Minneapolis Bridge Collapse--Sound off

[Kuciwalker]

Good

[Darius871]

gravity sucks

[Patroklos]

Does this count as the fifth or the sixth seal?

[Lord Avalon]

Was it Avian Aggressors unleashing Biochemical Warfare?!?!?

Pigeons stressed Minn. bridge
Dung was source of corrosion, if not factor in collapse

August 23, 2007
BY MARTIGA LOHN
ASSOCIATED PRESS

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: birds, specifically pigeons.

Inspectors began documenting the buildup of pigeon dung on the span near downtown Minneapolis two decades ago.

Experts say the corrosive guano deposited on the I-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 1987-89 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 buildup of droppings elsewhere.

Pigeons are drawn to bridges

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.

"Every time you get a little bit of moisture there, you wind up having a little bit of electrochemistry occurring and you wind up with corrosion," Langerman said. "Over a long term, it might in fact cause structural weaknesses."

Langerman emphasized that he wasn't saying pigeon dung factored into the collapse of the 40-year-old bridge. "Let's let the highway transportation and safety people do their job," he said.

Keeping pigeons off bridges usually requires a multipronged strategy that can include netting to block holes and surfaces, spikes to keep pigeons from landing, and sometimes poisoning, shooting or trapping the birds, said John Hart, a Grand Rapids, Minn.-based wildlife biologist with the U.S. Department of Agriculture.

The problem is that pigeons are naturally drawn to bridges and tall buildings because the birds are descended from cliff dwellers, said Karen Purcell, who heads Project PigeonWatch at the Cornell Lab of Ornithology. Bridges offer shelter from predators and flat surfaces for nesting and roosting.

"It's a nice fit for them," Purcell said.

http://www.freep.com/apps/pbcs.dll/article?AID=/20070823/NEWS07/708230348/1009/NEWS07

[BlackCat]

If I understand this right, then the yanks should change their anti-terrorist efforts from crazy religious fanatics to hideous evil pigeons. Wonder if the yanky nation is prepared for such a war

[Hueij]

Originally posted by BlackCat
If I understand this right, then the yanks should change their anti-terrorist efforts from crazy religious fanatics to hideous evil pigeons. Wonder if the yanky nation is prepared for such a war

Nah, there is a Gyro Gearloose story that shows how to scare birds away from bridges. Don't people read their classic comics anymore?

[BlackCat]

Originally posted by Hueij

Nah, there is a Gyro Gearloose story that shows how to scare birds away from bridges. Don't people read their classic comics anymore?

I've read AA for a decade or so back in the 60-70'es, but I can't recall that one

[Hueij]

Originally posted by BlackCat


I've read AA for a decade or so back in the 60-70'es, but I can't recall that one

I'll try to find the album and make a scan of the page tomorrow.

BTW, AA??

[BlackCat]

Anders And -> Donald Duck