The design of the Chesapeake Bay Bridge-Tunnel, specifically the tunnel part, makes a lot of sense now. Imagine a US navy port (Norfolk) being inaccessible if this happened there.
Baltimore's Key Bridge struck by cargo ship, collapses
351–360 of 1001 posts
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#352[flagged]
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#353Somehow 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…
I don’t drive boats or around water much but I’ve seen “bumpers” on bridge pylons before that make a collision more of a glancing blow and guide the boat to the side. I guess there wasn’t any installed on this bridge? Also, someone on Imgur pointed out that when this bridge was built boats that large weren’t a risk. That may or may not be true but sounds plausible.
> when this bridge was built boats that large weren’t a risk
Doesn't sound plausible to me. Very large Panamax ships were used in the 1970's when the bridge was built.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#354Earlier quoted context omitted.
Ships are hundreds of thousands of tons in weight and the momentum acts as a force multiplier. Plus it hit the pylon dead center, which is the worst case scenario. It’s not terribly surprising. I think there’s also an underlying expectation that any competent ship captain would at least be able to see that they’re on a collision course with the pylon well ahead of time and be able to compensate. Which obviously didn’…
The trajectory of the ship seemed near perfect right up until just before the bridge where I suspect it experience it's mechanical issue.
Interestingly, a surprising number of ship-ship collisions occur due to an unnecessary last minute evasive-action manoeuvre between ships that weren't actually on a collision course in the first place. There's a whole section devoted to this in the outstanding book 'Normal Accidents' by Charles Perrow.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#355Earlier quoted context omitted.
Just to put some numbers on this: The MV Dali (IMO#9697428) is a little over 95000 GT, or ballpark-ish probably around 114000 tons loaded (and it seems to have been loaded, which would make sense on departure). If it was going even 5kn (2.6 m/s) that'd be about 300 million newton-seconds, or about 3.3 times the momentum of a large jumbo jet like a 747 shortly at cruising speed (around 560 mph). It'd still have the sa…
> enormously massive objects moving very slowly messes with human perception and "common sense" Yes, hence warnings to amateur boat users (e.g. on a canal boat) not to try to stop a collision with the bank using your arms or legs. [Edit] Boats can also do things that are unintuitive if you are used to driving a car. E.g. turning round the centre of gravity when you steer rather than following the front wheels.
In the black powder era of warfare, soldiers were given similar warnings about “slowly” rolling cannonballs.
People would think they could stop them like soccer balls, and lose a foot.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#356Somehow 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…
This brings back to memory 911 conspiracy theories.
Many revolved around the unlikelihood that a building would collapse the way the towers collapsed just due to knocking out a few floors at the top. But the truth is all these mega structures are quite fragile and can instantly collapse in unintuitive ways.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#357I heard on the local radio here, with one of the DJs being an ex-cop, his contact with EMS said the driver of the boat called a mayday and said to clear the bridge. Nope, can't prove it, but I imagine it'll come out in the news soon.
So, not intentional.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#358Earlier quoted context omitted.
Just to put some numbers on this: The MV Dali (IMO#9697428) is a little over 95000 GT, or ballpark-ish probably around 114000 tons loaded (and it seems to have been loaded, which would make sense on departure). If it was going even 5kn (2.6 m/s) that'd be about 300 million newton-seconds, or about 3.3 times the momentum of a large jumbo jet like a 747 shortly at cruising speed (around 560 mph). It'd still have the sa…
> enormously massive objects moving very slowly messes with human perception and "common sense" Yes, hence warnings to amateur boat users (e.g. on a canal boat) not to try to stop a collision with the bank using your arms or legs. [Edit] Boats can also do things that are unintuitive if you are used to driving a car. E.g. turning round the centre of gravity when you steer rather than following the front wheels.
There are similar warnings for sailing vessels, but because the standing rigging of the ship is usually kept in high enough tension that putting your hands on a pilon to stop a collision might leave your hands vulnerable to being cut off by a mainsail's shrouds.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#359A lot of these ships are controlled via GPS to keep them in the channels. I wonder if this crash will entail a software bug or system failure.
Re: Baltimore's Key Bridge struck by cargo ship, collapses
#360Earlier 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.
> Bridges only last for roughly 50 years. https://en.wikipedia.org/wiki/The_Iron_Bridge Opened in 1781, still in service and perfectly safe. Of course, there are no container ships nearby. But I reckon you could sail a container ship under it, given enough water; and to damage the bridge supports, the container ship would need climbing equipment. 1781 isn't many years after the Declaration of Independence.
If there was enough water for the 48m beam, 24m airdraft container ship that just collapsed the Baltimore bridge to attempt to navigate under the 30m span, 16m high Iron Bridge I don't think the bridge would stand a chance...