Bridge Collapse in MN Part 2 8

[JAE]

The other thread was getting quite long so I thought I'd start a new one.

Here's a snippet from a news report today about some of the engineering thinking about dealing with the bridge in the months preceeding the collapse:

[blue]Documents obtained by the Star Tribune of Minneapolis for a story published Sunday reveal details of how officials decided to conduct periodic inspections of the bridge rather than repair it in the months before it crumbled.

According to the internal state Department of Transportation documents, officials were ready Dec. 6 to go ahead with a plan to install steel plates at several areas on the bridge as a patchwork fix amid reports that it was structurally deficient, as recommended by an outside consulting firm. The project was shelved after the state determined the process could actually weaken the bridge.

Instead, officials decided in January to go with periodic safety inspections that would look for any cracks in the beams that would warrant emergency repair. Senior engineer Gary Peterson said contractor URS Inc. assured them that any cracks could be detected before they posed a serious safety risk.

Inspections of 52 steel beams began in May but were suspended when concrete repairs began earlier this summer.

The inspection strategy was also deemed to be more cost effective, but Peterson and state bridge engineer Dan Dorgan denied that money played a role.

Engineers were to have met Aug. 20 to discuss whether the inspections were effective or if they had to go back to the plating idea.[/blue]

 

[apsix]

Lowering taxes will only work (sometimes) if you are currently in an over-taxed situation. There are also a few other factors which affect the well being of the economy!

 

[JAE]

Well, in the last 30 years, every time there's been a federal tax decrease the economy has improved drastically and revenues have gone up.

But you're right, there's a lot of factors and economics is quite a fog.

 

[bridgebuster]

Let's take a break from the vodoo science of economics and get back to the cause of the collapse: The pigeons did it.

http://www.foxnews.com/story/0,2933,294153,00.html

Someone sent me the following quote; taken from an Eng-Tips posting in 2004 (pretty much sums things up):

"Structural engineering is the art of molding materials we don't wholly understand, into shapes we can't fully analyze, so as to withstand forces we can't really assess, in such a way that the community at large has no reason to suspect the extent of our ignorance."

 

[boo1]

http://news.yahoo.com/s/nm/20070822/ts_nm/bridge_collapse_ice_dc;_ylt=AmltOxETBpQZ_x.20qbs1pF34T0D

Decicing chemicals, construction loads

 

[bridgebuster]

In 1980, a stay cable on the Brooklyn Bridge snapped (the BB is a hybrid - suspension & cable-stayed); the cable hit a tourist on the walkway killing him.

NYCDOT's Chief Engineer for bridge maintenance cited pigeon droppings as the cause. The media raked him over the coals; there were editorial cartoons in the local papers calling him a fool. At that time, no one really thought about pigeons.

 

[prost]

Why not consider pigeons? There is an instance long ago in which a security guard severely damaged an airplane on the ground by urinating on the landing gear. He was relieving himself on the gear, the surface pitted because of the acid in the urine, crack formed and propagated unexpectedly after many landings, gear collapsed and the aircraft was damaged.

Aren't the chemicals in pigeon droppings are as nasty as road salt? Uric acid, etc.?

 

[DarthSoilsGuy]

i'm way way behind on this and the previous thread in case this already came up.

i just had to post this article. it's for the birds.

http://www.nytimes.com/aponline/us/AP-Bridge-Collapse-Pigeons.html?_r=1&oref=slogin

(p.s. i believe this link will eventually expire to a NY-Times members only when it gets archived)

 

[Qshake]

Bridgebuster - that headline in the foxnews article on pigeon guano is the problem with media today or ever really.

Pigeon Droppings Contributed to Mn Bridge Collapse.....


I have seen the effects of 2' high mounds of pigeon guano on bridges, but I don't recall anyone from NTSB or MnDOT or any of it's hired consultants reporting that Pigeon Droppings specifically contributed to this very collapse. The media is really stupid. If they only knew how stupid this was.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[bridgebuster]

Qshake - we can't too much from the media; anything for a headline and higher ratings.

About two weeks ago Fox News, which is usually reliable, interviewed a forensic structural engineer. He praised railroads for the longevity of their strucutres and rambled on about our inability to build highway bridges to last 100 years. I looked out the office windows a few minutes ago and the Brooklyn Bridge is still standing. I e-mailed Fox tto explain that this engineer wasn't giving a fair and balanced report.

Anyway, back to pigeons. I've seen more than my share of 2' piles as well. When I started doing inspections in the early 80's there were warnings about the health hazards posed by breathing in pigeon droppings. In the early 90's NYSDOT issued warnings about histosplasmosis. Then again, I had an uncle who raised pigeons for 50+ years, it never affected him; go figure.

 

[DarthSoilsGuy]

My anonymous source has informed me that the pidgeons in the Twin City area have ties to Al Qaeda. Actions are being taken to investigate if there are any "sleeper flocks" in the NYC and DC areas.

 

[jimaitken]

While doing bridge painting inspections on bridges in northern Massachusetts I remember a bascule bridge over the Merrimack River that had the lift machinery removed 30 years previous. As part of the bridge cleaning contract the old machine pit had to be cleaned of several feet of pigeon guano... and I thought bridge painters had a dirty job.

 

[JStephen]

"They put safety labels on cigarettes why can’t we do something of the same for structures? At a minimum I think any structure that has been deemed unsafe or inadequate should be conveyed to the public so they can make a conscious decision on whether or not to use the structure."

I remember driving along the LA-TX border once, and came to a sign that said "Substandard Road- Next 19 Miles". So yes, it's been done.

The thing is, in most cases, you don't have a real choice about how to go. You could slap a warning sign on every bridge across the Mississippi, and then what are people going to do? Just stay on their side the rest of their life?

 

[bridgebuster]

I worked on the design of a truss over the Mississippi; hopefully it doesn't need a warning sign.

I didn't design the gusset plates; it was the guy in front of me.

 

[jdonville]

From Publication No. FHWA NHI 03-001, Bridge Inspector's Reference Manual

functionally obsolete – a bridge that has deck geometry, load carrying capacity, clearance or approach
roadway alignment that no longer meets the criteria for the system of which the bridge is a part

structurally deficient – bridges where 1) significant load carrying elements are found to be in poor or worse
condition due to deterioration and/or damage or, 2) the adequacy of the waterway opening provided by the
bridge is determined to be extremely insufficient to the point of causing intolerable traffic interruptions

Jeff

 

[unclesyd]

I think we should post a warning on all bridges.

"[red]Proceed at your own risk_xDOT[/red]"

This might help with future litigation.

 

[JAE]

Fine print on all future structure's cornerstones:


[red]All individuals entering this structure acknowledge, by the mere act of entering, that they understand and accept the potential exposure to danger by placing their carcass within or upon this structure, that any and all possible deleterious events can and may occur while within. These events include, but are not limited to full or partial collapses from:
a. Seismic Events
b. Deterioration
c. Pigeon Guapa
d. Lack of maintenance
e. Poor design
f. Construction errors
g. Union or non-union labor
h. Bird dung from other than pigeons
i. Sink-holes
j. Human resonance
k. Collisions with airplanes, ships, submarines,
hovercraft, monster trucks, wheel barrows, or
other vessels
l. Just about any other kind of dung
m. Earth Wind and Fire (good music huh!)
n. High winds from visiting politicians or other low
pressure zones
o. Sudden increases in gravity

The individual releases and holds harmless the building owners, shareholders, officers, employees, building designers, constructors, and anyone else, directly or indirectly connected with planet earth.

In the event of injury or damage of any nature (or perhaps even death) to the individual or anyone else caused by or incidental to the election of entering said premises, the individual acknowledges that it is totally his or her fault. Risk exists. Deal with it.[/red]

 

[msucog]

oh now jae, you've gone to far...expecting the general public to be reasonable...pretty funny though...i guess it's about like people being appauled that our volunteer soldiers die in war; all while they sit on the couch in their cozy home complaining about soldiers dieing in war.

 

[bridgebuster]

JAE - you forgot to include global warming on your list.

The Connecticut DOT does post a warning sign on highway & bridge construction projects. It says something to the effect that road use and State liability is limited.

 

[d2y]

We have traffic overload, media overload, stretched resources, and by the way, reliable news is an oxymoron.

I think we would all agree that to engineer is human, and stressful. Don't you love it?

 

[graybeach]

to continue JAE's list:

p. (a word that is homophone with the letter designation)