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Topic: Minneapolis Bridge Collapse

Gordon McLeod
Film God

Posts: 9532
From: Toronto Ontario Canada
Registered: Jun 99

posted 08-02-2007 02:25 PM

By its nature most concrete structures just like concrete itself have a finite life span compared to natural materials like stone
An engineer once told me most concrete will have a reduction in strength in about 10 years

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Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999

posted 08-02-2007 02:28 PM

Hey, you want to know how to build a bridge? Come to Brooklyn and we'll show you. 50yrs life span? That's a joke. Roeblings' Brooklyn Bridge was finished in the early 1880s, was build before bridge models could be tested in wind tunnels for aerodynamic integrety AND it was built for horse and buggy travel, not for cars. And.....IT IS STILL STANDING, long after many others built after it are gone. Interesting fact: the Manhattan side tower isn't planted in bedrock but only on sand. Now THAT's how you build a bridge!

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002

posted 08-02-2007 03:32 PM

quote: Gordon McLeod
An engineer once told me most concrete will have a reduction in strength in about 10 years

I would expect to see some reduction in that time, but how much? If it's 0.01% then it's no great problem; no structure is going to last forever. If it's 5%, then something is seriously wrong.

Glenfinnan Viaduct, in Scotland was built in concrete in 1901, and still seems to be in pretty good condition. web page Admittedly, the construction is quite different to most modern concrete structures.

quote:
Hey, you want to know how to build a bridge? Come to Brooklyn and we'll show you. 50yrs life span? That's a joke. Roeblings' Brooklyn Bridge was finished in the early 1880s, was build before bridge models could be tested in wind tunnels for aerodynamic integrety AND it was built for horse and buggy travel, not for cars. And.....IT IS STILL STANDING, long after many others built after it are gone. Interesting fact: the Manhattan side tower isn't planted in bedrock but only on sand. Now THAT's how you build a bridge!

I suspect that New York has more large bridges per square mile than just about anywhere else on Earth, most of them much more than fifty years old. Even the Verrazano-Narrows is now 43 years old. Most of them don't seem to be falling down, though some, such as the Manhattan Bridge, and the recently re-opened railway bridge between New Jersey and Staten Island have undergone some very heavy maintenance/refurbishment recently, and there is talk of replacing the Goethals bridge. If modern bridges are only expected to last fifty years then something seems to be wrong; whether in design, materials, construction or maintenance, I don't know.

I can think of very few bridges which have actually collapsed; there was the famous one that failed due to resonant oscillations when subjected to crosswinds, I can't remember the name.

I can think of a few in this country, oddly enough all of which were rail bridges. The Tay Bridge in 1879, I'm not sure if that was a design or materials failure. web page

Lewisham, 1957, where an overbridge was brought down after being hit by the wreckage of a train. Interestingly, the Wikipedia entry ror the accident states that the temporary bridge erected is still in use fifty years later. I haven't been that way for some time, but I remember seeing it still there a few years ago. web page .

Lastly, the Severn Rail Bridge, which partially collapsed after being hit by a barge in 1960. web page

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David Stambaugh
Film God

Posts: 4021
From: Eugene, Oregon
Registered: Jan 2002

posted 08-02-2007 03:56 PM

quote: Stephen Furley
there was the famous one that failed due to resonant oscillations when subjected to crosswinds, I can't remember the name

You're thinking of the Tacoma Narrows Bridge. There's decent quality video of it oscillating and finally collpsing there (that link be wikipedia) and probably many other places.

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 08-02-2007 04:45 PM

Perhaps the record for the shortest lasting bridge goes to the first Tacoma Narrows Bridge, which disintegrated a mere four months and six days after it was opened. The owner of a local camera shop filmed it in 16mm Kodachrome, and you can see the footage on this Wikipedia page (or buy the DVD from his son for $65 if you want to see it in colour, though this seems very expensive for an 8-minute film if you ask me) - very scary stuff.

Glad to hear that Bobby's cousin and Steve are OK.

Stephen: if memory serves me correctly, the Tay Bridge was a design issue. Wasn't the famous architect who designed it stripped of his knighthood or something like that?

Edit: great minds think alike!

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Bobby Henderson
"Ask me about Trajan."

Posts: 10973
From: Lawton, OK, USA
Registered: Apr 2001

posted 08-02-2007 05:31 PM

With regard to complaints about short life spans of bridges, there are some important points to consider, such as wear and tear beyond the original design capacity.

The I-35W bridge in Minneapolis was 40 years old. It was carrying 100,000 vehicles per day on average -which is likely a much higher traffic count than what it supported when opening in 1967. Many of those vehicles are heavy tractor-trailer rigs. One pass from a truck exerts wear and tear of the structure equal to as many as 2000 cars.

A concrete building structure can potentially withstand the elements for many decades. However the stresses to bridge and road structures posed by super-highway traffic are pretty severe, especially on urban roadways carrying hundreds of thousands of vehicles every day. Comparing a super-highway bridge to an old structure that only carried pedestrians and horse-drawn carriages is an apples to oranges thing.

Then you have to consider that most bridges built in recent decades are engineered to use as little in the way of building materials as possible -to save money.

A bridge like the Brooklyn Bridge was definitely "over-built" compared to today's standards of engineering. Some mention should also be made about how the Brooklyn Bridge (and many of the other large bridges in NYC) have had lots of rehab work done on them over the decades.

The Verrazano Narrows bridge is one of the youngest bridges in NYC. But when I moved to Staten Island in 1986 the bridge was getting all sorts of maintenance work and a new paint job. My family took the opportunity to walk across the top deck of the Verrazano bridge during a celebration of its 25th birthday in November of 1989. Somewhere I have a bunch of color slides I took while making the walk.

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Mike Heenan
Phenomenal Film Handler

Posts: 1896
From: Scottsdale, AZ, USA
Registered: Mar 2000

posted 08-02-2007 06:39 PM

quote: Frank
Hey, you want to know how to build a bridge? Come to Brooklyn and we'll show you. 50yrs life span? That's a joke. Roeblings' Brooklyn Bridge was finished in the early 1880s, was build before bridge models could be tested in wind tunnels for aerodynamic integrety AND it was built for horse and buggy travel, not for cars. And.....IT IS STILL STANDING, long after many others built after it are gone. Interesting fact: the Manhattan side tower isn't planted in bedrock but only on sand. Now THAT's how you build a bridge!

Hmmm, not so fast....

http://wcbstv.com/topstories/local_story_214173505.html

(CBS) MINNEAPOLIS The three governors across the tri-state have called for a review of all bridges following the devastating Minnesota bridge collapse, but there is one bridge in particular causing worries: the Tappan Zee, which spans the Hudson River.

It's long been known the Tappan Zee bridge has problems. A recent report from the Federal Highway Administration points out significant deterioration to the concrete and the structural steel of the bridge. The New York State Thruway Authority says it's working to address the problem.

There's reason to be concerned about the bridges in the region, which take on a heavy load from the overload of traffic especially within New York and New Jersey.

Of 2,027 bridges in New York City, the 124-year-old Brooklyn Bridge is only one of two to fail its most recent inspection. It's got problems, but the city insists those problems do not put the public at risk.

"The poor condition means there's components of the bridge. They are the approaches, and of the approach it's the bridge deck and some joints," said Lori Ardito of the New York City Department of Transportation. "Again, it is safe, but it just means that those components need to be rehabilitated."

That said, it's the older bridges that cause DOT officials the most anxiety. New Jersey's Pulaski Skyway, for example, was built in 1930 to funnel the Holland Tunnel traffic inland and would be replaced if the state could afford the billion dollar price tag.

Gov. Jon Corzine says they're keeping a close watch on it. "If there are unsafe bridges, they'll be shut down," he says.

Most bridges are physically inspected every two years unless a structural problem is identified. Many believe that's not enough protection and some experts say we should employ more electronics to sense extra wear or stress, such as technology available that enables remote monitoring of bridges.

Still, the biggest bridges in the area are often under continual maintenance. Crews were out Thursday, for example, on the Throgs Neck Bridge connecting Queens and the Bronx. In a phone conference Thursday afternoon, city DOT officials said the bridges connecting the boroughs are in the best shape in a decade.

"I want to reassure all New Yorkers that all of our bridges have been inspected in according to state and federal standards," Ardito said.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 08-02-2007 08:13 PM

Humm, I heard last night during the Prez's DOT secretary speaking that there were 80,000 bridges nationwide deemed unsafe and need replacing... Anyone else hear her say that?

Mark

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Mike Heenan
Phenomenal Film Handler

Posts: 1896
From: Scottsdale, AZ, USA
Registered: Mar 2000

posted 08-02-2007 09:35 PM

Didn't hear it but there's an article at the top of Drudge that says more than 70,000

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Steve Scott
Phenomenal Film Handler

Posts: 1300
From: Minneapolis, MN
Registered: Sep 2000

posted 08-02-2007 11:03 PM

For the sake of the busy day, here's my album containing a few photos of the day's tour around the scene. Nothing more spectacular as I was on my day off, thankfully & not among the would-be first responders if fate had treated me differently yesterday!

Again, a sunset shot of the abandoned superhighway; a view of late evening traffic levels that rival typical rush hours around here; the buckling approach to the non-bridge; the press conference with most representatives attending, this morning; and the freight car that was leaking last night, now subtly pinned underneath the former interstate overpass.

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 08-03-2007 02:40 AM

That freight train wagon looks like it was built to withstand a direct hit from a missile! Admittedly it's in the background and perspective may be playing tricks, but it seems as if the entire bridge deck is resting on its roof - the wagon doesn't look in any way deformed or crushed at all.

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Mark Hajducki
Jedi Master Film Handler

Posts: 500
From: Edinburgh, UK
Registered: May 2003

posted 08-03-2007 07:36 AM

quote: Bobby Henderson
The I-35W bridge in Minneapolis was 40 years old. It was carrying 100,000 vehicles per day on average -which is likely a much higher traffic count than what it supported when opening in 1967. Many of those vehicles are heavy tractor-trailer rigs. One pass from a truck exerts wear and tear of the structure equal to as many as 2000 cars.

The ever increasing weight of trucks, combined with the greater numbers is adding a lot of stress to many bridges (and roads in general).

This is one reason why the M6 Toll road near Birmingham UK, charged HGV (heavy goods vehicles) £10 compared with £2 for cars when it opened, however these were reduced since most drivers were using the old (free) section of the road.

quote: Leo Enticknap
if memory serves me correctly, the Tay Bridge was a design issue. Wasn't the famous architect who designed it stripped of his knighthood or something like that?

I think it was a combination of a flimsy design (which is why the Forth bridge was built so much stronger) and the use of substandard materials. Some of the old structure has been used to support the current bridge.

The rail crossings of the Tay also have cultural importance inspiring three clasic poems

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Mike Blakesley
Film God

Posts: 12767
From: Forsyth, Montana
Registered: Jun 99

posted 08-03-2007 10:43 AM

quote: Mark Gulbrandsen
I heard last night during the Prez's DOT secretary speaking that there were 80,000 bridges nationwide deemed unsafe and need replacing...

Did she say "need replacing" or "structurally deficient?"

On the news yesterday, they explained that "structurally deficient" could mean anything from "about to fall down" to "needs to be repainted." About half of the bridges in the country are supposedly in need of SOME kind of work, but they're not all about to cave in.

It's amazing how many bridges there are. The state of Montana has over 5,000 bridges.

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Louis Bornwasser
Film God

Posts: 4441
From: prospect ky usa
Registered: Mar 2005

posted 08-04-2007 06:38 AM

Note that they were busy repaving a structurally bad bridge. This is a bit like rearranging the deck chairs on the Titanic. Louis

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Leo Enticknap
Film God

Posts: 7474
From: Loma Linda, CA
Registered: Jul 2000

posted 08-04-2007 05:16 PM

If I'm reading the news reports correctly, the key issue appears to be finding a reliable definition of 'structurally bad' by which to examine other bridges in the aftermath of this incident.

We had what I guess might turn out to be a similar sequence of events: the preliminary investigation into the Hatfield rail crash in October 2000 suggested that the likely cause was 'gauge corner cracking', i.e. structural failure of the rail itself under the stress of a heavy, high-speed train passing over it. For about a year afterwards, temporary speed limits and diversions were put in place while virtually every inch of rail in Great Britain was checked for signs of the problem. Thousands of miles of rails were simply replaced on spec: the cost was enormous, the disruption huge, and to this day no-one really knows whether it was really necessary or if the problem was in reality confined to a small proportion of the total rails in use on the system. The only thing we know for sure is that a lot of engineering companies made a lot of money from the British taxpayer.

Presumably the issue as to whether the cause of the Minneapolis bridge collapse could potentially affect other bridges will be very high on the investigators' agenda. But I can't help suspecting that there'll be civil engineering contractors across the US and beyond looking to cash in on the fear that your local bridge might just have a problem...

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