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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?"
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
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
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.
"In 2003, Californians sent $50 billion more to Washington in federal taxes than the state received in federal expenditures. Representing a slight increase from levels that have held steady for three preceding years, the Golden State’s imbalance set a new record for any state, surpassing the previous mark (set also by California, in 2000 and 2001) of $48 billion."
http://www.calinst.org/pubs/balance2003.htm
Maybe if that weren't the case, California wouldn't be so broke right now.
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.
I strongly doubt that the welding is the culprit. "Faulty welding" doesn't happen on something of the scale of a bridge.
You're right on. If the author of the article would have watched any of the Caltrans news conferences, they would have answered some of his theories.
The weld that he claims failed was clearly described as only being tacked, not structurally welded. That weld wasn't supposed to hold the structure together, the tie rods were, which failed. One of the improvements they are making now is to replace the tacking with a structural weld, so that even if something broke, these pieces won't come apart. The other improvements center around reducing vibration, especially in the tie rods
Who wrote that article anyway? Some guy on the internet who looks at some pictures of the repair and thinks he knows what a bunch of engineers working on the problem didn't know?
You have no clue what you're taking about. Roman legionaries (who were paid) and paid laborers were used to build Roman infrastructure.
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.
Most highway work gets done at night. Late at night.
If you can figure it out, I have no doubt CA's dot.ca.gov website will show you where and when they're actively doing construction.
I drive around during the day and see cones.
I drive around at night and I see construction crews.
[Fuck Beta]
o0t!
In interviews I've seen, the architects stated that the assumption was that any collision would involve a plane (specifically a 707) lost in the fog, flying slowly and trying to land. Such planes would not be fully loaded with fuel since they would be at the end of their trip, and they wouldn't be piloted by terrorists pegging the throttles at top speed.
The scenario envisioned was more like what happened to the bomber that hit Empire State building in 1945. It wasn't that big of a deal.
The situation in Afghanistan in 2001 was similar to the situation in Cambodia in 1970. Inside the capital of (Phnom Penh/Kabul), the (Royal Family/Taliban) ran things. Outside the city limits, the countryside was controlled by (the Khmer Rouge/various 2-bit warlords like the Northern Alliance). (The Royal Family/The Taliban) had effectively zero power and influence outside the capital.
The reason why bin-Laden was so far out in the boonies (couple hundred miles!!) in Afghanistan was, even the Taliban didn't like him. Pre-Soviet Invasion, he was just some radical kid with a big checkbook, nobody really important other than having close family ties with the Saudi royals. Even the mujahadim thought he was a nutball. His real influence? About as far as the distance between his pen and his checkbook. And of course when the US demanded the Taliban immediately turn over bin-Laden, the Taliban, having just enough police to clamp down on Kabul and about as much real military to provide a couple hours' target practice to the Northern Alliance, told the US they just couldn't do that. Not wouldn't, couldn't, as in, having no capability of doing a particular thing, in this case, handing bin Laden over. The US of course instantly informed the entire planet of the 'Afghani government's refusal to hand over bin-Laden. About the only people to really listen were inside the US. Everybody else already knew that 'Afghani government' is one of those contradiction in terms like 'military intelligence' and 'jumbo shrimp'.
Understanding the scope of the problem is the first step on the path to true panic.
During a botched takeoff, the first thing a pilot does is to begin dumping fuel as fast as he safely can. Jet fuel is similar to kerosene, which evaporates quickly in the atmosphere, usually before hitting the ground.
Most aircraft cannot survive a landing with fully-loaded fuel tanks (unless the plane itself is carrying an unusually light passenger/cargo load).
Also, the flight patterns around Newark, JFK, Teterboro, and LaGuardia would all avoid lower manhattan, even in the event of a severe failure or navigational obstacle. Odds are, they'd end up in the meadowlands, the hudson river, or a residential area. Briefly browsing takeoff-related aviation accidents around NYC seems to confirm this.
The odds of a fully-laden jumbo jet hitting a building in lower Manhattan by accident are close to nil.
-- If you try to fail and succeed, which have you done? - Uli's moose