An underground vault fire and/or an explosion caused a power outage Sunday evening starting at around 6:30 p.m. which affected 1,400 PG&E customers in SOMA and shut the lights on the Bay Bridge. ABC7 also lost power in their studio momentarily during their 6 p.m. broadcast. The lights on the bridge remained off most of the evening, but there was no reported interruption in traffic flow. The explosion/fire took place at 2nd and Harrison, and the cause isn't known. Looks like it's underground explosion season again!

As promised, as part of their San Francisco Panorama broadsheet newspaper, the one-time printing of which is available today at various local booksellers for the special price $5, McSweeney's investigative report on the Bay Bridge is available online via The Public Press. The report includes multiple segments, including this nice timeline of the Bay Bridge's eastern span reconstruction, and this piece by Patricia Decker about the fabrication of the new span, which is being done by a Chinese vendor.

The main investigative piece, by Robert Porterfield and Patricia Decker, includes this up-to-the-minute bit of news about the $6.3 billion price tag for the bridge rising even higher:

Caltrans officials are expected to announce this week that problems in Asia, where the majority of the bridge is being manufactured, will push those costs even higher. Among those are problems with fabrication and shipping of critical steel components in China that could add $100 million or more to the final price tag, and international bickering over design drawings and blueprints that could ultimately cost tens of millions more.

The temporary repair made to the cracked eyebar on the Bay Bridge, according to KTVU, "remains problematic and will likely require that Caltrans to shut down the entire span again sometime in the near future." And that closure? Could come before the Christmas season.

A KTVU source says that "designers have settled on adding a second eyebar over the cracked one and inserting a longer pin to hold the two together.

Yesterday, if you recall, SFist told you about a UCB engineering professor who strongly, strongly suggests shutting down the bridge right this very second. Our poll on the same subject indicates that most of you agree with him.

UC Berkeley structural engineer professor Abolhassan Astaneh has some urgent words for the Bay Area. Specifically, he's calling for the shut down of the Bay Bridge. Now. Soon. Just do it, he says. Ever since the new S-curve opened, the Bay Bridge has seen numerous accidents, including yesterday's big rig fatality. And a UCB smartypants is demanding the bridge's closure.

"You have to shut down this bridge immediately," Professor Astaneh tells KTVU."There's no doubt about it ... If Caltrans lets the public go on that bridge, they are committing a violation of this national standard that is criminally negligent."

When asked about the new S-curve, Astaneh doesn't hold back. "This is the most...how do I put it? The most criminally negligent thing that any engineer can do; to put sharp curves in the middle of a straight bridge." (He suggests pruning down the five lanes on the bridge to just three at the S-curve "to give room to smooth out the curves for drivers.)

But wait, it gets worse.

Putting aside the S-curve controversy and recent cable rod snap, which promoted the bridge's closure in October, the real danger is the eyebar fix. Astaneh claims that "the repair means the bridge is vulnerable and that it cannot withstand 85 mph winds or a 7.3 magnitude earthquake as required under federal transportation guidelines."

Should we shut the thing down? Take our poll below to find out.

CalTrans has apparently been taken by surprise by how difficult Bay Area commuters (and Safeway delivery trucks) are finding it to navigate that new S-curve on the Bay Bridge. Following on that unfortunate grocery spillage last week, and following on 20 total accidents since the S-curve was added on Labor Day, they're committing to putting up big new signs that emphasize the slowing from 50 m.p.h. to 40 m.p.h. We ourselves have driven over it several times and had no trouble, but certainly no one wants to be driving defensively while going 50 m.p.h. around a curve. So for god's sake people, slow down! Oakand's not going anywhere!

As many in the local news/blog firmament will be repeating this week, Saturday marks the 20th anniversary of the Loma Prieta earthquake, which was not such a doozy of a quake in the grand scheme (a 6.9er) but was certainly big enough to be imprinted on everyone's memory and to put some much-needed infrastructure improvements into the pipeline. But what of those infrastructure improvements, twenty years hence?

The most obvious changes came from the collapse of the elevated Cypress Freeway viaduct in Oakland, which caused the majority of fatalities from the quake (42 of the 63 total dead [Note: the Chron has the total at 67]) and which led to the construction of the 980 freeway connection that now divides Oakland and West Oakland; from damage in the Marina district that led to much reconstruction; and from the collapse of pieces of the Central and Embarcadero Freeways in San Francisco which led to the renaissance of Hayes Valley, the Ferry Building and the waterfront.

For those of you killing time waiting to see if the Bay Bridge reopens on schedule, why not spend ten minutes watching this charming film, "The March of Progress," about the engineering marvel of the Key Route trains that once traveled back and forth on the lower deck of the bridge. The Key System served the East Bay from 1903 to 1960, and provided transbay service from the time of the bridge's construction in 1936 until 1958 when the lower deck was opened up to eastbound auto traffic.

Be forewarned, this old-timey documentary begins at, like, the dawn of time, and has to get through the Gold Rush and the '06 quake before it gets to talking about the trains. The bridge makes its first appearance at 7:10. And if you're wicked into this, you can watch part 2 here.

After an inspector discovered a crack in the eastern span of the Bay Bridge over the weekend, crews plan to hysterically work overnight in an effort to reopen the Bay Bridge on Tuesday morning during the early AM commute. According to CBS 5, "the damaged link — part of a network of eight similar pieces — is about 2 inches thick and was cracked halfway through." And, at a news conference on the Bay Bridge this morning, reports SF Appeal, California Department of Transportation spokesman Bart Ney said, "It is a monumental challenge to make it by 5 a.m." Which means Ney is saying that the bridge will be closed tomorrow, or he's positioning the workers to lauded as heroes if it opens at the scheduled 5 a.m. time. Either way, we'll let you know what the plans it when it's officially announced. But still, you should probably plan on finding another way across the bay for tomorrow morning.

Captin_nod put together this mesmerizing video featuring time-lapse photography of yesterday's ongoing Bay Bridge construction and the rising of last night's very lovely full moon.

You can also check out these Bay Bridge 360 live video cams all weekend.

In related news, SF Appeal reports that yesterday was BART's second highest day of ridership ever, and the transit agency has also apparently embraced social networking.

As Labor Day Weekend creeps to a dramatic opener, getting over the Bay Bridge will come to a halt in, oh, less than six hours from now.

In addition to completing the $6.2 billion earthquake-safety project, reports SFGate, "there are plans to change light bulbs, smooth out the asphalt and demolish the temporary toll plaza on the far-right side of the approach to the upper deck." Call boxes will be fixed, the tunnel will be cleaned, trees trimmed, and signs given a facelift.

Remember: BART will run all night during the bridge closure. Go here to find out what stations will be open for business during the wee hours of the night.