The Cypress Freeway structure failed specifically because it was built with substandard materials, insufficient re-bar, and poor concrete. It was about to fall down anyway. It was also sagging very badly between the supports - especially on the top deck. The sag was so bad that driving an old car with a worn front end suspension was down right dangerous. A speeding semi would bounce like mad bull - ever now and then knocking the trailer loose, causing a wreck.

And yes, as subsequent investigation discovered, the Division of Highways (now called Caltrans) knew it before it even opened! New young and still honest civil engineers, lost their jobs for pointing it out at the time. The excuse was that these engineers were too inexperienced to know what they were talking about and should have automatically deferred to older engineers. Actually, I suspect their only inexperience was in not knowing that somebody really didn't want to have to explain it to a judge.

BTW, BART aerials in the Cypress neighborhood performed flawlessly, with zero damage, while highways all over the region were damaged or colapsed. But notice that BART's support columns are much beefier than freeway supports, even though they carry much less weight. And what you see is just the tip of the iceberg - most of the mass is still below ground. Also very important is the fact that the directly fixated welded rails tie all the sections together right nicely - much better than highway bridge sections can be tied together. Besides all this, they're spending some of that money you so very much begrudge them, on making them even stronger.

Since I actually witnessed a very large BART girder bridge in Contra Costa slither and writhe with huge "S" waves during the 1989 quake, without suffering even the slightest damage, I'm not particularly worried about anything of BART's falling down. But unless those trains can ride a bucking bronco well, I'd expect they might get thrown off the tracks - handily! Of course, the Japanese have have already experienced a whole lot of that sort of thing.

Maybe they could use magnets, like Lionel did with its "Magnetraction".

Now that I'm getting silly, I'll ring off now!

OPB