Catastrophic bridge collapse

[AustinBoston]

By now most of you have seen the news.  I thought I would try to put it in context.

Interstate 35 runs from Laredo, Texas to Duluth, Minnesota.  Along the way, it goes through San Antonio, Dallas/Fort Worth, Oklahoma City, Wichita, Kansas City, Des Moines, and the last major metro area it goes through before ending in Duluth is the Twin Cities of Minneapolis/St. Paul, Minnesota.

In two places, Dallas/Fort Worth, and Minneapolis/St. Paul, the road splits, with one half going through each city.  In both places, the designers made a decision- rather than call it I35 in one city and I235 (or I435, I635, or I835 which would have been the standard designation), they would call the eastern split I35E and the western split I35W.  This decision was probably political, in both cases to avoid marking one city as the "main" city and the other as the "secondary" city.  Both halves go basically north-south.  Here, I35W goes through downtown Minneapolis and I35E through downtown St Paul.  In Texas, I35W goes through Ft. Worth and I35E through Dallas.

At 6:05 PM Central Time today, a section of I35W over 1/4 mile (400 meters) long collapsed and fell about 65 feet into the Mississippi river.  Witnesses said the center main section collapsed firat, then the end spans.  The rush hour was mostly over, but traffic would still have been heavy.  This section of highway served downtown Minneapolis, and was a total of eight travel lanes (four each way).  About 150,000 vehicles used this bridge each day.  This is approximately equal to half the population of Minneapolis.  It runs close to (I think within sight of) the Metrodome, where the Minnesota Twins and Minnesota Vikings play.  The main downtown area is to the west of the bridge.

The bridge was about 40 years old.  The main span was a steel archway under the bridge.  It had been inspected in 2004 and 2006, and no defects were found.  A stress test performed in 2001 showed some signs of stress but no cracks.

The deck of the bridge was under construction.  The roadway was down to two lanes in sections, with construction equipment and crews on the bridge.  There has been one unconfirmed report that a construction foreman ordered his crew off the bridge just before the collapse.  This may just be a rumor and may not be true.  Because it was 6:05 PM, he may have just let the shift go home for the day and it was misinterpreted as something else.

Reports are that about 50 vehicles were on the bridge when it collapsed; as of 10:00 PM Central Time local stations were reporting 6 confirmed fatalities and 38 injuries, including 6 critical.  One construction worker is unaccounted for.

A school bus full of children were just entering the bridge as it collapsed.  I have heard that ten chidren were brought to local hospitals, but I don't know if they were on the bus or in other vehicles.  The school bus did not go into the river.  PJay tells me now that the reports are that all of the children on the bus are OK.

The collapsed bridge landed on at least one surface road, West River Parkway, which runs parallel to the Mississippi on the western bank.  Two other roads, Bluff Street on the western bank and SE Second Street on the eastern bank may also have been affected.

The bridge also landed on a couple freight cars of a freight train.  No hazardous materials were on the train.  There is a freight yard under part of the bridge; I don't know if operations there will be drastically affected; they certanly will be partly affected.

There is a local road that crosses the river very near that point, the Cedar Avenue bridge.  I have not heard officially, but I don't believe the collapse has damaged that bridge.  As of 9:00 PM Central Time, that bridge was still closed.

I have crossed the 35W bridge dozens, if not a hundred times or more; PJay must have crossed it 300 times as part of her commute when she worked a contract in that area.  Our Son-in-law has only crossed it a handful of times, but he just started his duty at Fort Snelling last week; he would have crossed it at least at least 50 and parhaps 100 times before they closed on their house in St. Paul.  I spoke this evening with people who crossed it less than 20 minutes before the collapse.  

The entire support structure was under the bridge.  If you didn't look to the sides, you would not realize you were crossing the Mississippi.  For those of you familiar with the Big Muddy, the mile-wide Mississippi is only about 300-400 feet (95-125 meters) wide at that point.

One good thing to come out of the monumental 9/11 disaster is that plans are set up and practiced in order to deal with catastrophic events like this.  The number of injuries and fatalities and how they were handled by emergency workers was called "almost routine" by hospital staff.

This will become a monumental traffic nightmare.  All of the traffic that used that bridge will have to find another route.  The Cedar avenue bridge is nearby ad runs parallel, but is already at capacity.  In addition, it is only a four-lane, local bridge; it can't replace the 8 lanes lost.  From the north, some traffic will be able to switch to I-94, which runs parallel to I35W on the other side of the river a few miles to the west.  Those travelling through the city have a few more options, but at least one of those, I35E through St. Paul, is already jammed because of major construction at it's junction with I-694.

I am not as familiar with the problems this will cause on the south side of the city, but they will be just as bad.

I commute from the north, and this is a north-south highway.  I didn't normally take I-35W, but that is just beacuse it was a little easier for me to use I-94, which also runs north-south on the north side of the city.  When I ride with PJay (3-1/2 to 4 days a week), we drive in on I-94; on the other days, I use a park-and-ride and take the bus (which also uses I-94).  The busses are allowed to use the shoulder, which is a significant time savings in heavy traffic.  I am expecting the bus to be standing room only tomorrow, and possibly leave people at the curb.  A number of bus routes, including some that used to run every few minutes, used to use that bridge.

The city's only rapid transit line rins basically from downtown Minneapolis to the Moall Of America and does not cross the Mississippi, where the bottleneck is.

Grab your wallets, taxpayers.  Because this is an Interstate highway, most of the hundreds of millions of dollars it will cost to replace it will come out of your pockets.

Here is a link to a Google Maps view of the section that collapsed; the one that is no more is the largest one with the 35W mark on it.

Local news links:
http://wcco.com/ (includes images and video of collapsed bridge)

Austin

[SpeakEasy]

What in the name of heaven could cause such a thing to happen? Is anyone suggesting a terrorist act?

-Speak

[AustinBoston]

What in the name of heaven could cause such a thing to happen? Is anyone suggesting a terrorist act?

-Speak

No evidence of terrorism.  Eyewitnesses said no explosions were heard nor did anyone see anything else out of the ordinary.

The bridge was desinged in the late 1950's  or early 1960s.  It was completed in 1964 and was meant to last 80 years, but was designed for projected 1970's traffic levels.  It has been handling three or four times the designed traffic levels, and truck weight limits have risen significantly since then.

I have heard since last night's post that a 2006 Federal inspection showed evidence of cracking, and had recommended replacement of the bridge by 2010 (or maybe 2012), but it was currently being resurfaced so I don't think anyone was thinking of actually replacing it by then.

My guess would be a combination of factors was involved.  We know more about metal fateague today.  We avoid building long span bridges like this (nearby bridges have many sets of pylons instead of a single long span).  And the bridge was under-engineered for from today's standards.  In other words, it had too much traffic, was overloaded, was too old, too weak, and just gave up.

Wikipedia's list of bridge disasters lists nine major bridge colapses in the U.S.  (The list is incomplete, but gives us some ideas.)  Of those, four bridges were struck by something, three had structural failures, one was washed out, and one was improperly engineered.

There is no evidence anything in the river or on the roads under the bridge struck the bridge.

It is doubtful that the construction had an impact; the road surface has very little bearing on the structural integrity of any bridge.  Even the vibration of jackhammers for a few months of construction is nothing compared to the constant pounding of big trucks day after day after day.

The most recent interstate bridge collapse (that wasn't struck by something) I am aware of was the I-90 bridge over the Schohare Creek in New York (don't let the word "creek" fool you; it was a major bridge) in 1988.  Because of rain and dark of night, a number of people drove off that bridge to their deaths after the collapse.  That bridge collapsed primarily because soil under footings was washed away, but also because of poor and inadequate inspections and maintenance.  After this disaster, all of the interstate bridges in New York State were reviewed, and many were replaced.

In 1983, an interstate bridge in Connecticut collapsed.  The reports were that the pidgeons who roosted there in large numbers had abandoned the bridge a few weeks before the collapse.  In any case, that failure resulted in an inspection of all bridges in Connecticut with many being upgraded or replaced.  I remember remarking to PJay at the time that we could still be confident in interstate bridges because it was such a rare event, and because this would force everyone to make sure their bridges were safe.  But five years later, the Schohare Creek bridge I mentioned above went down; that was a bridge we used several times a year.

It's been 20 years since the Schohare Creek bridge, but this bridge is one we use often; our son-in-law crossed it twice yeasterday; PJay can almost see it from her building.

I may be wrong, but I believe the NTSB (National Transportation Safety Board) will head up the investigation on this.  They are the people who investigate airline crashes.  They are very thorough, and they will find the cause of this collapse.

My first contract in Minnesota was for MN/DOT, the Minnesota Department of Transportation.  I was introduced to one of the directors, and he asked how  thought transportation compared to Massachusetts.  I said "You don't know how good you have it."  There are roads everywhere.  Then I said "You don't know how bad it is."  Becasue there are few other options.

I'm glad I'm not at MN/DOT today; their lives are changed forever.

Austin

[Russinator]

Austin, thanks for the report. You went to a lot of work putting it together.

Russ

[AustinBoston]

Video of the actual collapse from a security camera:

http://www.wcco.com/video/?id=29690@wcco.dayport.com    

The video immediately following shows before and after shots of significant rust on the bridge struts.  If this ends up being the primary cause of the collapse, heads are ging to roll over this one.

The Minneapolis Star Tribute (where PJay is working as a contractor) is now reporting 4 dead and 79 injured with 20 still missing.  At midnight last night, they were reporting 9 dead...

Austin

[Hargus]

Austin,
         You and your family were the first ones I thought of when I heard the news last night. Thanks for the insight and information first hand. That particular bridge was 40 years old we (as you know) have bridges here that are older than that in Massachusetts. I think this will change things all around for bridge inspections, to bad it had to come to that.

Keep updating us first hand, I'm interested.

[AustinBoston]

Austin,
         You and your family were the first ones I thought of when I heard the news last night. Thanks for the insight and information first hand. That particular bridge was 40 years old we (as you know) have bridges here that are older than that in Massachusetts. I think this will change things all around for bridge inspections, to bad it had to come to that.

Keep updating us first hand, I'm interested.

There are several others here on PUT from the Twin Cities area.  As far as I know, PJay and I are the only ones who commute into Minneapolis from the north.  Kelly (click here for profile) and her children live north of St Paul (about 15-20 miles east of us).  I don't think she commutes into Minneapolis, but I could be mistaken.

The rest escape me now.  Most Twin Cities pop-uppers seem to hang around on PUX.

Austin

[AustinBoston]

Here is an alert for everyone...the U.S. Department of Transportation rated this bridge as "structurally deficient" starting two years ago.  I don't know how the DOT defines "structurally deficient," but it probably means politically that "this is something we will do when we get to it."  The bridge was being considered for work about 5 years in the future.

Here is the important thing...this DOT database lists hundreds of bridges as "structurally deficient" around the country.  It may be time for all of us to find out what our state, county, and local governments are doing to correct "structurally deficient" bridges.  They will tell you everything is fine, that you are not in the same boat as Minnesota.  It's a lie.  That's what they would have told us here on Tuesday.  It's what they would be telling us today if the collapse had happened in any other state.

Austin

[wavery]

I've been seeing a lot of pictures of the underside of that bridge, prior to the disaster. The rust in the pictures in inexcusable (in my mind).

I attended General Motors Institute. My degree is in Dealership Management but I also took several courses in engineering. Anyone that takes engineering classes starts out with the dynamics of "Bridge" construction and physics.

That type of bridge depends totally on the steel fasteners that hold it together. As we well know, Minnesota salts it's roads in the winter and we also know what a toll all that salt takes on steel members and particularly steel fasteners that really can't be inspected without removal.

Seeing those pictures, I was appalled at the amount of rust that was evident. It just appears that little has been done for many years to manage the rust on that bridge.

The other thing that seems a bit suspicious is the fact that both ends of the bridge failed simultaneously. That just seems extremely odd and lends itself to the suspicion of tampering.

I guess time will tell but I don't have a lot of confidence in the truth ever coming out in this disaster.

[AustinBoston]

I've been seeing a lot of pictures of the underside of that bridge, prior to the disaster. The rust in the pictures in inexcusable (in my mind).

Rusty bridges are standard fare all over the north, as are spalling concrete bridge abutments.  Of course, that doesn't make it excusable.  That would certanly fit my definition of "structurally deficient."

I attended General Motors Institute. My degree is in Dealership Management but I also took several courses in engineering. Anyone that takes engineering classes starts out with the dynamics of "Bridge" construction and physics.  That type of bridge depends totally on the steel fasteners that hold it together.

I helped my daughter build a bridge out of toothpicks, so I understand this.  The toothpicks are not usually what fails, it's the glued joints.

As we well know, Minnesota salts it's roads in the winter and we also know what a toll all that salt takes on steel members and particularly steel fasteners that really can't be inspected without removal.

Check out the Wikipedia article...they used quite a coctail of chemicals to try to prevent "black ice" on that bridge, and dispensed them automatically via an embedded system.

http://en.wikipedia.org/wiki/I-35W_Mississippi_River_bridge
magnesium chloride
liquid potassium acetate
other unnamed chemicals (corn by-products?  Huh?)

Seeing those pictures, I was appalled at the amount of rust that was evident. It just appears that little has been done for many years to manage the rust on that bridge.

Who knows.  I contracted for MN/DOT (in the group that was responsible for required archaeologial and historic surveys on new construction).  Everyone I met was professional, highly compentent, and overworked.  Knowing what was being put on the bridge, it's possible the joints were being painted every fall, and the paint stripped every winter by the road chemicals.

While the amount of rust does seem excessive, I have seen other bridges that bad.  If I had a chance, I know I could find coastal bridges in California that are as bad or worse.  Whether I could find a span that long or even an interstate highway bridge is subject to debate.

The other thing that seems a bit suspicious is the fact that both ends of the bridge failed simultaneously. That just seems extremely odd and lends itself to the suspicion of tampering.

That fooled me at first too.  But a careful examination of the video shows the near end hitting the water while the far end was still at least 20 feet in the air.  Keep the perspective in mind - you are looking lengthwise along 1,000 feet of bridge that fell 64 feet.  The falling vehicles are moving forward at 50 or more MPH.  But they do not appear to move at all because of the perspective.  It is more than possible that the bridge, as it started falling, moved towards or away from the camera (much more likely towards, IMHO), by 10 or 15 feet without being visible in the video.  A movement of two feet could be enough to cause the other end to fail.

I guess time will tell but I don't have a lot of confidence in the truth ever coming out in this disaster.

I do.  I have seen the way the NTSB works.  Right now, they are collecting video from at least a half dozen other security cameras, some of which we may never see.  They will be examined frame by frame, and when I say examined, I don't mean watched.  Known points will be measured and timed to determine speed and direction.  Eyewitnesses will be interviewed.  They will review every bolt, every rivet, and every document.  They will interview every contractor and every sub-contractor who ever did work on the bridge.  They don't give a rip about Minnesota politics.  They don't work for those whose heads will roll.  We will know.  The question is will we do anything about it.  I am sure we will here in Minnesota, as they did in New York after the 1988 bridge collapse.

What will be done about "structurally deficient" bridges in other states is what everyone should be concerned about.  They exist in your state.

Austin

[ForestCreature]

That collapse is horrific. I hope all from MN and their families are ok.
We have 3 bridges here in MI of that same design, the DOT is re - inspecting
each of them.

[Kelly]

There are several others here on PUT from the Twin Cities area.  As far as I know, PJay and I are the only ones who commute into Minneapolis from the north.  Kelly (click here for profile) and her children live north of St Paul (about 15-20 miles east of us).  I don't think she commutes into Minneapolis, but I could be mistaken.

The rest escape me now.  Most Twin Cities pop-uppers seem to hang around on PUX.

Austin

I don't commute into Minneapolis, AB.  I take an exit right before 35W off Hwy 36.  I have driven that stretch of 35W many many many times, though.

The only other Twin Citian that I can think at PUT right now is PLJ and I think they are in the southern part of the metro area.

[wavery]

I think that it is rather remarkable how many Gvm't Officials have made the statement, "Just because a bridge is rated, 'structurally deficient' doesn't mean that it isn't safe"..............................OMG people......that bridge was NOT safe....IT COLLAPSED. If you listen to these people, not one single person has said, "That bridge was not safe......"..........I say, "Get a grip". A lot of people are dead and injured.......to hell with the money. It is evident that one of four things are true. 1. Either someone screwed up big time on an inspection or 2. The rating system has some "acceptable risk" :eyecrazy:  factor built in that just cost lives or 3. the earth moved or 4. there was foul play . Bridges just don't have catastrophic failures for no reason.

As far as trusting the NTSB is concerned........I don't trust ANY GMT agency that has the power to not fully disclose all findings to the public.

If they are going to grade these bridges (which they do) they should be required to post that grade ON the bridge so that people can make a decision whether to use it or not. In California, we grade all of our restaurants and the grade is posted. I will NOT eat in any restaurant that is not graded "A" and you better believe that I would not drive on a bridge that is graded "Structurally deficient".

BTW,

Both sides of that bridge started falling at exactly the same time. The fall was nearly horizontal at first. That is very puzzling. The other thing is......the cars were not going at ah speed. They were traveling at 0-10MPH according to eye witness accounts, including drivers that were on the bridge.

My mother is burried about 2 miles from that bridge (Hillside Cemetery) and I have been across it many times also.

[dthurk]

We spent Wednesday night near Philadelphia (camped in a driveway) at the home of a couple who had lived in Minneapolis for many years and crossed that bridge thousands of times.  They have a son and daughter still living there, both of whom work at the Metrodome (hope that's the name of the stadium there).  A Twins game was about to begin, they were both at the stadium and had both driven over the bridge moments before the collapse.  We were informed of the collapse moments after it happened by their son calling.  I have never seen two people more distraught and relieved at the same time.

[aw738]

Wikipedia's list of bridge disasters lists nine major bridge colapses in the U.S. (The list is incomplete, but gives us some ideas.) Of those, four bridges were struck by something, three had structural failures, one was washed out, and one was improperly engineered.

This bridge crossed the river in the town that I work. Silver Bridge