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Author Topic: Forbes Avenue Pittsburgh bridge collapse  (Read 892 times)

Stephane Dumas

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J N Winkler

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Re: Forbes Rd Pittsburgh bridge collapse
« Reply #26 on: January 28, 2022, 05:24:04 PM »

I'm surprised a span that long and wide was rated for only 26 tons.

A close call all the way around.

Because of the condition underneath.  Maybe it's more surprising they still permitted vehicles up to 26 tons to drive on it.

Since load-posting is a first step for bridges whose structural deficiencies are deemed critical, I expect the decision to post for 26 tons to be put under the microscope:  why not a lower weight, and why not close the bridge altogether?

And regarding inspections...

Quote
Each of the fracture-critical inspection reports from 1994–2006 did note the presence of rust, corrosion, and section loss on gusset plates

I think the gusset plate issue must have been a continuing blind spot.  It wasn't just a question of failure to choose an adequate thickness--the original design was checked using a method that assumes gusset plates will have all the strength required and thus can be ignored.  MnDOT commissioned finite element analysis of the bridge before it collapsed and, from what I can tell, it did not surface the gusset plates as a problem in a way that would have told MnDOT it needed to take urgent action to forestall the collapse.
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kkt

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Re: Forbes Rd Pittsburgh bridge collapse
« Reply #27 on: January 28, 2022, 05:49:38 PM »

If the September inspection rated it "poor" is there a lower rating for "failure imminent, close the bridge today"?
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Big John

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Re: Forbes Rd Pittsburgh bridge collapse
« Reply #28 on: January 28, 2022, 05:53:21 PM »

If the September inspection rated it "poor" is there a lower rating for "failure imminent, close the bridge today"?

NBI: 4=poor, 3=serious, 2=critical, 1-failure imminent.  The failure imminent rating calls for a immediate closure.
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kkt

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Re: Forbes Rd Pittsburgh bridge collapse
« Reply #29 on: January 28, 2022, 07:50:33 PM »

If the September inspection rated it "poor" is there a lower rating for "failure imminent, close the bridge today"?

NBI: 4=poor, 3=serious, 2=critical, 1-failure imminent.  The failure imminent rating calls for a immediate closure.

Thanks.
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noelbotevera

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Re: Forbes Rd Pittsburgh bridge collapse
« Reply #30 on: January 28, 2022, 08:51:21 PM »

Hey, I drove over this bridge back in December! Kinda crazy that it didn't collapse on me while I passed over it.

I'm surprised that a relatively new bridge like this collapsed, but considered the sad state of infrastructure...
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tolbs17

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Re: Forbes Rd Pittsburgh bridge collapse
« Reply #31 on: January 28, 2022, 09:31:43 PM »

Hey, I drove over this bridge back in December! Kinda crazy that it didn't collapse on me while I passed over it.

I'm surprised that a relatively new bridge like this collapsed, but considered the sad state of infrastructure...
And with that happening. Now I'm afraid to drive on the Alligator River Bridge because I feel like that one will collapse next; it's due for a replacement anyway.
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zzcarp

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Re: Forbes Rd Pittsburgh bridge collapse
« Reply #32 on: January 28, 2022, 11:20:47 PM »

The questions I'd like answered is where was this bridge ranked on the list for a major rehab or replacement, and when was that maintenance scheduled (if applicable). We can call for more infrastructure funds, and, for a locally maintained bridge, if it's not ranked in the top several, it's not going to get replaced even if it rains federal money on the local government.
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roadman65

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Re: Forbes Rd Pittsburgh bridge collapse
« Reply #33 on: January 28, 2022, 11:29:06 PM »

Shouldn’t the recent transportation infrastructure cover this?
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Re: Forbes Avenue Pittsburgh bridge collapse
« Reply #34 on: January 28, 2022, 11:29:18 PM »

Fixed thread title, as it's Forbes Avenue, not Forbes Road.

 


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