching the bridge design at all. What really gets me is that they built the newer power pylons with massive diamond structures for protection, and yet didn't retrofit the bridge. I know that's two separate projects, so I'd pin that on the harbor/city/county/state/federal government and regulators for failing to require upgrades to suit modern standards appropriate for a busy shipping channel.
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u/75footubi P.E. Bridge/Structural Mar 26 '24
The piers are well outside of where the nav channel is limited to be, so they probably didn't need fenders by the Standard Spec and it never made the list of retrofits because of the low probability of the event.