Just to compare a freeway vs. light rail capacity, I found this site. Which claims a capacity of 1500 cars per lane per hour, I also found references claiming little over 3000 people per hour for car pool lanes.
So your nifty 4 lane freeway with 1 car-pool lane, has a capacity of about 9000 people per hour. While just one metro track with has a max capacity of about 1690 per 10 car train. Having one arrive every 4 minutes gets you a per hour capacity of 25,350 people.
And that's not even using double decker trains.
(Okay so I cheated, that was with fully loaded trains, including standing. Apparantly bart cars can have between 68 and 72 seats. A more comfortable capacity is 10,500 people per hour. Though the multi-deck cars have on the order of 140 seats per car, getting us back to 21,000 people per hour.
Another comment for universal happiness on trying to wean los angelinos off of cars, at some stations there should be car-sharing depots, so someone who still needs to drive everywhere can drive to their local station, take the train to near their destination, and then pick up a car for a few errands.
Last off I went to my therapist yesterday, and aparently she has a mentor off in new england whose also active in nature consvervatory. She told me that she told her mentor about what would make me happiest is the elimination of cars. The mentor was quite pleased with that. I'm assuming as it makes protecting all of those natural areas from sprawl far easier.
Finally to advance my master plan even futher, perhaps we could even try and experiment with a few car-free districts in LA. Choose a couple of areas around a metro station and allow developers to build row houses in the streets. So only the people. It seems like the best way to experiment to see if people are willing to walk a few minutes for less traffic noise, air pollution, and perhaps affordable houseing.