https://en.wikipedia.org/wiki/Fern_Hollow_Bridge
The bridge looks a little on the light side design wise but I don't see any major red flags. The concrete has maybe taken some?ÿ wear and tear but the major structural elements are steel. The news speaks of "heavy snow" but there only seems to be an inch or so on the ground.?ÿ
Street view from last September:
GE has street view from below but it is of very low resolution.
It was really cold yesterday morning here, -2?øF, and then warmer this morning, 26?øF. Not sure if that had anything to do with it. I have done stream surveys in that park on Nine Mile Run all the way to the river, but not on that tributary.?ÿ
Coincidentally, I taught a Structural Monitoring workshop at the PSLS conference on Wednesday, and afterward one of the district surveyors from a different district talked to me about how they have a lot of bridges that get hit or damaged. But, as I told him and others in the class, you need an initial survey to compare it against. I don't know if the abutments shifted or not, but if we had a scan or prior survey it would be easy to tell. Usually the as-builts I have seen around here is just someone stamping the plan and saying it was built like that.?ÿ
That is a major road, shutting it down for months is going to be a major traffic issue in that whole area.?ÿ
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Not that it would contribute to massive failure, but just observing, the guy tie to the left colum support is twisted, and why is the pvc pipe attached? ?????ÿ
Speaking of bridges, a few days ago I found the plans from 1951 for a county bridge spanning a river.?ÿ Sometime in the 1990's a county low-boy hauling a large bulldozer hit an upright or two with the dozer blade.?ÿ The bridge was closed until approved remedial action was taken.?ÿ The entire bridge was demolished and replaced in 2010.?ÿ The 1951 plans will remain in the county files until Twinkies disintegrate and there are no cockroaches to eat the crumbs.?ÿ?ÿ
From the WP
The bridge ?? which has been estimated to carry about 14,500 vehicles a day ?? has been rated in poor condition in inspections dating back to 2011, according to the U.S. Transportation Department??s National Bridge Inventory. The Pennsylvania Department of Transportation?ÿnotes?ÿthat a poor rating of a state bridge means that ??deterioration of primary structural elements has advanced.? A September 2019 inspection of the city-owned Fern Hollow Bridge found that both its superstructure and deck were in poor condition.
I would say the deterioration is complete. Miracle nobody was killed.?ÿ
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Just because I'm paranoid, doesn't mean they aren't out to get me.
The 1951 plans will remain in the county files until Twinkies disintegrate
You're suffering from the "Twinkie Myth".?ÿ Twinkies original "best by" date was only 25 days (45 days now), beyond which their taste and texture degrades slowly.?ÿ Decades ago I was a Twinkie aficionado but went on the wagon concerning sweets.?ÿ I don't even eat cookies nowadays.?ÿ Eight years after purchase I discovered a few Twinkies still in their cellophane wraps in the back of my pantry.?ÿ Rest assured they'd disintegrated into disgusting brown foamlike turds.
Not that it would contribute to massive failure, but just observing, the guy tie to the left colum support is twisted, and why is the pvc pipe attached? ?????ÿ
I don't know for sure but I'd guess that the PVC is connected to a drainage structure on the deck.
Andy
The bridge appears to have been built of irony.
Historic boundaries and conservation efforts.
It looks to me that the pier on the right side of the picture might have a bit of a lean to it.?ÿ
It looks to me that the pier on the right side of the picture might have a bit of a lean to it.?ÿ
I saw that too at first.?ÿ But I'm going to assume that's due to parallax in the image.?ÿ Any structure like that with a 'leaning' pier is not long for this world.?ÿ Had that pier actually been leaning the deformation of the deck probably would have rendered it untravelable.
mu $0.02?ÿ?ÿ
I noticed a new bridge over the Neosho east of Chanute since I was around there late 1980's.?ÿ Did some dozer haulers insurance pay for that?
@ridge?ÿ
No.?ÿ Normal wear and tear.?ÿ The new one was built on a new alignment to keep the old one open as long as possible for through traffic.?ÿ Did the same thing a few miles east over Big Creek.
Here is a picture taken by a dog-walker in 2018 ...
Wow. It seems that the question why it fell is answered. Now we have the question of how it was allowed to remain in use.?ÿ
I would say that those newer looking cables are there to handle tension, while that beam that failed likely was a compression member. But that is going to be a key question, why wasn't it shut down or fixed earlier. Note that they say that Pittsburgh has more bridges than any other city in the world, so you would think there would be some expertise. But the bridges have three different "owners", some are city, some are county, others are state. After the I35 collapse in Minneapolis, they did rehab a very large bridge nearby of similar design (Rankin bridge) to the I35 bridge with gussett plates.?ÿ https://g.co/kgs/uvvjDX
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