yes. BART is here as it is. yes, I use it regularly. The purpose of studying history should be to learn so as not to repeat mistakes. Other cities (notably NYC) have several incompatible subway systems. The major issue, here, is how to most usefully connect 'islands' of adequate transit--for instance from Marin to the East Bay. Do we extend the overly expensive custom made everything BART or the merely overly expensive but sort of off the shelf SMART? where should the "Polish Border" be?. As a foreign example, I read that there is now dual guage trackage in Vietnam so that Chinese trains can be through routed ove routes originally built by the French. If you have been following accounts of container trains from Chengdu to Western Europe, they must be retrucked or the containers craned from wide to standard guage in order to continue each trip.