If you can guarantee absolute time and/or space separation between freight & passenger, you can get away with "light" rail. Existing cases in CA for time separation are in San Diego (Escondido Branch, downtown to Tijuana and El Cajon where freight occasionally runs in the middle of the night) and San Jose (some parts of the Permanente Branch), and space separation in Sacramento (many parts of light rail) and San Jose (other parts of the Permanente Branch). I don't see NCRA being able to do the time separation thing with SMART - too much distance to cover, especially with industry work at least in Novato and Petaluma, in a few hours at night at normal (under 40 mph) freight speeds. So they'll need to do either spatial separation (separate freight track, like Sacramento does) or get (allegedly) FRA-compliant equipment so things can be done more flexibly (as the commuter railroads - not transit lines - do). I'm sure people at SMART and NCRA (??) have thought and talked about this, so why does it seem like they're still flailing around without a Plan?

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