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Baltimore's Key Bridge struck by cargo ship, collapses

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Re: Baltimore's Key Bridge struck by cargo ship, collapses

#711

Post by quinncom »

SushiHippie wrote: post #190
dredmorbius wrote: post #144

Earlier quoted context omitted.

Clip here, beginning at 1m23s, shows a (sped-up) edit of the ship approaching the bridge, with lights going out, on, and out again immediately prior to impact: https://yewtu.be/watch?v=Cs6PrRiIHEw&t=1m23s >

Curious, is there a specific reason you put links between ?

RFC 3986, from 2005: “Uniform Resource Identifier (URI): Generic Syntax”:

    Using  angle brackets around each URI is especially recommended as
    a delimiting style for a reference that contains embedded whitespace.
https://datatracker.ietf.org/doc/html/rfc3986>

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#712

Post by 1letterunixname »

Sky News was able to secure a civil engineer to give insight and analysis into this disaster in the morning hours.

It was a lightweight structure built in the spirit of minimizing cost and anticipating container ships that were approximately ¼ the mass that they are today. That giant ship smashing a critical base of support, the structure could not support itself and experienced rapid failure.

Necessary action item: Structure owners adjacent to commercially-important waterways should reassess their risks of collision by modern-sized extreme ships and mitigate where possible to preserve life-safety and sometimes property.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#713

Post by manzanarama »

samstave wrote: post #539
bastardoperator wrote: post #494

Earlier quoted context omitted.

The video is surreal, it looks like it barely bumps the bridge and 2 seconds later the entire thing is gone. I don't know what I was expecting, the bridge just looked extremely fragile, makes me wonder what other bridges are at risk of an event like this.

[flagged]

I have no idea what any of this means.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#714

Post by HeyLaughingBoy »

b33j0r wrote: post #208
Retric wrote: post #187

Earlier quoted context omitted.

Bridges only last for roughly 50 years. Considering such collisions are rare enough to make the news as a memorable event you can workout for yourself that the odds are quite low over a bridges lifespan. They are designed to withstand smaller boat impacts because they occur relatively frequently, but cost vs benefit on rare events that are difficult to mitigate is quite different.

Interested in this claim, because it sounds about right, except that I can’t name a bridge constructed in the past 50 years. The bridges we can all name are pushing 100+ right?

Living not too far outside Minneapolis, we rebuilt a bridge that rather famously came down a bit over 15 years ago.

https://en.wikipedia.org/wiki/I-35W_Mississippi_River_bridge

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#716

Post by londons_explore »

bobthepanda wrote: post #565
throw0101b wrote: post #550

Earlier quoted context omitted.

> I don't know what I was expecting, the bridge just looked extremely fragile, makes me wonder what other bridges are at risk of an event like this. The bridge style in question > Conversely, continuous truss bridges rely on rigid truss connections throughout the structure for stability. Severing a continuous truss mid-span endangers the structure. However, continuous truss bridges do not experience the tipping force…

cable stays are also generally more popular these days because of the differences in material. All other things being equal, concrete is generally a lot cheaper than a steel truss bridge these days

If they play the cards very carefully, they can pull out and recycle all the steel of the old bridge, and use that to pay for a new (cheaper) concrete bridge.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#717

Post by PeterCorless »

bobthepanda wrote: post #646
kazinator wrote: post #604

Earlier quoted context omitted.

I think the only reasonable goal would be to design the bridge to minimize damage to it, so that one damaged section doesn't bring down others. Building a bridge to actually stop the ship is not only infeasible, but it would likely kill (more) people onboard.

the modern practice is layers of defense; in addition to building a bridge that doesn't fail at a single point of failure, you also generally design what's around a bridge pier to stop or at least slow down the ship (by, say, running aground onto a bed of rocks around a pier)

For a bridge such defenses are called dolphins.

"A notable example of dolphins used to protect a bridge is the Sunshine Skyway Bridge across the mouth of Tampa Bay. In 1980, the MV Summit Venture hit a pier on one of the bridge's two, two-lane spans causing a 1,200-foot (370 m) section of the bridge to fall into the water, resulting in 35 deaths. When a replacement span was designed, a top priority was to prevent ships from colliding with the new bridge..."

Source: https://en.wikipedia.org/wiki/Dolphin_(structure)

The MV Summit Venture was a 33,900 deadweight tonnage ship. MV Dali was a gross tonnage of 95,128. Nearly 3× as large. It's questionable whether dolphins would have totally prevented such a tragedy.

Yet similarly, expect dolphins to be brought up as a key component of resiliency for any designed replacement bridge.

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#718

Post by tasuki »

marpstar wrote: post #634
sickofparadox wrote: post #429

Earlier quoted context omitted.

It's likely that a lot of people don't understand just how huge these ships are. I'd imagine that much of HN doesn't have a ton of firsthand experience with shipping yards or even close friends/relatives that work on these things. In my experience, almost nothing hides just how large it is than a giant ship.

My family and I drove through the Ports of LA/Long Beach on vacation last summer. A port is basically an entire city dedicated to getting things in/out of the water. Takes 15-20 minutes to drive through. You can't imagine the number of cranes/lifts. It's worth the drive through. This ship was carrying ~5,000 TEU (Trailer Equivalent Units). Imagine 5,000 fully packed semi trucks crashing into the single upright of tha…

Would it even stand a chance at 1 mph? If not, what is the speed that would make it imaginable for the bridge not to collapse?

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#719

Post by hwh47 »

TaylorAlexander wrote: post #66

Somehow I find it surprising how completely the bridge collapsed after the damage. I understand that a container ship collision is serious, but you could imagine a scenarios where the bridge slumps or buckles but doesn’t just disintegrate like that. It’s surprising that ships capable of doing this damage were probably regularly driving past it, and its safety as a thoroughfare depended entirely on those collisions no…

separate but pertinent question: what was the mv dali's air draft? (FSK bridge's clearance is 185'/56m) was the container ship going to fit under the bridge, i.e., perhaps the incident was an aborted attempt to crossing under the bridge?

Re: Baltimore's Key Bridge struck by cargo ship, collapses

#720

Post by mlrtime »

bastardoperator wrote: post #494
paddy_m wrote: post #438

Youtube tracking analysis from a knowledgeable mariner. He says that at about 1:24 AM the ship loses power (from video feed) while traveling 8.5 knots. at 1:25.30 power is restored. at 12:25.59 the ship shows smoke. The ship has already drifted in the channel. It is believed that at this time the ship applied full reverse power as evidenced by the black smoke. (My analysis: the ship drifted but hasn't turned in the c…

The video is surreal, it looks like it barely bumps the bridge and 2 seconds later the entire thing is gone. I don't know what I was expecting, the bridge just looked extremely fragile, makes me wonder what other bridges are at risk of an event like this.

F = MA

A looks like 'barely a bump' M is what got the bridge.

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