Barry.
Are you sure that the records show that the BART BOD. decided that Marin service was not viable? You may want to check the Main Independent Journal archives years back. Marin voters at that time vetoed BART in Marin and for many years pointed out that places like Pleasenton,Walnut Creek, and Antioch had paid for their share of BART many times over in taxes which paid off the bonds and didn't have service for decades after that. BART's excuse was that they didn't have the money to extend the service. I'm not flaming you, it's just that BART"s records and historic news print may indicate divergent views of the same subject. The other part about BART and Marin was how to get it, at that time, to San Francisco. The easiest way would have been through Richmond, Oakland and the BART under bay tunnel but the Richmond Bridge was not designed to accommodate trains and therefore a route could not be completed. Also reference the Golden Gate Bridge incompatibility with trains at that time. Behind the scenes, Marin was in a no-growth mode after seeing what they thought of as urban sprawl in the East Bay. They sure wanted no part of that. This is why Highway 101 was a two lane highway for decades. Make it easy to commute and we'll have urban sprawl.
R.E.Rail