How is it possible to use the same tracks as SF?
BART (for some reason even THEY don’t know) runs on NON-STANDARD track of 5’6” wide compared to 4’8.5” for standard (that is a quote from http://www.bart.gov/about/history/facts.aspx).
They wouldn’t use the BART tracks in a “blended” system; they’d use the Caltrain tracks. Caltrain currently runs passenger trains in the day / freight at night on a standard gauge rail from Gilroy through San Jose to San Francisco.
shhhhhh, that is next years grant study.
The plan is to use the same tracks as Caltrain, which is 4’ 8½” gauge.
BART’s gauge was the result of more useless government testing, which claimed that the wider track gauge (the only equivalent being in India, for the record) would result in better ride quality in crosswinds on elevated structures. Of course, what with plenty of trains running at much higher speeds on 4’ 8½” gauge traversing all sorts of structures, that absurdity has been long debunked.