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Started By
Message
re: Francis Scott Key Bridge in Baltimore has collapsed - container ship wrecked into it
Posted on 3/28/24 at 8:58 am to BRich
Posted on 3/28/24 at 8:58 am to BRich
quote:
Just about finished working on a rural bridge replacement project for the LADOTD in 9 different Parishes, 38 different small bridges.
quote:
Yet the Louisiana Hwy 90 bridges across the Pearl River are COMPLETELY CLOSED to traffic and there is NO IMMEDIATE PLAN in place to fix or replace them.
Those "rural bridges" have special funding allocated to them. You should know that. If they don't have that special funding, they would never get replaced as they don't have the high traffic (read: few people benefit from them) The Pearl River bridges have high traffic and therefore have to stand in line with the rest of the more major bridges for the mainline funding, which has to be spread out all over the state to satisfy the politicians.
1
Posted on 3/28/24 at 9:07 am to Tempratt
quote:
So what was the point of purposely blowing up part of the bridge?
Because container ship gas fires don’t melt steel
Posted on 3/28/24 at 9:08 am to Boudreaux35
I did some reading on that shipping board and learned some stuff. Evidently the mains use electric pumps rather than engine driven pumps for everything (fuel, lube, etc) and would have shut down on the blackout. I find that hard to believe but ill yield to their credibility. They are also saying the black stacking was from going full astern, and that timeline doesn't track in my head so I'm not sure what to believe. I dont think you could have blacked out, shut down, re-lit, cleared the faults and restarted the main all in that time but I don't have much slow speed engine experience. I'm sticking with my original theory, plant shut down main stayed online.
If main engine shutdown on blackout is accurate though, that's countless single point of failure possibilities and I'm amazed we allow stuff like that to operate without an escort around critical infrastructure. I'm amazed these things aren't crashing into shite daily.
If main engine shutdown on blackout is accurate though, that's countless single point of failure possibilities and I'm amazed we allow stuff like that to operate without an escort around critical infrastructure. I'm amazed these things aren't crashing into shite daily.
Posted on 3/28/24 at 9:20 am to DownshiftAndFloorIt
quote:
They are also saying the black stacking was from going full astern, and that timeline doesn't track in my head
Why doesn’t that track in your head
Posted on 3/28/24 at 9:22 am to olddawg26
I explained it. It does not seem plausible to me that they could have lost the whole boat, main engine included, and got the main engine back running and reversed in the timeline that all this happened in.
Posted on 3/28/24 at 9:44 am to DownshiftAndFloorIt
Doesn’t seem too far fetched to think they get the engine back, go emergency full astern, and it goes back within a 5-10 seconds. Seems pretty standard.
Posted on 3/28/24 at 9:48 am to olddawg26
Are you saying it's standard for a container ship to recover from a blackout including main engine shutdown to full astern in 5-10 seconds?
Posted on 3/28/24 at 9:52 am to olddawg26
quote:
Seems pretty standard.
Not starting a huge slow speed diesel in 5 -10 seconds. They use compressed air to start.
Posted on 3/28/24 at 9:53 am to DownshiftAndFloorIt
It’s not standard for a container ship to black out in the first place. But going from stopped to rpm movement especially after already being warmed up in under 10 seconds is normal.
Posted on 3/28/24 at 9:59 am to olddawg26
You have experience with this? I'm not arguing because I've personally never started a cross head engine, but I have started some large engines and blacked out more than one big ship before and I have a hard time believing that.
Posted on 3/28/24 at 10:04 am to DownshiftAndFloorIt
A little. That’s an 8 year old ship and should have a pretty decent start time on receiving rpms
Posted on 3/28/24 at 10:07 am to olddawg26
I dont understand how that is possible. Time to close the breaker on an emergency generator which is generally a self contained high speed unit is like 15 seconds from blackout at best. The medium speeds I've messed with took about 10 seconds to start. Blows my mind that a cross head engine could be clutched in in less than a minute from start signal.
Posted on 3/28/24 at 10:12 am to DownshiftAndFloorIt
You could be right I don’t have any experience in going from black out to everything working. Would you think the black smoke is just the generator getting a load? Could be that they never even got an engine back I guess
Posted on 3/28/24 at 10:21 am to olddawg26
quote:
Would you think the black smoke is just the generator getting a load
I'm sticking with my original theory that the main never shut down and the black stack is from the main going full astern, and the subsequent blackouts and relights are the egen coming online and tripping. I dont know of any blackout recovery proceedure that would attempt to restart the main plant without the egen coming online first but again, I don't know much about container ships.
It's also possible that the gear tripped but the main generators stayed running, the main engine tripped, and the blackstack was the main plant loading back up and then restarting and reversing the main. Everything I've ever done, if the main breaker opened for any reason the generators shut down automatically and the emergency kicked on and got on the buss. Main generator then restarted, got on the buss, egen got off, and non criticals could start coming in. It's possible that container ships are pure old school though - non-synchronizing gens and manual resets and stuff. Eta: even 80 foot pushboats must have auto-start generators now. I can't believe a container ship would be allowed to operate unescourted in US waters without at least that...
This post was edited on 3/28/24 at 10:22 am
Posted on 3/28/24 at 11:33 am to DownshiftAndFloorIt
To avoid the bridge they didn't even need the main though realistically did they? They already had forward momentum of 9 knots headed in the right direction. Seems like steering was the bigger issue here? The thrust over the rudder certainly helps, but it seems like they had no rudder control for a minutes(I didn't count) while they were covering the final 2/3s of a mile to the bridge? At 9 knots 2/3 of a mile would have taken 4 mins or so, so no real rudder control for 4 mins?
Posted on 3/28/24 at 12:02 pm to baldona
To an extent. It's more complicated than that. Relative speed over the rudder is what matters, so it's vessel speed minus current speed is the "steering" speed and you have to factor in wind speed and direction as well.
Posted on 3/28/24 at 12:08 pm to Ripley
Milage Mike Travels
Here is one of my favorite get drunk and watch YouTube Channels showing a dashboard camera as Mileage Mike drives over the bridge.
I hope when they rebuild it they name it "The Omar Little Memorial Bridge" yo!
Here is one of my favorite get drunk and watch YouTube Channels showing a dashboard camera as Mileage Mike drives over the bridge.
I hope when they rebuild it they name it "The Omar Little Memorial Bridge" yo!
Posted on 3/28/24 at 12:11 pm to DownshiftAndFloorIt
quote:
To an extent. It's more complicated than that. Relative speed over the rudder is what matters, so it's vessel speed minus current speed is the "steering" speed and you have to factor in wind speed and direction as well.
Weren't they also dragging an anchor?
Posted on 3/28/24 at 2:05 pm to JDPndahizzy
I'm a ME not civil so maybe you CE's can comment on how long it would even take to engineer a replacement bridge. Are there pre-engineered solutions a CE just need to throw in a few parameters and spit out drawings for a PE to review and stamp? Or would a bridge like this be a from the ground up design? I'd imagine just getting the supply chain up and running on a project like this would be several months in and of itself and that process doesn't start until there is an actual design and drawings.
Posted on 3/28/24 at 3:36 pm to DeoreDX
IMO the bridge up to the channel span would be standard concrete span, piling to piling. The tough engineering and design would be how they span the ship channel.
What’s hard to believe with a design that fragile, there were no bollards protecting it.
What’s hard to believe with a design that fragile, there were no bollards protecting it.
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