For high-speed rail to fulfill its potential, it must be one component of a low-carbon society. LA and San Diego need to become more like Berlin and Hamburg—and San Francisco and New York. That means being denser, with walkable and bikeable streets, public transit systems, and regional commuter rail lines to the suburbs. That would allow people to arrive in town on the train and hop on a bus or subway, or hail an affordable taxi, to get to their final destination and then get around while they are in town.
I’m sure I’ve mentioned before how big a fan of public transit I am. xkcd’s Subway Maps of North America diagram makes a woeful comparison to, for example, a London Tube map. The US is in need of some serious infrastructure investment.