Pigeon dung examined in bridge collapse

[TZ]

ST. PAUL, Minn. - Pounded and strained by heavy traffic and weakened by missing bolts and cracking steel, the failed interstate bridge over the Mississippi River also faced a less obvious enemy: pigeons.


Inspectors began documenting the buildup of pigeon dung on the span near downtown Minneapolis two decades ago. Experts say the corrosive guano deposited all over the Interstate 35W span's framework helped the steel beams rust faster.

Although investigators have yet to identify the cause of the bridge's Aug. 1 collapse, which killed at least 13 people and injured about 100, the pigeon problem is one of many factors that dogged the structure.

"There is a coating of pigeon dung on steel with nest and heavy buildup on the inside hollow box sections," inspectors wrote in a 1987-1989 report.

In 1996, screens were installed over openings in the bridge's beams to keep pigeons from nesting there, but that didn't prevent the building of droppings elsewhere.

Pigeon droppings contain ammonia and acids, said chemist Neal Langerman, an officer with the health and safety division of the American Chemical Society. If the dung isn't washed away, it dries out and turns into a concentrated salt. When water gets in and combines with the salt and ammonia, it creates small electrochemical reactions that rust the steel underneath.

http://news.yahoo.com/s/ap/20070822/ap_on_sc/bridge_collapse_pigeons
Interesting theory. I would like to know what people with engineering/physics/chemistry backgrounds think of this.

[pitohui]

1. the bridge who designer who didn't know pigeons perch/nest on bridges should be shot

that's what i think about it

come on, pigeons with their supposedly deadly dung are on ALL bridges, crap, let's not blame the pigeons for humanity's fuck up

this is just plain spewing of blame and trying to put it on somebody who won't litigate for libel

[TZ]

3. I think the point of the article was to say

that while all bridges have pigeon problems that many take steps to keep the buildup of dung down. Its possible that neglect of this angle helped contribute to the weakening of the structure. I do know that pigeon dung can be toxic to people, but I was unsure if it was really as corrosive as it claims. It seems reasonable based on the very basic chemistry I know that it could be...

[pitohui]

6. yes, and they took steps too, the nesting was stopped in 96

as for stopping them from perching you can't, without extraordinary efforts

i assure you that we have a great many pigeons in new orleans and our bridges are OLDER and manage not to fall down or if they do fall down it's because a barge or a major hurricane or storm surge hit them -- not some pigeon shit

it's just crap, stop and think about it, these people are making excuses for their own failures

don't tell the army corps of engineers or that will be their next excuse for why the levees failed, the pigeons done it!

also pigeon crap is toxic to people because it causes pigeon breeder's lungs and some other diseases -- bridges don't have lungs

[Canuckistanian]

2. The day pigeon dung can bring down a bridge

That's the day when we should re-think our whole concept of bridge engineering.

[Warpy]

4. People with urban backgrounds will tell you pigeons are just

RATS with FEATHERS. There is a reason Lehrer wrote "Poisoning Pigeons in the Park." There are some walkways in Boston that are impassible because the bridges overhead RAIN pigeon shit 24/7. Pigeon shit decorates historic ledges and most public art and collects around the foundations of all buildings. Pigeons harass anyone who tries to sit on a bench, demanding to be fed.

I wouldn't be at all surprised to find out that pigeon shit contributed to the bridge failure. The underlying reason, of course, was that it was GOP tax cuts at work, but knowing a contributing factor might slow down more destruction until we get rid of the GOP and conservative Dem leadership in our government and FIX IT ALL.

[pitohui]

5. and yet the bridges are not falling down in boston EOM

,

[Warpy]

12. Yet.

[Deja Q]

7. The shit has hit the fan? (or the bridge)

:hide:

It's a bit much to believe... especially when other studies had checked the maximum rated weight, which is nothing compared to the amount of trucks and SUVs these days.

[elehhhhna]

8. DU calls bullsh!t on the birdsh!t theory.

[pitohui]

9. yay for once we're all in agreement :-) EOM

,

[bullimiami]

10. the unexpected is the reason we have safety inspectors and

regulatory agencies.
theyve all gone corrupt/political now or been farmed out for profit to people who dont care and they money set aside to repair these things has been diverted or wasted.

[MiniMe]

11. That is just a bunch of crap nt

[Dr. Death]

13. They're investigating Sean Hannity?

Ba da boom!

Thanks, you've been a great audience.