# 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:** 6
**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, 3:07pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/101 "2024-03-26T15:07:22Z")
Ugh. I can’t imagine how tragic this is for the Baltimore roads department. Someone made the completely benign decision to send a crew to patch potholes on the bridge last night and the absolute unthinkable happened. The whole department is going to need some major counseling. ---
**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, 3:17pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/102 "2024-03-26T15:17:59Z")
> [@Jasmine](#): > > > [@BobLibDem](#): > > > > apparently the momentum of this ship far exceeded the design of the pier protection and it took out the pier and the spans it supported with ease. > > Oh, yeah! F = MA. Even if the acceleration is only, say 5 MPH, the incredible mass of a ship that large times an acceleration even that small produces an irresistible force. Nitpick from a former physics instructor: Acceleration is not measured in miles per hour. That is a unit for speed or velocity. The product of mass and velocity is _momentum_. So like @BobLibDem said, you could indeed properly say that the massive ship, even with a relatively low speed, still had a lot of momentum. Also note that Newton’s second law is better expressed as: **F** net = m **a** , in which the force in question is the _net_ force, and both force and acceleration are vectors. Applied to the present case of an inelastic collision between the ship and bridge support, you could say that the negative acceleration of the ship as it collided with the bridge support required a large net force on the ship, and by Newton’s third law, an equal and opposite force on the bridge support, which was large enough to separate the support from its footing. You could also look at the equation for conservation of momentum, but this is complicated by the fact that the bridge support was initially attached to the earth. ---
**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, 3:20pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/103 "2024-03-26T15:20:45Z")
> [@ZipperJJ](#): > > Ugh. I can’t imagine how tragic this is for the Baltimore roads department. Someone made the completely benign decision to send a crew to patch potholes on the bridge last night and the absolute unthinkable happened. The whole department is going to need some major counseling. Road construction work, especially at night, is already plenty dangerous due to the horrible surplus of drunk and/or inattentive drivers. It turns out they were supposed to be worrying about drifting containers ships too… ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [March 26, 2024, 3:24pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/104 "2024-03-26T15:24:00Z")
A friend of mine was an iron worker. He worked on many of the tall buildings in downtown Pittsburgh. He was comfortable working hundreds of feet above street level, walking on beams, etc, but he told me he turned down any jobs working on bridges. He knew the guy who had their leg smashed by a steel plate, requiring an amputation right on the bridge to free him for transport. > **[1978 Brady St bridge amputation](https://www.newspapers.com/article/the-tampa-tribune-1978-brady-st-bridge-a/43129951/)** > > Clipping found in The Tampa Tribune published in Tampa, Florida on 5/24/1978. 1978 Brady St bridge amputation ---
**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, 3:25pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/105 "2024-03-26T15:25:21Z")
> [@robby](#): > > Nitpick from a former physics instructor: Acceleration is not measured in miles per hour. That is a unit for speed or velocity. > > The product of mass and velocity is _momentum_. So like @BobLibDem said, you could indeed properly say that the massive ship, even with a relatively low speed, still had a lot of momentum. > > Also note that Newton’s second law is better expressed as: **F** net = m **a** , in which the force in question is the _net_ force, and both force and acceleration are vectors. Applied to the present case of an inelastic collision between the ship and bridge support, you could say that the negative acceleration of the ship as it collided with the bridge support required a large net force on the ship, and by Newton’s third law, an equal and opposite force on the bridge support, which was large enough to separate the support from its footing. > > You could also look at the equation for conservation of momentum, but this is complicated by the fact that the bridge support was initially attached to the earth. Assuming a total weight of 100K tons, that’s 200 million pounds of mass. Assume a decel of just 0.01 G, or 0.2 MPH per second, getting stopped from a forward speed of 5 MPH would take 25 seconds. And 0.01G of decel on a mass of 200M pounds requires a force of…2 million pounds exerted by the bridge against the ship. And the bridge ain’t made to take that kind of side load. ---
**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, 3:41pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/106 "2024-03-26T15:41:51Z")
> [@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? ---
**Author:** ![DWMarch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dwmarch/32/1010_2.png) [@DWMarch](https://boards.straightdope.com/u/DWMarch)\ **Post date:** [March 26, 2024, 3:49pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/107 "2024-03-26T15:49:27Z")
> [@Machine\_Elf](#): > > If that’s the case, then the ship is basically an unguided slow-motion missile, and there would have been little they could do except lay on the horn (for whatever good that might have done). See also the [Queen of Oak Bay](https://youtu.be/_4G47rjXTwE?si=piyIGdFqr-fSIYc9), a BC Ferries vessel that wrecked the Horseshoe Bay Marina for lack of a cotter pin. BTW, that ship is still in service making the same run between Nanaimo and Vancouver. ---
**Author:** ![Chefguy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chefguy/32/138_2.png) [@Chefguy](https://boards.straightdope.com/u/Chefguy)\ **Post date:** [March 26, 2024, 3:59pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/108 "2024-03-26T15:59:56Z")
> [@andrewm](#): > > Tugs are used, but only for the actual maneuvering in/out of the docks. Once it got off the dock and pointed outbound, it was on a perfectly straight run for three miles. It would be silly to tie up tugboats for that entire journey. Yeah, that’s what the pilots are for. Pilots at the mouth of the Columbia Rivera are legendary. ---
**Author:** ![Frazzled](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/frazzled/32/3368_2.png) [@Frazzled](https://boards.straightdope.com/u/Frazzled)\ **Post date:** [March 26, 2024, 4:24pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/109 "2024-03-26T16:24:19Z")
> Blockquote You say that F = MA is not the right equation. What is? It’s pretty close - Momentum = Mass \* Velocity. Acceleration is changing velocity, but momentum is just that raw hitting power that you’re talking about. ---
**Author:** ![Pardel-Lux](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pardel-lux/32/20182_2.png) [@Pardel-Lux](https://boards.straightdope.com/u/Pardel-Lux)\ **Post date:** [March 26, 2024, 4:28pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/110 "2024-03-26T16:28:13Z")
> [@Jasmine](#): > > You say that F = MA is not the right equation. What is? You are probably looking for the kinetic energy of the ship, E = 1/2 mv², where m is the mass of the ship, v² is the speed of the boat squared, if possible in SI units (kg, m and s) to get the result in Joule. The F = ma you quote would rather give you the force you should have applied to the ship to give it (her?) enough (negative) acceleration to stop the ship in time before it (or her, or whatever) hits the bridge. You would have to calculate the acceleration necessary to stop the ship in time before hitting the bridge, for which you need to know the speed of the boat and the distance to the bridge. Whatever those numbers were this goal was not attained. ---
**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, 4:35pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/111 "2024-03-26T16:35:10Z")
Looks like the BS conspiracy theories have already started. A FB friend said the video looked “suspicious,” and that the explosion (or at least smoke) on the boat was likely planned. 😒 ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [March 26, 2024, 4:37pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/112 "2024-03-26T16:37:54Z")
> [@Crafter\_Man](#): > > the explosion was likely planned. Ummm… what explosion? ---
**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, 4:40pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/113 "2024-03-26T16:40:05Z")
See the video in [FairyChatMom’s post](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/97). (I also edited to say “explosion, or at least smoke”). ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [March 26, 2024, 4:40pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/114 "2024-03-26T16:40:17Z")
> [@rocking\_chair](#): > > the crew on the bridge was repairing potholes on the bridge. the vehicle (s) on the bridge may have been their truck (s The video linked above showed several yellow blinking lights along the bridge roadway (just to the right of mid-span). That definitely looked like a working line of road work trucks. I hope they’re ok. Barring that, I hope they’re recovered swiftly to give the families what closure can be had. ---
**Author:** ![gnoitall](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@gnoitall](https://boards.straightdope.com/u/gnoitall)\ **Post date:** [March 26, 2024, 4:42pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/115 "2024-03-26T16:42:00Z")
I did. Nothing there resembled an explosion. ---
**Author:** ![Loach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/loach/32/350_2.png) [@Loach](https://boards.straightdope.com/u/Loach)\ **Post date:** [March 26, 2024, 5:12pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/116 "2024-03-26T17:12:01Z")
> [@Crafter\_Man](#): > > Looks like the BS conspiracy theories have already started. A FB friend said the video looked “suspicious,” and that the explosion (or at least smoke) on the boat was likely planned. 😒 I see these people online. It must be exhausting trying to fit anything that happens anywhere into a conspiracy. ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [March 26, 2024, 5:16pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/117 "2024-03-26T17:16:09Z")
> [@Loach](#): > > It must be exhausting trying to fit anything that happens anywhere into a conspiracy. I’m going to remember this line, and steal it from you. ---
**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, 5:21pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/118 "2024-03-26T17:21:05Z")
> [@Princhester](#): > > That’s a very broad brush you are painting with there given that “foreign flagged” means every country other than the USA. Substantial proportions of the world’s container vessel fleet are registered in Germany and the UK both of which have better reputations than US flagged vessels. Permit me to rephrase; ships operated by or for US-owned companies but registered under a “flag of convenience” (i.e. registered with a country with little in the way of controls or review of maintenance) are often not well maintained. There are very few ocean-going commercial vessels that actually operate under US flag except as required by the Jones Act for both tax and liability reasons. You are correct that Europe in general and Denmark specifically has rigorous maintenance and training standards for commercial vessels operating in their domains. > [@Frazzled](#): > > It’s pretty close - Momentum = Mass \* Velocity. Acceleration is changing velocity, but momentum is just that raw hitting power that you’re talking about. This statement is also a little ambiguous. Momentum is mass x velocity, and impulse (the “hitting power”) is the change in momentum (or the integral of applied force over the contact interval). Since momentum is always conserved irrespective of any material deformation or other conversion of kinetic energy into other forms (heat, light, acoustic, et cetera) it is the best quality to evaluate the ability of a moving body to knock over or propel any object it runs into, especially if the collision is inelastic (no bounceback) since you don’t actually have to know anything about the intermediate states during transfer of momentum. Since the acceleration of two bodies colliding will change over the duration of the impact, using kinetic energy you would have to integrate the (somehow measured) instantaneous accelerations to get a resulting state; using momentum, you just need to know the before state an assume some coefficient of restitution, or measure the before and after states of each body and derive the coefficient of restitution. > [@Crafter\_Man](#): > > Looks like the BS conspiracy theories have already started. A FB friend said the video looked “suspicious,” and that the explosion (or at least smoke) on the boat was likely planned. Initial expert from someone with actual expertise in maritime operations: [![](https://img.youtube.com/vi/qZbUXewlQDk/maxresdefault.jpg "Ship Lost Power Before Hitting Key Bridge in Baltimore") ](https://www.youtube.com/watch?v=qZbUXewlQDk) Stranger ---
**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, 5:21pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/119 "2024-03-26T17:21:43Z")
> [@Loach](#): > > I see these people online. It must be exhausting trying to fit anything that happens anywhere into a conspiracy. Against my better judgment I briefly poked my head into a website run by a (very) well-known conspiracy theorists. He is calling it a “Black Swan Event,” whatever that means. 🙄 ---
**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, 5:27pm UTC](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372/120 "2024-03-26T17:27:15Z")
> [@Jasmine](#): > > Oh, wow, how bad does your luck have to be for you to have an engine failure at that key moment?! Even if it happened sooner, could they have dropped their anchor and “dragged” the ship to a stop? The **[latest news reports on CNN](https://www.cnn.com/us/live-news/baltimore-bridge-collapse-03-26-24-intl-hnk/index.html)** are saying that the ship did indeed drop anchor to try to scrub off some speed. According to the timeline, the first signs of trouble occurred at 1:24AM, and the ship hit the bridge just three minutes later. There’s also mention that someone on the container ship placed an “emergency call” that gave officials time to begin closing the bridge to vehicle traffic. If that’s all true, then I’m really surprised a response could be mustered so quickly. 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? [Previous page](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372.md?page=5) [Next page](https://boards.straightdope.com/t/bridge-collapse-in-baltimore-2024-03-26/999372.md?page=7)