Earthquake safety.

How safe is the BART tunnel that connects the East Bay with San Francisco during an earthquake?

Is it safe as they say or is that thing going to collapse and fill with water?

I think everyone is DEAD!

And I think you're a jackass!

I'll just say this. There were operators that were in the tube during the 1989 quake, and they didn't even feel it. Other than at grade sections of trackway, the tube is probably the safest place to be during a quake.

isn't the transbay tube tunnel actually tunnelled through the ocean bay floor?

Enough of the tube questions please. Thanks.

Train Operator since 2003's picture

The Transbay tube sits on the bottom of the bay. It was designed to be able to shift 8 feet either direction if necessary during any quake. So far in the last 30 years or so it may have shifted as much as 6 inches throughout it's lifetime. The "stress areas" seem to mostly be where it connects to the dry portion of the track way. Just look in the tube from Embarcadero station and you'll see it's age but as you go further into it (closer to the bay) everything is looking pretty good.

I had an apartment mate who was doing a Master's in structural engineering at Cal. He told me that some of his professors (at one of the best structural engineering programs in the country) said that both the Bay Bridge and The Tube weren't so safe.

About The Tube, he said that it was originally *designed* to stretch and give in an earthquake and be safe. On the other hand, he claimed there was some construction or political screw up that made the construction of it not meet the original standards. He also claimed that the 1989 earthquake had already stretched it and so it was quite possible that after a big earthquake or two it could rupture and flood back into many of the downtown SF BART stations.

I personally don't know, but I believed him more than most since it was what he was studying and he would know more than most people.

i'm inclined to believe that too because of the age and it certainly must have been weakened in the last quake. the bay bridge spoke for itself in the last quake.

When you consider a 7.1 mag earthquake and only one section of the SFOBB's cantilever section collapsed, that isn't bad damage wise. The cantilever section is stressed/weighed vertically and the anchor piles are actually large pile driven redwood trees. The collapsed portion was the upper deck at the crest of an incline and dogleg. The bridge was up and running in 30 days - it says a lot about the solid construction practices back in the 1920's- 1930's.

Read up on the details of the trans-bay-tube and the SFOBB on sites such as Wikipedia.

Everyone must realize that nothing is earthquake-proof, but earthquake-resistent to certain measured engineering standards at the time the code was written. Proximity to the epicenter and the geological make-up of a particular area along with the type of structure all play a role. Some of the highest engineering standards utilized in earthquake prone environments was in Japan and one only needs to examine the aerial highway and transit infrastructure in Kobe after the 1995 earthquake (6.9).

ekliptikz's picture

Sweet we can make BART a water ride and charge more

Didn't Universal Studios down in LA have such an earthquake "thrill" ride patterned after the Embarcadero station?

ekliptikz's picture

Yea I remember that, it was part of the studio tour with like jaws and king kong and junk