# Bridge collapse in Baltimore {2024-03-26} **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Tags:** breaking-news\ **Created:** [March 26, 2024, 8:11am UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372 "2024-03-26T08:11:34Z")\ **Posts on this page:** 20\ **Page:** 7
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [March 26, 2024, 5:28pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/121 "2024-03-26T17:28:39Z")
> [@Machine\_Elf](#): > > Even if the call was placed at the first sign of trouble, could officials even _begin_ to shut down the bridge in less than three minutes? I think at least they could make the electronic signs at the approaches say “BRIDGE CLOSED; EMERGENCY; PULL OVER HERE” ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [March 26, 2024, 5:29pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/122 "2024-03-26T17:29:24Z")
So if it crashed due to a power loss, I can only think of three reasons it hit the support: 1) the ship was turning as it was going under the bridge, 2) there was a significant crosswind, or 3) there was a significant cross-current. Do we know if any of these are true? (If none are true, I would assume it would continue going straight after the power loss.) ---
**Author:** ![Just\_Asking\_Questions](https://avatars.discourse-cdn.com/v4/letter/j/ba9def/32.png) [@Just\_Asking\_Questions](https://boards.straightdope.com/u/Just_Asking_Questions)\ **Post date:** [March 26, 2024, 5:29pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/123 "2024-03-26T17:29:58Z")
> [@Crafter\_Man](#): > > He is calling it a “Black Swan Event,” whatever that means. It’s not as bad as you’d think. Rare, large impact, and easy to see in hindsight what caused it. > **[Black swan theory](https://en.wikipedia.org/wiki/Black_swan_theory)** > > The black swan theory or theory of black swan events is a metaphor that describes an event that comes as a surprise, has a major effect, and is often inappropriately rationalized after the fact with the benefit of hindsight. The term is based on an ancient saying that presumed black swans did not exist, until they were discovered in Australia in 1697, and it then became reinterpreted to mean an unforeseen and consequential event. > The theory was developed by Nassim Nicholas Taleb, starting in 2... ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [March 26, 2024, 5:32pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/124 "2024-03-26T17:32:13Z")
> [@Crafter\_Man](#): > > So if it crashed due to a power loss, I can only think of three reasons it hit the support: 1) the ship was turning as it was going under the bridge, 2) there was a significant crosswind, or 3) there was a significant cross-current. Do we know if any of these are true? (If none are true, I would assume it would continue going straight after the power loss.) I had the same thought. Like, if you’re driving your car and the engine fails don’t you keep going forward? To people who know: Do ships like that have dual propellers? Like one propeller on one side can stop sooner than the other, immediately sending you sideways? Or is it just one central propeller? ---
**Author:** ![Jasmine](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jasmine/32/2964_2.png) [@Jasmine](https://boards.straightdope.com/u/Jasmine)\ **Post date:** [March 26, 2024, 5:32pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/125 "2024-03-26T17:32:51Z")
Let me ask this. Does that ship have only ONE engine, or is it a twin engine setup? If twins and one failed and the other didn’t, or one failed sooner than the other, that could cause the turning, couldn’t it? ---
**Author:** ![Crafter\_Man](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crafter_man/32/458_2.png) [@Crafter\_Man](https://boards.straightdope.com/u/Crafter_Man)\ **Post date:** [March 26, 2024, 5:33pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/126 "2024-03-26T17:33:45Z")
Good point; yet another possibility. ---
**Author:** ![rocking\_chair](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rocking_chair/32/2918_2.png) [@rocking\_chair](https://boards.straightdope.com/u/rocking_chair)\ **Post date:** [March 26, 2024, 5:33pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/127 "2024-03-26T17:33:53Z")
at that hour of the morning, i would think you could shut it down quickly. getting the road crew off the bridge… there wasn’t enough time for that. ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [March 26, 2024, 5:35pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/128 "2024-03-26T17:35:07Z")
Wow…looks like MAYBE dropping the port bow anchor is what caused her to turn right. Maybe it would have kept going straight if they hadn’t done this. Can’t blame them for trying anything…but that would suck if it turns out to be this. (But I think ZipperJJ and Jasmine’s speculation is more likely – starboard engine/propeller dead, port one still operational → quick turn to the right). ---
**Author:** ![Darren\_Garrison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/darren_garrison/32/92_2.png) [@Darren\_Garrison](https://boards.straightdope.com/u/Darren_Garrison)\ **Post date:** [March 26, 2024, 5:35pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/129 "2024-03-26T17:35:08Z")
Everybody watch the video posted by Stranger: it answers several questions that have been posted since. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [March 26, 2024, 5:43pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/130 "2024-03-26T17:43:18Z")
> [@Jasmine](#): > > Let me ask this. Does that ship have only ONE engine, or is it a twin engine setup? If twins and one failed and the other didn’t, or one failed sooner than the other, that could cause the turning, couldn’t it? If Wikipedia is accurate, then it’s just one big engine: > **[MV Dali](https://en.wikipedia.org/wiki/MV_Dali)** > > Dali is a Singapore-registered container ship. As of 2024, her owner is Grace Ocean Pte Ltd. In March 2024, the ship collided with the Francis Scott Key Bridge in Baltimore, Maryland, United States, causing a catastrophic structural failure of the bridge and resulting in at least one casualty. > Construction of the Dali began in 2014 in HD Hyundai Heavy Industries' Ulsan shipyard in South Korea. > The ship is based on the "Hyundai 9000 wide beam" design, modified to increase container capacity fro... > [@JKellyMap](#): > > I think at least they could make the electronic signs at the approaches say “BRIDGE CLOSED; EMERGENCY; PULL OVER HERE” Maybe so…but whomever is receiving the call has to be convinced that the distress call is real, and then the information has to get from that person all the way through some chain of people to the person who can turn on the “BRIDGE CLOSED” sign. Moreover, I’m betting the ship captain didn’t place the call at the very first sign of trouble, i.e. it was probably substantially less than three minutes from the time a distress call was placed until the first efforts to halt traffic actually were implemented. I’m sure we’ll be able to read all about this in the accident report. There is of course already a Wikipedia page about the bridge collapse, no doubt being updated every few seconds by news hounds: > **[Francis Scott Key Bridge collapse](https://en.wikipedia.org/wiki/Francis_Scott_Key_Bridge_collapse)** > > On March 26, 2024, at 01:28 EDT (05:28 UTC), the main spans of the Francis Scott Key Bridge in Baltimore, Maryland, United States collapsed after the container ship Dali struck one of its support pillars. > Baltimore City Fire Department officials said that at least seven vehicles fell into the water. Two people were recovered from the river; one declined medical treatment while the other was transported to a hospital in critical condition. At least six people are believed missing. > The Franci... In good form, sources are being cited for the various factual claims in the article, including info about the closure of the bridge prior to impact. Here’s one: > **[Baltimore bridge collapses after powerless cargo ship rams into support...](https://www.bostonherald.com/2024/03/26/baltimore-bridge-collapses-after-powerless-cargo-ship-rams-into-support-column-6-people-are-missing/)** > > A container ship lost power and rammed into a major bridge in Baltimore, causing the span to buckle into the river below. The collapse plunged a construction crew into the dangerously cold waters. … From the article: > The ship’s crew issued a mayday call moments before the crash took down the Francis Scott Key Bridge, enabling authorities to limit vehicle traffic on the span, Maryland’s governor said. The article also mentions that the ship was moving at about 9 MPH prior to impact. That’s a lot of momentum. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [March 26, 2024, 5:47pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/131 "2024-03-26T17:47:37Z")
> [@Jasmine](#): > > > [@robby](#): > > > > The product of mass and velocity is _momentum_. > > The problem here is that I need the “Physics for Dummies” version of your post. LOL > > My definition of force: You walk slowly into me. You bump me backwards. No problem because I regain my balance and nothing hurts. You RUN into me. You wipe me out. It hurts. A lot. Your mass is the same in both cases. To me, the difference is the speed at which you hit me. You say that F = MA is not the right equation. What is? To answer this question without a bunch of complicating factors, let’s start off by simplifying things: assume we are on a frictionless surface (like a perfectly frictionless ice skating rink) and that I am sliding into you. Let’s also assume that after the collision, we stick together. (This last assumption is what is referred to as a “perfectly inelastic collision.” As an aside, in such a collision, kinetic energy is not conserved.) What is conserved (and is _always_ conserved in all cases) is momentum. Momentum is the product of mass and velocity. We can therefore use the equation: mme **v** _i_,me + myou **v** _i_,you = mme **v** _f_,me + myou **v** _f_,you Note that _i_ = initial and _f_ = final. We can further assume that your initial velocity **v** _i_,you is zero, and that both of our final velocities are the same, so **v** _f_,me = **v** _f_,you = **v** _f_ This simplifies the equation to: mme **v** _i_,me = (mme + myou) **v** _f_ If we know our respective masses and my initial velocity, we can then solve for our final velocity. The faster my initial velocity, the faster our final velocity will be. If we assume that the time of collision is the same in all cases, that means if I hit you with a higher initial velocity then you are being accelerated from zero to a higher final velocity in the same amount of time, which requires a greater net force on you. That’s why it hurts more. ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [March 26, 2024, 5:49pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/132 "2024-03-26T17:49:41Z")
> [@Jasmine](#): > > Does that ship have only ONE engine, or is it a twin engine setup? According to Mr. Google, tankers, bulk carriers, and container ships typically only have one propeller. This is done to maximize efficiency. Ships that have faster speed requirements like passenger liners typically have a dual propeller setup. As was mentioned above, this particular ship has a single propeller, so it is typical for its type. ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [March 26, 2024, 5:52pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/133 "2024-03-26T17:52:55Z")
> [@engineer\_comp\_geek](#): > > As was mentioned above, this particular ship has a single propeller, so it is typical for its type. So, scratch that theory. Isn’t it odd that it turned at all? Rudder malfunction? When the power goes off, one would expect a control surface to default to “maintain current configuration.” I know nothing, but this might make the “dropped anchor caused the turn” theory slightly more likely – even though it seems implausible that that little thing could cause a turn so quickly. ---
**Author:** ![flurb](https://avatars.discourse-cdn.com/v4/letter/f/51bf81/32.png) [@flurb](https://boards.straightdope.com/u/flurb)\ **Post date:** [March 26, 2024, 5:54pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/134 "2024-03-26T17:54:36Z")
> [@Machine\_Elf](#): > > Maybe so…but whomever is receiving the call has to be convinced that the distress call is real, and then the information has to get from that person all the way through some chain of people to the person who can turn on the “BRIDGE CLOSED” sign. I would hope the Port has an emergency SOP for just this sort of situation. Bridge failures are rare but not unheard of. Having a button that immediately throws up an “EMERGENCY: BRIDGE CLOSED” warning seems like a no-brainer. ---
**Author:** ![TroutMan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/troutman/32/6721_2.png) [@TroutMan](https://boards.straightdope.com/u/TroutMan)\ **Post date:** [March 26, 2024, 5:56pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/135 "2024-03-26T17:56:31Z")
> [@JKellyMap](#): > > Isn’t it odd that it turned at all? The video linked by **Stranger** has informed speculation on this. Based on that person’s assessment, the black smoke likely indicates they put the engine in full power reverse, which with a single-screw ship will cause it to twist and “careen” a bit. It’s also possible that dropping the anchor futher put it off course. He made the point that it might have been better to just let it drift straight through the gap, although we can’t know at this point if that was possible. ---
**Author:** ![robby](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robby/32/11048_2.png) [@robby](https://boards.straightdope.com/u/robby)\ **Post date:** [March 26, 2024, 5:58pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/136 "2024-03-26T17:58:44Z")
> [@Princhester](#): > > Tugs are only usually used for specific manoeuvres that vessels can’t manage on their own. > > Escort tugs are a not normal requirement for vessels in a reasonably straight channel. Where I’m from, it is usual for LPG vessels to have escort tugs but that is exceptional. For what it’s worth, when I was in the U.S. Navy serving on submarines, we always had an escort tug until we were safely out of the channel and in unrestricted waters. It was convenient because we could simultaneously drop off the pilot on the tug. When returning to port, the escort tug met us and also brought the pilot out to us. It was either a “belt and suspenders” practice, or may have also been because we had only a single main propellor, so if we lost propulsion in restricted waters with little room to maneuver, we had no real backup. Also nuclear submarines are expensive. ---
**Author:** ![JKellyMap](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jkellymap/32/15880_2.png) [@JKellyMap](https://boards.straightdope.com/u/JKellyMap)\ **Post date:** [March 26, 2024, 6:00pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/137 "2024-03-26T18:00:37Z")
> [@TroutMan](#): > > Based on that person’s assessment, the black smoke likely indicates they put the engine in full power reverse, which with a single-screw ship will cause it to twist and “careen” a bit. Got it - thanks. I bet this is the main reason. Bummer. Rather like certain plane crashes where, if the pilot had just let go of the controls, the plane likely would have leveled off on its own. (Air France 447 comes to mind, as does – for a few certain moments, anyway – Aeroflot 593). ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 26, 2024, 6:02pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/138 "2024-03-26T18:02:40Z")
> [@Crafter\_Man](#): > > So if it crashed due to a power loss, I can only think of three reasons it hit the support: 1) the ship was turning as it was going under the bridge, 2) there was a significant crosswind, or 3) there was a significant cross-current. Do we know if any of these are true? (If none are true, I would assume it would continue going straight after the power loss.) It appears that they _potentially_ reversed the single screw to arrest forward motion, and then dropped the port side anchor but too late to prevent the vessel from impacting the bridge support piling. Wind would not have a significant affect on this vessel (and you can see that the water is nearly flat), and this should have been near low tide (0211 EDT) so probably not much draw. However, when a vessel loses way there is no longer any control and it will go however the water flows, which is obviously incredibly dangerous with a vessel as large as this. More preliminary analysis from Sal: [![](https://img.youtube.com/vi/N39w6aQFKSQ/hqdefault.jpg "MV Dali Hitting Key Bridge in Baltimore - Track and Video Analysis") ](https://www.youtube.com/watch?v=N39w6aQFKSQ&t=4m) Stranger ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [March 26, 2024, 6:07pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/139 "2024-03-26T18:07:24Z")
> [@robby](#): > > It was either a “belt and suspenders” practice, or may have also been because we had only a single main propellor, so if we lost propulsion in restricted waters with little room to maneuver, we had no real backup. Also nuclear submarines are expensive. And also not a lot of visibility except for the conning tower and a couple feet of hull that sticks up out of the water. Stranger ---
**Author:** ![pjd](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pjd/32/3009_2.png) [@pjd](https://boards.straightdope.com/u/pjd)\ **Post date:** [March 26, 2024, 6:32pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/140 "2024-03-26T18:32:37Z")
I did that, and i’m only seeing 4 ! [Previous page](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372.md?page=6) [Next page](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372.md?page=8)