8 ms·

Florida Pedestrian Bridge Constructed 5 Days Ago Collapses, Multiple Casualties

88 points by guardiangod 9y ago

pram 9y ago
It appears that the intended final design includes suspension cables, but it looks like it was installed without them attached?
- superflyguy 9y ago
  Sounds like it was designed and built by software engineers!
  - deleted 9y ago
    [deleted]
    - deleted 9y ago
      [deleted]
  - macintux 9y ago
    A little early for jokes about a situation where people are (presumably?) still being rescued/recovered.
    - labster 9y ago
      Exactly. That was a bridge too far!
    - matte_black 9y ago
      That’s putting it lightly. People have certainly been killed.
- sitharus 9y ago
  It looks like a typical cable-stayed bridge. Often spans are installed in advance of cables by omitting heavy elements, like the deck, so the span is self supporting. The cables are then installed and anchored and the deck is fitted.
danso 9y ago
Apparently the elevated walkway was installed in less than 1 day (with major parts of it being pre-fab). But it sounds like it wasn't the complete project, which was expected to be finished in 2019: > Once it’s finished in early 2019, the new pedestrian bridge will link FIU’s Modesto A. Maidique Campus directly to the small suburban city of Sweetwater, where the university estimates 4,000 of its students live. http://www.miamiherald.com/news/local/community/miami-dade/west-miami-dade/article204506084.html http://www.miamiherald.com/news/local/community/miami-dade/w...
AndyKelley 9y ago
Looks like somebody hired a software engineer instead of an actual engineer.
- rm_-rf_slash 9y ago
  People died.
  - AndyKelley 9y ago
    Life is no less funny when someone dies, than it is less serious when someone laughs.
  - walshemj 9y ago
    You might not know this but Civil Engineers have a dark sense of humor and for major projects its jokingly said that the gods require a blood sacrifice.
    - akira2501 9y ago
      > its jokingly said that the gods require a blood sacrifice. Usually we're referring to something like a paper cut or a sharp edge on a prototype.
      - walshemj 9y ago
        Not in civil engineering large projects are inherently dangerous places to work.
    - rm_-rf_slash 9y ago
      My fiancé studied there. She’s still waiting to hear if anybody she knows was crushed under that bridge. This isn’t funny.
niftich 9y ago
As one can see in the installation video from last weekend, the bridge in question was the first span of a larger project, in which at least one other span would have to be installed above an adjacent canal to complete the crossing. A rendering [1] shows the completed crossing to be an asymmetric harp-type cable-stayed bridge, with cables supporting both the portion above the road (the piece in question), and the piece that's yet-to-be constructed to go above the water. In this design, it's usually not possible to (temporarily) install the cables solely on one side of the tower, as the loads on one side of the tower would collapse the tower. Therefore, it stands to reason that the cables were either to come into play at the very end, or if the bridge were constructed by cantilevering out from the central tower and attaching cables as you go. In other words, without trying to pass judgment on the cause, the cables are either a red herring (because the sub-spans are self-supporting), or the bridge was assembled in a terribly incorrect sequence. [1] http://www.miamiherald.com/news/local/community/miami-dade/west-miami-dade/article204506084.html http://www.miamiherald.com/news/local/community/miami-dade/w...
- Someone 9y ago
  On the rendering, it seems to me that the part over the water is significantly shorter than the now collapsed part. It also doesn’t look heavier per meter to me, and the tower seems to be perfectly vertical. That would make it impossible to fully ‘hang’ the part over the road from the tower. => It is quite possible that the span over the road was designed to be self-supporting. That would be a non-standard design, but we are so good at building such bridges that ‘being non-standard’ almost has become the standard.
AJ007 9y ago
Are bridges collapsing common? Looks like those involved had at least two other bridge related incidents in the past - http://www.miaminewtimes.com/news/fiu-bridge-collapse-construction-firms-accused-of-unsafe-practices-10176596 http://www.miaminewtimes.com/news/fiu-bridge-collapse-constr...
- sitharus 9y ago
  Not major infrastructural bridges, there's a list on Wikipedia: https://en.wikipedia.org/wiki/List_of_bridge_failures https://en.wikipedia.org/wiki/List_of_bridge_failures The US seems to have a lot, but there are a lot of bridges in the US. Construction is pretty risky though, there are often elements that are incompletely supported - engineers do plan for this and ensure they are strong enough.
jandrese 9y ago
Is it common for pedestrian bridges to be so overbuilt? Given the weight and span it sounds like it has a cross sectional area of about 75 square feet of concrete (a little less for the steel components, but still a lot) for a mere 15 foot traffic deck. It's not crossing an especially large span nor need to carry any substantial weight other than its own, so why does it need to be so heavy? Are they expecting trucks to run into it maybe?
- CapitalistCartr 9y ago
  They have to calculate for worst-case scenario. Imagine it were completely full of people. Dancing. Plus, people do ride motorcycles on them if they can get them on.
  - jersully72 9y ago
    And Mother Nature.
  - nugi 9y ago
    I have a few friends that easily outweigh my full size motorcycle.
- cdolan 9y ago
  People are surprisingly heavy per square foot - multiple times the weight of a car PSF.
giarc 9y ago
>The $14.2 million project was designed as a cable-supported bridge by MCM and Figg Bridge Design. Figg was hired to design the replacement for a bridge on I35 in Minnesota that collapsed in 2007 and killed 13 people. 1 paragraph later. >“In our 40-year history, nothing like this has ever happened before,” Figg said. EDIT - As others have pointed out... I misread these statements.
- kldavis4 9y ago
  They were hired to design the replacement, not the one that collapsed.
- maxerickson 9y ago
  They designed the replacement that was installed in 2008. The bridge that collapsed was designed by a different company in the 1960s. https://en.wikipedia.org/wiki/I-35W_Mississippi_River_bridge#Design_and_construction https://en.wikipedia.org/wiki/I-35W_Mississippi_River_bridge...
  - giarc 9y ago
    Oh I see... I've edited my comment.
mudil 9y ago
Famous video of "Galloping Gertie" Tacoma Narrows Bridge collapse in 1940: https://youtu.be/j-zczJXSxnw https://youtu.be/j-zczJXSxnw
gumby 9y ago
People died and FIU offered...yes, thoughts and prayers (look at the end of the article). Sigh.

88 points by guardiangod 9y ago

pram 9y ago

It appears that the intended final design includes suspension cables, but it looks like it was installed without them attached?

superflyguy 9y ago
Sounds like it was designed and built by software engineers!
- deleted 9y ago
  [deleted]
  - deleted 9y ago
    [deleted]
- macintux 9y ago
  A little early for jokes about a situation where people are (presumably?) still being rescued/recovered.
  - labster 9y ago
    Exactly. That was a bridge too far!
  - matte_black 9y ago
    That’s putting it lightly. People have certainly been killed.
sitharus 9y ago
It looks like a typical cable-stayed bridge. Often spans are installed in advance of cables by omitting heavy elements, like the deck, so the span is self supporting. The cables are then installed and anchored and the deck is fitted.

danso 9y ago

Apparently the elevated walkway was installed in less than 1 day (with major parts of it being pre-fab). But it sounds like it wasn't the complete project, which was expected to be finished in 2019: > Once it’s finished in early 2019, the new pedestrian bridge will link FIU’s Modesto A. Maidique Campus directly to the small suburban city of Sweetwater, where the university estimates 4,000 of its students live. http://www.miamiherald.com/news/local/community/miami-dade/west-miami-dade/article204506084.html http://www.miamiherald.com/news/local/community/miami-dade/w...

AndyKelley 9y ago

Looks like somebody hired a software engineer instead of an actual engineer.

rm_-rf_slash 9y ago
People died.
- AndyKelley 9y ago
  Life is no less funny when someone dies, than it is less serious when someone laughs.
- walshemj 9y ago
  You might not know this but Civil Engineers have a dark sense of humor and for major projects its jokingly said that the gods require a blood sacrifice.
  - akira2501 9y ago
    > its jokingly said that the gods require a blood sacrifice. Usually we're referring to something like a paper cut or a sharp edge on a prototype.
    - walshemj 9y ago
      Not in civil engineering large projects are inherently dangerous places to work.
  - rm_-rf_slash 9y ago
    My fiancé studied there. She’s still waiting to hear if anybody she knows was crushed under that bridge. This isn’t funny.

niftich 9y ago

As one can see in the installation video from last weekend, the bridge in question was the first span of a larger project, in which at least one other span would have to be installed above an adjacent canal to complete the crossing. A rendering [1] shows the completed crossing to be an asymmetric harp-type cable-stayed bridge, with cables supporting both the portion above the road (the piece in question), and the piece that's yet-to-be constructed to go above the water. In this design, it's usually not possible to (temporarily) install the cables solely on one side of the tower, as the loads on one side of the tower would collapse the tower. Therefore, it stands to reason that the cables were either to come into play at the very end, or if the bridge were constructed by cantilevering out from the central tower and attaching cables as you go. In other words, without trying to pass judgment on the cause, the cables are either a red herring (because the sub-spans are self-supporting), or the bridge was assembled in a terribly incorrect sequence. [1] http://www.miamiherald.com/news/local/community/miami-dade/west-miami-dade/article204506084.html http://www.miamiherald.com/news/local/community/miami-dade/w...

Someone 9y ago
On the rendering, it seems to me that the part over the water is significantly shorter than the now collapsed part. It also doesn’t look heavier per meter to me, and the tower seems to be perfectly vertical. That would make it impossible to fully ‘hang’ the part over the road from the tower. => It is quite possible that the span over the road was designed to be self-supporting. That would be a non-standard design, but we are so good at building such bridges that ‘being non-standard’ almost has become the standard.

AJ007 9y ago

Are bridges collapsing common? Looks like those involved had at least two other bridge related incidents in the past - http://www.miaminewtimes.com/news/fiu-bridge-collapse-construction-firms-accused-of-unsafe-practices-10176596 http://www.miaminewtimes.com/news/fiu-bridge-collapse-constr...

sitharus 9y ago
Not major infrastructural bridges, there's a list on Wikipedia: https://en.wikipedia.org/wiki/List_of_bridge_failures https://en.wikipedia.org/wiki/List_of_bridge_failures The US seems to have a lot, but there are a lot of bridges in the US. Construction is pretty risky though, there are often elements that are incompletely supported - engineers do plan for this and ensure they are strong enough.

jandrese 9y ago

Is it common for pedestrian bridges to be so overbuilt? Given the weight and span it sounds like it has a cross sectional area of about 75 square feet of concrete (a little less for the steel components, but still a lot) for a mere 15 foot traffic deck. It's not crossing an especially large span nor need to carry any substantial weight other than its own, so why does it need to be so heavy? Are they expecting trucks to run into it maybe?

CapitalistCartr 9y ago
They have to calculate for worst-case scenario. Imagine it were completely full of people. Dancing. Plus, people do ride motorcycles on them if they can get them on.
- jersully72 9y ago
  And Mother Nature.
- nugi 9y ago
  I have a few friends that easily outweigh my full size motorcycle.
cdolan 9y ago
People are surprisingly heavy per square foot - multiple times the weight of a car PSF.

giarc 9y ago

>The $14.2 million project was designed as a cable-supported bridge by MCM and Figg Bridge Design. Figg was hired to design the replacement for a bridge on I35 in Minnesota that collapsed in 2007 and killed 13 people. 1 paragraph later. >“In our 40-year history, nothing like this has ever happened before,” Figg said. EDIT - As others have pointed out... I misread these statements.

kldavis4 9y ago
They were hired to design the replacement, not the one that collapsed.
maxerickson 9y ago
They designed the replacement that was installed in 2008. The bridge that collapsed was designed by a different company in the 1960s. https://en.wikipedia.org/wiki/I-35W_Mississippi_River_bridge#Design_and_construction https://en.wikipedia.org/wiki/I-35W_Mississippi_River_bridge...
- giarc 9y ago
  Oh I see... I've edited my comment.

mudil 9y ago

Famous video of "Galloping Gertie" Tacoma Narrows Bridge collapse in 1940: https://youtu.be/j-zczJXSxnw https://youtu.be/j-zczJXSxnw

gumby 9y ago

People died and FIU offered...yes, thoughts and prayers (look at the end of the article). Sigh.