Back to previous post: Internet Time-wasters II

Go to Making Light's front page.

Forward to next post: We’re not led, we’re kept

Subscribe (via RSS) to this post's comment thread. (What does this mean? Here's a quick introduction.)

August 1, 2007

Minneapolis bridge collapses
Posted by Teresa at 08:00 PM * 211 comments

One entire span of the Minneapolis 35W freeway bridge has collapsed into the Mississippi. WCCO-TV is carrying live streaming video.

We have so many friends and readers in Minneapolis/St. Paul. Could you please let the rest of us know how you are? Minn-StF has a check-in site.

More: Elise Matthesen says that cellphone service in the Twin Cities appears to be scrod—not surprisingly, since the bridge carried a lot of telecommunications infrastructure, and everyone’s simultaneously trying to phone their friends and relatives there. She suggests you send e-mail instead.

Comments on Minneapolis bridge collapses:
#1 ::: James D. Macdonald ::: (view all by) ::: August 01, 2007, 08:39 PM:

This is the sort of thing that the Incident Command System (ICS) was designed to handle.

No surprise that cell phones are clobbered. When you're making your emergency plans, make comm plans that don't rely on cell phones.

And, consider setting up rally points -- places where you and your party will re-gather if the world falls apart, you get separated, and comms are down hard.

#2 ::: Teresa Nielsen Hayden ::: (view all by) ::: August 01, 2007, 08:40 PM:

The newscasters are blathering about heavier-than-usual traffic, resurfacing repairs, and a reported jackhammer as possible reasons for the bridge's collapse. None of those sound to me like they're anywhere near the right magnitude.

#3 ::: Teresa Nielsen Hayden ::: (view all by) ::: August 01, 2007, 08:45 PM:

Whoever's in command of the situation is smarter than Rudi Giuliani -- they're keeping responders out of areas that could get hit by a secondary collapse.

#4 ::: elise ::: (view all by) ::: August 01, 2007, 08:49 PM:

We took notes on what happened, I think. Because yeah, preserving responders and all that, it's kind of key.

#5 ::: punkrockhockeymom ::: (view all by) ::: August 01, 2007, 08:51 PM:

Heavier than usual traffic?

Teresa at #2: I agree with you about magnitude. Maybe I just don't understand anything about what makes a bridge collapse, but I'm looking at the pictures of the bridge on CNN, and if "heavier than usual traffic" does THAT, I'm not driving anywhere, any more, EVER, until someone tells me all about the unique structural defects of that bridge. Because, um, oh. my. God.

In the view CNN keeps showing, there's a lonely white car that looks like it was one moment from plunging in over the edge of the collapse. How on earth did that driver keep the car from going over? There's an Explorer a bit further back that seems to have had the right idea and turned the car sideways to keep from sliding in. And it's all godawful. But that white car...we keep coming back to it. If I'm the white car owner, and I'm okay, well then I just got religion, writ large.

#6 ::: elise ::: (view all by) ::: August 01, 2007, 08:52 PM:

OK, for those of you watching news coverage, here's what they aren't giving yet on MSNBC, because as they said they don't have a Minnesotan handy:

They are showing footage of the collapsed 35W freeway bridge, and right next to it is another bridge with arched supports. That bridge is the 10th Avenue bridge.

#7 ::: Patrick Nielsen Hayden ::: (view all by) ::: August 01, 2007, 08:56 PM:

I hate to contradict a Minneapolitan, but according to Google Maps, while that other bridge connects to 10th Avenue on the east side, it's in fact called the Cedar Avenue Bridge.

#8 ::: elise ::: (view all by) ::: August 01, 2007, 08:58 PM:

punkrockhockeymom: They were reportedly doing construction on/near the bridge when it went down.

MSNBC just said "cellphones are inoperable at this time -- can't explain that in the slightest." Well, the 35W bridge carried a LOT of fiber, a lot of telecommunications infrastructure. Dunno if that is why, but might factor in.

The "nearby pedestrian bridge just out of frame" that MSNBC referred to might be the pedestrian bridge that they made out of the old railroad bridge James J. Hill built across the Mississippi. (For those of you who have played the computer game Railroad Tycoon, that railroad bridge is the bridge that Jo Walton exclaimed over when she saw it for real, because it's the image of what you get in the game when you upgrade to stone bridges.)

#9 ::: Anna Feruglio Dal Dan ::: (view all by) ::: August 01, 2007, 09:00 PM:

Good GRIEF. I've never seen anything like this.

#10 ::: Linkmeister ::: (view all by) ::: August 01, 2007, 09:00 PM:

I don't see how the injury count can be low, but I hope it is.

The ASCE puts out an annual report on the nation's infrastructure. The 2006 report reads as follows under the Bridges section:


Between 2000 and 2003, the percentage of the nation's 590,750 bridges rated structurally deficient or functionally obsolete decreased slightly from 28.5% to 27.1%. However, it will cost $9.4 billion a year for 20 years to eliminate all bridge deficiencies. Long-term underinvestment is compounded by the lack of a Federal transportation program.

So I suppose this shouldn't come as a huge surprise.

#11 ::: elise ::: (view all by) ::: August 01, 2007, 09:01 PM:

Yeah, you're factually correct.

http://en.wikipedia.org/wiki/Cedar_Avenue_Bridge_(Minneapolis)

"The Cedar Avenue Bridge crosses the Mississippi River near downtown Minneapolis, Minnesota and also in proximity to the University of Minnesota. An established street name is Tenth Avenue Bridge since the north end of the span meets 10th Avenue Southeast. "

I'm showing my age, and my U of M vintage, I guess.

#12 ::: elise ::: (view all by) ::: August 01, 2007, 09:04 PM:

A note to underscore what Jim is always telling us, this report was on WCCO's website:

"I thought it was just construction going on ... it was a free fall all the way to the ground," said one person who was on the bridge at the time. "Thank God I was wearing my seat belt. The only thing I was hit was the steering wheel."

See? WEAR YOUR SEAT BELTS. It helps in more situations than you might imagine.

#13 ::: elise ::: (view all by) ::: August 01, 2007, 09:05 PM:

Jayminy Crismuss, they already have the Wikipedia article on Interstate 35W updated with news of the collapse.

#14 ::: beth meacham ::: (view all by) ::: August 01, 2007, 09:06 PM:

Glad to see people checking in. It looks pretty horrendous.

I, too, will be very surprise if there are indeed only three fatalities. That's a lot of cars falling a long, long distance.

#15 ::: Fragano Ledgister ::: (view all by) ::: August 01, 2007, 09:11 PM:

It sounds pretty horrible. The pic on CNN.com makes it look as if the bridge was sliced by a gigantic knife.

#16 ::: Melody ::: (view all by) ::: August 01, 2007, 09:14 PM:

I rarely decloak on ML, but Oleander and are fine. I was on that bridge coming home from work about 4.5 hours before it collapsed. I've been telling him for 6 weeks that I've been scared to drive on it with all of the jackhammers taking off the bridge deck, and now this. I can't think, all I can do is sob and wait on word from our friends and family...

#17 ::: Avram ::: (view all by) ::: August 01, 2007, 09:15 PM:

Patrick, I think you may have just done the equivalent of telling someone "No, that's not the 59th Street Bridge, it's the Queensboro Bridge."

Also, while researching this comment, I discovered that there's something called the National Bridge Inventory that assigns unique ID numbers to bridges.

#18 ::: CaseyL ::: (view all by) ::: August 01, 2007, 09:18 PM:

How awful. My thoughts are with the people there.

If it had been a suspension bridge, I could see how one support strut going could bring down the whole span. But it looks like a trestle bridge, and I don't know if the same dynamics apply.

What was the weather like the last couple of years? If the temperature changes were very drastic, with a lot of moisture, that possibly could have weakened the structure with many thin, deep cracks not readily apparent to inspectors.

#19 ::: punkrockhockeymom ::: (view all by) ::: August 01, 2007, 09:20 PM:

Melody at #16:

My heart goes out and my prayers are with you and your loved ones. I'm glad you're safe. I hope everyone else is.

#20 ::: CJ ::: (view all by) ::: August 01, 2007, 09:22 PM:

I usually make a policy of lurking heavily, but wanted to say thanks for the post. I work at the U of M, drive over the 10th ave bridge every day and saw that bridge chock full about an hour before it collapsed. I'm trying to account for everyone without being able to use a cell phone, and while I don't think anyone from my Real Life posts here it really helps to know that I'm not actually isolated, even though I feel it.

Sorry for babbling. And thanks.

#21 ::: Melody ::: (view all by) ::: August 01, 2007, 09:24 PM:

CaseyL, you may be more correct than you know. About an hour ago, our Channel 5 news had a bridge expert on air, when they received a report from 2006 that there were cracks reported in the supports. He backpedaled and generalized his response after his first WTF reaction, but it was evident on air that it shocked him to some degree.

Summers here are almost always steamy, and it has seemed particularly hot the last few years, but that could be just my imagination.

#22 ::: Melody ::: (view all by) ::: August 01, 2007, 09:27 PM:

...and many thanks to you all from myself and Ed (Oleander) for your thoughts and good wishes, they mean a great deal.

#23 ::: Seth ::: (view all by) ::: August 01, 2007, 09:27 PM:

Though the odds of them being in that part of the Twin Cities at rush hour was slim, calling my parents and getting the "all lines busy" message from cel and land lines for ten minutes was still a pretty horrifying experience.

Luckily, I've been able to get in touch with my sister and other friends in the area (including one who works less than a mile away) via email, IM, and forums.

So I fully support what Jim said in the first response: in a time of crisis, be prepared to use alternate communications channels. And I'm going to take to heart what he said about planning those channels before the disaster occurs rather than waiting until it does and scrambling. It might just be what convinces my mom to treat email more seriously.

#24 ::: Teresa Nielsen Hayden ::: (view all by) ::: August 01, 2007, 09:30 PM:

Unique ID numbers, good idea.

Jim, they did an interview with the ICS guy who was recently training the local DOT guys, but they just kept asking him about the bridge -- didn't understand what he was about.

Elise, Karen says she heard about it from your mother, and they all say thank you very much for getting word to them.

#25 ::: Patrick Nielsen Hayden ::: (view all by) ::: August 01, 2007, 09:31 PM:

Avram, #17: "Patrick, I think you may have just done the equivalent of telling someone 'No, that's not the 59th Street Bridge, it's the Queensboro Bridge.'"

That exact thought had just occurred to me.

#26 ::: Anticorium ::: (view all by) ::: August 01, 2007, 09:33 PM:

Has anyone had any luck dialing land lines in the 612 area code? Some folks I know are trying to get in touch with a friend there to verify she's okay, but we're getting nothing but fast busy.

#27 ::: Edward Oleander, RN ::: (view all by) ::: August 01, 2007, 09:35 PM:

For those of you who have friends or family in this area, the Red Cross is setting up a web site (don't have the URL yet). check redcross.org

HCMC patient info hotline...612.873.3400

Cell phones are still mainly out; I couldn't reach my boss at the Red Cross chapter where their doing triage and feeding the rescuers...

#28 ::: Tristan ::: (view all by) ::: August 01, 2007, 09:36 PM:

I got through to my family (651 area code), and they're ok. Haven't tried anyone in 612 though. Supposedly there's a baseball game tonight, so lots of people may be downtown for that.

#29 ::: Seth ::: (view all by) ::: August 01, 2007, 09:38 PM:

Has anyone had any luck dialing land lines in the 612 area code? Some folks I know are trying to get in touch with a friend there to verify she's okay, but we're getting nothing but fast busy.

Best I managed was a single ring from a 612 number, after which it dropped immediately to a busy message rather than voice mail.

#30 ::: elise ::: (view all by) ::: August 01, 2007, 09:39 PM:

Anticorium, the cellphone service here is hosed, and probably landline service is hosed too, due to lots of fiber being carried by the bridge. Telephone calls crossed that bridge all the time, and nobody thinks about them....

My suggestion: if they can possibly try e-mailing, that'll work a lot better.

#31 ::: elise ::: (view all by) ::: August 01, 2007, 09:44 PM:

Ah! Some local cellphone service working now.

#32 ::: Teresa Nielsen Hayden ::: (view all by) ::: August 01, 2007, 09:44 PM:

Tristan, there is a baseball game going on. They didn't cancel it because that would just dump a lot more traffic into an already difficult situation.

#33 ::: Edward Oleander, RN ::: (view all by) ::: August 01, 2007, 09:46 PM:

Anticorium #26 .... We're having some luck with 612 from local landline here... send me the info and we'll try for you... RNcalledEd@comcast.net

#34 ::: Teresa Nielsen Hayden ::: (view all by) ::: August 01, 2007, 09:50 PM:

Oleander, that's the same thing I was doing on 9/11 -- people could get through to me long distance via chat, and I could get through to their friends and relatives on local land lines.

#35 ::: JoXn Costello ::: (view all by) ::: August 01, 2007, 09:58 PM:

The video I saw (from the Fox News(!) affiliate -- both the CBS and ABC affiliates have much less useful coverage) made it clear that both north and south piers are still standing, so whatever happened to the bridge happened in the span, not in the supports.

My family is all okay; my aunt had crossed the bridge only a minute before it collapsed, but is uninjured. Not that you know any of them :-)

#36 ::: Tristan ::: (view all by) ::: August 01, 2007, 09:58 PM:

I'm in shock. I grew up in Minneapolis. I have friends who went to the U of M. I've driven over that stretch of highway. My thoughts are with everyone who's still waiting to hear.

I suppose we'll have an explanation for this eventually, but right now it just seems so random. I think I need to stop looking at the pictures.

#38 ::: fidelio ::: (view all by) ::: August 01, 2007, 10:05 PM:

#1 Jim, #24 Teresa--I think I heard the same guy on MSNBC that Teresa mentioned--he finally got what he had been doing with the local emergency responders across, and was able to explain that they looked to him to be doing what they were supposed to--he mentioned staying back in the safe area, and setting up a system that avoided political issues, among other things, such as getting good communications going among the responders, IIRC.

I have to cross the Cumberland River twice a day, going to and from work, as does my landlord--we are looking at the tube and feeling our skins crawl from head to toe.
When I visit my mother and brother in Kansas City, I cross the Ohio and the Mississippi twice, and the Missouri four times, in a round trip. On my next trip, I imagine I'll be even more skittish about them than usual.
Bridges need constant, active maintenance, and too many don't get it. Corrosion is a big enemy, and can work on structure unseen and unsuspected--and please take that as a general observation bridges in general, and not a wild-assed guess about the cause of this horrible event.

Our best wishes to everyone in the Twin Cities area, and strength and courage to the emergency workers on the scene.

#39 ::: Teresa Nielsen Hayden ::: (view all by) ::: August 01, 2007, 10:07 PM:

And while we're on the subject of the news from Minneapolis, Steve Brust is now a grandfather.

#40 ::: Rachel ::: (view all by) ::: August 01, 2007, 10:46 PM:

The reports I've been seeing say that the bridge was a single-span steel bridge. If true, collapse in the middle would be enough to bring the whole thing down.

#41 ::: Marilee ::: (view all by) ::: August 01, 2007, 10:49 PM:

Teresa, I posted that in the Open Thread yesterday. I meant to post it sooner, but forgot.

#42 ::: Joyce Reynolds-Ward ::: (view all by) ::: August 01, 2007, 10:52 PM:

Oh. My. God.

My thoughts go out to all of you in the Twin Cities area. Hoping all is well.

And for those in the PDX area...um, you might want to have cautious thoughts about the Sellwood Bridge. I have nightmares about that one, and they're saying it should have been repaired or replaced 30 years ago.

#43 ::: Teej ::: (view all by) ::: August 01, 2007, 10:53 PM:

Minneapolis mayor reported 6 confirmed deaths at a press conference about 45 minutes ago, but that recovery was still ongoing in the river. There are at least 2 dozen injuries. There have been many survivors, even people who dropped the full height in their cars, as well as a school bus full of children.

The bridge was built so that there are no pylons (spelling on that might be botched) in the center of the river - the span is supported entirely by the supports on the two banks. The construction on the bridge was resurfacing and apparently involved lots of jackhammering for several days. No one knows if that contributed or not. One of the construction crew workers is still unaccounted for.

A friend was on the river on the Mississippi Queen for his company annual party when the bridge collapsed, about 15 minutes from going under it. At last report nearly an hour and a half ago, they were heading back upriver to de-board at some as-yet-unknown port.

(And I think that occasionally should be added to your spelling reference. I can never remember how to spell that one!)

#44 ::: Brooks Moses ::: (view all by) ::: August 01, 2007, 10:53 PM:

punkrockhockeymom @ 5: Heavier than usual traffic does not do that, at least not by itself. It may possibly be that if the bridge is already essentially broken for some other reason, the traffic is enough to be the final straw, but that's about all it is.

My impression of the usual safety factors on bridges is that they're very well beyond sufficient to make it safe to pack cars on top of them as tightly as they will physically go.

CaseyL @ 18: The same dynamics apply to truss bridges as suspension bridges, though not necessarily as strongly. It's still a matter of the fact that having one support go will cause all of the corresponding supports to suddenly carry a lot more load, a that may be enough to break them too, at which point you've got a chain reaction gone critical.

I've also seen cases in engineering textbooks where some undetected cracking was happening in the supports, so that when one of them failed, the others were already weakened by corresponding cracks, and definitely couldn't handle the sudden extra load.

#45 ::: Greg London ::: (view all by) ::: August 01, 2007, 10:55 PM:

The newscasters are blathering about heavier-than-usual traffic, resurfacing repairs, and a reported jackhammer as possible reasons for the bridge's collapse. None of those sound to me like they're anywhere near the right magnitude.

Every once in a great while, a barge going down the Miss will hit a bridge and take it out.

Exxon Valdez, but with a boatload of corn.

I would not be surprised, however, if it was something small. Stress cracks. Rusted cable. Galloping-whatever that bridge taken out by wind that hit resonant frequency. Or maybe someone cut a bolt to replace a beam, but didn't realize that the guy who was supposed to put in the support jig beforehand didn't get around to it.

#46 ::: Kathryn Cramer ::: (view all by) ::: August 01, 2007, 10:58 PM:

We are at NASFIC and someone (I think coming from the Minneapolis direction) told us about it when we were on our way out to dinner. What we were intitally told is that it was a construction error.

Siince we came back, we've been watching CNN for a little while and there's not a whole lot of info. (Anderson Cooper seems to be trying really hard to get someone to tell him why, but it ain't happening.)

#47 ::: Anticorium ::: (view all by) ::: August 01, 2007, 10:58 PM:

Oleander@33: Thanks for the offer, but it turns out the number I have is outdated. I got through but was rewarded by a message telling me the number is changed, but not to what.

#48 ::: Marilee ::: (view all by) ::: August 01, 2007, 11:01 PM:

My local news is saying the mayor said 7 dead.

#49 ::: Bill Burns ::: (view all by) ::: August 01, 2007, 11:05 PM:

The Mianus River Bridge, carrying I95 in Connecticut, collapsed in 1983 from the failure of just two pin and hanger assemblies.

#50 ::: George Smiley ::: (view all by) ::: August 01, 2007, 11:08 PM:

@9: "Good GRIEF. I've never seen anything like this."

I have. And that was at rush hour, too. Fortunately, the World Series between Oakland and SF, was to start minutes later, and a huge fraction of folks the Bay Area were perched in front of their TVs instead of clogging I880 as they normally would.

Like everyone else here, my thoughts are with thefine folk of the Twin Cities. Hope as many of you and yours are as safe as possible.

#51 ::: Kathryn Cramer ::: (view all by) ::: August 01, 2007, 11:09 PM:

What I think, in the end, is that this will be seen as symptomatic of the same problems that lead to the destruction of New Orleans: inadequate attention to national infrastructure. However, the key phrase I just heard from MSNBC was "work on the joints," which is to say that they were doing repair work on the joints of the bridge. 2 of the 4 lanes were closed because of construction.

I have a fascination with the collapse of the Tacoma Narrows Bridge. Resonance patterns were important in that bridge collapse. I am very curious about what might be meant by work on the joints, because that can take us into Tacoma Narrows territory.

#52 ::: eric ::: (view all by) ::: August 01, 2007, 11:14 PM:

Wow. I'm looking at that as a former bridge structural engineer (small e, not a PE). Wow.

There are a lot of secondary failures there, mainly spans being pulled off of their expansion joint pads. That's the sort of thing that they've spent the last 30 years fixing in earthquake zones after the Loma Preita quake.

I can see two possible main failures:

A stability failure over the abutment could lead to the bridge collapsing down and sideways. This would probably be related to heat or corrosion, but there would need to be some other trigger. An unbalanced load, or something.

It's also possible that it was a tension failure over the other abutment, but that's been discounted a bit by the engineer in one of the clips. This one could be related to the construction or corrosion or cracks.

And, I note, there are a few bridges that look a little like that one in Seattle...

#53 ::: Kathryn Cramer ::: (view all by) ::: August 01, 2007, 11:15 PM:

Key phrase from Fox News "more of a metal fatigue failure than a concrete fatigue failure."

#54 ::: Magenta Griffith ::: (view all by) ::: August 01, 2007, 11:18 PM:

This is why I am keeping my landline. I haven't been able to check on friends with cell only, but someone who was supposed to stop and couldn't by got through a little while ago, no problem - landline to landline.

If you want to check on MnStf and other locals, there is a check-in post on Live Journal:
http://community.livejournal.com/mnstf/94019.html

#55 ::: Magenta Griffith ::: (view all by) ::: August 01, 2007, 11:20 PM:

Whoops, didn't notice that the check-in was part of the main topic. I'm a bit fried.

And it hit 92 degrees today, and is still in the upper 80's. May have been a contributing factor.

#56 ::: Avram ::: (view all by) ::: August 01, 2007, 11:20 PM:

Actually, on closer examination, turns out those bridge ID numbers are only unique within a state. Given that, you'd think they'd stick a state identifier on 'em, but it doesn't look like they do.

#57 ::: Patrick Nielsen Hayden ::: (view all by) ::: August 01, 2007, 11:20 PM:

Teresa and I saw the same thing that "George Smiley" (hey, tell Karla hello!) links to in #50 -- just a few days after the event. Along with the World Trade Center site a few days after 9/11, it's one of the truly weirdest and most upsetting things I've ever seen.

#58 ::: P J Evans ::: (view all by) ::: August 01, 2007, 11:23 PM:

I read Linkmeister @ 10 and my first thought was 'a month's worth of Iraq could have paid for that.' (Probably wrong, but it would surely have paid for a year's worth of repairs.)

I second George Smiley's comment on the Bay Bridge. There's a picture in my memory of a vehicle perched on the edge of the place where the section dropped. Also memories of similar pictures from other quakes in other locations, where the structures failed and the brakes didn't.

#59 ::: James D. Macdonald ::: (view all by) ::: August 01, 2007, 11:32 PM:

One reason I have a roll of quarters and a pre-paid phone card in my Urban Survival Bag is because in the event of a major catastrophe cell-phone service won't be reliable.

#60 ::: Margaret Organ-Kean ::: (view all by) ::: August 01, 2007, 11:34 PM:

While it's possible that a lot of cable was taken out with the bridge, another factor in the phone problems is the everyone calling everyone else problem - the exchanges are overloaded. I saw this with Mt. St. Helens, and I've seen it several times since as a result of being responsible for business telecommunications for a business on the same exchange as a major ticket company.

Eric @ 52 - er, which Seattle bridge? Galloping Gertie was a Tacoma bridge. Mind you, it's not like ours don't fall down.

#61 ::: Laurel Krahn ::: (view all by) ::: August 01, 2007, 11:36 PM:

For those interested in this stuff, Shaun Kelly has been posting his observations from listening in on the radio chatter in his LJ: kalikanzeros.livejournal.com

And Nancy McClure posted a good picture to give you a better idea of where the bridge is located:
http://www.hand2mouse.com/mcclure/bridgecollapse.jpg

#62 ::: James D. Macdonald ::: (view all by) ::: August 01, 2007, 11:37 PM:

Re: #58

If we paid for bridge repair at the rate we're paying for Iraq, we'd get 'em all done in a bit under seven years.

As I keep saying: Who need bin Laden when you have Murphy?

#63 ::: Stefan Jones ::: (view all by) ::: August 01, 2007, 11:48 PM:

One of the locals interviewed on NPR said something interesting:

The fallen deck floated for a time, allowing passengers in the car to get out.

I've avoided TV coverage up to now. I might just turn on CNN for a bit so I can visualize what happened.

* * *

Discussion about cell phone outages makes me think:

Man, I wish we had a competent Federal government. Incidents like this should lead to Lessons Learned conferences and fixes to our communication infrastructure.

With Bush, we'll get some trite expressions of sympathy and some bluster about building the bridge bigger and better.

#64 ::: Edward Oleander ::: (view all by) ::: August 01, 2007, 11:50 PM:

Update:
7 confirmed dead, one construction worker missing. As of 2230, there were 60 people taken to local hospitals, with at least 6 critical, but likely more.

No attempts have yet been made to get under the main sections, especially under water. Rescue workers will try searching the river tonight, but this is difficult due to currents and darkness. Just now the operation went from "rescue" to "recovery" mode.

The bridge passed muster in 2006, but there were notes made regarding cracks in the crossbeams that support the girders running with the road bed. That note clearly alarmed a safety engineer KARE interviewed, but he admitted that he is not familiar with this bridge.

The main bridge was a single span arch bridge built in 1967. It was considered unique at the time for the size of the open central span (about 550 ft long and 65 ft above the water at the apex). Overall the bridge was about 1000 ft long and the entire thing went apparently within just a few seconds.

No clear word on where the collapse started. One woman saw light poles swaying and stopped in time. A school bus with 50-60 kids was on the bridge but were all rescued by others involved in the collapse (Some of whom had just fallen 50 feet...now THERE is real balls!). 12 kids were taken to the hospital and 2 were serious. See the City of Minneapolis website for a hotline for out-of-towners. Also see www.redcrosstc.org for info or to donate to the Red Cross.

The Red Cross can be reached all night at 612.871.7676 for those seeking loved ones.

Estimates vary, but between 50 and 100 vehicles may have been on the bridge. No idea on how many are under water or under the larger sections.

The phones are in better shape now, both cell and landlines...

MY THANKS to everyone for their words of comfort. Melody, who works just a couple blocks from the bridge, drove over it just a few hours before the collapse, and several of her co-workers also use the bridge during rush hour. She was quite upset, and also sends her thanks to everyone.

#65 ::: Edward Oleander ::: (view all by) ::: August 02, 2007, 12:06 AM:

Credit where credit is deserved:

Target Stores just delivered an entire 18-wheeler full of water and food supplies to our Red Cross chapter for the EMS and investigative workers.

#66 ::: Joyce Reynolds-Ward ::: (view all by) ::: August 02, 2007, 12:11 AM:

Apparently there's some locals liveblogging over on Firedoglake and DailyKos as well.

#67 ::: JESR ::: (view all by) ::: August 02, 2007, 12:13 AM:

Margaret Organ-Kean @60 I think eric was referring to the I-5 bridge over the Lake Washington Ship Canal, which is of a similar vintage and even higher than the 35 bridge, or possibly the long viaduct over the southern end of the Duwamish Valley. Or the Albro bridge, perhaps. Seattle is full of bridges in bad repair, with known problems. The Ship Canal bridge is undergoing repairs right now, as is the much older )and more like the Embarcadero Fwy) Alaska Way Viaduct.

Going cheap on road taxes (thanks, Tim Eyman, you asshole) is an invitation to disaster. Today, disaster took up the invitation. (And I'm freaking out about my cousins and Uncle in the twin cities).

#68 ::: CaseyL ::: (view all by) ::: August 02, 2007, 12:26 AM:

Seattle had Galloping Gertie, the Tacoma Narrows bridge, back in the 40's. It had just opened, too. Also, a few years ago the brand-new I-90 concrete pontoon bridge sank when the access doors to the pontoons were left open and lakewater flooded in (years of lawsuits over that one; but no injuries, because it sank slowly enough to clear everyone off).

The current Big Bridge Issue here is the Alaska Way Viaduct, a huge elevated highway that runs along the waterfront. It's a vital part of the transportation system, and was badly cracked in the February 2001 earthquake. It's been repaired and retrofitted, but the feeling is that it needs to be replaced. The city is divided over whether to build another elevated viaduct, or dig a huge tunnel and run the highway through that, or build a surface highway. (Whatever they do, while it's being done, the commute - already a nightmare here - will resemble one of the Outer Circlesof Hell.)

This being Seattle, where we study and discuss things to death and our city officials are chronically unable to make decisions, I had doubted anything would actually be done until the damn thing up and collapsed. But the 35W disaster will likely concentrate a few minds here.

#69 ::: Will A. ::: (view all by) ::: August 02, 2007, 12:32 AM:

Just checking in. I was about two exits south at the time, headed further south and away while entirely oblivious.

#70 ::: JESR ::: (view all by) ::: August 02, 2007, 12:43 AM:

Seattle =/= Tacoma, please. I'm traumatized already by sitting on the bus in Olympia and hearing people say "here in Seattle."

Seattle has plenty of problematic bridges (I didn't mention the Lacey V. Murrow /520 floating bridge, even) and doesn't need, really, to appropriate the ones belonging to entirely different counties.

(Sorry, but I socialize with WS-DOT bridge inspectors, and it takes me strangely some times.)

#71 ::: Anna Feruglio Dal Dan ::: (view all by) ::: August 02, 2007, 12:43 AM:

Oh, I've seen plenty of disasters, but usually there is an earthquake, a flood, a fire, a collision with a plane, or SOMETHING. The Tacoma Narrows had resonance (so did the pedestrian bridge in front of the Tate Modern, aka The Wobbly Bridge, but they fixed it.)

This... is like a piece of the sky falling down.

The Vajont Dam disaster was worse, but I wasn't born yet at the time.

#72 ::: elise ::: (view all by) ::: August 02, 2007, 01:07 AM:

Edward Oleander: "A school bus with 50-60 kids was on the bridge but were all rescued by others involved in the collapse (Some of whom had just fallen 50 feet...now THERE is real balls!)."

Indeed so. I love my town. As the WCCO website says:

"New at 10:34 p.m.:

One young man helped all of the children out of the back door of the bus that contained 60 children. Instead of rushing to safety many other people ran to the bus to help the children. All of those kids are safe."

Because that's what ya do. Having just fallen 50 feet or not.

#73 ::: Naomi ::: (view all by) ::: August 02, 2007, 01:19 AM:

There's an interesting article in one of the local papers about witnesses who became rescuers. For those (like me) who like reading the EMS Geekery posts here, it's fascinating reading.

#74 ::: MWT ::: (view all by) ::: August 02, 2007, 01:34 AM:

One thing I've not seen mentioned anywhere yet is how deep the river is, how wide, how fast the currents, etc. Does anyone know?

#75 ::: Dan Bennett ::: (view all by) ::: August 02, 2007, 01:36 AM:

Joyce @ 42 -- I thought the same thing about the Sellwood Bridge.

It looks like The Oregonian had the same thought:

http://www.oregonlive.com/news/oregonian/index.ssf?/base/news/1186026912213310.xml&coll=7

#76 ::: Edward Oleander ::: (view all by) ::: August 02, 2007, 01:49 AM:

#74 -- The river is about 300-400 feet wide there, and for the most part less than 10 feet deep. There is significant silting, so a dredged channel is maintained. There is a lock and dam just upstream, so the current is fairly swift and visibility poor. Considering the debris involved, diving will be very hazardous, even in daylight...

#77 ::: eric ::: (view all by) ::: August 02, 2007, 01:58 AM:

Margaret Organ-Kean @60 -- I was referring to the Fremont bridge and the I5/ship canal bridge, both old trusses. There's also Deception pass as well, but that's hardly Seattle.

Re Concrete vs steel failures: Concrete really doesn't fatigue in the same way that steel does, since steel fatigue is a tension failure, and tension failures in concrete are quick and dramatic. That's why concrete is never designed in tension. Fatigue failures in steel are very slow until the crack reaches a critical length, and then suddenly very fast.

It's unlikely that the bridge deck caused this failure, since anything that would fail with the deck would tend to be pretty locally redundant and not supporting a whole lot. It could have contributed to it by allowing access to tension members, but that's a different issue.

I'd put my money on either a tension member going in fatigue or a buckling failure as the whole truss flopped over. Or both, in either order.

#78 ::: Margaret Organ-Kean ::: (view all by) ::: August 02, 2007, 02:06 AM:

JESR and Casey at #67, #68, #70

I live in West Seattle - the Alaskan Way viaduct is a major big deal to me! When the Nimitz went, the first thing I heard on the radio made me think it was ours.

The Alaskan Way viaduct is a real mess - it's built on fill and there's the earthquake damage. On the othe hand, an engineer I know has talked to some of the engineers inspecting the viaduct and he thinks they've been pressured to turn in reports that things are worse than they are. Take that for what it's worth - second hand gossip. If you want a motive - well, whether the viaduct is OK or not, the sea wall in that area is definitely not, and if the city builds the tunnel, they could use part of the federal/state funds to rebuild the seawall.

If the seawall goes, I don't give a hoot for the chances of the viaduct or the buildings down by it. They're all on fill, and the one I worked in for five years (a new building, too) used to rattle like there was an earthquake going on every time a freight train went through.

Don't even get me started on the commute - the day after the 2001 earthquake it took us 2 hours to get out of West Seattle, because the viaduct was closed.

I was just curious as to which one Eric was thinking about, since I have several personal disaster candidates - including the South Park bridge, the 520 (getting hit by a barge cannot have helped it), and the Fremont bridge (not that it will fall down so much as that it will get stuck some fine day).

And, what I forgot in my earlier post - good thoughts to the Twin Cities and those with relatives and friends there.

#79 ::: Linkmeister ::: (view all by) ::: August 02, 2007, 02:30 AM:

Here's a blog post from a Minneapolis blogger who lives across the street from the bridge. His photos have been posted to Flickr.

#80 ::: Bruce Cohen (SpeakerToManagers) ::: (view all by) ::: August 02, 2007, 03:14 AM:

There's not much I can say or do just now to help in this situation, except that I hope for the best for all who were on that bridge, and for all who had friends and loved ones there. I can say, FWIW, I've been very impressed with what I've heard about the reactions of people on the scene; they're in the best Jim Macdonald tradition.

For Portland people worried about the Sellwood Bridge: the best course is just to keep your eyes on the traffic when you go across. Looking at the pieces peeling off the bridge will only lead you to dark thoughts of disaster to come. If denial doesn't help, use the Ross Island Bridge instead.

#81 ::: Madeleine Robins ::: (view all by) ::: August 02, 2007, 03:15 AM:

My God. Words fail. Given the extent of the devastation, if the final count is really only seven, it's damned lucky.

As with the hours after the World Trade Center, I am so grateful for the check-in area on the web.

#82 ::: janeyolen ::: (view all by) ::: August 02, 2007, 03:44 AM:

Here in Scotland, I turned on the morning news at 6:30 and the bridge collapse was the first and biggest story. I knew that son Adam and wife Betsy, kids, plus John Sjogren and girlfriend were even then in the air on the way here.

So I was able to relax on that front. But then of course I started worrying about all my many Minn. friends. Various websites helped. Still need to know about the rest of the Pucci clan, but sure that Betsy will know about that and will tell me when they get here this afternoon.

Jane

#83 ::: Patrick Nielsen Hayden ::: (view all by) ::: August 02, 2007, 07:15 AM:

What exactly happened: excellent visual storytelling from the Minneapolis Star-Tribune.

(And yes, they label the non-collapsed bridge the "10th Av. Bridge," so Elise and Avram were both right.)

#85 ::: Erik V. Olson ::: (view all by) ::: August 02, 2007, 08:26 AM:

On cells phones. If you have a tower connection, but you can't make a call, you can often get a text message through. SMS runs on the control channel, it doesn't need to setup and tear down a full voice connection for the message. Cell networks are built around having many phones talking on the control channels, to track what phones are in what cell at a given moment.

But the better answer is "do they *need* to know this bit of information right now?" And often, even the message "I ain't dead" isn't crtical.

"I'm not dead, but I might be soon..." is, but an hour's extra worry is an annoyance, not a critical problem -- esp. if the calls you are trying to make keep the person who's in real danger from calling for help.

So. In an emergency, ask yourself -- does the person I'm trying to contact *need* to know what I'm going to tell them *right now.* If the answer is no, wait until the comm crunch has cleared.


#86 ::: MWT ::: (view all by) ::: August 02, 2007, 08:26 AM:

#76 Edward Oleander: Thanks muchly. Dive rescue was exactly what I was wondering about...

I passed that Star Tribune diagram to the folks over at Wikinews, and now they're looking into making a free version of it for their article.

Incidentally one of the passing comments they had in the IRC channel was:
"07:34:34 <DragonFire1024> whay does FOX News have to lie: The bridge was NOT ruled structurly deficient"

Thought some of you might find that amusing. ;) (And on an even farther, completely unrelated tangent, this article might be entertaining.)

#87 ::: Laurel Krahn ::: (view all by) ::: August 02, 2007, 08:42 AM:

I must say, the press conferences from both Hennepin County Medical Center and from the Minneapolis police are very impressive. People seem to really know their stuff and be covering every angle I can think of (and then some).

Neil Gaiman's been listed as "okay" on the check-in page for quite some time. We're still awaiting word on some local fans.

#88 ::: Laurel Krahn ::: (view all by) ::: August 02, 2007, 09:32 AM:

I've now gathered all the links I've posted in one place with more to come I'm sure.

#89 ::: PixelFish ::: (view all by) ::: August 02, 2007, 10:18 AM:

I had the same thought as George @50 re: disasters of this magnitude. (And actually, every time I drove the Bay Bridge, or the route off of Cesar Chavez to downtown, my mind would inevitably run the "What if there's a big earthquake right NOW," scenarios. Also, a few months ago, they had a major overpass collapse in the Bay Area right near the Bay Bridge when a tanker truck full of gas crashed, exploded, and then proceeded to burn down the overpass that was directly above it. Fortunately nobody got hurt in that one though....but it's easy to imagine the toll had the overpass been crowded with folks. As it was, transit in the Bay Area was pretty affected, and the repairs--not cheap.

I can imagine the impact with this incident will be felt for some time in the Twin Cities but it looks like the people on the ground are acting intelligently, so hopefully the reconstruction and revival will go well.

My thoughts are definitely with the folks of the Twin Cities at this time. I'm a little selfishly glad that everyone on my F-list has checked in BEFORE I heard the news--I didn't even have time to worry about any of them. Stay safe, folks.

#90 ::: John ::: (view all by) ::: August 02, 2007, 10:32 AM:

"Between 2000 and 2003, the percentage of the nation's 590,750 bridges rated structurally deficient or functionally obsolete decreased slightly from 28.5% to 27.1%. However, it will cost $9.4 billion a year for 20 years to eliminate all bridge deficiencies. Long-term underinvestment is compounded by the lack of a Federal transportation program."

First off, I'm a civil engineer, licensed PE, working as a highway design engineer. NOT a bridge engineer, but I work with those guys all the time, every day, so I'm familiar with what goes into a bridge.

That quote above is very, very misleading. A bridge can end up on the "deficient" list for something like too-narrow shoulders, old bridge rails, bad pavement, narrow lanes, etc, that don't mean "it will fall down if nothing is done soon". Not saying all bridges are ok that are on that list, just that not ALL of them are like that.

RE: this bridge collapse. Eyewitnesses said it was groaning and shaking right before it collapsed. To me, that sounds as if it had a failure in some critical member (and in a steel truss bridge, ALL the members are critical) that cascaded into more and more members as they couldn't take the extra stress. I don't think the work on the bridge caused it to collapse, or "heavy traffic". Even cutting a bolt by mistake shouldn't have caused this, given the high factor of safety built into every bridge. No, something gave way that shouldn't, and the rest of the support members couldn't handle that sudden extra loading.

The Washington Post got hold of the latest bridge inspection report that said there were signs of fatigue in structural members, but nothing to warrant immediate replacement.

Which makes me wonder; was it inspected completely (metal truss bridges are maintenance whores), did they inspect 'nearly' all the bridge, or just representative parts of it (i.e. the easiest to reach portions)? If they did inspect all the bridge, then did the engineers realize that a truss structure is stable only as long as all the members remain intact, and one failure (given deterioration everywhere) can lead to a catastrophic collapse?

Or, did the inspection report deliberately downplay the severity of the fatigue so as to not force the state to spend hundreds of millions of dollars they didn't have to repair/replace the bridge?

#91 ::: Greg London ::: (view all by) ::: August 02, 2007, 11:10 AM:

This article says that there are 20-30 people still missing, a number of cars underwater underneath the bridge, and that the road crew had been working on the joints of the bridge.

#92 ::: Jakob ::: (view all by) ::: August 02, 2007, 11:13 AM:

John #90: If they did inspect all the bridge, then did the engineers realize that a truss structure is stable only as long as all the members remain intact,

How likely is this? I mean, I know this from my structures lectures, and I was an aeronautical engineer (although I don't do it professionally). Is it really plausible that you'd have engineers inspecting a bridge with so little knowledge?

I understand that the maintenance works were on the bridge deck. I'm assuming that whatever they were doing there wouldn't affect the primary structure, unless they accidentally damaged it in some way. Or managed to tweak the bridge's resonant frequency in a bad way.

#93 ::: Vir Modestus ::: (view all by) ::: August 02, 2007, 11:38 AM:

Stefan @63:

With Bush, we'll get some trite expressions of sympathy and some bluster about building the bridge bigger and better.

Actually, Bush spent about 1 minute with sympathy, then the rest of the press conference he spent blaming the Democrats for not passing his budget the way he wanted it.

That and the Republican governor of Minnesota vetoing a gas tax that would have helped pay for infrastructure. I wonder how long the higher taxes = bad equation will hold up when you add death and destruction to the math.

#94 ::: Paula Lieberman ::: (view all by) ::: August 02, 2007, 11:44 AM:

#68 CaseyL

Boston's Big Dig is continuing in the news.... the good news and the bad news about modern design and engineering, is that with all the high resolution modeling, designers don't do the level of overdesign/overbuilding that enabled e.g. the Empire State Building to be essentially undamaged from being smashed into by an airplane.

Engineers used to have to use much larger amounts of safety margin in their designs, because the slop factors regarding how "safe" something was were larger... and when in doubt, overbuild/make stronger.

The nasty thing about modern design, is that it doesn't allow for implementation errors... or trying to speak English instead of "you have been working with too damn much badly written engineer-generated stuff!," people make mistakes, designers made bad assumptions about e.g. "manufacturability" (oops, too much geekspeak again... there's what the design expects, and then there is what can actually be built... one of the most representative examples was commercial defense contractor versus MIT Lincoln Lab, and I heard -both- sides of the stories.... commercial defense contractor: "Lincoln Lab designs equipment it takes a Ph.D to manufacturer and maintain." Lincoln Lab, "If they were competent they wouldn't have any problems building it!"

Reality check--MIT Lincoln Lab designers almost all have at least masters' and most of them doctorates, and the technicians who do most of the equipment building (some of the designers have made stuff, but it takes time away from designing; one of my old college dormmates when he worked there, who was a very hands-on designer, was frustrated for months at the lack of a tech meaning he had to build the hardware himself, which meant taking time away from his design work) have bachelor's degrees. They do precise specification of tolerances--tolerances which commercial organizations have trouble meeting on production lines--Lincoln Lab is an R&D outfit, not a production facility, and works to narrower tolerances than the commercial world... so, Lincoln lab designs assume a higher level of skill and stricter tolerances than the commercial world, while the commercial world looks at Lincoln Lab and sees a bunch of MIT academic-world R&D people with no concept of commercial realities and capability and limitations. The Lincoln Lab types don't allow for commercial organizations being sloppier than the techs and designers at MIT/less able to work to very precise narrow tolerances, and the commercial types are annoyed that Lincoln Lab doesn't take into account what the tolerances that commercial productions lines are, and that ordinary mortals working at defense contractors aren't going to achieve on a production line what R&D techs overseen by PhD designers at MIT, can do on experimental and prototype equipment.

Getting back to bridges and other things--people make errors doing things, and sometimes the errors are deliberate--a contractor just agree to cough up $40,000,000 or more for deliberately using substandard concrete in the Big Dig. That is ONE of the causes of the tunnel leaks--corrupt contractors putting in lower quality material than the design calls for.

Then there's the epoxy, one of the causes of a failure that killed a woman some months ago, the epoxy used was not the correct grade needed for the application, and it failed, and the bolts failed, and down came the now-unbolted panel onto the car.

There's the originally-called-the-John-Hancock-tower, of which the lawsuits resulted in -sealed- documents determining the causes of that building's problems sending glass panes sailing down into the streets of Boston... some if it may have been that the design was one which was impossible to be constructed to the as-designed tolerances, there were also rumors that the pile driving wasn't done as designed, and there were issues about the design, too--exactly what happened, again, was kept -secret-....

But again, modern design, there is the issue that there is the design, and there is the issue of what peope build/can build/errors in materials, tolerances, putting things in backwards, inspection (things don't always get properly inspected, and some things are almost impossible to inspect properly), fake paperwork... how much can/should be allowed on design, to accommodate "the contractor is going to use substandard materials intentionally or by fraud from the subcontractors or by unintended happenstance," the labor makes minor mistakes while constructing things, etc.?

But back to tunnels--the Big Dig involves mega-engineering. But it leaks... a lot of that is from not enough margin to allow for incompetence and fraud, along with having slime like Bechtel management controlling things and the Republicraps calling the shots that gave slimeball Bechtel the control.

If Seattle-Tacoma want to put in a tunnel, there's the experience of The Big Dig to consider...

#95 ::: P J Evans ::: (view all by) ::: August 02, 2007, 11:57 AM:

Puala L @ 94

Leaks in tunnels ... part of the Red Line tunnel in downtown LA leaks. Seems that when they built the first phase of it, when they installed the semi-permeable membrane that was supposed to keep moisture out, and let it flow out from inside, they installed it wrong side to. So they have a tunnel section where moisture comes in, and stays in. (I have an opinion of that kind of construction, which can't be printed.) They haven't yet figured out a way to moisture-proof the outside of the concrete tunnel. 'I don't woory about lava in the subway, just floods.'

#96 ::: Paula Lieberman ::: (view all by) ::: August 02, 2007, 12:08 PM:

The bridge on route 2 in Cambridge over the railroad tracks near the Alewife MBTA station has never been anything OTHER than "deficient" from the day that Cambridge forced the state to limit it to being two lanes in each direction... it's inadequate in capacity for traffic, and was from the get-go, the day it opened it was deficient, even though it was brand new bridge and structurally sound...

There's "deficient" because something is structurally flawed, "deficient" because the maintenance is creating flaws, and "deficient" because it's in the wrong place, the design has issues for traffic flow and capacity that were INTENTIONAL as with that bridge in Cambridge, etc.

It's possible for something to have structural flaws and be safe--ugly additional supports to prop something up, for example, that take the load off the flawed part, or for there to be design flaws that additional support compensates for (for years, the roof of Kresge Auditorium at MIT was covered with lead, that annually the flowed down load got trimmed off, and perhaps melted, and reapplied to the top of the dome, to compensate for design flaw which generated a crack in the roof, until eventually the building got a new domed roof replacing the flawed design one...)

#97 ::: Claude Muncey ::: (view all by) ::: August 02, 2007, 12:08 PM:

CNN has security camera video of the collapse. It looks like the failure point might be to the right of the picture. I clearly shows distinctly the failure of the center section, then the approach sections.

#98 ::: eric ::: (view all by) ::: August 02, 2007, 12:23 PM:

@97 Argh. That security camera footage doesn't show where it started, only where it didn't. But it clearly explains the part of the bridge that fell onto the railroad tracks.

It looks to me like the side that started it all fell slightly to the side, so I wonder if some of the bracing failed, starting the box of the truss to rack sideways.


#99 ::: michelel ::: (view all by) ::: August 02, 2007, 12:30 PM:

Last night on MSNBC, Olbermann talked to some kind of expert (I didn't note exactly who he was). The guy mentioned that he's in the Northeast, where bridges were recently evaluated and found to be in very poor condition. Olbermann was stunned. I just thought, "Old news." In Massachusetts, anyway, they rechecked all the bridges (as I recall) a few years ago and found a ludicrous number of problems due to lack of maintenance or regular inspection. There hasn't been money ... and there still isn't. The story just got old and forgotten.

I want states to add a huge gas tax for bridge remediation.

But several years ago, on a three-day weekend, a policeman noticed that one of the bridges on the north side of Boston had a large drop at one of the seams. They shut down the bridge, causing backups for tens of miles, I think. A lot of people were cranky that the bridge was shut down as a precaution when officials weren't sure it would fail. I thought it was a pretty smart decision, and right now I'm loving the policeman who reported the condition.

#100 ::: Claude Muncey ::: (view all by) ::: August 02, 2007, 12:33 PM:

Eric, there are eyewitness accounts to the effect that one side failed first, then the rest went with it. (There are others reporting what looked like concrete dust being blown out to the side as the first noises occurred.) I agree, this video does not show the failure itself, but it pretty much identifies were to start looking for evidence of the cause.

#101 ::: elise ::: (view all by) ::: August 02, 2007, 12:55 PM:

Patrick, one of the reasons we call the Cedar Avenue Bridge the 10th Avenue Bridge is because we call the MN-77 Bridge the Cedar Avenue Bridge. Hope that clears the whole thing up.

#102 ::: pat greene ::: (view all by) ::: August 02, 2007, 12:58 PM:

Along with the Cypress structure/I-880 collapse, I still remember the Sunshine Skyway collapse (following a freighter hitting the bridge). It's a little hard to forget, since the state turned long sections of the old bridge into what must be the world's longest fishing piers when they built the new bridge. Every time I visit my mom and go over the new bridge, I look over and see the remains of the old.

#103 ::: elise ::: (view all by) ::: August 02, 2007, 01:00 PM:

OOps. My link-fu is weak, apparently.
It should be http://www.johnweeks.com/bridges/pages/mn03.html
for the MN-77 Bridge link.

Drat it all, it won't let me post the link to the picture. I must be doing something wrong. Text keeps disappearing as I preview it.

Going to go do something constructive now.

#104 ::: CaseyL ::: (view all by) ::: August 02, 2007, 01:03 PM:

If Seattle-Tacoma want to put in a tunnel, there's the experience of The Big Dig to consider...

Oh, yeah. Believe me, the Big Dig gets mentioned quite a bit - in a cautionary, not exemplary, way.

Folks, we've been coasting for 20 years on not maintaining things as they were designed to be maintained. Bridges, airplanes, school buildings, sports stadiums... if there's no money to be made doing it - if, indeed, it's going to *cost* money and cut into the bottom line (or, worse, if it means raising taxes) - then it just ain't gonna get done. And all the structural bills are coming due at once.

#105 ::: John ::: (view all by) ::: August 02, 2007, 01:14 PM:

Jakob #92:

The inspectors looking at bridges often aren't engineers; they are state personnel trained on what to do, what to look for and how to fill out the report. MNDOT may have engineers inspecting their bridges but that would surprise me if they did.

RE: modern structures built to closer tolerances and smaller safety factors due to better design and materials. Wasn't this bridge built, though, back 40 years ago? This structure should have been designed with redundancy all through it.

Looked at the CNN video; it doesn't really tell me anything that could lead to finding out what happened (other than the center span didn't snap in two in the middle and fall). Not seeing the end to the right, which is where the collapse started, means we don't know if it buckled near the pier, slipped off the pier somehow, or what.

#106 ::: Teresa Nielsen Hayden ::: (view all by) ::: August 02, 2007, 01:16 PM:

John (90):

"RE: this bridge collapse. Eyewitnesses said it was groaning and shaking right before it collapsed. To me, that sounds as if it had a failure in some critical member (and in a steel truss bridge, ALL the members are critical) that cascaded into more and more members as they couldn't take the extra stress. I don't think the work on the bridge caused it to collapse, or "heavy traffic". Even cutting a bolt by mistake shouldn't have caused this, given the high factor of safety built into every bridge. No, something gave way that shouldn't, and the rest of the support members couldn't handle that sudden extra loading."
Thank you! There was no way that jackhammer vibrations or bumper-to-bumper traffic could have taken down an otherwise sound bridge. Suggesting that resurfacing operations might have done it was even dumber -- not only was it the wrong magnitude of fault, but the road surface was visibly the only part of the bridge that held together.

My guess when I saw the former bridge was that one section had collapsed and the others followed it down, the same way that one standard coming loose can take down an entire wall-to-wall bracket-and-standard shelf system.

That was interesting, about all the members of a steel truss bridge being critical. They always look so squared-up and sturdy.

#107 ::: JESR ::: (view all by) ::: August 02, 2007, 01:30 PM:

Margaret Organ-Kean @78, believe it or not, the WS-DOT bridge inspection people have no agenda in "making things look worse" since their inspections are primarily internal documents used for setting priorities on maintenence, repair, and replacement. That the politicians and newspapers filter them to the public through their own lack of structural engineering and mathematical skills is where the bunkum comes in.

I sat through twenty years of squabble down here about the 4th Street Bridge over the Deschutes at Budd Inlet; luckily, we were close enough to the epicenter of the Nisqually Quake that it took that bridge out of debatable status without injuring anyone. It was in slightly better shape in the matter of concrete and steel wear than the south entrance to the Viaduct (which is being repaired, now, independent of any other outcome).

#108 ::: Paula Lieberman ::: (view all by) ::: August 02, 2007, 01:31 PM:

Why the Roman Empire is better than Gorge Bush's Amerika:

1. Roman roads, bridges, aquaducts, sewers, and even some buildings are still extant today and many of them in everyday use

#109 ::: Claude Muncey ::: (view all by) ::: August 02, 2007, 01:41 PM:

OK, label this completely premature and underinformed speculation . . .

Looking at the photos and the visual that Patrick referenced, it appears that the video I linked to above is on the western or downtown side of the river, looking across to the eastern side. What we see is the failure appears to occur to the right of the picture, at the western side of the bridge. The bridge snaps off rather cleanly at the eastern support, and you can see the straight edge of that clean break through the dust, until the now unbalanced load from the rest of the eastern approach pulls it over.

Looking at the whole bridge from the north you can see the clean break on the eastern side clearly on the right, the central span looks like it dropped and hit pretty much in one piece, but the western side (to the right on this picture) looks like a mess.

Here is a picture of what looks like that eastern side where that clean break is quite visible -- this matches what is seen in the video.

The western pier shows a very different story. The break appears to be ragged and violent and you can see that the bridge frame has been twisted over flat -- completely off it's support, in fact.

I wonder if when the cause is determined, if it will involve just this area of the bridge.

#110 ::: Claude Muncey ::: (view all by) ::: August 02, 2007, 01:43 PM:

Whoops, one too many if's on that last post.

#111 ::: JESR ::: (view all by) ::: August 02, 2007, 01:50 PM:

John @105, the Bridge Inspectors I know have usually got ASE degrees (paid for by the state and focussed on bridges). Strangely enough, people with ME degrees are not especially eager to take jobs which involve tedious and meticulous work and high levels of physical risk (from being attacked by nesting Perigrine Falcons to being whacked on the bottom of a bridge during an earthquake- there's a BI in a persistant vegetative state from injuries incurred in the Nisqually Quake). They couldn't design a bridge from the ground up, but they are experts at what makes bridges fall down.

But there are a whole lot of damned bridges, they can't be inspected daily, and some things, especially metal fatigue, don't give a lot of warning. And then there's the problem that bridges that were designed 40-60 years ago, using what were then novel materials and techniques, are now at the point where they are showing unexpected problems. The I-90 and Hood Canal floating bridges sunk when a combination of materials degradation and wind load overcame their designed bouyancy, for instance.

Finally, there's the Silver Bridge factor: flawed materials, included in the bridge construction due to incompetence or malice, failing catastrophically on a bright afternoon. It's a lot more common than Galloping Gertie, which was a straight failure of engineering imagination to take the effect of cross winds into account.

#112 ::: John ::: (view all by) ::: August 02, 2007, 01:53 PM:

Teresa,

A truss is a very strong structural design; it can withstand forces a lot greater than any of the individual members could handle because the forces are spread out among all those segments. But, it has to stay intact; if, say, a lower tension member failed, the other members could be overloaded to the point that they'd fail too.

That CNN video is so frustrating. If the start of the collapse had been in the screen, that could provide a clue as to what started the failure. If the deck just suddenly fell in an intact piece, then something caused it to slip off the pier holding it up. If it buckled, then that would be similar to a structural failure in the truss itself. Either way there should be evidence remaining that the investigators will find to determine what happened.

#113 ::: P J Evans ::: (view all by) ::: August 02, 2007, 01:59 PM:

John @ 112

It makes me want to post a simple load diagram somewhere. Maybe several, for the various truss types, with the same overall load. (The best part of statics class, IMHO.)

#114 ::: Suzanne ::: (view all by) ::: August 02, 2007, 02:11 PM:

Scary, scary stuff. I ride (rode) my bike under that bridge almost every day.

The folks pitching in and the emergency responders from HCMC (my employer) and elsewhere were amazingly efficient and brave.

Apparently they've decided it's safe enough to send divers down.

#115 ::: John ::: (view all by) ::: August 02, 2007, 02:22 PM:

P J Evans #113

I know what you mean; trusses are odd creatures and force diagrams often explain better than trying to describe what's happening.

#109: are you sure the bridge started collapsing from the west end? If that's the twisted end, then the center span did not just slip off that pier; it got pulled off and took the western end span with it until everything tore apart. A failure in the main tension members somewhere in that truss might have done that; the deck would buckle and drag the nearest end off the pier.

The eastern end was probably seated on the pier and not strongly attached to the end span; that long center span would need room to expand/contract and tying it on both ends to the outer spans wouldn't be that great an idea, as it would limit the movement. We're not talking a great deal of movement, though, a few inches at most, so there's no chance of it slipping off the bearings it sits on.

#116 ::: Seth Breidbart ::: (view all by) ::: August 02, 2007, 02:53 PM:

Sharon couldn't reach my office phone yesterday (shortly after the collapse), but my cellphone worked.

The fiber optic cable in the bridge might explain why it fell down: was there a backhoe in the vicinity?

#117 ::: fidelio ::: (view all by) ::: August 02, 2007, 03:09 PM:

#111--JESR--thanks for mentioning the Silver Bridge--it had been nagging at the edges of my memory, but I couldn't pull up enough of the details, beyond recalling that there was corrosion of a significant member involved--and that the corrosion didn't show up on regular inspections.

We're currently doing a lot of bridge work in Tennessee, as a result of deferred maintainence and recent reinspections that showed what a lousy idea that had been, but at least we haven't had the additional aggravating factors of harsh winters (with possible corrosion from snow-melting compounds) and seawater.

Since I Am Not An Engineer, I won't claim that wikipedia's piece on trusses is all that and a bag of chips, but it may be a useful starting point for folks who'd like to know more about these usefull critters. If there's a better introduction for the non-engineer, please let us know where to go and look!

#118 ::: Lori Coulson ::: (view all by) ::: August 02, 2007, 03:15 PM:

JESR @111: The Silver Bridge (shudder)

We used to cross that one several times a year on our way from Columbus to Roanoke and back. As a matter of fact, we'd just been over it the weekend before it fell.

I have never been comfortable driving over bridges since...

#119 ::: P J Evans ::: (view all by) ::: August 02, 2007, 03:21 PM:

Here's a page with mouse-over diagrams of some simple trusses. Mousing over the diagrams shows how it deforms under a load, with other stuff, like tension and compression, shown.

#120 ::: Erik Olson ::: (view all by) ::: August 02, 2007, 03:36 PM:

Suggesting that resurfacing operations might have done it was even dumber -- not only was it the wrong magnitude of fault, but the road surface was visibly the only part of the bridge that held together.

If anything, resurfacing might have reduced the load on the bridge -- if enough lanes were closed, there might less less load on the bridge than normal.

#121 ::: Tania ::: (view all by) ::: August 02, 2007, 03:38 PM:

fidelio @ #117: It's not a quick guide like the cool stuff PJ Evans gave us at #119, but I've always enjoyed the books of Henry Petroski. I quit engineering to study remote sensing, so I'm not an engineer, just a an engineering groupie.

To Engineer Is Human would probably be the best place to start, considering the circumstances.

#122 ::: Dan Blum ::: (view all by) ::: August 02, 2007, 03:43 PM:
the good news and the bad news about modern design and engineering, is that with all the high resolution modeling, designers don't do the level of overdesign/overbuilding that enabled e.g. the Empire State Building to be essentially undamaged from being smashed into by an airplane.
Or, for that matter, the level of overdesign that has enabled the Brooklyn Bridge to just remain standing. There were lots of other suspension bridges built around the same time as the Brooklyn Bridge. They all fell down in relatively short order.
#123 ::: OG ::: (view all by) ::: August 02, 2007, 03:44 PM:

If anything, resurfacing might have reduced the load on the bridge -- if enough lanes were closed, there might less less load on the bridge than normal.

WaPo reported this morning that four of the eight lanes were closed due to resurfacing.

No way that bridge was carrying higher-than-normal loads.

#124 ::: P J Evans ::: (view all by) ::: August 02, 2007, 03:45 PM:

Tania, I liked Why Buildings Stand Up (Why Buildings Fall Down should also be good, but I haven't read it.)

#125 ::: fidelio ::: (view all by) ::: August 02, 2007, 03:49 PM:

PJ, Tania, many thanks--I grew up more on less on the campus of an engineering school, and so was infected with the coolness of engineering at an early age, although I have no resemblence to any actual engineer.

#126 ::: John ::: (view all by) ::: August 02, 2007, 03:59 PM:

Bridge engineers take into account all sorts of loads on their structures; the dead load (weight of the structure itself), live load (weight of the vehicles it will carry), wind loads (Tacoma Narrows is in their minds), future resurfacing and/or widening, and even environmental loading (snow/ice).

The largest of all these loads, however, by far, is the dead load. Design for that and everything else is nearly incidental to the sizing of the structure (suspension bridges being a special case). IOW, if all they designed for was the dead load, everything else would not have overstressed the structure, but bridge engineers being what they are, they factor in all those other loads in their equations just to be sure.

I'll be very surprised if anything that the contractor was supposed to be doing contributed in any way to this collapse.

#127 ::: JESR ::: (view all by) ::: August 02, 2007, 04:28 PM:

John, what I have been wondering about is the unfortunate combination of some occult fault in a truss and the live load being unbalanced by the lane closure. I'm a little distrustful of steel truss construction, having seen the result of a high-tension electrical line being broken by a direct lightening strike leading to the twisting collapse of the adjacent steel pylon ( one of the kind I called "dresses" as a child), not to mention the Husky Stadium construction collapse. My impression is that the wrong thing breaking result in massive deviation amplification over the entire structure.

#128 ::: Laurel Krahn ::: (view all by) ::: August 02, 2007, 04:35 PM:

Yes, four of the eight lanes were closed.

Traffic on that bridge usually moves at a rather brisk pace (at least in my experience), but with half the lanes closed, it was bumper to bumper, reportedly traffic was going about 10 miles per hour.

Some people did avoid that bridge because of the construction and fewer lanes, but it was still darn slow.

It is the busiest bridge in MN, a couple years back they said 140,000 vehicles went across it in a single day, that number's gotta be higher now. Except when lanes are closed.

#129 ::: Allen Baum ::: (view all by) ::: August 02, 2007, 04:45 PM:

RE: dead loads & incidental live loads.
A few years back (well, maybe 20?) when the Golden Gate bridge celebrated its 50th anniversary, they closed the bridge for the celebration & let people walk across on the roadbed.

That stopped when the bridge started visibly (very visibly) sagging, because it was completely packed with people -

The pictures of the sagging are a bit scary. People packed together weigh a lot more than vehicles packed together in teh same area. (Assuming they're not all circus clown vehicles, anyway)

#130 ::: Linkmeister ::: (view all by) ::: August 02, 2007, 05:07 PM:

Allen @ #129, Google gives me a local TV video of that Golden Gate Bridge anniversary. It's a special KPIX presentation, and it's ten minutes long.

You're right, it was 20 years ago exactly.

#131 ::: Kathryn from Sunnyvale ::: (view all by) ::: August 02, 2007, 05:50 PM:

Reminded by this event and by JM's essays, I wrote up a post on an important but forgotten (literally) step in emergency phone contacts.
As part of emergency preparation planning:
Memorize a few key phone numbers. Check that your teenager has done so too.

Quoting:
"Too many people rely solely on their cell phone as their phone book, rather than memorizing a few key numbers. This is especially true for teenagers and young adults. If their phone is broken, flooded, lost, stolen or juiceless then they can't call you.

As you put together an "emergency phone check-in spot," take all your potential numbers and run them through What Does My Phone Number Spell? If a number makes an easy to remember word or phrase, then give than number a +3 on "likely to be used."

How do I know this? One art project at Burning Man has been a fake-looking but fully operational phone booth that allows free phone calls to anywhere in the world... As I've hung out by it, a great many people have come up only to say "I'd love to call my sister in Japan / my friend in NYC / my parents in London... but I don't have my cell phone with me, so I don't have any numbers!" I've noticed that the probability of this goes up as their age goes down.

Ask your family and friends in your emergency contact circle which numbers they have memorized, and help them find ones that are easy for this.

#132 ::: Nicole J. LeBoeuf-Little ::: (view all by) ::: August 02, 2007, 06:13 PM:

designers don't do the level of overdesign/overbuilding that enabled e.g. the Empire State Building to be essentially undamaged from being smashed into by an airplane.

[possibly off-topic curiousity]

Is there any truth to the anecdote that a volunteer-built Habitat for Humanity house is sturdier than a professionally contracted construction for that reason? A professional "knows" he only needs two nails at the top of each strut, and he wants to save on nails; the volunteer isn't so sure and isn't conversant with the expense sheet, so he hammers in a few extra.

(I've been on a Habitat site, but most of the hammering tasks I was assigned involved foundation-pouring frames, not the part of the structure meant to last.)

#133 ::: joann ::: (view all by) ::: August 02, 2007, 06:23 PM:

The Austin newspaper site reports that the state of Texas has announced that 4% of the bridges in the state are "structurally deficient". The problem is, they won't say which ones.

#134 ::: John Houghton ::: (view all by) ::: August 02, 2007, 06:40 PM:

Nicole, I expect that if that is true, that the pro knows how to place the minimum number of nails effectively, and that volunteers don't have the knowledge or motor control to do that.

#135 ::: Alan Hamilton ::: (view all by) ::: August 02, 2007, 08:07 PM:

I found this picture troubling. This pier is noticeably leaning. Although it's possible it was moved by the collapse and not the other way around, it seems to me that the connections to the bridge would break before enough force was applied to move it this much.

#136 ::: JESR ::: (view all by) ::: August 02, 2007, 08:20 PM:

Allan Hamilton, you know, in the catalogue of persistantly destructive natural forces, plain old flowing water is hard to beat for efficiency over time..

Which is the disturbing thought your disturbing picture immediatly brought to mind.

#137 ::: MikeB ::: (view all by) ::: August 02, 2007, 08:36 PM:

PJ at #124 op cit,

I recommend Structures: Or Why Things Don't Fall Down. The author was a British materials scientist with a marvelously dry sense of humor.

It's on my short list of the Best Introductory Science Books Ever (along with The Language Instinct, The Blind Watchmaker, and the not-to-be-underestimated Molecular Biology Made Simple and Fun.)

#138 ::: eric ::: (view all by) ::: August 02, 2007, 11:52 PM:

Alan @135 -- I think that's the (east) side that's in the security camera view, and it's clearly the secondary side from that footage. The pier that's at the center of it all appears to be back on dry land in this graphic.

And slightly off topic, the I90 bridge sinking was a combination of construction and weather. They were installing watertight doors in the cells, and sawing concrete to do so. There were also some access holes in the side of the bridge that weren't well covered. The contractor drained cut water from the concrete sawing into some of the cells, lowering the freeboard of the bridge. So, long weekend, big storm, bridge riding lower than usual, and none of the watertight doors were actually closed.

So, the net result was calling out a fleet of tugboats to temporarily provide anchorage for the other I90 bridge that had it's anchor cables cut by the sinking one.

That's why I'm not going to rule out the construction. It's always possible that something stupid happened. A damaged brace, a blocked expansion joint, something.

The other thing that struck me about this is that the secondary failures would have been a lot different in an earthquake zone. The bridges were pulled off their small thermal expansion bearings, and just fell. In zone 3 & 4 (west coast), those are all tied together so they can't just fall off.

#139 ::: JESR ::: (view all by) ::: August 03, 2007, 12:24 AM:

eric, I forgot about the construction factor with the Mercer Island Bridge; construction was not part of the cause of the Hood Canal bridge sinking, though. Of course, the biggest problem there was wind load, although faulty concrete composition was also implicated.

(Bridge freak, as you may have guessed- also, Dad built forms for the original Galloping Gertie, and one of my cousins built forms for the third Tacoma Narrows bridge).

#140 ::: Claude Muncey ::: (view all by) ::: August 03, 2007, 12:52 AM:

First, a correction. In my post @ 109 I said:

Looking at the whole bridge from the north you can see the clean break on the eastern side clearly on the right, the central span looks like it dropped and hit pretty much in one piece, but the western side (to the right on this picture) looks like a mess.
The picture I linked to was from the north, but I was thinking of the excellent graphic that Patrick linked to, which is looking from the south. The sides of the river that I cited, east and west, were correct, but the references to the picture, left or right, from the north were backward. My error.

John @ 115 -- I am not a engineer, nor do I play one in video games. However, if you watch the video and compare it to pictures certain things seem apparent:

  • The end of the center span that broke off cleanly, leaving the tilted up section shown in many pictures (including the one you cited, Alan @ 135) and can be seen in the longer shots as being on the eastern side of the Mississippi.
  • This means that the video security camera was on the western bank, just to the north of the bridge, below the level of the bridge deck, looking east. The eastern side of the center section is in the picture, but the western side is off the right side of the video frame.
  • Survivor reports (which are incomplete) seem (at this very early point) to indicate that the failure happened in two stages: at first there was a loud grinding noise accompanied by one side of the bridge, at least at one point, tilting or dropping down on one side. Then the entire central section went into what several people called "free fall".
  • When you watch the video, the first part that you see dropping is at the far right edge of the screen, toward the western bank. Only after it has dropped some feet does the bridge appear to fracture or drop on the eastern side. On the video you can see the clean edge of the eastern approach for a second, before it fails, pulled back to the east by the weight of the approach. While there looks like some displacement of the pier itself, the truss elements that would have rested on it appear to be largely intact, and the proper elements remain close to the pier as well.
  • I don't think we can read the story on the western side yet -- I certainly can't. But it is true that this is the side where the roadway is pitched to one side, as some of the survivors described. And there is a lot of twisting on this side.
  • The center section dropped so neatly that there are cars sitting on it as if they had just driven out onto it.
To my untutored eye this all seems to point to some kind of failure somewhere on the western side, perhaps just to the east of the western pier. But I could be completely wrong as well -- we may not have any better idea for weeks, with so much of the bridge underwater.
#141 ::: Rob Rusick ::: (view all by) ::: August 03, 2007, 04:28 AM:

Would it be plausible to design a system for bridges which would monitor stress and/or alignment, and flash some lights or sound a siren if elements were getting badly out of tolerance? At least a red light stopping further traffic from going out onto the bridge.

Or is a typical bridge collapse like an avalanche? Things are stable, until suddenly they're not.

#142 ::: Greg London ::: (view all by) ::: August 03, 2007, 08:57 AM:

Fix it or look at it some more? this article says the state chose to look at it some more.

After a study raised concern about cracks, the state was given two alternatives: Add steel plates to reinforce critical parts or conduct a thorough inspection of certain areas to see if there were additional cracks. They chose the inspection route, beginning that examination in May.

It also mentions a four fout crack that had been fixed with bolted steel plates.

#143 ::: Greg London ::: (view all by) ::: August 03, 2007, 08:58 AM:

that's "four foot crack."

#144 ::: jmmcdermott ::: (view all by) ::: August 03, 2007, 09:33 AM:

a total aside, but strangely interesting in the distant sort of way that people who are far removed tragedy have of looking in...

one of the survivors was quoted in my newspaper saying "It was like a movie."

when, actually, the movie is the simulation and this horrible tragedy is the real.

that is all.

may all of your friends and family be safe!

#145 ::: Dave Bell ::: (view all by) ::: August 03, 2007, 09:37 AM:

One of the things happening to the big suspension bridges in the UK is that suspension cables are corroding. The Forth Road Bridge has lost somewhere between 8% and 10% of the initial cable strength, and a second bridge has been built across the Severn,

The following is a part of a piece on the Forth Estuary Transport Authority site.

“Cable corrosion is not unique to the Forth Road Bridge. Our sister bridge at the Severn recently identified even more advanced corrosion and have already introduced traffic restrictions. Several USA bridges are also experiencing similar problems, including the Ben Franklin in Philadelphia and the Bronx-Whitestone in New York. In Sweden the Hoga-Kusten, only opened in 1997, is also affected. Others, such as the Humber and the Golden Gate, have not yet inspected their cables."

Have materials changed since 1937? I recall hearing a lot about the developments in bridge deck design, to get around the wind problems that affected the Tacoma Narrows bridge, which allowed a lighter deck structure and so a potentially longer span.

Maybe it's something as simple as the thickness of the individual cable strands.

But it would be foolish to assume that the Golden Gate is OK.

(And does anyone call the boss of FETA the big cheese?)


#146 ::: Greg Morrow ::: (view all by) ::: August 03, 2007, 01:24 PM:

If you're like me, you wondered how bridges got rated on what criteria: The FHWA's Bridge Rating System, under which the I-35 bridge in Minneapolis was apparently rated "Poor". (cite for rating.)

Personally, I would have lumped poor, serious, critical, imminent failure, and failure into a catchall category labeled something like "OMG fix right now", but then I don't have to answer to a budget committee.

Today's Thing I Did Not Know: spall. It is not surprising that we'd have a word to describe a particular category of failure evidence.

#147 ::: Josh Jasper ::: (view all by) ::: August 03, 2007, 04:03 PM:

Gothamist has the rundown on NY's bridge rating situation

As many people wonder about the state of the bridges in the New York City region, in the wake of I-35 collapsing in Minneapolis, the city's Department of Transportation is trying to reassure residents that our bridges are safe. Though many bridges meet the definition of "deficient" - 19% of bridges are in "fair" or "poor" condition, 15% meet the federal definition of "structurally deficient" - a DOT first deputy commissioner Lori Ardito says, "In New York, we do not have any bridges that are structurally deficient."

Ardito explained the Brooklyn Bridge's poor rating, "There's only components of the bridge that are in poor condition. They're actually the ramps leading to the bridge, not the span of the bridge. If the bridge was deemed unsafe, we would have to close it." The components of the Brooklyn Bridge in poor condition include "rusting steel joints...deteriorating brick and mortar on its ramps...roadway deck on the Manhattan and Brooklyn approaches."

Seeing as it's in such bad shape, we've decided to have a sale. Any interested bridge buyers can contact me with paypal info.

#148 ::: Kathryn Cramer ::: (view all by) ::: August 03, 2007, 07:08 PM:

In response to the Minneapolis bridge collapse, Stephen Wolfram has written a short essay on how we could learn to build better briidges: http://blog.wolfram.com/2007/08/the_space_of_all_possible_bridge.html

#149 ::: Linkmeister ::: (view all by) ::: August 03, 2007, 07:29 PM:

Josh @ #147, Listen, if you get disappointed buyers, I've got some wonderful swampland in Florida, so send 'em my way. Guaranteed to be drained by the Army Corps of Engineers within the next millenium; get in on the ground floor!

#150 ::: Linkmeister ::: (view all by) ::: August 03, 2007, 08:31 PM:

Since I gratuitously slurred Fresno above, I thought it only fair to post a picture of something I saw there a long time back.

#151 ::: Linkmeister ::: (view all by) ::: August 03, 2007, 09:09 PM:

Rats, posted that in the wrong thread. Sorry.

#152 ::: JESR ::: (view all by) ::: August 03, 2007, 09:42 PM:

The Post-Intelligencer has an assemblage of articles about the plethora of disturbing bridges on the front page today. The Alaska Way Viaduct (US 99) has ratings over its length which vary from 31.5 down to 9 on the same scale which gave the 35W bridge a 53. Pictures and explanations at Answer.com.

There's a picture of the 520 floating bridge at the top of the article here which gives an idea of one of the reasons there's a lot of discussion involved in replacing it.

#153 ::: P J Evans ::: (view all by) ::: August 03, 2007, 11:14 PM:

Linkmeister @ 151

Well, get enough of them on a bridge, and you could get interesting results. For the bridge; I don't think the elephants would be enjoying it.

The photo of the center section in the river with the cars still sitting on it is - amazing.

#154 ::: Brooks Moses ::: (view all by) ::: August 04, 2007, 12:34 AM:

Kathryn @ 148: Interesting. But, unfortunately, pretty much what I was expecting from Wolfram; it's a nice theoretical exercise, perhaps, but entirely unrelated to any of the real-world problems that cause bridges to fail.

(Also, and here I know I'm giving in to biased nitpicking, at least half of his "potential new bridge structures" at the bottom of that post have elements that can't do anything, which means that he's pretty much starting out with the wrong computational space to optimize over. Which, combined with a lack of even mentioning that there's some effort required in finding the right space, sort of gives a ... half-baked impression to the whole thing.)

#155 ::: Stephanie Zvan ::: (view all by) ::: August 04, 2007, 12:47 AM:

One thing to note in your emergency contact planning: make sure whomever you're calling to check in has at least one non-cordless phone on their end. Power was out in my part of south Minneapolis during the event (unrelated reasons--started half an hour before and lasted half an hour after). Since the cordless phones don't have batteries in their base stations, they weren't ringing. Only the standard phones, which draw their power from the phone line, were ringing.

Not that I was anywhere near them, since I didn't know anything was happening until the power came back on and I was reconnected to the world. Still, the principle is sound. Major disruptive events are not unlikely to be accompanied by power outages.

#156 ::: elise ::: (view all by) ::: August 04, 2007, 02:32 AM:

P J Evans - One reason why some of those cars were still sitting on the center section is that traffic was so slow. It's a lucky thing, too; if cars had been zipping over the bridge at normal speed, nobody would have ridden the concrete down to the river or the riverbanks, and we would have had many more deaths.

Traffic at 10 mph or less, half the lanes closed, particular ways that the bridge went down, the fact that the train the bridge fell on wasn't carrying anything flammable or explosive, and that the Mississippi Queen was still in the lock instead of under the bridge as it would have been a few minutes later: all these things probably made it a lot better than it could have been.

That said, there's a lot of sadness on my street today, because one of the people who was killed is from a couple of blocks down. I'm sure there's a fund going for his wife and baby; I'll find out tomorrow, I hope.

#157 ::: Bruce Cohen (SpeakerToManagers) ::: (view all by) ::: August 04, 2007, 03:19 AM:

P J Evans @ 95

I think the contractor responsible for that inside out vapor barrier ended up doing construction in Portland. The house we had previous to the current one had a crawlspace underneath, and there was a vapor barrier between the insulation and the subfloor. Come the rains of November our first year there and the insulation turned to a sodden mass. [sarcasm[ The subfloor stayed dry, though. [/sarcasm] It's dumb things like this that make me think that we can't completely rule out the construction on the 35W bridge as contributory to the collapse. Though it seems awfully unlikely have been a primary cause; the forces involved are just too small compared to the normal loads the bridge would have to withstand.


CaseyL # 104

And all the structural bills are coming due at once.

Nope, not even close. There are over 70,000 bridges in the US listed as in need of repair. They'll be failing, probably at a fairly high rate, for decades to come.

#158 ::: Edward Oleander ::: (view all by) ::: August 04, 2007, 04:03 AM:

I have just returned from the bridge. The south end is only 100 yards from our local Red Cross chapter. At 3am I was amazed to find that the police officer controlling the nearest checkpoint on the road beneath the south end was, in fact, my next door neighbor. I was able to get much closer than any but an official few. I stood within 50ft of the famous school bus.

The immensity of the collapse just cannot be conveyed by the pictures on TV or on-line. Even from 600 ft away, the remains of the north pylon and span rear up as though within reach. The remains of cars unseen from the overhead shots peek out from under thousands of tons of slowly-settling death. In the relative quiet of night, the sounds of a deflating steel spiderweb could be heard over the diesel generators. We didn't need to be told where the line of "too close" was...

I couldn't help wondering if any the dozen or so of my street patients who live in the scrub along the riverbank were "home" when their "roof" caved in. Probably not at that time on a hot day, or at least I hope so...

The immensity of the response is perhaps the only thing larger than the immensity of the collapse. Blood banks that won't be accept new donors for two weeks because of the backlog of appointments. Would-be volunteers from Montana to Alabama to Maine ready and willing to fly out at their own expense just to hand out coffee and sandwiches to tired rescue workers. Fifty clergy from 200 miles around answering a call from the Minneapolis Police Chaplains to provide pastoral care to the families of missing people waiting at a local hotel command post for word on their loved ones. A nun of nearly 90 who carried in her massage chair to offer hugs and neck rubs to all would hold still long enough for either. Outback Steakhouse and the 24/7 supply of hot food to hundreds of police and rescue workers. Famous Dave's and the 500 rib dinners... so far.

And the topper... My 4am request to McDonalds for 200 cheeseburgers, which was answered with ... and I shit you not... "You want fries with that?" as well as a refusal to take our money....

A few of the calls I took myself on Friday: A jet & water ski demo group willing to underwrite a demonstration to benefit the Red Cross. Toshiba asking to completely fund a blood drive... Build-A-Bear willing to fully fund regular people making Teddy Bears the mail here for giving to kids...

Later today... the human cost... gotta go sleep now... been over 44 hours since I got any...

#159 ::: Valuethinker ::: (view all by) ::: August 04, 2007, 09:37 AM:

156

(I should preface that my only contact with the Life Insurance industry, other than as a customer, was 2 years in the 1980s fixing COBOL programmes).

What you allude to brings me to a relevant point (if potentially one that could be seen as heartless):

- term life assurance is available to most folks, very cheaply. A 20 year policy can carry your family until your children are grown up.

Don't get distracted by insurance salesmen trying to sell you variable or universal life products. The commissions mean they aren't worth the tax advantages, for most people. Life insurance is for insurance, not savings (which should be done through IRAs, 401ks etc.).

But a rule of thumb of total life insurance (including free life insurance from work, professional associations etc.) of up to 10 times your income is not unreasonable.

(certainly 6-8 times is prudent).

Straight term life is a highly competitive area between insurance companies, and it's fairly easy to compare policy terms. Choose insurers with high credit ratings (AM Best rates insurers for financial strength).

After 9-11 I went and doubled my coverage. Cost me the equivalent of about USD60/month. I realised how much my family would actually need, if I wasn't around to provide it-- yes my partner can work, but there is childcare etc.

#160 ::: Lila ::: (view all by) ::: August 04, 2007, 10:05 AM:

Josh @ #147: "If the bridge was deemed unsafe, we would have to close it."

Therefore, a la the mayor in "Jaws", whatever happens we can't deem a bridge unsafe? (cf. the air traffic controllers and their little CO problem .

Edward @ #158, I don't say this very often, but GO MCDONALD'S! And Target, and Outback, and all the rest.

#161 ::: John ::: (view all by) ::: August 04, 2007, 11:13 AM:

Ok, the media is having a field day with the Sufficiency Rating (SR) of this bridge, and the category it was in of "structurally deficient" that resulted in it having a SROk, the media is having a field day with the Sufficiency Rating (SR) of this bridge, and the category it was in of "structurally deficient" that resulted in it having a SR

The SR system is a Federal rating system for bridges to help states rate a structure and determine when they should start considering them for replacement. Federal 80% bridge replacement funding is available for any structure with a SR

However, just because a bridge has a SR

"Structurally deficient" as the SR rating uses that phrase, means the bridge has deterioration structurally that can be remedied with proper maintenance. A maintained structure can still have a low SR, but the older the bridge the more expensive (and extensive) the maintenance becomes.

I'm currently replacing one with a SR of 3, in fact; it has a weight limit of 2 tons and sways noticeably when driven across if you're standing on it (I've done this). It's a truss bridge built in the 1890's, dismantled and reassembled in its current spot in 1921. It has not fallen down yet thanks to constant maintenance efforts.

The other category is "functionally obsolete"; this covers a bridge that does not meet current bridge design standards for such things as lane/shoulder widths, vertical clearances, rail design, superelevation, and even the pavement condition on the bridge itself. A structurally sound bridge can still have a low-ish SR if it does not meet current bridge standards, but that doesn't mean it is unsafe.

The I-35W bridge was apparently inspected on a biannual schedule, and some serious cracking was found the last time, but it wasn't considered serious enough for immediate remedial action. I have not read anything that tells me they have used any inspection method other than Mk I eyeballs; at the least once those cracks were found they should have started X-ray and stress testing on the most critical tension bearing members at minimum. They did know it was a "fragile" system (i.e. no redundant safety built in, if a truss member breaks the whole thing falls down) but nothing was done to shore up the suspect areas.

This is just my partially-informed opinion from 2000 miles away, but ISTM that bureaucracy has reared its ugly head in this one particular case. The inspectors found some serious defects that should have been addressed, but someone decided to just keep watching it instead of applying some remedial corrective applications. That someone is going to have to answer for that.

#162 ::: John Houghton ::: (view all by) ::: August 04, 2007, 12:12 PM:

158 Edward Oleander (158):
The easy part of doing Mass Care for a front page disaster is getting free food. The hard part, in my experience, is not getting too much food dropped at your door at one time. There seems to be a magic tipping point for a disaster when resources just start appearing at your door and needs to be managed. The trick for the In-Kind Donations people is to manage the relationship so you aren't throwing stuff away, and so you build a useful relationship that you can exploit in the future. "Thanks so much for the offer, but we're overwhelmed with food right now -- but we'll still be needing help on Tuesday, can we count on you then?" And building a relationship with a contact at the company that you can exploit later.
Lila, "Go McDonalds" indeed - while I'm not fond of drive-through-burgers in general, McDonalds and the like come through with large quantities of food on short notice, and frequently gratis, for even the smaller disasters that don't get big, instantaneous public notice (house fires with 20 firefighters on the scene, forex).

#163 ::: Bruce Cohen (SpeakerToManagers) ::: (view all by) ::: August 04, 2007, 12:29 PM:

Brooks Moses @ 154

Typical of Wolfram not to mention that there's a lot of prior art in engineering mechanical components using evolutionary techniques.* In fact, he may not even know about it, as he seems to be one of those brilliant theoreticians who doesn't care much about other people's applications.

Interestingly, evolving designs, especially under varying conditions, results in some useful shapes that a classically-trained 19th or 20th century engineer would sneer at; they're not aesthetically pleasing in symmetry and often not even very regular in shape at all.

I'd be very curious to see the result of someone taking a standard bridge design and evolving it under stresses known to cause failure over time.


* Google gave me just under a million hits** for "mechanical design with evolutionary algorithms" and a random scan of the first few pages showed that most of the high relevance hits were references to unique papers or conference notices.

** I used the same search string on Amazon and got 10 hits, 2 of which were on embedded computing design. But I got a bad case of sticker shock: those two were the only books priced below $100***

*** $ 99.95 is not below $100. I use interval arithmetic when comparing prices.

#164 ::: JESR ::: (view all by) ::: August 04, 2007, 12:55 PM:

Bruce Cohen @163: when it comes to bridge components, the evolutionary jump seems to be in the size and weight of components which can be fabricated as a single piece and transported overland as opposed to being welded/rivited onsite; the completion of the new Tacoma Narrows Bridge (the one that opened last month) was delayed because an expansion joint was too large to be transported over I-90 on its first trailer (too great per-axle load). Fewer on-site connections, fewer possible failure points.

#165 ::: CHip ::: (view all by) ::: August 04, 2007, 05:24 PM:

Wolfram's article (and followups) connects to a subthread started by Paula. How much more likely are mistakes when the structure has some complex "evolutionary" design rather than the relatively simple repetition of the arch or truss? The Big Dig examples that Paula cites were all relatively low-level screwups, but I'm not convinced supervisors are more careful than line workers, e.g.
- Why weren't those epoxied bolts slanted to distribute the load, instead of being drilled straight in? (My first reaction; I suppose it would have been too hard to do, but the fact that Plan A is too hard to do right should suggest to someone that it's time for Plan B.)
- Petroski's description of the KC Hyatt collapse notes that plans (not just execution) were changed in a way that doubled the load on some structural members. \Some/ change was necessary -- the original design required threading several rods for ~35' -- but this change should have been identified as dangerous.

#166 ::: Edward Oleander ::: (view all by) ::: August 04, 2007, 06:12 PM:

I have just returned from the bridge. The south end is only 100 yards from our local Red Cross chapter. At 3am I was amazed to find that the police officer controlling the nearest checkpoint on the road beneath the south end was, in fact, my next door neighbor. I was able to get much closer than any but an official few. I stood within 50ft of the famous school bus.

The immensity of the collapse just cannot be conveyed by the pictures on TV or on-line. Even from 600 ft away, the remains of the north pylon and span rear up as though within reach. The remains of cars unseen from the overhead shots peek out from under thousands of tons of slowly-settling death. In the relative quiet of night, the sounds of a deflating steel spiderweb could be heard over the diesel generators. We didn't need to be told where the line of "too close" was...

I couldn't help wondering if any the dozen or so of my street patients who live in the scrub along the riverbank were "home" when their "roof" caved in. Probably not at that time on a hot day, or at least I hope so...

The immensity of the response is perhaps the only thing larger than the immensity of the collapse. Blood banks that won't be accept new donors for two weeks because of the backlog of appointments. Would-be volunteers from Montana to Alabama to Maine ready and willing to fly out at their own expense just to hand out coffee and sandwiches to tired rescue workers. Fifty clergy from 200 miles around answering a call from the Minneapolis Police Chaplains to provide pastoral care to the families of missing people waiting at a local hotel command post for word on their loved ones. A nun of nearly 90 who carried in her massage chair to offer hugs and neck rubs to all would hold still long enough for either. Outback Steakhouse and the 24/7 supply of hot food to hundreds of police and rescue workers. Famous Dave's and the 500 rib dinners... so far.

And the topper... My 4am request to McDonalds for 200 cheeseburgers, which was answered with ... and I shit you not... "You want fries with that?" as well as a refusal to take our money....

A few of the calls I took myself on Friday: A jet & water ski demo group willing to underwrite a demonstration to benefit the Red Cross. Toshiba asking to completely fund a blood drive... Build-A-Bear willing to fully fund regular people making Teddy Bears the mail here for giving to kids...

Later today... the human cost... gotta go sleep now... been over 44 hours since I got any...

#167 ::: Edward Oleander ::: (view all by) ::: August 04, 2007, 06:14 PM:

ooops...

#168 ::: John ::: (view all by) ::: August 04, 2007, 07:29 PM:

Drilling bolts into the supporting material at an angle means the bolts have to be longer, because instead of one force on them (pulling down), you've got three; a bending moment and a vertical and horizontal pulling force. Plus, the material nearest the outer end is likely to spall or break under the forces, so you risk compromising the material (even if it is in solid rock).

Drilling (or using epoxy) in a vertical hole only requires countering the pulling force, which is a lot easier to accomplish.

#169 ::: Bruce Cohen (SpeakerToManagers) ::: (view all by) ::: August 04, 2007, 08:16 PM:

CHip, JESR

I'm not sure we're using the word "evolution" in the same way. I'm talking about a technique used to automatically generate designs on a computer using some form of evolutionary algorithm.* The ides is to simulate different designs, picking the ones that perform best according to some set of metrics, then generate variants of those and test them in turn. The results are, of course, only as good as your tests, but human design has the same problem.

This isn't just theory, by the way. If you've ridden on an airliner you may have trusted your life to evolutionary design. Turbo-jet engines have been designed using this technique.

* It's confusing to talk about this because there are several competing techniques with similar names: evolutionary algorthms, genetic computing

#170 ::: Vicki ::: (view all by) ::: August 04, 2007, 08:30 PM:

The other thing "functionally obsolete" means, if I read the explanation correctly, is "this is a perfectly good bridge or tunnel, but we're trying to run more traffic over it than it was built for." This suggests that "functionally obsolete" bridges wouldn't be so if more people carpooled, or traveled at off hours.

Given the extent to which road-building creates traffic (if you build it, they will drive), and given population growth, almost any bridge or road that was worth building at all is likely to be labeled "functionally obsolete" after a while.

#173 ::: "Charles Dodgson" ::: (view all by) ::: August 05, 2007, 01:30 PM:

To answer CHip's question at 165 more directly, properties of "evolutionary" designs depend an awful lot on both the constraints on the evolutionary process (e.g., steel structures with only standard types of welds and connectors), and on the fitness function.

As to fitness: if you give preference to designs that are more resistant to, say, wind shear, or multiple structural failures, then you'll probably get something out that resists those fairly well. If not, though, you probably won't, and these things are pretty good at finding loopholes in the fitness function. My favorite example is an attempt to evolve a design for an analog oscillator; what the experimenters actually got was circuits that functioned as tuned radio receivers, picking up EM oscillation in the environment. (Brief popular writeup here; full paper here, though as usual for happy lab accidents, it's formally written up as though they were trying to evolve radios to begin with --- you have to look at the fitness function to see what they were actually trying to do). This is what they got for building and testing actual circuits, which would be a somewhat more expensive proposition with actual bridges. The flip side, though, is that if you evolve in simulation, you're at the mercy of any physical stress or effect you forgot to simulate.

I don't mean to imply that evolutionary methods are too flaky to use at all; as others have pointed out, they've already been used in some pretty demanding applications. But I expect that the designs you get still need to be validated by conventional means.

#174 ::: Bruce Cohen (SpeakerToManagers) ::: (view all by) ::: August 05, 2007, 01:54 PM:

"Charles Dodgson" @ 174

But I expect that the designs you get still need to be validated by conventional means.

Absolutely. What bothers me is that there are people in the civil engineering field who seem to believe that you don't have to validate sims that were created by humans rather than evolutionary programs. Assumptions in testing and verification affect the quality of the result no matter where the design comes from.

The advantage of evolutionary design is that if the assumptions about the operating regime of the end product are correct, you are likely to get a design that's at least as close to optimal as a human designer would, and possibly better, because you'll have examined more alternatives.

#175 ::: David Sucher ::: (view all by) ::: August 05, 2007, 05:04 PM:

As to statements about the Alaska Way Viaduct (AWV) in Seattle such as "...It's a vital part of the transportation system, and was badly cracked in the February 2001 earthquake. It's been repaired and retrofitted, but the feeling is that it needs to be replaced."

In fact it has NOT yet been repaired or retrofitted because the damage has been a useful stalking horse for grander plans.

People use events to further theii own agendas. The damage to the AWV has been used as an excuse by people who want to tear down the AWV in order to build a tunnel or simply to tear it down because they prefer what's called the 'surface/transit' option.

Simply repairing the AWV was never seriously considered because the damage to the structure offered politicians and certain activists plausible reasons to simply tear it down.

Luckily, now fully six years later, the authorities were unable to come up with the money, the political will or the practical scenario to do anything dramatic so we are on our way to simply repairing it. Thank goodness.

Btw, the statement above that "...the feeling is that it needs to be replaced" is a statement which must be challened repeatedly. On its own terms it relies only on subjective "feeling" and such emotional response was been pushed by people who wanted to replace the AWV, not as a result of any sort of fair-handed analysis.

There is an awful lot more to this story. One of the themes with the AWV is how politicians, along with a complacent media, can use what is admittedly a real but handleable problem and transform the agenda into something far more enormous. In Seattle the issue was a viaduct which was damaged. The political solution? Transform the whole downtown. Sound vaguely like Iraq? The old bait-and-switch? Yes. The parallels are striking except that here in Seattle the voters were asked to make an open-ended financial commitment (to a tunnel) and had sense enough to say no. Sometimes the power of the purse is real handy.

#176 ::: glinda ::: (view all by) ::: August 05, 2007, 05:44 PM:

David Sucher@175: I still can't believe that people want to put in a tunnel. Below sea level, at the waterfront, in soil that's subject to liquefaction. I'm not an expert on engineering, but it just seems like a really, really stupid idea - if a major earthquake could damage bridges or the viaduct, couldn't it collapse the tunnel?!

#177 ::: John ::: (view all by) ::: August 05, 2007, 05:49 PM:

Appreciate the graphic animation of how a truss structure could fail. It describes what I've been saying; a truss is a very strong system, but it's only as strong as its weakest member.

If the whole system is degraded due to age, fatigue, inadequate maintenance, and then you have a member fail, the whole system starts a cascading progression of failure as each member in turn is subjected to more loading it can handle until the whole structure collapses.

I doubt the I-35W structure failed exactly as the animation shows, but it is illustrative of how such a failure could occur.

#178 ::: David Sucher ::: (view all by) ::: August 05, 2007, 07:58 PM:

Glinda @ 176.
I misspoke if I gave the impression that the tunnel was still very much alive today. But as of six months ago our Mayor and many others were arguing for it strenuously; the public vote killed it -- and it was a "beauty contest" vote without even any specif financial authorization attached.
But I am sure that there are diehards who wish to see the idea revived.

The current idea of the day is to simply tear down the viaduct and substitute some sort of enhanced combo of bus/rail/surface street for the grade-separated viaduct.

Yes, I know to out-of-towners it may sound obvious and fetching: tear down the viaduct and "connect the city to its waterfront." But it's a bit more complex than that and I believe it fairly certain -- and I think it's being born out by the actions of our Governor -- that we will simply fix it.

The lesson from the Viaduct? For me it is that sometimes a nice idea may be simply that: a nice idea which is too expensive, complex and risky to actually be able to succeed.

•••

Btw, maybe "bait-and-switch" is not the best characterization for the Iraq War, I see. The basic idea is that a politician takes a serious but containable problem with a variety of answers and focuses on only one grand solution and doesn't even let any of the other solutions be discussed but diminishes them as "impractical" and "not serious." Maybe it's more of a Trojan Horse situation. though that's not right either. Anyway, that was the situation in Seattle around the Viaduct: you have a leaky roof so you use that problem as an excuse to build a brand new house 5 times as large as you have right now.

#179 ::: P J Evans ::: (view all by) ::: August 05, 2007, 08:31 PM:

glinda @ 176

Well, it could be done the way that BART did their transbay tube - as I recall, they dug a trench and lowered prefab concrete sections into it, then connected them. It was described as being like two parallel strands of spaghetti, anchored only at the ends of the strands. Probably be easier to build on land, since they wouldn't be working under water.

#180 ::: CHip ::: (view all by) ::: August 05, 2007, 09:35 PM:

Bruce, Charles: I was addressing not the design (which I'm nowhere near competent to judge) but the difficulty of executing a more complex design; e.g., the sketches in the Wolfram article showed braces at what look like random locations -- although I assume they're actually key where they are and couldn't be moved around.

John: would a longer bolt not do even more to distribute the load, which was the point of toenailing? And how much difference would spalling make when the load is thus spread? (Would the spalling lead to a general breakdown? And even if so, is there no advantage to having the failure on the surface where it can be seen, instead of down a hole?) My point was that relying solely on the adhesive properties of the epoxy, instead of the mechanical support that comes from putting adjacent bolts at opposed angles, made the system insufficiently redundant.

#181 ::: David Sucher ::: (view all by) ::: August 05, 2007, 10:38 PM:

Glinda.
There may or may not be technical issues with a tunnel in terms of safety.
My objection to it is largely that there are better ways to spend a discretionary $2-3 billion.

#182 ::: JESR ::: (view all by) ::: August 05, 2007, 11:22 PM:

David Sucher,

What's being "fixed" is the parts of the Viaduct which have the lowest safety ratings, especially the south approach where the earthquake damage was the most severe.

What's not being fixed is the widespread misapprehension that the thing can be repaired sufficient to survive a quake on the Seattle Fault, or that it can be rebuilt on its current footprint without blocking the views which feed the economy of businesses west of first (say, the Athenian and Lowe's cafe at the Market) not to mention the ability of people in passenger vehicles to see off the bridge deck, due to the requirement to use solid concrete safety barriers.

Not that it matters: the first excavation for new construction near the waterfront is going to open the state and the city to demands for archaeological mitigation which will eat the transportation budget for a decade. Since the sea wall has to be replaced, the viaduct is going to go begging until it falls down or is torn down and replaced by surface streets.

#183 ::: David Sucher ::: (view all by) ::: August 06, 2007, 12:31 AM:

JESR @182 wrote that "Since the sea wall has to be replaced..."

I have heard that claim repeated many many times and whenever I ask for the source of the information -- something more than "the Government says..." -- I get a blank stare or a sneer of derision as in "Everyone knows..." (Like everyone knew that Iraq had WMDs?)

Well everyone does not know. While I agree with a bit of what you say above, I would like to gently challenge you to offer the source of information which allows you to say with such absolute clear certainty that "...the sea wall has to be replaced."

(Btw, I blogged on this very point several years ago and as of 2003 the facts did NOT show that the seawall had to be replaced in its entirety or even for the most part. Google my blog for seawall.)

#184 ::: JESR ::: (view all by) ::: August 06, 2007, 01:47 AM:

David Sucher, I admire your optimism, but since the people I've talked to, in government and out, tend to think the published reports about the seawall are probably somewhat soft-pedaled, excluding, for instance, the likely effect of a 6" rise in sea level (the low end of the global warming impact) and minimizing the remote sensing data in preference for the slightly more optimistic visual survey data.

#185 ::: John ::: (view all by) ::: August 06, 2007, 05:25 AM:

Chip @ 180:

Certainly a long enough bolt can be used to overcome the various forces on an angled drill hole, but why make it more complicated? The bolt has to be larger to resist the bending moment, the hole has to be longer to compensate for the added horizontal component to the forces, and then you've got to strengthen the outer surface of the concrete to avoid the spalling the moment and vertical forces are going to put on the bolt.

Believe me, it is a lot easier to design for only a vertical pulling component on a connection holding something in place; toenails, whether they are bolts or nails, are never a first choice when connecting two things together. Most bolts in concrete/rock I'm aware of required a 'pull test' to verify that they will stay in place after they were installed; the problem with the Big Dig bolts was that there was no factor of safety. Four small bolts held up multiton slabs of concrete, and the design required all four at full strength to hold them safely.

Apparently a "pull test" was not required on --all-- the bolts or they would have found the weak ones; it was probably done on a 'representative sample' if at all. Modern epoxies I know of that are used to anchor bolts in place are often stronger than the rock/concrete around them; when they have to be removed for some reason I've seen the rock break before the epoxy does.

#186 ::: Kevin Reid ::: (view all by) ::: August 06, 2007, 08:54 AM:

"Charles Dodgson" #173: Thanks for the link to the paper! I've been wanting more information on that story.

#187 ::: "Charles Dodgson" ::: (view all by) ::: August 06, 2007, 09:14 AM:

Kevin@186: Google knows all, Google tells all. (In this case, a search on "evolve oscillator" pulls the New Scientist report onto the first page; that gives the names of the researchers, and "evolve oscillator layzell" gives you the paper).

#188 ::: David Sucher ::: (view all by) ::: August 06, 2007, 10:28 AM:

ESRP at 184.

It's not my affable optimistic nature which is at issue but the avoidance of reality-based analysis for both the viaduct itself and the seawall. Your non-response that "...the people I've talked to, in government and out, tend to think the published reports about the seawall are probably somewhat soft-pedaled..." is quite typical of the way the discussion has proceeded: hot air.

If you don't have an answer to my question from #183 then maybe a simple "I don't have such a source" would be a good response.

#189 ::: JESR ::: (view all by) ::: August 06, 2007, 12:29 PM:

David Sucher, having checked out your blog and your publications, all I can say is that you have the bigger links and all I have is personal communication with the people who are actually doing the studies.

I do know, though, that WSDOT engineering has nothing to do with WMD in Iraq.

#190 ::: Brooks Moses ::: (view all by) ::: August 06, 2007, 01:07 PM:

CHiP @ 180: ...the sketches in the Wolfram article showed braces at what look like random locations -- although I assume they're actually key where they are and couldn't be moved around.

No, they're random. The idea is, approximately, if one tries random ideas and picks the best ones, forms new semi-random ideas that are similar to the best ones, and iterates, that eventually one gets to a good idea. The sketches are just the initial random ideas. Wolfram is hypothesizing that the best ideas will look similar, based on what amounts to a theory that we're not actually smart enough to recognize the difference between a good design and a bad design on sight.

My point was that relying solely on the adhesive properties of the epoxy, instead of the mechanical support that comes from putting adjacent bolts at opposed angles, made the system insufficiently redundant.

Insufficiently redundant it apparently was, but bolts at angles are, I'm pretty sure, the wrong solution. Partly this is one of the things that amounts to not building designs that are cleverer than we can analyze; partly it's that combining bending loads, shearing loads, and tensile loads in the same thing is (if I'm remembering my classes on the subject from a decade ago correctly) just a bad idea in general, because you get uneven stresses in the bolt, and thus stress concentrations both in the bolt and in the epoxy, which make the overall connection worse than one that's got symmetry working for it.

If you want to do something like what you're thinking of, a better solution is probably a bolt with a J-hook at the end. But, as John mentioned, that's not really the weak point. In addition, the problem is a design that assumed that no bolts would fail, and making them less likely to fail doesn't really help with that fundamental error.

That's the same reason Wolfram's ideas are solving the wrong problem; the critical flaw isn't one of using the wrong sort of design, but one of not using it safely (in whatever way), and changing designs to one that we have even less experience with using safely is not going to be an effective solution to that problem.

#191 ::: P J Evans ::: (view all by) ::: August 06, 2007, 01:34 PM:

Brooks @ 190

I refer to this, here in California, as 'every time there's an earthquake of any size, we learn seomthing else that doesn't work'. It's evolutionary, but not fast.

#192 ::: Jane H ::: (view all by) ::: August 06, 2007, 02:02 PM:

Just a quick note on possible contributing factors: On the Thursday prior to the collapse, there was a fast and violent thunderstorm which moved through the area, and possibly straight-line winds. 90+ degree days followed, with high humidity. All while they were tearing up concrete and pooring new concrete on half of the bridge, while all the traffic was diverted to the other half. I've seen references to the jackhammer, but I suspect there was more impact from a train going underneath the bridge when it collapsed. I suspect it was that vibration, combined with the rush-hour weight and possible additional damage to the cracks in the preceding days which triggered the collapse.

#193 ::: David Sucher ::: (view all by) ::: August 06, 2007, 02:17 PM:

JESR at 189.

If you have good information -- not just "I have personal communication..." -- please share. If studies exist which can back-up your statements, please provide the links.

#194 ::: JESR ::: (view all by) ::: August 06, 2007, 03:52 PM:

David Sucher, have you gotten on the phone and talked to the people who wrote the engineering studies for WSDOT and City of Seattle? Because that's what I did, for starts. And then I started running down the people at environmental consulting firms (with whom I'd established communications when I was being an energetic environmental activist for the Audubon Society, back when I was young and healthy) and the people who've contributed to historic and archaeological analysis. All of the contact information is available from public documents. WsDOT-Engineering is not a secret cabal; it's actually pretty easy to get them on the phone. They're not perfect; in general they're terrible at dealing with the interaction of transportation improvements and changes in settlement systems; in specific, the current head of landscaping and vegetation management is a total asshat (my latest windmill to tilt: he's mandated spraying for weed control, and has managed to wipe out prairie wildflowers from Tacoma to Vancouver WA).

Going through what they've told me, my reading of the engineering documents, and what's hit the papers, what it looks to me like is that, for the seawall as the viaduct, there are some places which are in OK shape (short of a subduction zone quake of 8 or greater, in which case little if anything stands) but in the Yesler's Landing/Coleman Dock area the combination of the age of the structure (which has implications for both wood preservation techniques and actual design problems), the original composition of the beach (glacial/riparian/tidal beach interlayering), and the high organic content of the fill make it ripe for collapse in much smaller quakes. Further north, where the seawall postdates the regrade, it's in better shape and has compact mineral fill, which gives the wall greater strength.

One would note that both the viaduct and the seawall have their greatest weakness at the south end, which is closest to the surface manifestations of the Seattle Fault; whether this is consequent or merely coincidental, I wouldn't venture a guess. It is also true that the first photos of what would be Seattle indicate that the same area had the greatest density of Duwamish structures; as is common throughout history, the place most popular for modern settlement was also the most populous place in the past. Which brings up my other point, in regard to funding: the estimates I've seen (all from published sources, mostly the two Seattle dailies and the proceedings of the Transportation Board) are gravely underestimating the cost of archaeological mitigation.

For the record, since IANAE but rather an archaeologist by training, and also IANASV (Seattle Voter), I would have been a No/No voter on the referendum, and am of the opinion that, during the period of construction of any full viaduct replacement, the behavior of drivers and shippers would change sufficiently that a four lane surface street with pedestrian overpasses would suffice, but that's just my opinion. As is the rest of this, but I am trying to base my opinion of the best information I can chase down.


#195 ::: David Sucher ::: (view all by) ::: August 06, 2007, 08:19 PM:

JESR,
Fixing a portion of the seawall adjacent to the ferry terminal is a very different proposition from having to replace the whole 2 miles of it, which is the impression left by proponents of both the Tunnel and the Surface/Transit option. They want to make things sound as bad as possible -- "The WMDs are on the launch pad right now!!" -- so that they can justify their own proposals. The reason no attention was paid to the Viaduct Repair is because it was too cheap. which is a parallel to the way in GW Bush didn't want to pay attention to enhanced inspections.

People at every level of government can distort facts to further their own tangential programs, unless they are watched very carefully. In the case of Seattle's Viaduct, there has been little critical thinking because so many people had agendas which could be served by tearing down the Viaduct. Thus no one wanted to really examine if it could be repaired nor how much of the Seawall needs complete replacement or just repair.

#196 ::: JESR ::: (view all by) ::: August 06, 2007, 09:08 PM:

David Sucher, there are two things at work here which are less sinister than you're proposing.

One of them is that even the parts of the seawall and the viaduct which are in the best condition are nearing the end of their usable life; the viaduct's best section has a rating below 40 on the scale where the 35W bridge got a 53, and the seawall near the cruise ship terminal is taking considerably more land and sea traffic than it was when the earlier studies were made, giving the Boat Street section about a fifteen year life expectancy.

The other big concern for the city, especially the downtown business interests, and for the regional transportation system planners, is that patching the worst bits as they become nonfunctional means constant construction and therefore constant detours. Add that to the insufficient seismic engineering over the length of both structures and there's plenty of "reality based" reasons to take care of the whole thing at once, even if that is not the priorities you prefer.

None of the government bodies you're talking about are strapped for projects upon which to spend their money; the 520 bridge, resurfacing I-5 between Orilla Road and Milton, additional seismic retrofitting on the Ship Canal bridge, storm water control on the east side of Capitol Hill... not to mention the state-wide long term obligation to restore salmon habitat where spawning access was blocked by inadequate culvert diameter (the court case which I think is "Various Indian Tribes versus The Washington State Department of Transportation" is an interesting read, although my copy is long gone) and the jolly spot of trouble east of Snoqualamie Summit on I-90 (where, for the out-of area folks, a patch of bad rock has started to crumble and fall onto the road, with fatal results) are all quite capable of sucking up every dime available well into the future.

#197 ::: David Sucher ::: (view all by) ::: August 06, 2007, 09:39 PM:

JESR,
"... Boat Street section about a fifteen year life expectancy."

Where is this Boat Street section on the Central Waterfront? Boat Street is on Lake Union. Are you speaking of the area of the waterfront near the Boat Street Cafe on Western?

And where do you get these figures -- "fifteen year life expectancy" -- which you throw out with such blissful certainty?

We are talking so far past each other that I think we might want to reconsider the nature of our disagreement. My initial question to you was a very very simple question concerning your backup for the statement that the "seawall has to be replaced." (Emphasis on seawall and with no qualifications.) You still have not provided me a reference which would convince a fair-handed observer of the nature and extent of the seawall problem. Yet you know the problem to the degree that you can make predictions about how long a particular section will last.

My other & larger remarks about the nature of government mis-representation on the whole viaduct/seawall issue and the parallels to Iraq can be refuted by some sort of objective study -- that doesn't mean studies by proponents, btw, though even they might be useful if the source is taken into account.

You have refused to provide any references for your statements (except the very vaguest generalities.)

#198 ::: JESR ::: (view all by) ::: August 06, 2007, 10:16 PM:

David Sucher, I got the 15 year life expectancy quote from the PI article on the seawall; I got "Boat street"(which I know perfectly well is on the north side of the ship canal and Lake Union, between Stone Way and Pacific) from Bay Street by way of a fun little trick my brain does by reversing pairs of associated words. The Bay Street portion of the seawall runs from Bay south to Bell, and is where the primary terminal is for passenger loading and unloading of cruise ships has been built.

I gave you my conclusions. I told you where I got the information upon which I based my conclusions. That's about all I can do right now, since my goal in pursuing the information was to make informed decisions when I vote and not to be prepared to win internet arguments.

#199 ::: ethan ::: (view all by) ::: August 07, 2007, 12:20 AM:

Christ, people, calm down.

David Sucher: Judging by your "view all by," which shows that aside from your snarky, ill-tempered comments in this conversation you've only ever made one comment here before, I'm guessing you feel very strongly about this particular subject and no other. You can feel as you please, but keep in mind that this is a very constricted way to live, and also don't take it out on others.

Thank you.

If I have stepped out of my bounds here by saying this (lord knows I've made a big stinky fuss here in the past), then I will apologize and retract.

#200 ::: David Sucher ::: (view all by) ::: August 07, 2007, 01:21 AM:

JESR,
I don't believe that a story in the P-I -- unless it's a first-person report which starts "I saw..." -- is proof of anything except that the paper printed a story. Even that first-person report is of only limited value because the reporter is not likely to really understand what s/he is seeing. The only serious documentation which proves anything at all (i.e. in relation to the structural condition of something like a seawall or a bridge etc) would be a study from a qualified engineer which contained photos, sketches, lab reports etc etc. All else is hearsay.

Ethan at 199,
Thanks for asking.
How the public makes decisions is indeed important to me, as I assume it is to you and JESR et al. Rigorous & widespread discussion should be the precursor to major public decisions. Such discussion needs to have all the alternative courses of action put on the table. We have a Viaduct in Seattle which was damaged by an earthquake in 2001.. A public vote in spring 2007 shot down the two alternatives put before us by the politicians. Many people believed that the Viaduct and the Seawall had been damaged and needed immediate work. But as a means to an end, the politicians spun the story so that mere Repair would not work but that we needed to tear it down and do "something else." Of course there is neither the money nor the agreement about what that "something else" should be. So at long last we are doing what we should have done 6 years ago and repairing the Viaduct and those limited parts of the Seawall which actually need repair, which is only a small portion.

Btw, I really appreciate your interest and would be happy to take you on a tour should you ever visit Seattle. The whole situation is quite interesting and the lessons for public decision-making (here's where I am referring to the Iraq War tragedy) are striking, though of course as I noted, the good news is that in Seattle we had a chance to vote on what to do (because the costs were getting into the $4-5 billions and the State had set aside "only" $2 billion for what was presented as the cheapest solution.) Nonetheless, I saw some of the same myths about the need to totally replace the Viaduct and Seawall (rather than Repair) being bruted here and it reminded me of the scare talk about Iraq and WMDs. In both situations we have politicians taking a small seed of truth and trying to grow it in only one direction, if you follow the imagery. To paraphrase Rumsfeld, "You do policy with whatever facts are convenient." The claim that the Viaduct and the Seawall had to be totally replaced and could not be repaired was a "convenient mistake" (I get prissy about calling people liars) which allowed two different groups to argue for their own programs, partly on the basis that the Viaduct had to come down.

Ethan, I hope that helps.

#201 ::: Bruce Cohen (SpeakerToManagers) ::: (view all by) ::: August 07, 2007, 09:36 AM:

David Sucher,

What ethan was saying, and what I was planning to say until ethan got there first, is not that we're arguing with your conclusions, or with the way you reached them. We're simply asking you to maintain as civil a level of discourse as you can in discussing the issue. I realize that it's a hot button for you, and I can understand why; it's difficult to watch your local government bumble around a decision that costs more and more no matter which way it's made, the longer they delay it.

But some of the rhetoric you used on JESR was less than measured, and some of it came awfully close to personally insulting, which she did not in any way deserve, despite that she disagrees with you. Please just dial the intensity down a notch and continue the discussion. You may be able to convince us without having to overwhelm us.

#202 ::: David Sucher ::: (view all by) ::: August 07, 2007, 11:18 AM:

If JESR is offended I am sorry for that. But I don't see anything I wrote which even comes remotely close to "personally insulting."

#203 ::: P J Evans ::: (view all by) ::: August 07, 2007, 11:39 AM:

The LA Times is reporting that inspections of similar bridges in CA have been completed and that none of them appear to be in dire need of repairs.
One of them is a bridge, fortunately carrying a surface street rather than freeway, crossing the main rail line north from LA.

David Sucher @ 202
Go back and read JESR @ 194. You seem to have missed that she talked to WSDOT.

#204 ::: JESR ::: (view all by) ::: August 07, 2007, 11:55 AM:

To confirm: yes, David, I felt not only offended, but personally attacked.

Just, you know, FYI.

#205 ::: ethan ::: (view all by) ::: August 07, 2007, 01:05 PM:

I'm hesitantly calling in my troll bingo.

#206 ::: Mary Aileen ::: (view all by) ::: July 19, 2011, 08:23 PM:

How's the rebuilding going?

#207 ::: Xopher HalfTongue sees hypnosis spam ::: (view all by) ::: September 10, 2011, 11:02 PM:

Your eyelids are getting heaaaaavy...

#208 ::: Naomi Parkhurst sees hypnotic spam ::: (view all by) ::: September 10, 2011, 11:04 PM:

And a calorie-free comment, too.

(I mean, I'd love to be proved wrong, but it seems unlikely.)

#209 ::: Stefan Jones ::: (view all by) ::: September 10, 2011, 11:48 PM:

Shucks. I turned in hoping to find a post with a whirling spiral pattern.

#210 ::: Naomi Parkhurst ::: (view all by) ::: November 05, 2011, 06:15 AM:

I think it's spam.

#211 ::: David Goldfarb agrees it's spam ::: (view all by) ::: November 05, 2011, 06:21 AM:

I concur.

(I enjoy "concur". It's a fun word to say.)

Welcome to Making Light's comment section. The moderators are Avram Grumer, Jim Macdonald, Teresa & Patrick Nielsen Hayden, and Abi Sutherland. Abi is the moderator most frequently onsite. She's also the kindest. Teresa is the theoretician. Are you feeling lucky?

If you are a spammer, your fate is in the hands of Jim Macdonald, and your foot shall slide in due time.

Comments containing more than seven URLs will be held for approval. If you want to comment on a thread that's been closed, please post to the most recent "Open Thread" discussion.

You can subscribe (via RSS) to this particular comment thread. (If this option is baffling, here's a quick introduction.)

Post a comment.
(Real e-mail addresses and URLs only, please.)

HTML Tags:
<strong>Strong</strong> = Strong
<em>Emphasized</em> = Emphasized
<a href="http://www.url.com">Linked text</a> = Linked text

Spelling reference:
Tolkien. Minuscule. Gandhi. Millennium. Delany. Embarrassment. Publishers Weekly. Occurrence. Asimov. Weird. Connoisseur. Accommodate. Hierarchy. Deity. Etiquette. Pharaoh. Teresa. Its. Macdonald. Nielsen Hayden. It's. Fluorosphere. Barack. More here.















(You must preview before posting.)

Dire legal notice
Making Light copyright 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014 by Patrick & Teresa Nielsen Hayden. All rights reserved.