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What Happened To the Bay Bridge?
farnsworth writes "Tony Alfrey has put together a fascinating page with some history, analysis, and possible explanations for what ultimately went wrong with the recent emergency repair of the San Francisco-Oakland Bay Bridge. The bridge has been closed for days and is not scheduled to open for days to come, hugely inconveniencing more than 250,000 people a day. His analysis touches on possibly poor welding, a possibly flawed temporary fix, and the absence of a long-term fix or adequate follow-up by Caltrans, the agency responsible for the bridge. Slashdot is a great engineering community; what other insights do you have on the bridge situation?"
For several work mornings the headline on "the new" CNN.com has been "Bay Bridge still closed."
In my head I hear it in the voice of Chevy Chase.
"General Francisco Franco is still dead!"
Four years ago I bought that bridge along with a package of subprime mortgages to highly qualified homeowners.
McSweeny's has a great article on this, broad reaching in its investigation of the many problems at hand. One thing that troubles me: I have seen many times in the California University and Transportation groups, failure to use earthquake retro-fit funds - they simply use them elsewhere. Its only when a problem like this arises that we learn they have not been used.
They should have used duct-tape!
Things like this can't be rushed, plain and simple. Carefully executed planning is what's needed to take on these types of projects.
Sure the commuters will have to wait a little bit longer while repairs are done, but it sure beats the mess they're in now.
"The difference between genius and stupidity is that genius has it's limits" - Albert Einstein
The USA is small. Think bigger than just the 250k people. The whole infrastructure in the USA is lagging in maintenance, care, repairs and/or replacements. The USA needs trillions to fix this problem but other shenanigans of course have higher priorities. P
I knew people had been talking about the state falling apart due to budget problems, but i didnt think they meant it literally
Good people go to bed earlier.
Lets see, when you have a pretty much bankrupt state (California), a bridge that is too necessary to fully replace without inconveniencing many people, the fact that it isn't exactly in a stable environment, with wind, rain and corrosion everywhere is it any surprise that a bridge that has been up for over 70 years needs some emergency repairs?
Taxation is legalized theft, no more, no less.
No, Slashdot is mostly made up of computer janitors; the greatest insight you'll get out of most of the posters here is, "hurrr durr, the bridge must've been running Windoze! LOL!", with maybe a little "omg the twin towers were collapsed by EXPLOSIVES!!!!"-style conspiracy theory and "THE GOVERNMENT IS BAD!!!" braindead libertarianism thrown in for color.
Software piracy is victimless theft.
There are four bridges running east/west over the bay, it just happens that there is only one in this particular (useful) location. Also, given that the Bay Bridge has to connect to Yerba Buena island, there's not really a lot of room for another one right next to it. So there is redundancy, but you have to deal with the physical realities of the area.
People use other bridges and the bart.
To say there isn't redundancy, is simply silly.
The engineering authority in charge of the bridge and repairs already gave their answer to this on the morning news (yesterday, I think):
They found the crack. They designed the "band-aid": the saddle, T-bar, rods, etc. They had it fabricated and installed.
In subsequent days, they went back up to look at how it was doing. They found that it was vibrating more than they thought it should: it wasn't as rigid as it was designed to be. They recognized that this would lead to fatigue and failure.
They began designing the improved "band-aid" and planned to install it sometime in coming weeks.
To their surprise, *perhaps* related to unusually high winds, the system failed sooner than they thought it could.
The completed their improved design and are now installing it. (And they are counting their blessings that nobody was killed: they got lucky, that way.)
-t
If their goal was to improve the safety of the bridge, then they totally succeeded.
As far as I'm concerned, if a piece of a bridge that has active traffic on it falls off, putting people on the bridge in danger, something went wrong SOMEWHERE.
Actually, they are currently building another bridge right next to it. These fixes are all to a structure that they hope to retire in a few years.
The cake is a pie
The Oakland Bay Bridge isn't much of a landmark, really. In any case, it is *extremely* important to note that the western span of the Bay Bridge, which is a suspension bridge, is perfectly sound, as is the landmark (but less used) Golden Gate Bridge. All of these problems are with the eastern span, which is a cantilever bridge.
The cake is a pie
As a hobbyist welder, and someone who has worked with welders in an industrial setting, I strongly doubt that the welding is the culprit. "Faulty welding" doesn't happen on something of the scale of a bridge. If it's one welder working, maybe. But this bridge repair would have had dozens of welders working. No one person's welding could have broken a bridge. Sure, they were under a time crunch, but that doesn't result in shoddy welds. It means more welders are put on task. Those guys are trained and certified and their work is defined by specs that they follow and then is inspected by city or state engineers. If the welding is the problem, it means the original spec was faulty.
Seth
$5 / month hosted VPS on linux = awesome!
Raids of Public Transportation Funds
nearly $2.5 billion was diverted away from transportation programs
A word fitly spoken is like apples of gold in pictures of silver --Proverbs 25:11
The Bay Bridge is not the only way from Oakland to San Francisco, there's the Richmond-San Rafael bridge to the North and San Mateo bridge to the south. There's also BART and various ferries and worst case scenario a trip through the South Bay and then up the peninsula. There's lots of ways into the city even if one of the bridges is out of service for some reason. The past two labor day weekends the Bay Bridge was shut down for repairs (the latest of which apparently caused the current problems).
The positioning of the Bay Bridge is limited by the layout of both San Francisco and Oakland. The Bay Bridge already spans one of the narrowest points between the cities and is bisected by Yerba Buena Island to reduce the effective length of the individual spans. There's nowhere else to really put another bridge in the area. There's no other spots with convenient freeway locations on both sides of the bay which would require whole new sections of freeways be build which means buying out a whole bunch of land that people already live on and a host of other problems. This construction would be in addition to building a whole new bridge.
I'm a loner Dottie, a Rebel.
The real problem is that we should recognize that bridges, and especially landmark bridges, stay standing indefinitely and should therefore quit designing the damn things with puny 50-year design lives!
"[Regarding the 'cloud,'] ownership was what made America different than Russia." -- Woz
Meanwhile, in Segovia (Spain), the Roman aqueduct is still up & running :
http://en.wikipedia.org/wiki/Aqueduct_of_Segovia
Without mortar, with just granite blocks on top of each other, it is more than 2000 years old.
I can't help but wonder when mankind began to suck at building anything that should last more than a few years....
I was under the impression that the bridge had to go through Yerba Buena not to serve the island population (who are only there because the bridge makes it convenient I imagine), but because the bay is too deep and without a firm bedrock to otherwise locate the middle section of the bridge securely.
Possibly that was only a concern when it was originally built, but regardless, you would essentially need to route it in the same path as otherwise you'd need a new landing point on the Oakland side and there's Alameda in the way.
It really irritates me when I-95 between Baltimore & DC is referred to as "the Beltway". There are TWO separate beltways in the area: the Baltimore Beltway circling Baltimore, & the Capital Beltway circling DC.
It took me a while to figure out but then I realized: CALTRANS only actually employes three guys.
Driving the 15 in San Diego, I wondered why there were all these construction sites with absolutely no one working. Eventually I pieced it together... CALTRANS only employs three guys and one of those has to hold the sign.
Sure, they could just do one tiny little roadwork at a time. But that'd completely give away the hundreds of millions CALTRANS budget is being spent on three construction workers with the rest going to hookers and blow. Instead, they dump cones everywhere, dig holes everywhere, then quickly move on to the next site. Sure, you'll never actually see a CALTRANS guy working but it sure as hell looks like they must have a lot of people doing the work if they can dig up that much crap and have roadworks every couple of hundred yards.
So, when judging the bridge collapse, try not to blame the three overworked guys. They're doing the best they can. Their job was to put up some cones, slap on some duct tape in the two minutes they had assigned, then get on to making somewhere else look busy. If you want to blame someone, figure out who spends the other 99.9% on those hookers and that blow. Imagine how much could be achieved if his habit went to pay for actual workers instead.
Consider yourself lucky Californians. Us dwellers of Northern New York have a much bigger problem than you have if we want to get to Vermont. The NY DoT let the Crown Point Bridge, one of only two bridges across Lake Champlain fall into utter disrepair and it is now closed indefinitely. The shortest 'detour' to go across the lake and into Vermont adds around 100 miles to the trip, just to get to the crossing.
The failed part was fabricated in Arizona.
The revolution will be mocked
In my experience most of the problems are in the northern half of D.C.'s Beltway. The area between D.C. and Baltimore might slowsdown but it never completely stops (except accidents of course). And Baltimore's beltway is good except for the area around I-83 (which is a poor design).
A couple times I've suggested extending I-85 up to Philadelphia and beyond, so as to provide an alternate route for traffic (especially truckers who are going straight through from Richmond-to-Philly without stopping), but neither the Congress nor the AAA seems to hear. Oh well.
"I disapprove of what you say, but I will defend to the death your right to say it." - historian Evelyn Beatrice Hall
No, Slashdot is mostly made up of computer janitors.
I do get that feeling now and then.
Many years ago, I went to a serious engineering school. There, the final exam in a course in structural engineering was this:
At the final exam, each student had to design a link to attach two pins some distance apart. There were obstacles between the pins and the link had to go around then. The design was to be for a specified grade of aluminum and had to support a specified load. Students knew in advance what the exam would be, except for where the obstacles would be. For the exam, you sat at a drafting table, and turned in a drawing.
The link you designed was then machined out of aluminum by a machinist. It was put in a testing machine and placed under the specified load. If the link broke, you failed the course.
If the link didn't break, it was weighed. Lower weights yielded higher grades for the course.
This is how good structural engineers are trained. (I'm not one. I was in EE/CS, and we had a different make-or-break exam.)
The city is so nice and uncongested today. I don't own a car, so admittedly I am very biased, but I would be quite content just to leave the bridge closed. Plus it puts the focus on public transit, where a compact city like SF should be focused. For example, BART (the subway) is running 24 hour service this weekend. As strange as it may sound, despite being an urban environment we don't have 24 hour subway service normally!!!
It's surprising that they had trouble there. That's a big, stiff truss span, with lots of cross-bracing. Those usually don't have serious wind problems. (The Tay Bridge disaster was, of course, one involving a truss bridge. But it was badly designed and very badly fabricated.) The worst case for wind is a long, narrow, thin span. The Tacoma Narrows Bridge collapsed through that kind of failure, and the Golden Gate Bridge was vulnerable to it. In 1951, during high winds, the Golden Gate Bridge deflected enough that one side of the roadbed was 11 feet higher than the other. Stiffening trusses were added under the span. (These are big trusses, each over 20' high, but the bridge is so huge that few people noticed the retrofit.)
In the 1989 quake, the Bay Bridge had an upper deck section break at the joint between the high truss span and the lower spans. That was an impedance mismatch - the two sections oscillated in different ways, and the stress at the transition point was enough to break bolts. When the Bay Bridge was designed in the 1930s, those problems weren't well understood, and could not yet be simulated.
The problem seems to be that the quick fix for the crack was underdesigned. That was recognized within days, and a second fix was under construction.
The damaged eyebar could be replaced, but that requires fabricating a new eyebar and some specialized tooling to take off the load from that whole eyebar chain during repair. This span will be torn down in a few years, when the new span is finished, so that may not be worth it.
I agree it is important. It keeps drivers from clogging up my train ride every morning. But it isn't a "landmark" in the sense that tourists don't go to look at it. (Except for the dumb ones suckered by locals saying "it's being repainted...the gray is the primer.")
The cake is a pie
Sir, I can make no claims as to the veracity nor contrewise of your premises.
However, should they prove to be true then surely a far greater mystery is how it has stayed up so far.
Verily thine,
B. Franklin.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
Bridges aren't that expensive, it's the assembly and installation that kills you.
Not that this wasn't entirely predictable.
I suspect that California educated engineers had a lot to do with the problem. A panel had to decide how to fix the problem. The panel was composed, by law, of one gay, one lesbian, one transvestite, one Mormon, one Moslem, one Black, one Hispanic - the list goes on and on.
You REALLY don't know how things work in California.
We got rid of the Mormon after the Prop 8 debacle.
Perhaps if the state...
Perhaps if you know what the fuck you were talking about. This is why it is pointless to listen to anobody on Slashhdot, 99% of the comments are bullshit.
All the bay bridges, except the Golden Gate, are managed be the Bay Area Toll Authority and funded by tolls. Educate yourself.
http://bata.mtc.ca.gov/
Slashdot - The great and glorious cluster fuck of Internet wisdom.
Bridges aren't that expensive, it's the assembly and installation that kills you.
... so it's like buying Ikea?