Happy Birthday San Francisco-Oakland Bay Bridge!

[Amanita]

Happy 73rd Birthday, San Francisco-Oakland Bay Bridge!!

73 years ago, the city of San Francisco witnessed an engineering miracle.
A massive bridge unlike any other now spanned the entire width of the bay, joining San Francisco and Oakland. It had been an undertaking epic even by today's standards, pushing the limits of bridge engineering as designers at the time understood it.

The statistics were impressive- the deepest foundation piers ever created for a bridge, twin suspension spans joined at a central anchorage, the widest and highest tunnel ever dug, the list went on.

On november 12, 1936, the people of San Francisco celebrated the opening of their miracle bridge with one heck of a party, that lasted for three days.
Sadly, this bridge has not recieved the love she deserves, being overshadowed by the Golden Gate Bridge, which was being built at the same time, and opening 6 months later. Even Golden Gate's chief engineer Joseph Strauss had harsh words for her- "That's no bridge, that's a trestle!"
Just like the Golden Gate, Bay Bridge was the result of several of the finest minds in the engineering business coming together, most notably Charles H. Purcell and Leon Moisseiff, among others.

Although she has served her two cities in relative obscurity these past 73 years, her life has been far from dull and uneventful.
On an average day, she handles about 280,000 vehicles
Her twin suspension spans are unique in the world- there are no other suspension bridges joined at a central anchorage in this manner.
She's had her eastern span struck by a small plane, had a segment of deck collapse during the 1989 earthquake, undergone a major seismic retrofit, survived a collision with a container ship, and has recently suffered the indignity of a cracked eyebar, and subsequent failure of the repair job, which led to about 5 days where she was closed to traffic.
And by 2013, her eastern cantilever span will be replaced by a unique self anchored suspension span.

For some more cool facts, I refer you here:
http://baybridgeinfo.org/history
http://baybridgeinfo.org/projects/west-span
Aww heck, the whole bay bridge news site is pretty sweet, check the whole thing out!
http://www.dot.ca.gov/baybridge/archive.htm
http://en.wikipedia.org/wiki/San_Fra...and_Bay_Bridge
Here's some more info on that plane crash:
http://www.check-six.com/Crash_Sites/BayBridgeT33.htm
A cute article about both bridges:
http://www.fhwa.dot.gov/infrastructure/2bridges.cfm

And here's a really cool construction video I just found!
http://www.liveleak.com/view?i=5db_1236982604



So let's celebrate by showing love and posting some pictures of this necklace-lighted Iron beauty! I'll get the ball rolling with a couple of my own pics:

[plinko]

While I love the western span of the bridge (double suspension!), the eastern span is downright ugly. It'll be exciting to see the new eastern span open (if they can ever get it completed). Then both sides will be highly photogenic.

[Duffstuff129]

Cool bridge, but the giant block of concrete in the middle of the span kinda takes away from its quality.

[Amanita]

That giant block of concrete would be the central anchorage. Unfortunately there was really no way to camoflauge it or make it "blend in" like they could with the yerba buena anchorage. I remember seeing a picture of it painted with a giant candle when the bridge turned 50 in 1986.

Another cool fact- the cable necklace lighting was originally supposed to be a temporary 50th birthday ornament- kind of like those celebs wearing pricy borrowed jewellery to those awards shows. However, people liked the new cable lights so much that they began handing over dollar bills to the toll collectors (bridge toll at the time was 50 cents) in order to finance making them permenant.

[Steely Dan]

cool thread. how far along is construction on the east span replacement bridge? when is it scheduled to open?

[Fusey]

The last I hard the new eastern span is going to open in 2013.

[Gordo]

Originally Posted by Fusey

The last I hard the new eastern span is going to open in 2013.

For replacement of a portion that has been considered seismically unsafe since 1989! Damn, we're fast. I'd plan on 2016 for anyone looking to come for a visit, just to be assured of it being open

Just over $6 billion is the current cost (original estimate was $1.3 billion I believe? May have been even lower), so I'm hoping that we can keep it below $10 billion. It'll be really shiny though.

[plinko]

^I know the approach roadways are well underway, but what about the tower? Have they even set the anchorage for it yet?

IIRC, Caltrans was having alot of trouble even finding bidders for the tower portion of the bridge and in the end there was only one? The single tower suspension is going to be unique, to say the least...

[Gordo]

^No work on the anchorage yet. IIRC, that won't happen until about 24 months out from the completion date. The major work of the next year and a half or so is on the Yerba Buena island approach and anchorage. And yes, it did come down to a single bidder for the tower.

[BTinSF]

Originally Posted by Duffstuff129

Cool bridge, but the giant block of concrete in the middle of the span kinda takes away from its quality.

As someone who drove across the bridge about 30 minutes before a section of it collapsed in 1989, I focus my mind on that "chunk of concrete" underneath me when I'm driving across it ever since and it's very reassuring.

Other than "self-anchored" ones (like the new eastern span), suspension bridges need an anchorage for the cable on either end. The Bay Bridge western span is really 2 suspension bridges end to end, each with the cable anchored on land at one end and in that "chunk of concrete" on the other.

[BTinSF]

Originally Posted by Gordo

^No work on the anchorage yet. IIRC, that won't happen until about 24 months out from the completion date. The major work of the next year and a half or so is on the Yerba Buena island approach and anchorage. And yes, it did come down to a single bidder for the tower.

What's all this then? http://baybridge360.org/#/poi/sas_foundation_work

[BTinSF]

Originally Posted by plinko

The single tower suspension is going to be unique, to say the least...

The SAS contract is the largest public works contract in California’s history
The SAS is the signature portion of the new East Span
The SAS is designed to resist earthquakes
The SAS will have a single cable that loops over around a single tower
The SAS will be the largest bridge of its kind in the world
Take a simulated fly-through of the completed East Span!
Anticipated Completion Date: late 2013
Height of tower: 525 feet
Total length of SAS roadways: 2047 feet (624 meters)
Length of main span: 1,263 feet (385 meters)
Amount of steel used for the SAS roadways and tower: 67,000 tons

Source: http://baybridgeinfo.org/projects/sas

Simulated fly-through: http://baybridge360.org/#/poi/east_span_flythrough

[Gordo]

Originally Posted by BTinSF

What's all this then? http://baybridge360.org/#/poi/sas_foundation_work

Ah, I feel stupid, and stand corrected. I was even out there a couple months ago and didn't notice any work on it.

[peanut gallery]

That Bay Bridge 360 site is cool. Thanks for posting it, BT.

I remember reading that the foundation work for the SAS was proceeding and the western approach is pretty much ready to go. Now, they seem to be working on the YB transition. From the site BT posted, that needs to be in place so they can build out the SAS roadway from there.

I have read very little about the eventual demo of the old bridge. I did a little searching and it appears they will take it apart in sections, which will be loaded onto barges. So, no big dramatic explosion with fireworks, etc.

[peanut gallery]

These are now almost a year old and I posted them before, but since they fit the thread:





More at the link.

[Chicago3rd]

Is there much difference in appearance of the western portion of the Bay Bridge since they completed the retro fit?

[BTinSF]

Originally Posted by Chicago3rd

Is there much difference in appearance of the western portion of the Bay Bridge since they completed the retro fit?

No. The only thing I noticed them doing was adding a substantial amount of additional concrete around the foundations of the towers, the "central anchorage" and the landside anchorages. I didn't notice anything being done to the steel parts of the bridge.

The ramps and elevated freeway structure that leads to the bridge in San Francisco was completely rebuilt, though. And it should be noted that the "stimulus" included money to begin a similar project on what's called "Doyle Drive", the analogous structure leading to the Golden Gate Bridge:


Source: http://www.sfgate.com/cgi-bin/object...18UKHA.DTL&o=1

[Amanita]

Actually, Bay Bridge's western span did get a lot done to its steelwork. It's just not that noticable because a lot of it was "under the hood", so to speak.
You can read more here:
http://baybridgeinfo.org/projects/west-span

Note the picture on top, which shows the black netting over parts of the towers.

Also take a look at the first picture in this thread, one of mine showing a close up of the tower. Look at the underside of the uppermost horizontal part at the top of the tower- note that it's latticed. Then look down at the underside of the x-brace immediately below it. That used to be a latticework of steel too, but they've either replaced or reinforced that old latticework with solid steel plate.
Also, have a look at the 4th picture down on the page I linked to- notice the steel beams that make up the bridge's stiffening truss. Those were once made of thousands of small steel pieces riveted together, and are now replaced by one-piece perforated steel crossbeams. That way they don't have thousands of rivets just waiting to fail in the event of an earthquake.

Bay Bridge ended up with something few women want- major weight gain. To the tune of 17 million pounds! Mind you, that 17 million pounds are all solid steel, making her much stronger than she previously was. I definately suggest reading the article linked to here, it should prove helpful.

[BTinSF]

Well, the question was about any change in appearance and all I can tell you is that, as someone who's been staring at the thing for going on 28 years, it doesn't look noticeably different to me. You'd hardly notice even the additional concrete but I recall them doing the work on that so I know it does appear a little different (not much really). But as I said, I don't even recall noticing work being done to the steel.

Remember that both this bridge and the Golden Gate are under constant maintenance. There's painting and inspection being done almost constantly. So the presence of netting here and there or people working up on the structure is not unusual. And unlike the recent closures required to do work on the cantilever span, I can't recall anything done to the suspension span that required a closure.

[Amanita]

I'm quite familiar with the constant inspections and ministrations of the painters and ironworkers on those magnificent bridges. As the Caltrans page said, the work on the western span was almost all done while the bridge was open to traffic. I would not be surprised if anything requiring closures was done at night, when fewer people would notice or be inconvenienced.
So as I said, a lot of the improvements that Caltrans talks about were of the "under the hood" variety, nothing that would alter the bridge's good looks noticably. And yes, I do think that San Francisco-Oakland Bay Bridge is nice looking, especially her western suspension spans.