Authorities say pigeon poop contributed to bridge collapse

Trains Magazine General Discussion
1

Makes one wonder how many railroad bridges are affected, too.

From: The Associated Press

ST. PAUL, Minn. (AP) – 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.

“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,” said Langerman. “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 thei

2

That’s interesting… I had no idea what the chemical make-up of pigeon dung was. It makes interesting reading, and now I am sure, in the great state of Illinois, IDOT is going to be taking another look at our friendly pigeons…aka “rats with wings”

3

“Let’s hurry up and blame something before they blame us”

BLAME CANADA! (Theme from South Park the Movie)

I know the words are a bit modified but thats the first thing I thought of when I read the report.

Paul

4

It was also reported a couple weeks ago that pigeon poop obscurred the steel, thus preventing it from being properly inspected. They also complained about too many spriders living on the bridge, and too many spider webs. But these pigeon and spider excuses are so pathetic that I am amazed they are being offered. No matter whether pigeon poop hid defects or cause them, it is the job of the state inspections authority to inspect the bridge and certify it safe. Either move the poop and look at the steel or close the bridge.

There is no pigeon excuse unless inspectors can prove that so many pigeons happened to land on the bridge that their weight overloaded it. And even that should have been taken into account as a design issue.

Speaking of load weight, the NTSB has determined that there was 288 tons of construction equipment and materials on the bridge that was involved with the resurfacing work at the time of the collapse.

5

I know that bird droppings of most kinds will damage the finish on new cars. If you don’t wash it off fairly quickly it will destroy the clear coat and permanently dull the finish.

Bird Guano from a South American Island was mined during the immediate pre-Civil War Era for its Nitrate content to make Gunpowder. Slaves were used for the mining as the life expectancy of the miners from breathing in the Dust was short.

6

The Bird dodo article is worthy of The Onion…not the AP.

7

I don’t think the idea of pigeon droppings playing a role is hogwash. There is a reasonable cause to believe it could have been a contributory factor in some capacity. This is not being toted as an end-all explanation. No one seriously believes this is the central cause. However, this is in no way an excuse for what happened. The authorities knew it was there; it had to be cleaned.

8

Typical reaction to this sort of thing - Ignore it, and maybe it’ll go away.

Give it 40 years of not going away and the result could easily be serious degradation of the structure.

I once encountered a situation where a relief tube in the aft compartment of a KB50 had leaked undetected for an extended period of time. The problem was discovered when the weakened skin blew out, causing a drop in pressurization. The tube was 1/4" in diameter. The area where skin and stringers had been eaten away was about the size of a dinner plate. The hole would have easily passed a softball.

If human urine can do it, I’m sure that pigeon poo can.

Chuck (modeling Central Japan in September, 1964)

9

How long ago did they retire the KB-50s? I am guessing it was not too long after the KC-135s came along.

10

Just to be clear, I am not suggesting that pigeon poop could not have caused the collapse. What I am saying is that any explanation for a direct cause such as pigeon poop, spiders, construction project overloading, or lack of funds is overridden by the main point that inspectors must guarantee the safety of the bridge or close it. Considering what occurred in the face of that awesome responsibility, it is no wonder that we are being offered excuses.

11

Bucyrus has it exactly right. If necessary get a fire engine to blast the spiders and the pigeon poop out of there, or put it on a river barge to get the center sections clean; but do your job of actually inspecting the structure.

Next time it might be wise to insist on a design that is less attractive to the birds.

12

Sounds to me like a case of “passing hte poop”, whoops I mean “passing the buck”. I recall many times my dog ate my homework during high school, but I never managed to convince my teachers to “give me a pass” for that reason.

13

Not sure how you get a firehose to a long span of bridge over a river!! Inspectors had to be lowered down the side of the bridge on ropes to look under. They tried in the limited time they had (time is money) to see everything they could, but they apparently couldn’t completely clean every piece of the bridge just in case some of the dirt, droppings or whatever were covering an almost microscopic hairline crack or joint problem.

Unfortunately, I’m sure many of the people in the general public who are now complaining that the bridge maintenance and inspection crews were lax were a year ago happily voting for politicians who pledged to not raise taxes even to help boost the crumbling national infrastructure.

14

Hey folks, I was born and raised in the New York City area (a.k.a.: The Pigeon Capital Of The World) and I have personally seen hundreds (if not thousands) of pigeons sitting on bridge girders over the years and have never heard of a bridge falling down in that area…and most of the steel bridges in the New York area are much older than the one recently impacted in Minneapolis.

15

Okaayy… That’s rather odd… Their explanation makes some sense, but it’s kinda odd all the same.[:-^]

16

Hello,

I work aircraft structures for FedEx and we are involved in a situation similiar to the one Chuck speaks of. I’m repairing a 727-200 that has severe fuselage skin corrosion at the aft lavatory service panel. These panels are deactivated on our aircraft but apparently “blue water” residue from the previous operator of the aircraft seeped down between the stringers and skin and began to do it’s damage. The pressure from the corrosion caused the rivit heads to shear and the fuselage skin to bulge outward. I’m now looking at about a two square foot cutout of fuselage skin which is located next to the aft pressure bulkhead, which makes this a complex repair. Waiting on Boeing engineering for a repair drawing. The stresses and pressures caused by corrosion can be enormous. I’ve seen corrosion areas, usually aluminum or alloy steel, bend and break stainless steel and titanium components that are rather heavy and thick.

Take care and be safe!

Gregory

17

There’s no shortage of companies with equipment and expertise to clean Bridges and other steel structures. Hydroblasting equipment (basically a super powerfull industrial sized power washer) is used to clean guano, ect. There was an episode of “Dirty Jobs” on the discovery channel where host Mike Rowe demonstrated how it’s done. Many of these firms have truck mounted multi jointed telescoping work platforms which can get men and equipment under and into a bridge’s structure.

18

Well, you can bet that corrosion due to pigeon guano played some role, be it however small. The problem with this bridge, and with all structures, is that you have to look at all contributing factors and analyze their synergistic effect. Looking specifically at this bridge, you have 40 years of weathering, 40 years of pitting due to pigeon guano, 40 years of high frequency cyclic loading, 40 years of high amplitude (rush hour) cyclic loading, X number of repair/resurface/reconstruction loadings, etc.

The weathering, guano and cyclic loadings reduce the strength of the structure little by little. There was construction loading, coupled with the high amplitude, high frequency loading of rush hour. Put all of that on a weakened structure and you have a recipe for catastrophy.

The cause of the bridge collapse will be revealed, but we already know the reason: lack of adequate quality inspections.

19

As alluded to above, it is systemic, and systems thinking is what will ultimately provide both the cause(s) and the remediation. I think the most insidious aspect of the systemic failure cannot be attributed to any one factor more than our homosapiens’ penchant for taking the easy way out. That applies all the way down the line, from those in charge down to the great unwashed electorate. If I am correct, you should see a lot of squawking and threats and lawsuits and…you name it…from a whole bunch of strata. Finger pointing, head ducking, alliances suddenly where there were none, strange bedfellows very chummy…

But my point is that it really comes down to our preferences for the status quo as we understand it. If we really wanted that to change, and for us to have truly accountable leading engineers, executives, legislators, and such, we know what we have to do.

20

The probable cause sure does point that way, unless something really fluky is found to be a cause that can be said to be an act of god. Bridges start to wear out the day they are opened. That is why there is a federal inspection program in place to guarantee that bridges do not become unsafe. It is similar in its rigid requirements to the federal locomotive boiler code enforcement. You have to learn the condition of all of the metal.

It is quite popular for politicians to blame the people who resisted higher taxes. But that is a worse excuse than pigeon poop. That lame excuse is a political ploy to expand the government on the back of this tragedy. Even MNDOT ran away from the funding excuse because they know that it is a bogus, transparent stunt.

It is true that a bridge will collapse if it is not maintained, and maintenance costs money. But a lack of money cannot possibly be the cause when you have agencies in place that only have the two options:

  1. Guarantee the safety of the bridge.

  2. Close the bridge.

Our so-called crumbling infrastructure is being used like a cash cow to pull in revenue that can be spent for anything else they happen to want. If they fix the roads and bridges they kill the cash cow. And then they won’t have their several hundred millions of dollars that they siphon off the highway budget and spend on bike trails every year in Minnesota, for instance.