Bridge Analysis

MoDOT Completes Preliminary Study of Minneapolis-Type Bridges
156 Deemed Safe So Far, Remaining 76 Will Get Further Study

Preliminary studies of all Missouri bridges with gusset plates similar to the collapsed bridge in Minnesota are complete, with many already confirmed as safe, Missouri Department of Transportation bridge engineers announced.

Engineers are evaluating the state's 232 truss bridges.

Read more....

Missouri took the NTSB’s press release seriously as all jurisdictions were urged to do. Meanwhile, Oberstar tried to make political hay out of Rosenker’s preliminary findings. MoDOT Director Pete Rahn knows, in a real world, he must not ignore NTSB (to his own peril if a bridge collapses), but Oberstar has the luxury of politicizing the real world report.

Even Louisiana is following suit.

William D. Ankner, Louisiana Department of Transportation and Development Secretary designee, said the recent federal report citing the steel plates connecting the beams of a bridge’s frame as the probable cause of the Minneapolis bridge collapse caused Louisiana to check its own bridges more closely.

"After the Aug. 1 Minneapolis bridge collapse, DOTD bridge inspectors reviewed and analyzed the inspections of all truss bridges in Louisiana," Ankner said. "However, in light of the federal government’s findings I have directed DOTD engineers to begin an immediate review of the plate design of all similar bridges in the state.
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Isn't it amazing how engineers can read the NTSB report and take prudent action while a politician attacks the reporting NTSB chairman to try and score political points? Motives make all the difference in the world. Engineers try to preserve life and save themselves enormous embarrassment and culpability. Democrat politicians embarrass themselves trying to destroy Republicans who clearly are not at fault while not sensing any guilt whatsoever.

Somewhere in Missouri and Louisiana there certainly must be some Democrats among the engineers who knew they needed to take prudent action. Three cheers for Democrat engineers!

Duplicity

Isn’t it amazing how Oberstar and other Dems can denigrate a person’s ability and integrity if they are a Bush or Pawlenty appointee? Rosenker’s integrity is attacked because he is a Bush appointee. Molnau’s integrity is attacked because she is a Pawlenty appointee.

Oberstar is the senior Democrat on the Transportation and Infrastructure Committee and has oversight of the NTSB and its chairman, Rosenker. And yet Oberstar pawns himself off as a public servant when he takes Rosenker to task for his report, which obviously hinders the Dems cause. Oberstar wants us to think his motives are honorable while Rosenker’s and Molnau’s are political. Oberstar thinks he has a right to meddle in the process to get a report he wants. That right is reserved for Dems alone.

Nothing New

Rep. James Oberstar felt compelled to attack NTSB Chairman Mark Rosenker to keep up the Democratic attack on the GOP for the bridge collapse. In a courtesy of hand-holding the Representative, Rosenker met with Oberstar to explain a few things that he seemingly could not understand by hearing and reading the NTSB report.

No new information comes from this meeting. The gussets were still undersized and the undersized gussets were not compromised by corrosion. See our previous post. According to MPR, "Rosenker said he meant only that the under-designed gusset plates didn't show signs of corrosion." We knew that from the NTSB report. See also the Strib report on the meeting.

Oberstar’s letter to Rosenker is in contrast to his official web site which has a press release that shows he had an accurate understanding of the NTSB report as of January 15 and a measured response to it. Oberstar knew all along there was nothing to be clarified by Rosenker. On his web site, he even praised the benefit of the NTSB’s report on the undersized gussets so all governmental agencies can review their bridges.

This duplicity is disgusting for it is pure pandering to show Big Daddy is looking out for us. Don’t expect an apology from Oberstar for trying to make something out of nothing. With the web available to all of us, it is easy to find this hypocrisy. Thank you Al Gore for inventing the Internet!

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Update

Read the New York Times article on the topic.

Oberstar Pouts

Rep. Oberstar criticizes NTSB chairman's 35W bridge findings
The Minnesota Democrat said corrosion and cracking should not have been dismissed as possible fatal flaws.
By KEVIN DIAZ, Star Tribune

Minnesota Democrat Jim Oberstar, chairman of the House Transportation Committee, fired off a critical letter to the head of the National Transportation Safety Board (NTSB) on Wednesday, saying it was "highly inappropriate" for him to dismiss corrosion and poor maintenance as possible causes for the Interstate 35W bridge collapse.

Read more...

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Oberstar can’t quit stirring the pot because, in the words of the reporter,

"A design flaw would give Oberstar and other DFLers less of an opening to hold officials at the Minnesota Department of Transportation and Gov. Tim Pawlenty responsible for what they view as a lack of inspection and proper maintenance on the bridge."

Rosenker has been attacked for being a Bush appointee. Now it is Rosenker’s inexperience at NTSB that Oberstar attacks. Any excuse will do for him to avoid facing reality when he is determined to pin the cause on the GOP. Rosenker, speaking for the NTSB, identified a design flaw that resulted in the bridge collapse and stated corrosion or lack of maintenance did not bring the bridge down. Undoubtedly, the NTSB examined all the beams and gussets and noted the condition of each.

If we were allowed to examine each gusset, I would suggest that the average non-engineer could identify which gussets broke and if corrosion were involved.

• We could identify gussets that bent as a result of a bridge section collapsing.
• We could identify gussets that cracked sometime ago because the metal surrounding the crack would be rusty.
• We could identify gussets that cracked very recently because the metal surrounding the crack would be bright and shiny.
• We could identify gussets that flaked and crumbled due to corrosion.
• We could identify gussets that cracked from the top or from the bottom.
• If we looked at a bent gusset with some corrosion on it, we could tell if it was bent due to the leverage of a collapsing section or the result of corrosion.
• We could identify gussets that were sheared and ripped.
• We could identify gussets that were of different thicknesses.
• And if we identified gussets that were thinner than others and sheared, we would conclude the gussets were undersized compared to the rest.

A person does not need to be an engineer to identify these features about gussets. In the real world, a group of non-engineers selected randomly from society who were given opportunity to look at the gussets would be able to draw some highly accurate conclusions. That group may not be able to identify the first gussets to break, would not be able to do the mathematical calculations, would not be aware of all the forces at work on the bridge structure, may not be able to identify what caused the undersized gussets to break now and not previously and it could not identify the actual problems before the bridge collapsed. However, that group would be able to identify the sheared gussets and whether corrosion was the cause of the shearing of those gussets.

Oberstar deliberately underestimates the capability of the NTSB even though our group could come up with a report with a high degree of accuracy. In fact, if Mr. Oberstar (randomly selected and unprejudiced) were in that group, he would be able to identify which gussets broke and if corrosion were involved.

But since Oberstar wants to play politics with safety, he will instinctively reject the obvious. And instinctively, Oberstar projects on to the NTSB his very own politicizing of the bridge–Rosenker is a Bush appointee and inexperienced. Is everyone at NTSB a Bush appointee and inexperienced? Oberstar must have corrosion as the cause for failure because undersized gussets don’t cash in politically as corrosion may.

Oberstar does not ever have to be right, so he can keep carping. The NTSB must be right the first time they make a report because safety and credibility are riding on their work. Oberstar doesn't have to live in the real world; the NTSB does.

NTSB Doing Its Job

While Steve Murphy and Company are sniping at Pawlenty and Molnau and even NTSB Chairman Mark Rosenker for being a Bush appointee, NTSB is calmly and proficiently doing its job for the public.

The report on the St. Anthony bridge can be found here. Look at the picture of the bridge beams and gussets on page 14. Here is another diagram of the bridge. This report is complex, but I urge you to skim through it to learn a few things.

• Learn how little you know about bridges and forces and the dynamic interplay of forces.
• Look at the complex mathematical formulas in the report.
• If you can do the math, thank a teacher.
• If you can’t do the math, thank God that someone else can so bridges are built properly or can be analyzed to be inadequate.
• Realize that Steve Murphy doesn’t have a clue what he is saying when he retorted, ". . . the report is "not worth the paper it's printed on"."
• Realize that the NTSB has published the data and their reasoning for the bridge collapse so that any engineer can check it. If the NTSB is not right in their calculations, some engineer will find it.
• You know the NTSB checked and double checked and triple checked all their work.

Empirical evidence is extremely difficult to refute. Murphy doesn’t even attempt to deal with the facts. He just dismisses the report as worthless.

Based on this report the NTSB issued this press release. Missouri, the Show Me state, didn’t count the report to be worthless as Minnesota’s Senate Transportation Chair does.

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MoDOT Studying Minneapolis-Style Bridges

Statement from Director Pete Rahn In Response to Federal Findings

Missouri Department of Transportation Director Pete Rahn issued the following statement today in response to yesterday's federal report citing gusset plates (steel plates that connect the beams of a bridge's frame) as the probable cause of the Minneapolis bridge collapse.

Knowing what likely caused the Minneapolis bridge collapse is a big help to us, and I appreciate the quick work of the federal officials involved. We're using their recommendations in the study we've begun today of all 232 truss bridges on the state highway system - these truss bridges are the type that use gusset plates in the design. Any deficiencies we discover will be corrected immediately.

Read more....

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Hats-off to the NTSB for their work identifying the structural design flaw in the bridge. This is of such import that their preliminary report calls all jurisdictions to check the design calculations for this type of bridge in order to prevent similar catastrophes.

Hats-off to the NTSB for their calm and staid work in the face of the taunting, mocking, dismissive, unhinged left in Minnesota. The motoring public is served by the NTSB and not Murphy. When the final report is out, Murphy will still not realize he is out of touch with reality. In the meantime, don’t pay any attention to any of his ideas. His gussets have collapsed.

Politicizing the NTSB

The hyperventilating reaction to the preliminary NTSB report, demonstrates that science is being politicized. How can a report about some hard, cold, steel plates trigger such hot-headed carping? The reason–people who have already made up their minds are not interested in facts.

The NTSB tested the ½" x 6' x 10' steel plates, probably for tensile strength, bending capacity, compression load, shearing force, brittleness, contaminants and more. It found the material in the steel plates was not defective.

However, the NTSB found the 16 plates were undersized for the work they were intended to do in the bridge. The plates should have been 1" thick. The NTSB said this flaw was in the bridge structure from the day it was constructed according to blueprints. It was a design flaw.

These 16 large plates gave way and started the bridge collapse. However, the NTSB said explicitly they did not know what caused the undersized plates to give way. The final report will not be complete for months. If we are sane, we will wait for the final report.

Senate Transportation Chair Steve Murphy (DFL-Red Wing) said, “I've always said, 'Let's wait for the report.'” That’s good practice, but now that the preliminary report is out, Murphy said “the report is "not worth the paper it's printed on."” So why is the report he was waiting for now worthless? Because “. . . NTSB's initial conclusion was reached with the assistance of an engineering consultant hired by MnDOT.”

Minnesotans deserve much better than this from the Senate Transportation Chair. The same tests on the 16 gusset plates can be conducted repeatedly and the same conclusion will be reached. The material was not defective. The same mathematical formulas can be recalculated numerous times with the same results, showing the plates were undersized. All this data and the calculations will be in the final report for any person to review. So a MnDOT hired engineering consultant who assists NTSB would have every reason to be accurate and forthright. Murphy willfully attacked the integrity of that engineer and the NTSB.

Facts are stubborn things. But Murphy will not let facts get in his way. He must have evidence during the next few months before the legislative recess to attack Molnau and Pawlenty and lock his enormous tax increases on us for transportation as he sees fit. The NTSB report is dismissed as worthless.

He wants his own report. He and the senate will spend $500,000 of our money on their own hired guns to come up with a report before the legislature adjourns. It will be impossible for Murphy to demonstrate his hired report will not be prejudiced and therefore worthless. Yet in Murphy’s mind, his worthless report will trump NTSB’s worthless report.

Murphy has unequivocally demonstrated that he is not qualified to be the Senate Transportation Chair, let alone a senator or even a member of a jury. Senate District 28 would do all of Minnesota a big favor by voting him out of office. Better yet, Murphy should resign.