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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

#831

Post by ifwinterco »

trilbyglens wrote: post #582
jordanb wrote: post #495

Earlier quoted context omitted.

The problem is with steering. The rudder on a ship this big is going to be wall of steel several stories tall with gears as big as car. Warships have several independent backup steering options reducing finally to a worm gear at the top of the shaft with a winch handle big enough to put a gang of men on it. But ships like this will have none of that. They will have a small wheel or joystick on the bridge and if power…

Wouldn't a ship like this have bow thrusters? Seems like otherwise it would be impossible to get into port without a tug.

Bow thrusters are only effective at very low speeds due to the Coandǎ effect

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

#832

Post by egberts1 »

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…

Other photos of aftermath shows an anchor dropped. Was wondering if he dropped anchor before the impact.

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

#833

Post by Cheer2171 »

chx wrote: post #766
xp84 wrote: post #753

Earlier quoted context omitted.

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??

> just how unpopular would it be to abandon Baltimore??

You underestimate how much vitriol is coming from the Right about Democratic-leaning cities. Baltimore is 60% Black and voted 87% for Biden in 2020. Baltimore isn't on the top of the list of cities they like to claim are failures, but just wait.

My dad is deep in the Right-wing media econsystem and he is convinced that the downtowns of Portland and San Francisco have been burned to the ground and the entire region is a lawless anarchy.

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

#834

Post by ericyd »

hermannj314 wrote: post #392
ericyd wrote: post #339

Earlier quoted context omitted.

A bunch of people die and this is your response?

There is no reason to expect someone to have a rational approach to transportation-related fatality in any direction. Drunk drivers will kill approximately 40 people today in America. Most people won't care about that or demand a congressional response or blame politicians, etc., so it is no more heartless to not care about a few dead people on a bridge either.

Sure, the difference is that when I hear about drunk driving fatalities I don't immediately jump to economic opportunism.

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

#835

Post by ericyd »

h2odragon wrote: post #376
ericyd wrote: post #339

Earlier quoted context omitted.

A bunch of people die and this is your response?

It sucks they died; but our life goes on. For almost all of us, there's nothing we can do to help anyone immediately effected by this incident. Would you have everyone else stand idle in mourning and respect? For how long?

More than a couple hours I guess

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

#836

Post by naasking »

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.

> I don't know what I was expecting, the bridge just looked extremely fragile

The strongest man in the world probably seems pretty solid. Put him at the bottom of a 3 degree grade and release the brakes on a full tractor trailer and he'll seem fragile too.

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

#837

Post by qingcharles »

culebron21 wrote: post #566
jcgrillo wrote: post #555

Earlier quoted context omitted.

I'm not sure what configuration of props a ship like this has, but in my experience with a 40ft sailboat with a single propeller you have absolutely no rudder authority while reversing. I've read that some large ships also are direct drive--there's no transmission between the engine and the propeller, so "reversing" (if it's even possible) entails shutting down the engine and restarting it in reverse. This can be don…

This reminded me of an old physics book I read where author claimed that Titanic also lost rudder control and yawed because of full reverse.

Titanic was a “triple screw steamer,” meaning it had three propellers - port, center and starboard. The port and starboard propellers were capable of being reversed, while the center propeller could only propel forward. You can see this in the 1997 movie as they show the props when they throw the ship into reverse.

The center prop (that only goes forward) is the one directly behind the rudder, so the theory is partly that they lost some steering advantage when they lost the center prop.

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

#838

Post by pja »

reaperman wrote: post #778
FredFS456 wrote: post #768

Earlier quoted context omitted.

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.

I can’t find any bridges which have a barrier that can protect against a fully loaded container ship. I have seen plenty of barriers which would protect against personal watercraft and smaller working ships like smaller tugs/coast guard ships/shrimping boats, etc. But a loaded container ship at 8 knots is not going to be stopped by anything remotely feasible. Container ships weigh between 50,000 and 220,000 tons. A U…

https://en.wikipedia.org/wiki/Dolphin_%28structure%29?wprov=...

If they're designed to stop a bulk carrier then presumably they can stop a container ship.

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

#839

Post by naasking »

anigbrowl wrote: post #527
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.

It's not the impact, it's the fact that it just keeps pushing. Movies commonly use slow motion and time extension via editing for destruction scenes because (as we've just seen) real time doesn't always look impressive to the untrained eye. Also, there's a lot of mass concentrated in that ship. It's the equivalent of hitting a window with a sledgehammer. Small recreational vessels could probably crash into those pylo…

Indeed, the whole bridge failed because the impact didn't exceed the impact strength of the bridge's material, which means the whole bridge bent until the deflection exceeded the tensile strength of the material. A missile impact with the same total energy would exceed impact strength and would probably have destroyed only part of the bridge.

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

#840

Post by mhb »

squigz wrote: post #762
mhb wrote: post #329

Earlier quoted context omitted.

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?

LMGTFY:

https://en.wikipedia.org/wiki/Value_of_life

United States

The following estimates have been applied to the value of life. The estimates are either for one year of additional life or for the statistical value of a single life.

    $50,000 per year of quality life (the "dialysis standard",[39] which had been a de facto international standard most private and government-run health insurance plans worldwide use to determine whether to cover a new medical procedure)[40]
    $129,000 per year of quality life (an update to the "dialysis standard")[41][40]
    $7.5 million (Federal Emergency Management Agency, Jul. 2020)[5]
    $9.1 million (Environmental Protection Agency, 2010)[42]
    $9.2 million (Department of Transportation, 2014)[43]
    $9.6 million (Department of Transportation, Aug. 2016)[44]
    $12.5 million (Department of Transportation, 2022)[45]
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