“People recognize the traffic in this town is unbearable,” said Villaraigosa, 53. Without significant mass- transit improvements, the city estimates average speeds across Los Angeles at rush hour will drop to “just 7 miles per hour by 2020,” he said.
That's from an Alan Ohnsman article in Bloomberg. I'm not a traffic engineer, but it seems like there are enormous opportunities to expand public transit in LA. Huge swaths of the metropolis are densely populated (by some measures it's the most densely populated city in the U.S.) and even if people will not, with good reason, abandon their cars, they would use them less frequently if attractive alternatives were available for some routes.