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I-35W Final Report due shortly
3

I-35W Final Report due shortly

I-35W Final Report due shortly

(OP)
NTSB Advisory
National Transportation Safety Board
Washington, DC 20594
November 6, 2008

SAFETY BOARD TO MEET, ADOPT A FINAL REPORT ON I-35W BRIDGE ACCIDENT


--------------------------------------------------------------------------------

The National Transportation Safety Board will hold a public Board meeting on its investigation of the I-35W bridge accident in Minneapolis, Minnesota on Thursday, November 13 at 9:30 a.m., in its Board Room and Conference Center, 429 L'Enfant Plaza, S.W., Washington, D.C.  The meeting is expected to last two days.

About 6:05 p.m. central daylight time on Wednesday, August 1, 2007, the eight-lane, 1,907-foot-long I-35W highway bridge over the Mississippi River in Minneapolis, Minnesota, experienced a catastrophic failure in the main span of the deck truss. As a result, 1,000 feet of the deck truss collapsed, with about 456 feet of the main span falling 108 feet into the 15-foot-deep river. A total of 111 vehicles were on the portion of the bridge that collapsed. Of these, 17 were recovered from the water. As a result of the bridge collapse, 13 people died, and 145 people were injured.  

A live and archived webcast of the proceedings will be available on the Board's website at http://www.ntsb.gov/Events/Boardmeeting.htm. Technical support details are available under "Board Meetings." To report any problems, please call 703-993-3100 and ask for Webcast Technical Support.  

A summary of the Board's final report, which will include its findings, probable cause and safety recommendations, will appear on the website shortly after the conclusion of the meeting. The entire report will appear on the website several weeks later.  

Directions to the NTSB Board Room: Front door located on Lower 10th Street, directly below L'Enfant Plaza. From Metro, exit L'Enfant Plaza station at 9th and D Streets escalator, walk through shopping mall, at the CVS store (on the left), and take escalator (on the right) down one level. The Board room will be to your left.

###

www.ntsb.gov

 

RE: I-35W Final Report due shortly

Interesting that a replacement bridge has been designed and built before the report is complete on the old one.

RE: I-35W Final Report due shortly

The report will be very interesting to see if they can find find a single reason or a combination consisting of original design, construction inspection, modifications and new loads, restoration precesses, unbalanced loads from construction in progress and general deterioration.

I am looking forward to the report since I was involved in the original bridge, drove over it for many years and fished under it (inspected and observed frequently for years).

The new bridge administrative/design/construction concept was a "no-brainer" because of economic factors. The design build with a early completion bonus was much more economical than the design, low bid and then construct condidering the quick need and the seasonal construction period.

It was good to see economics, design and construction used to gether. Now I know why economics was included as a required class for engineers when I went to school.

The upcoming report will have little immediate economic effect, but it could have some good long tern effects on design, inspection and maintenance, so that is why it had a slower time frame. (Not to defend the parties, but to understand the benefits)

Dick

RE: I-35W Final Report due shortly

Dick,

Yes, I guess I was commenting more about the quick production of a new bridge than the duration of the investigation of the old.  I also look forward to reading the report.  Often more is learned from failures than from research.  I have been one of many who have been guilty of speculation about the primary cause, that being in my mind simply drafting error in the original documents, but now we will know.

RE: I-35W Final Report due shortly

The production of the new bridge was certainlt done fast and the combination of design and construction was very efficient. Everytime I had a chance to look at the 24x7 production od the segmnents and erection logistics, it said a lot for the abilities of the designers and contractor. They certainly spent a lot of overtime to take advantage of the predictable weather conditions.

I am not surprised at the time for report considering the beauracracy and politics of a public failure. The number of factors and history make it difficult to apply any real numbers to assess a single factor which the news media wants so they can draw out the "what ifs" of the other factors using expert consulatants.

Dick

 

RE: I-35W Final Report due shortly

A recent leak of information and the Minneapolis Star Tribune pointed to only the underdesigned gusset plate as the reason for the bridge's collapse.  

I would be very surprised if this is the only reason it is collasped and if so, would feel an injustice to the engineering community.

Regards,
Qshake
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RE: I-35W Final Report due shortly

(OP)
I agree with you 100% QShake.

I've seen broken gusset plates on a suspension bridge stiffening truss but the cause was a built-in design flaw that created excessive torsion.

I've seen plenty of old trusses with deteriorated gusset plates that were still carrying heavy loads and functioning well.

I recall reading that some of the gusset plates were field welded to members as part of a repair program. If that's true, fatigue failure is a possibility.

Right now based on the published information I'm not convinced. I still suspect that the frozen roller nests had something to do with it.

RE: I-35W Final Report due shortly

Only about 3 or 4 more days defore the report is released.

The prliminary reports I have read and heard say the "primary" cause was the gusset plates. This indicates there could be other contributing causes or combinations of contributing causes.

The under designed plates were an obvious factor that could not be eliminated as a factor. Because of the modifications, weathering and construction are other obvious items leading to the immediate collapse.

I hope the report includes the other possibilities and addresses the possible connections (no pun intended) to the collapse. We could all learn from the unfortunate tragedy/problem.

Dick

RE: I-35W Final Report due shortly

I am sure that it was this sole gusset plate that caused the bridge to have a horrible rating, have the engineer advocate replacement ASAP (which Minn. DOT took to mean 12-14 years) need need anual inspections.
I have not read all the reports, and have not read very much at all about it lately, but although the gusset plate was deficent, was it ever determined that the plate was the cause of the collapse? Or is that what we find out this week?
 

RE: I-35W Final Report due shortly

Yes, that is what we are waiting for.  The undersized gusset plate issue did not affect the bridge rating, as it was an unknown fault, even apparently to the engineers who had previously done extensive reports on the bridge.

RE: I-35W Final Report due shortly

2
Here is the webcast portal for the hearings if anyone is interested. The report will be available in two to three weeks.

The AP reported today that another factor that is being considered is the storage of 575,000 lbs of construction material in the area of one of the failed gusset plates. The AP source also stated that even with additional weight if the bridge had been designed right this additional weight wouldn't have been a problem. The contractor had permission to put the materials on the bridge from the MDOT.

http://www.capitolconnection.gmu.edu/ntsb/live/ntsblive-cc.htm

 

RE: I-35W Final Report due shortly

Some information today states the investigation is focusing on the upper gusset plates, especially at Node U-10. The biggest problem is trying to ascertain which of the plates failed first. Which I would assume to determine is the additional weight might have been a factor.  

RE: I-35W Final Report due shortly

Correction to my last sentence in the my last post. I was talking on the phone and trying to digest, think and type
at the same time. I maybe able to do two but never three things at the same time.

Correction:
"Which I would assume is to determine if the additional weight on the bridge contributed to the failure.

From information I received they have practically ruled out problems with the bearings.

RE: I-35W Final Report due shortly

unclesyd -

I agree that the major cause of the failures was mainly due to the proverbial "underdesigned gusset plates". There was no major corrosion and the bending on the plate was due to either initial construction or excess loads during the life and modifications, which will be hard to determine without the original design calculations. - Hindsite is always 20/20.

The bridge functioned well enough (although maybe not as designed) for 40+ years and was modified with some widening and new crash rails etc., through the years. This could have provided a false sense of security. In addition, the deck reconstruction, current construction activities and materials storage may have placed additional and unpredictable loading patterns since the traffic was also switched during the process.

I have not had a chance to read the report, so I can only offer some engineering opinions.

I.
From what I understand, the contractors were given "carte blanche" permission to operate on the deck during the reconstruction. It would be interesting to see if there was any real analysis on the possible effects on the old structure. The permission is understandable because of the variability of materials and mobile equipment. Since the traffic was diverted frequently and the construction process is variable, this could lead to some very interesting unbalanced loading conditions on an old structure. Since this was a contracted maintenance/upgrade, I assume the contractor had no knowledge of the actual structural condition and bid on the contract as presented. This may be behind the choice of a design/build contract for the new bridge.

II.
I have not been able to find out if any analysis of the structural capacity of the old bridge had been determined based on the recent condition.

III.
The "thin" gusset plate must have been due to the engineering calculations or a drafting error. Certainly it was not a cost cutting thing because of the minimal material cost, but it may have matched with the other members to create a clean detail to design, detail and build. Unfortunately, the details of the design are not available, so the parties can only rely on the information known or provided. It is unfortunate that the over-designed members and connections attract loads and ruin the conservative assumptions made by designers.

IV.
The NTSB report wil not end the subject. There will still be the costly law suits against the parties including, the MNDOT (unless they have immunity), contractors, subcontractors, people traveling in the opposite direction that contribute to the non-symetrical loading and even the auto manufacturers that produce cars to sense upcoming problems (sick joke, but they claim to be able to parallel park cars without driver assistance).


I hope we are able to sift out enough facts to learn from the disaster and prevent future ones that may occur.

Dick

RE: I-35W Final Report due shortly

You bring up some good questions. We will know more when the report is released. However, here are my thoughts on your questions.

I The stockpiling of materials is common in bridge construction and is generally not investigated. This is based on the assumption that dumped materials are not pushed up much on bridges and occupy about the same area they would have in the truck, thus not significantly altering lane load. Staging I think is looked at from a structural point of veiw, but not in great detail. After 40 years, loads on the bridge shift and cutting it apart may change stresses in unaticipated ways.

II This is what I didn't like. Apperently the standard practice for widning the bridge is to check a few main members and if they are sufficent, it is assumed the whole load path is sufficent. My understanding is that when they modified the bridge the load path was not checked except for a few members and that even after the collapse, the feds were okay with that.

III My understanding is that it was probably a drafting error in that the wrong gusset plate was detailed for that connection.

RE: I-35W Final Report due shortly

If I may ask, why wouldn't a bridge or in fact any equipment that has been labeled "Structurally Deficient" warrant a little more attention if it is going to operate out side it's normal environment?
Or is it the "Devil is in the details" in this case.  

RE: I-35W Final Report due shortly

Good points raised by all.  I do agree with unclesyd who asks why a structure that is labled structurally deficient, doesn't warrant additional structural analysis before, during and after major reconstruction.

Some will say that the bridge's structurally deficient rating (happening in a span of a single year when it went from 7 to 4 wherein it stayed until it's collapse) wasn't really addressing the structural capacity.  True, in a way, because the rating is Federal technical language that the bridge should be on a list programmed for replacement.  Since that process takes about 10 years to complete with all the environmental processes etc, the sooner it's on the list the better.  

Others will say that the bridge was labeled structurally deficient because it caused some engineers to lose sleep over the myriad of poor conditions the bridge was facing.

I tend to be in the latter category and feel this bridge should have received more attention structurally before more weight was added, more traffic allowed, and conditions to continue to deteriorate.  Such a evaluation would have, in likelihood found the underdesigned plates.
 

Regards,
Qshake
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RE: I-35W Final Report due shortly

I think we all agree in principle, except for one thing.  This bridge was investigated, as reported in very extensive and presumably expensive reports, but the deficient gusset plates were not identified.  Hopefully an explanation for that failing will be forthcoming.

RE: I-35W Final Report due shortly

I found conclusion #12 (in the synopsis) that "Current Federal and State design review procedures are inadequate to detect design errors in bridges" to be very interesting.  The associated recommendation involves owners developing procedures to detect and correct bridge design errors before the design plans are made final.  

Does this mean that owners have to check calculations that have already been checked and sealed by a consultant?  Either that or have an independent design reviews done by an alternate consultant?

Working for an owner of bridges and other infrastructure, I get calculations to review all the time, but there is no set procedure that covers what I should do with them.  I have even been admonished by management for digging into calculations that have been PE sealed.

Usually I will do a few spot checks.  If I find a significant mistake, I will plow through the whole thing.  Or if the calcs call for reducing the capacity of some of our equipment, I will thoroughly check to make sure the reduction is really needed.  My procedure is not really scientific, and sometimes I only look to see if the calculations seem to be well organized and referenced and if each page is signed by a preparer and a checker.

I find major errors in sealed calculations way too often, so I am looking forward to seeing what procedures that the FHWA comes up with.  
 

RE: I-35W Final Report due shortly

Yes, that is where this is going and even to the point of having consultant companies peer review entire sets of calculations.  This is common practice in the UK.  I think that MnDOT now requires peer reviews for bridges greater than 200' spans.

 

Regards,
Qshake
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RE: I-35W Final Report due shortly

greybeach,

"major errors in sealed calculations way too often", this is really disturbing. I hope the US engineering system fixes this gaping hole, what is the PE stamp really worth then?

VOD

RE: I-35W Final Report due shortly

VOD and others - This has been a disturbing trend in the American market and I'd like to know how others handle it.  These days clients want everything faster and for less money.  This puts immense pressure on design firms to produce, produce and produce.  

Sadly in the old days when this mistake was made, I feel there was always more time to review.  Obviously this incident doesn't bear that out, but overall, I think we had more time then than we do now.

Regards,
Qshake
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RE: I-35W Final Report due shortly

Qshake and VOD,

I am also very disturbed.  There should be some consequence for the PE who seals flawed work.  Besides me placing a mental black mark next to their name, I don't know how that would work.

I work on the client's side and really try to extract quality work from consultants.  One big problem I see is that work is not carried out in an orderly manner at the beginning.  The consultant just starts out tossing a bunch of stuff together from previous jobs instead of thinking things through.  This puts them in a catch-up position from day one.  Clients wanting things faster is certainly an issue, but so is consultants agreeing to produce things faster when they can't do it correctly.

I too wonder how others handle this.

RE: I-35W Final Report due shortly

(OP)
graybeach,

Here's my $0.02:

First there's the financial reality of the consulting business. Clients have a bottom line cost for a project. Most agencies are fair. On the consultant end some accountant who runs the company sets an effective multiplier that needs to be achieved. So we end up backing into a labor cost to keep the accounting department happy. This usually means using lower priced, less experienced people to do a job.

We can't have people sitting around billing their time to overhead. So we end up overstaffing a job, trying to find productive work for everyone. As a result, the PM or project engineer doesn't have time to think things through before getting into production. He's too busy with finding busy work for people.

Sometimes, agencies take a hard line about the price. They don't want to pay what is fair and reasonable. As someone i worked for many years ago said, "Engineers are like prostitutes fighting over a customer." We'll take a job at a low price and roll the dice.

I agree with QShake about schedules. Sometimes they're not realistic and the job suffers because no one has had the time to develop a realistic work plan. On the other hand, when projects are delayed and drag out well beyond the original schedule things are forgotten, new people get involved; a new learning curve starts.

I also think there's too much reliance on computers in the belief that they can produce a job in less time. I find that CAD drafting often takes longer than when it was done by hand. There's also a reluctance to question computer output - seems like some forget GIGO - a few months ago one of the younger engineers here analyzed a statically determinate truss and came up with results for a number of that were completely wrong. I ended up doing it by hand because she couldn't figure out why. All I kept hearing was that the STAAD people told her the model was correct.

Anyway, I think I rambled on enough.  

RE: I-35W Final Report due shortly

Graybeach,

I have had many similar experiences, on both sides of the fence.  The public wants everything perfect, but nobody wants to pay for perfection.  I also have found significant errors in final work from other engieers.  Sometimes the errors result from an over reliance on corect computer generated results; sometimes a careless error that should have caused a reviewer to scratch his head and say, "This answer just can't be correct." and unfortunately some just don't know they are in over their head.  For my part, I understand not a civil engineers are adept at solving structural problems.  What I don't understand are the many who choose to be structural engineers that are not adept at the work.  With the budgets we are working within, I don't see the problem getting fixed either.  That doesn't mean that I think this problem can be fixed by money alone.

RE: I-35W Final Report due shortly

bridgebuster,

Wow. We don't work at the same place do we?

In all seriousness, I think you summed it up well. I think your extended schedule comment is dead on. Roadway project schedules make it very difficult to maintain continuity on the bridge design teams. There are usually many months and often a year or more between the concept, preliminary and final design phases. There is often another 6 months to a year before shop drawings are reviewed. Everybody has to stay busy with the work that is available at any given time. It is not unusual for each phase of the bridge design to be handled by a different person, and the learning curve starts over again.

RE: I-35W Final Report due shortly

(OP)
jorton,

thanks for your reply. You never know, we might work for the same company given the size of my employer - then again, I think things are the same in most mid-sized & large firms.  

RE: I-35W Final Report due shortly

I hear you Bridgebuster.  This is definitely the situation in our industry.

I am starting to think making owners responsible for design flaws would be a very good thing.  Maybe it will force them to establish realistic schedules and pay more for quality engineering.  In any case, more requirements for peer reviews means more work for the civil/structural profession, so they will have to pay either way.

Meanwhile, I try to structure RFPs with firm scopes and qualification requirements.  Sometimes I am even able to justify not taking the low bid.
 

RE: I-35W Final Report due shortly

I'm not sure that I am enthusiastic about becoming a peer reviewer.

1. It doesn't pay nearly as much as actually performing the design.
2. The peer reviewer has no control. The designer retains all control in addressing or even acknowledging the peer review comments.
3. If the designer goes to court, the peer reviewer is going with him.

So basically there is less money, less control but the same exposure to litigation. Even if the peer reviewer is faultless he has still incurred the lost time, lost litigation cost and tarnished name.

Also, will it give the designer a false sense of security? I can foresee folks extending beyond their reach and/or not being as thorough because they have a peer review to back them up. Maybe I'm just pessimistic today?

RE: I-35W Final Report due shortly

(OP)
graybeach,

How does your agency typically contract for services?

One agency we do a lot of work with uses a qualifications based proposal and they specify how many resumes and projects to include and how many pages for a technical approach. They try to amke life easier. They're usually fair with the fee negotiation. Our problem comes later on when our accounting department dictates the multiplier they want.

Another agency usually uses a dollars per point selection- Bid/Proposal Score. We've never had any success winning work this way. There's two reasons: They use a boiler plate scope of engineering services that is generally  far in excess of the anticipated construction scope and cost.  

When we try to price the job based on the scope weend up with a bare labor cost that is way high - add in a high overhead and we're dead in the water - but the agency always directs everyone to price the job based on the engineering scope as written. When I look at a winning "bid" I know that they can't do it for that price. Unfortunately, our business development people have never tried to find out what part of the scope of services will never be required.

We've won bridge inspection jobs based solely on price; competing against other pre-qualified firms.

 

RE: I-35W Final Report due shortly

It sounds like the above discussion is why the State of Minnesota went with a design-build package and a complicated system to evaluated the individual proposals and leave the major responsibility in one lap. The fast track schedule required probably had something to do with it also.

The winning package was about $40,000,000 over the other proposals, but they did the work to comply and understand the scope and requirements. - Fortunately they finished 2 months early and collected a bonus. The group did some other projects in the area, not nearly as many as the unsuccessful proposers.

I still wish I could find out exactly how and when the designs were verified/checked, but the gross liability rests with the prime contractor and its engineers.

RE: I-35W Final Report due shortly

"The winning package was about $40,000,000 over the other proposals, but they did the work to comply and understand the scope and requirements."

Um, I doubt very much that any of the other contenders did not do the work to comply and understand the scope and requirements.

Hg

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RE: I-35W Final Report due shortly

The other bidders were all lower, but according to the bidding/prposals for the desgn/build package they did not do enough to be awarded the contract.

The others were not amateurs, but the proposals did not rate high enough to get awards. - They were out-sold and ended up being out-performed since the awarded company also collected a $20,000,000 +or- bonus for early completion in compensation for the 24x7 schedule, overtime and winter heat.

The other proposers were well known contractors that have done a many big projects in the area and are currently doing numerous traditional projects that are the typical design, low bid, construct, inspect and complete jobs. The winning proposer was a consortium that has also done some local projects in addition to other national projects.

It looks like a game where someone was out-sold and out-presented using the same documents. The result has been successful - so far.

Dick

RE: I-35W Final Report due shortly

greybeach et al.

All very good points and realities. Here in Ontario, not saying we have this figured out either, but there is a rating system that the Ministry of Transportation gages consulting firms based on many factors and prequalifies consultants for varying complexity of work.  In our situation, cost is not the only factor and there are many times firms have won with a much higher fee.  This is a model that Clients may want to consider, we should all play a part in improvement of the industry.  Keeping the public in the loop and aware of the far greater benefits will eventually bear fruit.

RE: I-35W Final Report due shortly

To say the losers "ended up being out-performed" is unfair--they never got a chance to perform, so how does anyone know how they would have done?

There was a factor in the bidding that had to do with rating the qualificiation of team.  In the presentation I saw, the ratings for the top handful of contenders were in the 90s for the top one and down to the 60s for the others.  That was a completely subjective factor; there's no way that anyone able to put together a submittal of that nature is only 60% qualified to handle the job, or that they were only 2/3 as qualified as the top bidder.

This is being touted as a great example of A+B bidding where they got to consider factors other than low bid, but the way I see it, they just got to pick whoever they wanted for undisclosed reasons (like maybe they wanted a concrete bridge, not a steel one, but were afraid to piss off the steel industry by putting that in their requirements) and completely sidestep the financial side of the bidding process.

(No, I'm not an interested party; I don't work for a design consultant, a contractor, or a fabricator, and I don't live in MN.)

Hg

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RE: I-35W Final Report due shortly

Bridgebuster et al,

We prefer lump sum contracts for engineering work, and we grill "low bidders" (I hate using term for design professionals) to make sure they understand the scope.  We try to root out and reject low ball proposals.  We can do this because our civil work is usually pretty small potatoes (compared to designing large bridges), and we have capable in-house engineers.

I wonder if the current economic situation will make matters worse or better.


 

RE: I-35W Final Report due shortly

By saying "out performed", I was referring to the entire effort including the presentation that had to addresss the intent and specifics required for the proposal. - Some may use the term "out sold", but the early completion is part of the total performance package.

Before the proposal due date, the winning consortium meet with many local groups because of the logistics and traffic. After the project started, they had site tours regularly and every engineering and construction group around was at the site at least once where the construction people and design people were available. The proposal even included options on the color of the bridge and the shape of the piers since the site is very visable.

The early completion was due to a number of factors.

1. The contractor secured an area near one end of the bridge to construct a heated shelter to start making the concrete elements in February, virtually on site and only had to haul the others to the opposite side of the river over an adjacent bridge at night. It was vitually an on-site precast plant near the ready-mix plant.

2. The spring and summer weather was good and the contractor used a lot of overtime (24x7) to take advantage of that. This permitted the on-site finishing concrete to go in early and not encounter the typicial weather problems possible in October, Novemeber and December. Concrete temperature and curing was not a problem. A few years ago, the area got 28" of snow in October.

3. The bridge was basically built on a solid, known limestone foundation.

4. Because of the locations of the I35W exit ramps north and south of the bridge, traffic ended up being diverted well around the actual construction area.

MNDOT did a good job of adding temporary lanes to several roads and divert the traffic around the area without total jam-ups, but over-all travel times were definitely increased. The trucks using I35 were forced to use alternate routes or take the loop freeway, which caused some problems 10 to 20 miles away. Unfortunately, the sister route to I35W is I35E that goes through St. Paul and a portion is limted to 45 mph and trucks are not permitted and it is called a "boulevard", although many people refer to it as a "learners freeway". The time, traffic delays, extra mileage were all a part of the the formula that provided the big completion bonus (half of the extra cost to the community).

Because of the disaster, there was a big inspection effort made in Minnesota on all bridges. Many problems were found, at least one major bridge is being replaced and several replacement dates were moved up significantly and the inspection procedures have been revised, so there was a silver lining in part of the black cloud. Since most of the problems found related to steel, the choice of concrete was generally approved by the public after the actual contract award. No one complained that the project was completed early.

It was an interesting project to observe. It was a good job of selling, engineering, construction and public relations. I assume the engineering was sound, since the firms have built many bridges around the country. It is not my place to check the designs even if I was a bridge inspector at one time in my past life before I was registered.

RE: I-35W Final Report due shortly

It's also noteworthy that of the four bidders in I35, three went with steel and one with concrete.  The three steel bidders were all in the mid to high 60s and the concrete alternate was in the 90s.  

I don't think it coincidental that a steel bridge collapses and a concrete bridge goes up.  

Nor do I buy into the argument that the three bidders didn't do the work to deserve the win either.  I believe all bids were earnest.

Regards,
Qshake
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RE: I-35W Final Report due shortly

Another point to ponder is about the time of bids were out there were a lot of questions about steel availability and deliveries. At the time I was involved in one project that was delayed for a considerable time due to structural steel deliveries. At the same time I heard of a couple of jobs in the Northeast USA where several projects were reworked to use concrete instead of steel. That didn't help much as they ran into the avowed cement shortage.  

RE: I-35W Final Report due shortly

Qshake--exactly.  It can't possibly be coincidence that three significantly less costly steel alternatives lost to a more expensive concrete alternative.  My completely unsubstantiated belief is that they just plain wanted concrete, but were afraid or perhaps even unable to put that in the contract requirements.  (I've seen one industry scream when another's product is given preference when they think it ought not to be; perhaps the Powers That Be didn't want to deal with possible legal challenges on that front.)

I talked to someone from one of the losing teams who said they'd considered a concrete alternative, but the steel alternative cost less (and of course both would have been structurally adequate), and if they'd simply been told there would be a preference for concrete, they would have put that alternative forward.  The winning team perhaps out-guessed more than out-sold.  It does happen.  Sometimes you guess wrong about what the client's hidden agenda is, and you lose; sometimes you guess right and you win.

Hg

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RE: I-35W Final Report due shortly

HgTX,
Have you considered this bidding process might have been a deliberate ruse based on some one's hidden agenda?

I have seen several big contracts that were swung on the hands of a Rolex Watch or walked in a pair of Justin Boots.  

RE: I-35W Final Report due shortly

One item to note is that the winning team engineer does not do steel, only concrete.  And I know that they heavily market in Minnesota.  I think the combination of ambiguity in the bid specs and agency fear of steel along with good marketing the by winning engineer is what won this contract.

Regards,
Qshake
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RE: I-35W Final Report due shortly

Qshake -

I agree with your general concept, but I am not sure where the marketing efforts came from (engineering firm, contractor/consortium or marketing consultant).

First, all of the designs from the various proposers must be considered to be adequate for the engineering purpose.

Second, because it was a design-build system with a tight schedule, the design must meet the site and possible weather conditions in order for the contractor to do the job on time and profitably, so it was a joint effort (single responsibility) and not a low bid situation where many could be accused of contributing to problems.

Third, all the parties were making proposals using the same documents, requirements and knew the rating system in advance used to determining the award.

If you look at the proposals available, there was a dramatic difference in the quality of the presentations, the information provided, previous projects and the attention to the public concerns after the bridge went down and a vital lifeline for the economic community was severed. The economic benefits of half of the reduced community cost for the early completion was determined by the MNDOT engineers. - I remember being required to take economics as part of my engineering curriculum in addition to the economics portion of my highway classes.

The winning proposal stressed the engineering ability, history and willingness to make the project wotk and satisfy the needs of the highway users (and some of the bike path people).

The run of the mill traditonal firms went the route of a bridge to provide a low price, which was not good enough to meet the proposal rating system. It is like the old saying, "You can always do it cheaper", but it might not be right for the conditions and future needs.

It is unfortunate that engineers (I am one) are usually so poor at revealing their value, what they have done (beyond photo boards, resumes and normal, routine presentations) and what they can do to justify the cost of good engineering. Engineering (including proper construction knowledge/experience), like all professions must be willing to promote the benefits or at least make them openly available. - Unfortunately, the associations and groups we rely on just do not have a budget to really do this, so you only see it when it is needed to be shown.

Even the carpet bagging political candidates (with $40,000,000 budgets) would not touch the question of the contracts and awarding methods. It is fortunate that the bridge was not completed before the National Republican Convention or politics could have gotten into the mix of opinions.

Just promote the value of engineering openly and not just internally.

Dick

RE: I-35W Final Report due shortly

Dick -

I'm not really really being critical of the winning work or any of the firms in the winning team.  I do admit to a bias in your third point that all teams knew the requirements.  I think the requirements were very ambiguous, and in my opinion they favored an accelerated solution.  

The accelerated solution is where the winning team made a historical decision in my opinion.  Knowing that a concrete bridge would take longer to build how can we set up our operations to ensure (or minimize risk) to win over the conventional solution, steel.  It's apparent now that the work is complete that the gamble paid off and it really reflects well on the team and industry as a whole that we can overcome the odds when we put our minds to it.

I only mention the marketing aspect as the winning engineer does only concrete bridges and will typically move into a market that is ripe and begin to market the heck out of concrete bridges and the like.  To my knowledge they've been doing the Minnesota market since the Wabasha bridge and along with that time invested the collapse of a STEEL bridge worked well in their favor.  So I suppose in summary I'm just saying that the company had the benefit of advanced marketing for concrete bridges and the coincidence of the failure of a steel bridge.

I'm not begrudging the winning team a well deserved win.
 

Regards,
Qshake
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Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
 

RE: I-35W Final Report due shortly

Final report has been issued.  Failure attributed to design error by Sverdrup and Parcel.  Gusset plates should have been twice as thick.  Original calculations not found, so not clear if error was by commission or omission.

NTSB finds that gusset plate deficiency never found in any of the inspections or assessments because it is the usual assumption that the connections are more conservatively designed than the members.
 
http://www.ntsb.gov/publictn/2008/HAR0803.pdf

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