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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

#761

Post by 16bytes »

ProllyInfamous wrote: post #665
16bytes wrote: post #543

Earlier quoted context omitted.

What you are proposing isn't feasible from an engineering perspective. This isn't like putting a guard rail up. To make damage from collisions "impossible" you'd have to build embankments up so high that the bridge would effectively be sitting on solid ground the entire way across and no ships could pass anywhere. Sure, there are ways to mitigate collisions and the new bridge they build will no doubt be more resilien…

How about instead of adding "bumpers," it becomes required for a tug boat to help guide past infrastructure spans like bridges, rail, gas.

There is already something like this in use: harbor pilots, who have specialized knowledge of specific ports and board vessels to navigate them through critical transit zones. It is reported that there were pilots on board navigating at the time of the collision.

Tugs are used in tight locations, but they can only change a ship's speed at a very slow rate compared to that ship's engines. By analogy, you can pull a train car and get it moving by yourself, but if that thing is moving at 5mph you aren't stopping it by yourself in any reasonable distance.

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

#762

Post by squigz »

mhb wrote: post #329
squigz wrote: post #291

Earlier quoted context omitted.

How many people would need to die for it to be justified in your eyes? Or maybe just focus on the potential loss of cargo from trucks on the bridge, if that helps you.

How many? It depends on the opportunity cost of installing and maintaining whatever half baked thing (lights, sirens, computer vision, AI, barriers) it is OP is envisioning on how many thousands of bridges versus the frequency of issues it will prevent. This calculation is done all the time but not so much by the "if it saves only one x" crowd of clever solution proposers.

Out of curiosity, how much is a human life worth in these calculations?

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

#763

Post by dboreham »

araes wrote: post #541
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…

Current personal suspicion after watching your linked video (excellent discussion by the wgowshipping author) is: Catastrophic engine failure (1:24) causing wide scale power loss. No rudder control, rudder drift, and ship alignment drift (1:24-1:25:30) Power restored and ship reengages prop with bad ship/ruddder alignment (1:25). However, ship is now pushing itself into a further bad turn. Pilot likely stomps the bra…

This seems like a system architecture error. Boats do weird shit sometimes and so bridges need to be deigned to not fall down when a boat crashes into them. Requiring a huge boat to be steered to meter resolution when clearly that's not always going to happen is top shelf stupidity. Up there with backup generators in the basement below the water table.

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

#764

Post by mschuster91 »

epcoa wrote: post #617
ultrarunner wrote: post #557

Earlier quoted context omitted.

I'm once again impressed that subject matter experts are out there on every topic, and they are often capable of quickly and accurately disseminating information about an event far better than the local news.

> event far better than the local news. That’s such a ludicrously low bar that I’m not even sure this would qualify as a compliment to these alternative producers.

One might expect that local news are well connected with those who actually did construction, planning and whatnot of such projects, or emergency responders, or disaster mitigation, or people specialized in local geology / hydrology to show up challenges...

The sad truth is that "local" news more often than not barely has any local people any more, a lot of content is directly ripped off from others (especially fire dep't or police reports, with the added problem that no one challenges the copaganda), or not local at all but produced/sourced by central agencies, or theoretically "local" reporters have such large areas to cover that they can't reasonably build relationships with experts.

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

#765

Post by jameshart »

HarryHirsch wrote: post #549
hgfghj wrote: post #521

Earlier quoted context omitted.

That ship had a 10,000 TEU capacity and was actually hauling a little under 5,000 TEUs. An empty container weighs a little over 5,000lbs, and a full one can be up to 67,000lbs. If you do the math, you find that it’s just an astronomical amount of momentum, and there’s no effective defense for a bridge that needs support in more than 30 or so feet of water.

there’s no effective defense for a bridge that needs support in more than 30 or so feet of water You put in sheet piling 50 meters upstream, and you fill the box with rocks. That's state of the art practice, nowadays, but that bridge was 50 years old.

According to the marine traffic track shown in the YouTube analysis above, the ship looks to have been heading through the channel, but then nosed in right under the bridge. Would have sailed right past upstream dolphins, and rammed the pylon from the inside anyway.

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

#766

Post by chx »

xp84 wrote: post #753
1letterunixname wrote: post #722

Earlier quoted context omitted.

I hope the next POTUS makes good on Biden's promises because Baltimore and Maryland will need federal assistance since they can't afford such a burden. And I assume there will lawsuits to recover costs as this caused economic damage and risk to life (8 people unaccounted for at current time).

I'm kind of confused how a President can promise something like that. He doesn't have any power to appropriate money, and given his party's lack of control of Congress, I'd argue he can't promise anything. Not to mention that one can scarcely find a "bluer" area than Baltimore -- I would assume that the most proudly right-wing politicians would be more than happy to let Baltimore suffer to score points with their pol…

> It's my intention that the federal government will pay for the entire cost of reconstructing that bridge and I expect the Congress to support my effort

This is what he said. I would expect Congress to play along too -- just how unpopular would it be to abandon Baltimore??

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

#767

Post by efitz »

jameshart wrote: post #748
rightbyte wrote: post #575

Earlier quoted context omitted.

> my experience with a 40ft sailboat with a single propeller you have absolutely no rudder authority while reversing. I have to protest here. Reversing and using the rudder on a 40ft boat works perfectly fine. I've done it on multiple sailing boats. You need to hold tight so that the rudder wont slap you if using a stick.

Isn’t there a pretty big difference in how much rudder authority you get between just making way astern, and having the engine in full reverse while still traveling forwards at seven knots?

It's complicated.

The rudder is a wing, it's just vertically oriented and underwater.

The rudder is capable of stalling, just like any wing. The rudder only produces lift related to the flow of water over the rudder. The lift produced by the rudder is what is experienced as turning force. The tiller or wheel changes the angle of attack.

I used to helm a racing sailboat with a high aspect (long & narrow) rudder. It could provide a lot of turning force but stalled easily. It didn't work as well under power as it did under sail; I suspect this was due to the turbulent flow off of the propeller, which was forward of the rudder.

On the Dali, the rudder should have been providing some turning force due to the 7+ knot flow of water over the rudder. Full reverse propeller might have impacted that; I can't comment because I've never helmed a ship that large.

Additionally, a single-propeller vessel like the Dali, will have "prop walk" - asymmetric thrust that pushes the stern of the craft one way or the other while the propeller is rotating.

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

#768

Post by FredFS456 »

dboreham wrote: post #763
araes wrote: post #541

Earlier quoted context omitted.

Current personal suspicion after watching your linked video (excellent discussion by the wgowshipping author) is: Catastrophic engine failure (1:24) causing wide scale power loss. No rudder control, rudder drift, and ship alignment drift (1:24-1:25:30) Power restored and ship reengages prop with bad ship/ruddder alignment (1:25). However, ship is now pushing itself into a further bad turn. Pilot likely stomps the bra…

This seems like a system architecture error. Boats do weird shit sometimes and so bridges need to be deigned to not fall down when a boat crashes into them. Requiring a huge boat to be steered to meter resolution when clearly that's not always going to happen is top shelf stupidity. Up there with backup generators in the basement below the water table.

My civ engineer friend says that bridges are supposed to have barriers in front of their pylons for this particular reason - in the event of a collision, the barrier would be destroyed but not the pylon.

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

#769

Post by efitz »

joelshep wrote: post #689
traceroute66 wrote: post #649

Earlier quoted context omitted.

> How many pilots, trained or not, really have any experience with a 100,000 ton ship in a crash situation with responses where seconds matter? I think you are missing the point. Clearly I am speculating, but I don't think any more experience would have helped in this event. Why ? I think what happened today was almost entirely down to not being able to fight the basic Laws of Physics. Its a well known fact that enor…

To continue the speculation ... as a ship that size is slow to turn or halt, that seems to suggest that even if the ship hadn't suffered a power failure then it would have passed quite close to the bridge pier anyway. Was that expected?

Yes, it was expected. Ports have "channels", essentially traffic lanes. Until the first power failure, the Dali was in the proper lane and would not have collided with anything if she had remained there.

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

#770

Post by sib »

Joker_vD wrote: post #473
paddy_m wrote: post #461

Earlier quoted context omitted.

It shouldn't happen. There will be investigations. I think that having a properly operating ship is the captain's responsibility. But the ship's pilot [1] (not captain) should know exactly how the boat will handle and the exact course of action. Pilots are extremely well paid ($200-$400k) and the tests are very stringent. Friends have told me that the Narraganset Bay pilot test involves drawing every shipping navigat…

Where do you get those salary numbers from? The info about this "Dali" ship is not private: [0], and it lists the master's salary as $10,200 per month. [0] https://www.balticshipping.com/vessel/imo/9697428/seafarers

In this case, a seemingly pedantic distinction matters:

Pilot != Master

Pilots are very highly paid

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