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]

 

[Jordonlaw]

csd72,

You said that "In the UK they brought in corporate manslaughter laws which held the directors accountable for such incidences." Well if it worked then I'd agree with you. No one has yet been charged with corporate manslaughter although many should have been. Herald of Free Enterprise sinking, Hatfield train crash and now Stockline Plastics explosion all show the worse cases of corporations ignoring safety.

In my company apparently "safely is the highest priority" but in practice its the bottom line that's most important. Until someone (in the UK or US) gets put away for killing people then this problem of technical specialists being ignored will continue.

I also think JAE is correct in saying that they're may be other causes other than the known deficiencies that caused the collapse. The good news is that its the engineers who do the collapse inspections and write the reports.

 

[JAE]

The problem I have with prosecuting engineers for manslaughter, or even corporate executives, is that it is very difficult, in structural collapses, to pin the blame solely on one person.

If someone is prosecuted it's one person who perhaps shared a small percentage of the blame, but was the one who got punished.

Some collapses certainly can be identified as ONE PERSON's negligence, but not many. Usually a collapse is a comedy of errors and circumstances. Some do deserve punishment so I'm not advocating limiting all liability all the time.

In addition, for cases like the MN bridge, there is always some level of risk inherent in any structure. Thus, owners, DOT's, engineers, etc. must ALWAYS weight relative risks and cost/benefits.

There is no such thing as a completely RISK FREE structure, but unfortunately our societies today want the world to be perfect, without risk, and anyone in authority who allows more than zero risk to occur is somehow guilty of a nefarious crime? I just don't see it that way.

 

[fasboater]

I feel that if someone has been informed of a potential problem and they choose not to act due to cost or what ever the issue then they are the one caught holding the bag and should be punished accordingly. If its negligence on the part of the professional engineer there are already thing in place to deal with this although I don’t feel that this is the same issue as someone that is making a conscious choice to allow a hazard to human life without that person knowing. 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.

 

[rb1957]

i quite agree JAE, management (who make the decisions) will squirm and weasle "I'm not an expert, I acted on the experts recommendations"; the engineer will say "if the bridge was inspected properly it wouldn't have failed"; the inspector's lawyer would ask "what never?"; and the negineer will be forced to say "well, hardly ever. the probability of failure is 1E-6 if the loading is accurate" lawyer "so how accurate is the loading ?"
engineer "i used data from manuals, measurements from the site, traffic forecasts from DOT" ...
and so it goes !

negligence could be proven if the inspector falsified the record, or if the engineer fulphed the calcs, but could the decision maker get dragged into this (probably not?)

 

[rb1957]

fasboater,
IMHO, and presumably JAE's as well, that's a bit of a perfect world viewpoint. risk is everywhere, 99% of decisions increase the risk to someone. and what about the 95000+ similar bridges (ie similar declared "deficient") ?

 

[BSE05]

Thanks to bridgebuster, that was a good explaination of the structural investigation process. It certainly is more rational than its label. The term "structurally deficient" certainly needs some modification. As we see the media has gone into "chicken little syndrom" with that label.

Unfortunatley the general public has very little understanding of what engineers do. The little publicity we get is usually linked to a major disasters. The engineering profession typiclly doesn't get very good coverage due to the media's general lack of engineering knowledge.

 

[bridgebuster]

Thanks SteelyLee. You're on-target about the public's lack of understanding.

JAE - I agree with your last post.

As engineers we're often caught between the proverbial rock and a hard place. I don't know about anyone else, but, I don't have a crystal ball that's going to tell me when a structure will collapse. From experience, we can tell when a structure is in imminent danger of collapse but there are many circumstances where we cannot predict the time to failure.

There are probabilistic methods to determine like fatigue crack growth and tests to detrmine concrete durability but can anybody truly say "this bridge (or wall, or building) is going to collapse in 24-hours"? Unfortunately, we're sometimes forced into that situation.

Here's an example of how the media and the public twist things:

In June, two engineers in my group inspected a publicly-owned retaining wall; they reported the condition as poor. The wall is next to a condo; during the inspection someone on the condo board brought out an architect, who also lives there. Anyway, the architect thought he was a self-proclaimed expert on walls and he told my guys it's about to collapse. Granted, it's in poor condition - because of certain elements that are driving the rating score - and something needs to be done but I don't think it's about to collapse. Last week, a neighborhood paper had a story about the wall (the local politicians are involved), they got a copy of our report and wrote "according to the inspection report it's a disaster waiting to happen."

We never said that; we only said it's in poor condition.

Gotta go now, but I have another story - about a concrete bridge but sort of a reverse scenario from the wall.

 

[Atomic25]

Hard pill to swallow guys, but there are outdated inadequate structures on every street corner of the US, not just bridges. It's just the normal fiscal balance of life. From the little info I have, I think said engineers made professional judgments that are in line with the constraints of the system. The normal system takes risks, it has to or else we'd be taxed to bankruptcy.

It's the lawyers and uneducated public who need to point fingers just to get some resolution and live in their naive world that everything is 100% safe.

 

[JsTyLz]

Everyone is blaming the politicians about not spending the money to fix the bridge but have any of you ever said yes to paying more taxes??? I'm sure there are a few but, truly if MN had posted a tax increase for the reason of updating bridges that were deemed structurally deficient, I bet the proposition would have been slammed and almost no one would have voted for it.

 

[jimaitken]

"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."

How do you do that without scaring the travelling public un-necessarily and cause them to lose confidence in the processes and steps that have aready been put in place? The majority of the "structurally deficient" bridges have problems that will not cause catastrophic failure .This must be true because the majortiy of these bridges have NOT fallen down.

There are inspection and rating programs that were put in place by FHWA as a result of the Silver Bridge Collapse and for the most part these programs DO work. Warnings are posted at problem bridges as a result of this by the DOT. Bridges are posted for maximum un-permitted loads (I have not heard if the I-35 bridge was posted) based on the results of the rating program and inspections.

We have to trust the system that is in place. That being said we should also look for ways to improve upon it.

 

[HgTX]

People in this thread are making absolute statements like "I feel that if someone has been informed of a potential problem and they choose not to act due to cost or what ever the issue then they are the one caught holding the bag and should be punished accordingly," but there is simply NO WAY to address all "potential problems". For some large percentage of "potential problems", the choice MUST be made to do nothing; the question is which problems are addressed and which are not.

We have no idea where the money that was not used to fix the MN bridge was spent (and since the money wasn't marked as "$$ not spent on bridge repair", no one knows this). Perhaps, as a random and completely invented example, there was a program to add rumble strips along the edges of the state's highways that would not have been funded if the choice had been made to repair the bridge. And perhaps choosing to repair the bridge instead of adding the rumble strips might have meant more than 12 traffic fatalities over the next several years from people falling asleep and driving off the road.

There are finite (and seeminly ever-decreasing) resources, and increasing demand. Part of managing a state highway system involved deciding how to allocate the resources. And yes, allocating them here means not allocating them there. Always. Problems are documented, problems are noted, and not all problems are solved. That's reality. And not everyone within the organization will agree with all the decisions. That is also reality. If you go looking for someone who can say, "I told you so," you'll probably find them. That is not an automatic indicator of negligence on the part of the agency.

I'm not saying that it's impossible that there is some blame and liability to be assigned in the MN case, but people should get off their high horses and stop assuming that there surely must be.

Hg

Eng-Tips policies: faq731-376

 

[casseopeia]

I never agreed to allow my taxes to fund junkets to China either.

"If you are going to walk on thin ice, you might as well dance!"

 

[JAE]

Everyone is blaming the politicians about not spending the money to fix the bridge but have any of you ever said yes to paying more taxes???

heh.

The economic record shows that when you LOWER taxes, government revenue goes UP due to better economic conditions. This isn't an opinion, it's a proven fact.

So what you are saying doesn't make sense. Raising taxes deters the economy and REDUCES revenue over the long haul.



I'm in agreement with many above that you can identify risk (which is always everywhere) but it does not follow that you can identify collapses.

 

[DRC1]

Actually, we pay alot in taxes for roads and bridges. about 15 cents a gallon for the highway trust funds. However, Much of it was "borrowed" by the general fund and reduced the levels of available funding until TEA1. However, under the current administration, continuous funding for roads and bridges came to halt for many states due to opposition to the required levels of dedicated funding for roads and bridges. As a result many states were unable to do much for those years. Now even though SafetyLu is in place, at much lower funding levels than needed to address the problems, Money for projects flows slowly.
When asked about the condition of the roads and bridges, the engineering community as a whole has said "Yeah its low, but they are still okay." We need to scream "Hell yeah they need work. We can't fix them all at once, but we can do as much as we can"
I don't know if criminal charges as dicussed in earlier posts should be brought, but the engineering board should look at the company that wwrote the report and decide if they exercised competent engineering judgement in recommending inspection over repairs.

 

[jimaitken]

I do not think we should be so quick to pass judgement on the engineer or the DOT in this instance. The engineer and DOT people involved will be questioned I am sure and if they were negligent it will come to light, but as engineers, particularly bridge and structures we have make decisions based on our engineering judgement. In this case (From what I have read) the bridge was inspected, the problems were thought to have been identified, and the plans and alternate plans were presented to the owner. Hopefully The owner made a decision that they believed was in the best interest of the public based first on safety then on fiscal responsibilty. Apparently none of the posters on this forum were involved with the decision so all the rest of us can do is speculate on why the bridge collapsed and what the smoking gun looks like.

 

[Atomic25]

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

Yea right, who the heck is going to do that? Cities like St. Louis and Nashville would have a major panic. Do you know what would happen if the a average sized New Madrid seismic event occurred?? We're talking about entire portions of downtowns leveled.

 

[jike]

My wife grew up in a 3rd world country and when they came to a bridge, they would unload everyone from the bus and then the bus would drive across the bridge empty and then the passengers would walk across.

 

[JAE]

....and I would hope the passengers walking across would use a stutter step to avoid resonance in the bridge!!

 

[TDAA]

Quote:
Everyone is blaming the politicians about not spending the money to fix the bridge but have any of you ever said yes to paying more taxes???

heh.

The economic record shows that when you LOWER taxes, government revenue goes UP due to better economic conditions. This isn't an opinion, it's a proven fact.

So what you are saying doesn't make sense. Raising taxes deters the economy and REDUCES revenue over the long haul.

Well, in Coloraod Springs, it was voted to increase the sales tax, with the funds to marked for transportation projects. I was at an ASCE meeting where one of the City Engineers siad that it was an exciting time to be in his position, because they finally had the money to do projects.

These projects have ranged from radius changes at intersections with restriping to a few single point urban interchanges.

I am sure our city engineering would not agree that we should have lowered taxes so that we can wait for the economy to pick up to the point that there are millions flowing in. Maybe at thatpoint, they could repair the failing bridges here? Or perhaps that money would be better suited for something else.

 

[JAE]

TDAA - your dripping with sarcasm. I can feel it!!

My statement is based on federal taxation patterns over the last 20 to 30 years and do not reflect short term effects of local/state taxes.

I also wonder how long those taxes continued to go to that City Engineer's projects. Eventually they all get mushed up into myriad other programs and bureaucracy.